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The impacts of timber harvesting on residual trees and seedlings in a tropical rain forest ecosystem, southwestern Nigeria

The impacts of timber harvesting on residual trees and seedlings in a tropical rain forest... International Journal of Biodiversity Science, Ecosystem Services & Management Vol. 6, Nos. 3–4, September–December 2010, 131–138 The impacts of timber harvesting on residual trees and seedlings in a tropical rain forest ecosystem, southwestern Nigeria V.A.J. Adekunle and A.O. Olagoke Forest Ecology Research Unit, Department of Forestry and Wood Technology, Federal University of Technology, Akure, Nigeria This study examined logging damage to non-targeted neighbouring plant species and the forest ecosystem in a tropical forest in Ondo State, southwest Nigeria. Tree growth variables were recorded before and after felling, as was the number of crosscut logs. All plant species damaged during harvesting were enumerated and identified and the nature and level of the damage was also determined. Data providing demographic information, causes of damage to residual plants and measures to reduce the damage were obtained from the loggers using questionnaires. Data were collected on selective logging of 41 tree species. Despite selective logging practices, during felling, plants were damaged, soil compacted and the ecosystem disturbed. The observed damage to residual trees and seedlings ranged from 5% to 70% and it is therefore concluded that reduced impact logging and training of loggers is necessary to minimise the impacts. Keywords: logging; reduced impact logging; Ondo State Introduction These forms of damage are aggravated through insuffi- cient planning, improper operational techniques, lack of The term logging is the sum of all the processes, operations operational skill, loggers’ level of competence and lack and activities that make it possible for mature trees to be of serviceable modern felling tools (Eroglu et al. 2009). extracted for onward transmission to factories or places of According to Panayotou and Ashton (1992) about 340 secondary conversion (Ogbonnaya 2002). It encompasses trees, including saplings and wildlings of economically tree felling, de-branching, cross-cutting, skidding, loading valuable species, are destroyed for every tree extracted and primary transportation. Logging is a very lucrative from lowland tropical forests in Malaysia. business in Nigeria today and provides employment for Timber harvesting with insufficient planning, improper many Nigerians. Each of the above activities related to log- operational techniques and lack of control of operations ging has considerable impacts on the livelihoods of many results in severe damage to forest soil, forest trees and people. In Nigeria, while a selective system is the pre- seedlings (Akay et al. 2007; Eroglu et al. 2009). The dominant method of logging in the free areas, clear felling only available felling tool in Nigeria is the motorised through allocation of forest compartments to concession- or power chainsaw, but dragging of felled trees, packing aires is common in forest reserves. Mature trees of the into gantries and loading into lorries are generally done desired economic species are identified and removed. In manually with chains and winches. These processes are the government reserves, logging is controlled by policies primitive and tedious, and have the potential to disrupt the and laws enforced by the State Department of Forestry, and ecosystem (Olajide and Udo 2005). In addition, there is these must be strictly adhered to by both loggers and con- usually vegetation destruction during road construction for cessionaires. Government control on logging in the free transportation of logs and construction of gantries. As a areas is limited to the issuance of permits or licenses to result, many standing young trees, saplings and wildlings loggers after payment of all necessary fees (Adetula 2008). of economic value are destroyed. Adekunle and Ige (2006) Currently, the removal of timber occurs in an uncontrolled view logging as a major agent of biodiversity loss, Ola- manner, without strict adherence to the laws or payment Adams (1994) reported that about 17.74% of residual of appropriate fees and levies. Such illegal operations are trees suffer logging damage and about 8.00% of virgin termed ‘illegal logging’ (Pfeil et al. 2007). Furthermore, ground is left bare and damaged after felling operations. logging operations are responsible for forest destruction in These forest operations neglect the principle of sustain- Nigeria; therefore, sustainable logging is ipso facto nec- able forest management. Thus, proper forest harvesting, essary and desirable to attain an appropriate and socially well-planned logging techniques, review, execution and acceptable level of deforestation. enforcement of logging policies and adoption of reduced Severe damage is usually inflicted on the forest ecosys- impact logging are essential for achieving sustainable for- tem during logging activities. The damage includes forest est management in Nigeria. This will substantially reduce soil compaction, damage to other trees and plants, cutting the impacts of logging on the vulnerable environment. of seedlings, trampling, wildlife killing or chasing away Moreover, appraisal of the extent of logging activities and and encroachment into opened forest by land grabbers. *Corresponding author. Email: adewoleolagoke@gmail.com ISSN 2151-3732 print/ISSN 2151-3740 online © 2010 Taylor & Francis DOI: 10.1080/21513732.2010.534976 http://www.infomaworld.com 132 V.A.J Adekunle and A.O. Olagoke the impact of logging on the residual plant species is Tree stem damage assessment required to promulgate and enforce operational and appro- The three damage measures used by Eroglu et al. (2009) priate logging policies in Nigeria. This study therefore and Weimin et al. (2008) were employed to quantify investigated the calamitous impacts of logging on residual stand-level damage severity. These are percentage of stems trees, neighbouring plant species and wildlings in the tropi- damaged, percentage of basal area lost and a ‘stand-level cal rain forest ecosystem in southwestern Nigeria. This can damage index’. As tree stems often suffered multiple dam- be achieved by assessing the causes and the colossal extent age types and events, we created an ‘integrated stem of damage to the trees and plant species during logging damage code’ by combining all information/indices of activities. Precautionary measures employed by the loggers uprooting, breakage, leaning and leaned on into a single to minimise damage to other non-targeted plants were also code ranging from 0 to 3. We defined a damaged stem explored and appropriate strategies for sustainable logging as code 3 if the tree sustained severe damage (i.e. com- practices in the state are recommend. pletely uprooted, ≥90% canopy lost or leaning towards the ground); code 2 if a tree sustained substantial dam- age (i.e. partially uprooted, 35–90% canopy loss, leaning Methods but supported by other trees or pinned on the ground by Study area fallen neighbours); and code 1 if a tree sustained mod- est damage (i.e. 10–35% canopy loss, leaning >10% or This research was carried out in the tropical rain forest bent with >10% crown displacement). Code 0 was used ecological zone of Owo Forest Reserve, Ondo State, south- for minor or no damage. The integrated stem damage code west Nigeria. Ondo State is an agrarian state spread over 2 ◦  ◦ ◦ reflects multiple damage attributes for a stem and therefore a land area of about 14,788,728 km (4 30 –6 E, 5 45 – o  ◦ should more accurately reflect tree damage status than the 8 15 N. Owo Forest Reserve lies at approximately 4 E and individual components assessed. 4.5 N. It is located within the rain forest ecological zone (Onyekwelu et al. 2005), which has been described in detail by Nwoboshi (1982), Okojie (1996) and Adekunle (2002). Logger experience and reports on causes of logging The climate is the humid sub-tropical, indicating that the damage to non-targeted plants reserve is basically within the tropical rain forest zone, which is dominated by broadleaf hardwood trees that form The questionnaire survey of 40 professional tree log- dense layered stands. gers, popularly referred to in Nigeria as ‘operators’, was designed to collect information on the demographic char- acteristic of the loggers, major causes of damage to other Data collection trees and seedlings during felling operations and precau- A total of 41 economic, indigenous and high value tim- tions to mitigate such damage. The questionnaires were ber species allocated to loggers and available for felling filled in by the loggers and retrieved on the spot. An inten- were selected, clearly marked and numbered before felling. sive interaction was carried out with key informants such as forest guards and government officials involved in logging Total heights and diameters at the base, middle, top and at activities and the enforcement of forest laws, especially breast height (DBH) of the selected trees were measured those involved in logging in the state. before felling. The surrounding residual plants and the con- dition of the environment were observed closely and noted prior to felling of marked trees. Post-felling damage to the Data analysis affected residual plants was assessed as follow: Tree species classification and frequency The botanical name of every living tree with a (1) Herbs: damaged herbs were identified and counted DBH ≥ 10 cm encountered in each field plot was recorded. according to species, noting the types and levels of Each tree was recorded individually in the field forms; damage, and expressed as a percentage. palms and vines were not measured and efforts were (2) Shrubs, trees and tree branches: The species were made not to omit any eligible stem in a plot. All plants identified, enumerated and their height and diam- were classified to family and the number of species in eter at the base, middle, top and DBH measured. each family was obtained for tree diversity classification. Broken tree branches with a diameter ≥10 cm were Species relative densities were estimated and expressed as also measured and their frequencies noted. a percentage. Plant species identification Basal area and volume calculation The botanical names of the trees to be felled and those The basal area of each standing tree and of damaged trees affected by felling were recorded at the felling sites. In were estimated using the formula of Avery and Burkart cases where a botanical name was not known, it was iden- (2002): tified by its local name. The local names were translated to correct botanical names using Gbile (1984) and Keay πD Basal area m = . (1989). 4 International Journal of Biodiversity Science, Ecosystem Services & Management 133 The corresponding volumes were obtained using the Apocynaceae, Euphorbiaceae, Sapotaceae, Meliaceae, Newton formula of Husch et al. (2003): Mimosaceae and Moraceae) only one species was felled during the period of study. Khaya ivorensis had the highest mean DBH and mean volumes of 122 cm and 71.23 m , πH 3 2 2 2 while Ceiba pentandra had the highest total DBH and Volume m = D + 4D + D , b m t mean basal areas of 1017 cm and 1.19 m . The least mean and total DBH, basal area and volume were obtained for Mansonia altissima. The results of this study show that an where H is the height (m), D the DBH (m), D the diameter average of three trees was removed per species. The mean at base, D the diameter at middle, D the diameter at top m t DBH, basal area and volume of timber production in the and π = 3.142. 2 3 study area therefore was 93.12 cm, 0.79 m and 20.07 m . Data obtained for this study with the questionnaires The taxonomy and growth variables of damaged tree were subjected to descriptive statistical analysis in form species during logging activities are presented in Table 2. of frequency percentage distribution and ranking of The observation recorded during the study revealed that responses. The chi square non-parametric test was used to 154 standing stems belonging to 26 tree species were dam- test for association between respondents’ educational level aged in the process of logging. Cola gigantea had the high- and logging efficiency, respondents’ years of experience est frequency among the damaged species (47 trees), fol- and level of tree and seedling damage. lowed by Allophylus africanus (27 trees), and Terminalia superba (20 trees). Apart from Ricinodendron heudelotii, Results whose frequency was 11, other damaged species had a fre- quency of less than 10. Damage was done to only one stem The results enumerated in Table 1 show the taxonomy each of 11 tree species. A total of 38.00% of the affected and growth variables of the harvested 41 timber species. trees belonged to the Sterculiaceae, which was represented Among these, Ceiba pentandra had the highest frequency by five species, while 14.00% belonged to Combretaceae, (nine trees), followed by Cordia millenii (six trees), with represented by two species. Excluding Caesalpinaceae, minimum of one tree each of Ricinodendron heude- Mimosaceae and Ulmaceae, have two species each that lotii, Khaya ivorensis, Antiaris africana and Mansonia were also among the damaged tree species, only one altissima felled. The study revealed that two species species each of the other families was damaged during of Combretaceae, Sterculiaceae and Caesalpinaceae and the logging processes in the study area. While C. gigantea of eight other families (Bombacaceae, Boraginaceae, Table 1. Logged tree species and family, frequency, DBH, basal area (BA) and volume in a tropical rain forest ecosystem. Total Total Total DBH BA volume 2 3 Sl./No. Species Family Frequency (cm) (m ) (m ) 1. Afzelia africana Caesalpiniaceae 4 212 0.88 15.28 2. Alstonia boonei Apocynaceae 2 130 0.66 10.72 3. Antiaris Mimosaceae 1 70 0.38 4.88 africana 4. Brachystegia Caesalpiniaceae 5 480 3.65 80 eurycoma 5. Ceiba Bombacaceae 9 1017 10.71 301.59 pentandra 6. Cordia millenii Boraginaceae 6 588 4.62 89.28 7. Khaya ivorensis Meliaceae 1 122 1.17 71.23 8. Mansonia Sterculiaceae 1 50 0.20 3.00 altissima 9. Milicia excelsa Moraceae 2 126 0.68 12.24 10. Pachystela Sapotaceae 2 166 1.10 14.72 brevipes 11. Ricinodendron Euphorbiaceae 1 70 0.38 4.88 heudelotii 12. Terminalia Combretaceae 2 320 4.26 72.44 ivorensis 13. Terminalia Combretaceae 3 285 2.28 115.86 superba 14. Triplochiton Sterculiaceae 2 182 1.32 26.86 scleroxylon Total 14 11 41 3818 32.29 822.98 Mean 3 93.12 0.79 20.07 134 V.A.J Adekunle and A.O. Olagoke Table 2. Taxonomy and growth variables of damaged tree species in the tropical rain forest ecosystem. Total Total Total DBH BA volume 2 3 Sl./No. Species Family Frequency (cm) (m ) (m ) 1. Afzelia Africana Caesalpiniaceae 2 42.00 0.14 4.80 2. Albizia lebbeck Mimosaceae 3 246.00 1.59 21.96 3. Allophylus Sapindaceae 27 594.00 1.08 13.23 africanus 4. Aningeria Sapotaceae 1 10.00 0.01 0.07 robusta 5. Anopyxis Rhizophoraceae 1 53.00 0.22 3.28 klaineana 6. Antiaris Mimosaceae 2 70.00 0.28 2.70 africana 7. Brachystegia Caesalpiniaceae 3 285.00 2.10 25.77 eurycoma 8. Ceiba Bombacaceae 7 378.00 1.82 41.51 pentandra 9. Celtis zenkerii Ulmaceae 2 88.00 0.32 4.96 10. Cola gigantea Sterculiaceae 47 3102.00 17.39 313.96 11. Cordia millenii Boraginaceae 5 330.00 1.75 31.85 12. Enantia Annonaceae 1 16.00 0.02 0.84 chlorantha 13. Ficus capensis Moraceae 1 39.00 0.12 1.09 14. F. exasperata Moraceae 3 54.00 0.09 0.81 15. Grewia mollis Tiliaceae 1 30.00 0.07 0.97 16. Khaya ivorensis Meliaceae 1 54.00 0.23 3.21 17. Mansonia Sterculiaceae 6 294.00 1.20 14.22 altissima 18. Pycnanthus Myristicaceae 1 41.00 0.13 1.86 angolensis 19. Ricinodendron Euphorbiaceae 11 198.00 0.33 4.07 heudelotii 20. Spathodea Bignoniaceae 1 18.00 0.02 0.39 campanulata 21. Sterculia Sterculiaceae 4 176.00 0.60 9.56 rhinopetala 22. S. tragacantha Sterculiaceae 1 44.00 0.15 2.39 23. Terminalia Combretaceae 1 101.00 0.79 28.28 ivorensis 24. T. superba Combretaceae 20 1020.00 5.20 91.60 25. Trema orientalis Ulmaceae 1 19.00 0.03 0.18 26. Triplochyton Sterculiaceae 1 55.00 0.24 3.43 scleroxylon Total 26 17 154 7302.00 35.92 626.99 Mean 6 47.42 0.23 4.07 had the highest total DBH (3102 cm), T. ivorensis had the During the study, 1571 economic plants (four species) highest mean DBH (101 cm), mean basal area (0.79 m ) were destroyed on the felling sites during logging oper- and mean volume (28.28 m ), while Aningeria robusta had ations. These are the major plant species occupying the the least mean and total DBH, basal area and volume. The forest floor of tropical rain forest ecosystems of southwest total basal area of trees damaged by selectively logged was Nigeria, especially where there is good light penetration. 2 2 35.92 m and the mean damage per tree was 0.23 m . Chromolaena odorata, an invasive plant species in Nigeria, The basal area percentage index of stems damaged was common, followed by Pennisetum purpureum and was 54.00%. Palisota hirsute, while Thaumatococcus daniellii was least About 26.00% of the damaged trees had attained affected. merchantable size, with individual trees having a DBH The common causes of damage to residual plants dur- of >48.00 cm. The undergrowth damaged during tree ing logging activities were obtained from the respondents felling processes in the study area is presented in Table 3. (Table 4). All tree fellers claimed to be using power International Journal of Biodiversity Science, Ecosystem Services & Management 135 Table 3. Most damaged understory species during logging activities in the study area. Sl./No. Species Family Frequency Percentage Rank 1. Chromolaena odorata Asteraceae 629 40.03 1 2. Palisota hirsuta Commelinaceae 298 19.00 3 3. Pennisetum purpureum Graminae 539 34.33 2 4. Thaumatococcus daniellii Marantaceae 105 6.65 4 Total 4 4 1571 100 Table 4. Causes of damage to residual plant species during logging. %of S/N Causes of damage respondents Rank 1 Felling flaws/Incorrect determination of felling 35 1 direction 2 Illogical construction of skidding and 77 forwarding roads 3 Poor felling equipment 13 5 4 Incompetence of tree fellers (chainsaw 29 2 operators) 5 Non-removal of attached climbers prior to 96 felling 6 Wind prevalence while felling 25 3 7 Presence of obstructions 3 8 8 Felled trees bending/leaning towards dense 14 4 populations of other plant species Note: Total figure can be higher than 100% because some respondents made more than one choice. Table 5. Types of damage inflicted on residual plants during felling operations. %of %oftotal respondents’ Sl./No. Type of damage damaged trees responses 1. Clearing of vegetation 41.98 56.22 2. Breaking of branches and boles 25.30 30.50 3. Leaning and leaned into 5.34 10.55 4. Uprooting of surrounding trees and shrubs 27.38 2.73 chainsaws for felling of trees. The majority of them (35%) to residual plants was total removal and clearing of trees reported felling flaws or incorrect determination of felling and vegetation on the route and close to trees to be felled. direction as the first causes of damage to non-target plants This affected about 42% of total trees that were logged during felling. This was followed by 25% who lamented (Table 5). Uprooting of trees by the loggers during skidding that some tree fellers (chainsaw operators) are not compe- and road construction and by the felled logs accounted for tent enough to handle felling machinery. These are the set about 27.5% of total damage. Another important type of of operators without training or skill. Other reported causes damage is falling on other trees of the felled trees (25.3%) of damage to plant species include a lack of control over and in the process, breaking the boles and branches. Trees the wind and the falling force of trees, which make con- that were leaning and leaned on as a result of felling were trolling the direction of fall very difficult to control, and less pronounced (5.3%). As tree stems often suffered mul- non-removal of climbers and lianas attached to trees to be tiple damage types and events, the integrated stem damage felled. The presence of obstructions, such as rocks, river code was used by combining all information/indices of courses, etc. close to the trees to be felled was also reported uprooting, breakage, leaning and leaned on. The results by a few respondents (3%) as a cause of damage to plant show that the highest proportion (52%) of total damaged species. Table 5 shows the types and severity of damage trees was in scale 3, followed by 34% in scale 2, 10% in caused by the felled trees on other trees and seedlings dur- scale 1 and only 4% in scale 0. ing this study. The observation and assessment of felling The frequency with which the respondents mention a sites was corroborated by the respondents’ (tree loggers certain type of damage (%) to non-targeted trees and under- and forest guards) reports on the types and levels of dam- growth from each of the logging operations is ranked and age to residual plants. The commonly encountered damage presented in Table 6. Highest damage, as observed in the 136 V.A.J Adekunle and A.O. Olagoke Table 6. Logging operations and their damage to residual most common (37.5%), with a range of ages from 20 to 60 plants. years involved in logging. Only 2.5% of loggers did not have some formal education. Among loggers, 52.5% have Number of been loggers for 10 years and only 25% were skilled in Logging operation respondents Percentage timber felling. The remaining loggers came to the profes- Felling 15 33.33 sion through their friends (37.5%) and through wood-based Skidding and loading 7 15.56 industries (17.5%). The results of this study also show that Gantry construction 5 11.11 the majority of the operators (95%) had no training; their Road construction 18 40.00 skills increased according to the time spent on the job. Generally, the performance efficiency on a particular job strongly depended on the number of years of experience, field, occurred during road construction. This was corrob- their age and education level. orated by the majority of the respondents (40%) and by government agents in charge of log control. This was fol- lowed by the huge damage attributed to felling, as observed Discussion and reported by 33.33% of respondents and forest guards. Minimal damage was recorded during skidding/loading The flourishing timber industry has evidently grown and gantry construction according to the remaining respon- beyond the forests’ regeneration capacity, with poor con- dents. Loggers’ perception of the deleterious impacts of ventional harvesting practices and the wanton destruction logging activities to the forest ecosystem is presented in of forest ecosystems during logging operations, which are Table 7. The highest proportion of respondents (63%) indi- undoubtedly inimical to sustainability of forest resource cated that they were aware that logging operations could management. Most of the seedlings and saplings are result in soil compaction, erosion and infertility. A total severely damaged (when cut, trampled or uprooted) during of 55% were conscious that logging could cause defor- logging operations, reducing their natural ability to succes- estation and ecosystem destruction and 43.00% expressed sively replace the harvested trees in the future. This present their knowledge of severe injuries caused to neighbour- study has clearly revealed that major damage is done to ing trees, seedlings and understorey plants during logging the remaining trees during felling and transportation of operations. About 23% of loggers reported the implications the targeted tree species. Clatterbuck (2006) corroborated of logging activities on wildlife. the occurrence of such damage and further stressed that The loggers suggested some measures for reducing residual tree species are devalued and may not recover logging damage to untargeted trees and the entire forest to become better grade timber. Limbeck-Lilienau (2003) ecosystem (Table 8). The results show that 80% of respon- noted that fungal infections and decay are common when dents favoured proper determination of felling direction, trees are wounded. Hence, logging damage, especially particularly in areas with sparse tree populations, as the bole-breakage, stem splitting and debranching, could lead most important damage-reducing measure during tree to fungi infections and decay of damaged tree species and felling. The second proposal was the use of competent open the door for other pathogens to infest the trees. Some and well-trained tree fellers (73%) and stopping felling tree species that are mildly injured could recover from the when the wind is strong and weather conditions are not stress inflicted during logging activities. favourable (63%). The remaining 55% considered that The socio-economic characteristics of the loggers show engaging experienced skidding operators and prohibition that the majority have good experience, education and are of the use of heavy log evacuation equipment (40%) were mature, attributes that have contributed to their present other common measures that could be used to minimise expertise. Nevertheless, adequate training could improve logging damage. The demographic characteristics of the their competence and further reduce the destruction of loggers are shown in Table 9. The majority of tree log- the ecosystem during logging activities. The results of this gers (92.5%) were married. The age group 31–40 years was study also revealed that the loggers are aware of the damage Table 7. Effects of logging on forest ecosystems according to the loggers. Number of Logging damage to forest ecosystems respondents Percentage It leads to destruction of neighbouring trees and forest understory 17 42.5 It results in deforestation and ecosystem destruction 22 55 It results into soil compaction, erosion and loss of soil fertility 25 62.5 It may result in destruction of soil fauna and exposure of wildlife to direct attacks from predators and hunters 9 22.5 It results in destabilisation of the forest ecosystem 10 25 It may deprive wildlife of their habitats 16 40 It may cause extinction of some plant and animal species 14 35 Note: Figures are more than 100% because some respondents made more than one choice. International Journal of Biodiversity Science, Ecosystem Services & Management 137 Table 8. Respondent opinion of various logging damage reduction measures. Number of Logging damage reduction measures respondents Percentage During Use of appropriate felling machine 20 50 felling Employment of competent tree fellers with adequate 29 72.5 training Proper determination of felling direction, especially 32 80 in areas with a low plant populations Felling should be stopped during high winds or not 25 62.5 carried out while wind is blowing During log Skidding and transportation should be done by an 22 55 evacuation experienced skidding operator Timber evacuation route must be constructed in areas 11 27.5 with low plant populations Prohibition of the use of heavy log evacuation 16 40 equipment caused to the forest ecosystem during logging. This is in highest number of respondents considered road construc- conformity with reports of other authors (Ogbonnaya 2002; tion as the chief contributor to damage to other plants Eroglu and Acar 2007; Eroglu et al. 2009), which indicated and the ecosystem during logging operations. In addition, that damage to residual stands due to timber harvesting logging roads open up the forests to shifting cultivation, involve tree felling, hauling of logs, road construction encroachment and permanent settlement. Bruenig (1996) and log transportation. Bruenig (1996) and Dykstra and stated that excessive skidding and log transportation could Heinrich (1996) noted that between 30% and 75% of lead to excessive soil compaction and erosion. This leads to logged areas can be seriously affected by roads, tractor unsustainability of felling cycles of 25–50 years, and cycles trails, landings or just through bulldozers. A similar trend of 60–100 years are more realistic. Nonetheless, skid trails was found in the present study, which revealed that the and skidding cannot be dispensed with during log extrac- tion, although skidding damage could be minimised by Table 9. Demographic characteristics of the tree fellers in planning the trails and utilising optimum trail spacing. Ondo State, Nigeria. Now that timber harvesting has become a very lucra- Characteristics Percentage tive venture, damage can only be abated by taking pre- cautions and through adequate training of loggers. The Marital status Married 92.5 working practises and experience of chainsaw operators Single 7.5 and skidders can considerably minimise logging damage. Total 100 Maintaining a minimum number of straight skidding trails Age (years) 20–30 20.0 31–40 37.5 and directional felling of trees towards skidding trails 41–50 32.5 and away from areas of dense plant species are critical 51–60 22.5 among the suggested measures to avert logging damage. In Total 100 addition, proper forest harvesting, especially well-planned Education status No former logging techniques are required to maintain site productiv- education 2.5 Primary school 27.5 ity and ensure sustainable management of forest resources Secondary school 50 (Dykstra and Heinrich 1992). Eltz and Bruhl (2001) have Tertiary education 20 confirmed that reduced impact logging causes less direct Number of years as damage to the environment compared to conventional prac- power saw operator 1–3 0 4–6 25 tices, and this should be promoted, especially in developing 7–9 22.5 countries such as Nigeria. >10 52.5 Total 100 Route into this job Learning 25 Conclusions Environmental influence 20 The results of this study show that logging activities are Employed by a causing obvious damage to neighbouring plant species. wood industry 17.5 Damage was recorded during felling, skidding gantry and Through a friend 37.5 road construction. Most of the damage was attributed to Total 100 Training received Yes 5 excessive and indiscriminate logging, use of inexperienced No 95 tree fellers and skidders and lack of adequate training. Total 100 Forest clearance during road construction causes more 138 V.A.J Adekunle and A.O. Olagoke havoc to the environment than the fallen trees. Bole break- Eroglu H, Acar HH. 2007. The comparison of logging techniques for productivity and ecological aspects in Artvin, Turkey. J age and splitting, leaf removal, suppression of herbs and Appl Sci. 14:1973–1976. soil compaction are the dominant types of damage to resid- Eroglu H, Öztürk UO, Sönmez T, Tilki F, Akkuzu E. 2009. The ual plants and the ecosystem during logging. Loggers are impacts of timber harvesting techniques on residual trees, fully aware of the adverse impacts of continuous log- seedlings, and timber products in natural oriental spruce ging activities on the ecosystem. However, skill and taking forests. Afr J Agric Res. 4(3):220–224. Gbile ZO. 1984. Vernacular names of Nigerian plants – Yoruba. all necessary precautions during logging operations could Ibadan (Nigeria): Forestry Research Institute of Nigeria. potentially reduce the amount of damage associated with Husch B, Charles IM, Thomas WB. 2003. Forest mensuration. timber harvesting. 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Sustainable Forest ground-based logging equipment on forest soil. Polym J Management in Nigeria: Lessons and Prospects. Forestry Environ Stud. 16:371–376. Association of Nigeria Meeting in Kaduna; 2005 Nov 7–11. Avery TE, Burkart HE. 2002. Forest measurement. 5th ed. New p. 297–303. York (NY): McGraw-Hill. Onyekwelu JC, Adekunle VAJ, Adeduntan SA. 2005. Does a Bruenig EF. 1996. Conservation and management of tropical rain- tropical rainforest ecosystem possess the ability to recover forests: an integrated approach to sustainability. Wallingford from severe degradation? In: Popoola L, Mfon P, Oni PI, (UK): CAB International. editors. Sustainable Forest Management in Nigeria: Lessons Clatterbuck WK. 2006. Logging damage to residual trees fol- and Prospects, Proceeding of the 30th Annual Conference of lowing commercial harvesting to different overstory reten- the Forestry Association of Nigeria; 2005 Nov 7–11; Kaduna, tion levels in a mature hardwood stand in Tennessee. In: Nigeria. p. 145–163. Connor KF, editor. Proceedings of the 13th Biennial Southern Panayotou T, Ashton P. 1992. Not by timber alone: economics Silvicultural Research Conference. General Technichal and ecology for sustaining tropical forests. Washington (DC): Report SRS–92. Asheville (NC): US Department of Island Press. Agriculture, Forest Service, Southern Research Station. Pfeil EV, Backhouse M, Reiche M. 2007. FLEGT – combating Dykstra D, Heinrich R. 1992. Sustaining tropical forests through illegal logging as a contribution towards sustainable devel- environmentally sound harvesting practices. Unasylva. 43: opment. In: von Pfeil E, Backhouse M, Reiche M, editors. 9–15. Communication from the Federal Ministry for Economic Dykstra DP, Heinrich R. 1996. Forestry codes of practice: con- Cooperation and Development. Topic 180, December 2007, tributing to environmentally sound forest operations. Rome: Bonn, Germany. FAO, FAO Forestry Paper 133. Weimin X, Robert KP, Dean LU. 2008. Changes in forest struc- Eltz T, Bruhl CA. 2001. Ecological evaluation of forest manage- ture, species diversity and spatial pattern following hurricane ment using leaf-litter ants and stingless bees as indicators. disturbance in a Piedmont North Carolina forest, USA. J TOB Publication No. TOB F-IV/5e, Germany. Plant Ecol. 1(1):43–57. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png International Journal of Biodiversity Science, Ecosystem Services & Management Taylor & Francis

The impacts of timber harvesting on residual trees and seedlings in a tropical rain forest ecosystem, southwestern Nigeria

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International Journal of Biodiversity Science, Ecosystem Services & Management Vol. 6, Nos. 3–4, September–December 2010, 131–138 The impacts of timber harvesting on residual trees and seedlings in a tropical rain forest ecosystem, southwestern Nigeria V.A.J. Adekunle and A.O. Olagoke Forest Ecology Research Unit, Department of Forestry and Wood Technology, Federal University of Technology, Akure, Nigeria This study examined logging damage to non-targeted neighbouring plant species and the forest ecosystem in a tropical forest in Ondo State, southwest Nigeria. Tree growth variables were recorded before and after felling, as was the number of crosscut logs. All plant species damaged during harvesting were enumerated and identified and the nature and level of the damage was also determined. Data providing demographic information, causes of damage to residual plants and measures to reduce the damage were obtained from the loggers using questionnaires. Data were collected on selective logging of 41 tree species. Despite selective logging practices, during felling, plants were damaged, soil compacted and the ecosystem disturbed. The observed damage to residual trees and seedlings ranged from 5% to 70% and it is therefore concluded that reduced impact logging and training of loggers is necessary to minimise the impacts. Keywords: logging; reduced impact logging; Ondo State Introduction These forms of damage are aggravated through insuffi- cient planning, improper operational techniques, lack of The term logging is the sum of all the processes, operations operational skill, loggers’ level of competence and lack and activities that make it possible for mature trees to be of serviceable modern felling tools (Eroglu et al. 2009). extracted for onward transmission to factories or places of According to Panayotou and Ashton (1992) about 340 secondary conversion (Ogbonnaya 2002). It encompasses trees, including saplings and wildlings of economically tree felling, de-branching, cross-cutting, skidding, loading valuable species, are destroyed for every tree extracted and primary transportation. Logging is a very lucrative from lowland tropical forests in Malaysia. business in Nigeria today and provides employment for Timber harvesting with insufficient planning, improper many Nigerians. Each of the above activities related to log- operational techniques and lack of control of operations ging has considerable impacts on the livelihoods of many results in severe damage to forest soil, forest trees and people. In Nigeria, while a selective system is the pre- seedlings (Akay et al. 2007; Eroglu et al. 2009). The dominant method of logging in the free areas, clear felling only available felling tool in Nigeria is the motorised through allocation of forest compartments to concession- or power chainsaw, but dragging of felled trees, packing aires is common in forest reserves. Mature trees of the into gantries and loading into lorries are generally done desired economic species are identified and removed. In manually with chains and winches. These processes are the government reserves, logging is controlled by policies primitive and tedious, and have the potential to disrupt the and laws enforced by the State Department of Forestry, and ecosystem (Olajide and Udo 2005). In addition, there is these must be strictly adhered to by both loggers and con- usually vegetation destruction during road construction for cessionaires. Government control on logging in the free transportation of logs and construction of gantries. As a areas is limited to the issuance of permits or licenses to result, many standing young trees, saplings and wildlings loggers after payment of all necessary fees (Adetula 2008). of economic value are destroyed. Adekunle and Ige (2006) Currently, the removal of timber occurs in an uncontrolled view logging as a major agent of biodiversity loss, Ola- manner, without strict adherence to the laws or payment Adams (1994) reported that about 17.74% of residual of appropriate fees and levies. Such illegal operations are trees suffer logging damage and about 8.00% of virgin termed ‘illegal logging’ (Pfeil et al. 2007). Furthermore, ground is left bare and damaged after felling operations. logging operations are responsible for forest destruction in These forest operations neglect the principle of sustain- Nigeria; therefore, sustainable logging is ipso facto nec- able forest management. Thus, proper forest harvesting, essary and desirable to attain an appropriate and socially well-planned logging techniques, review, execution and acceptable level of deforestation. enforcement of logging policies and adoption of reduced Severe damage is usually inflicted on the forest ecosys- impact logging are essential for achieving sustainable for- tem during logging activities. The damage includes forest est management in Nigeria. This will substantially reduce soil compaction, damage to other trees and plants, cutting the impacts of logging on the vulnerable environment. of seedlings, trampling, wildlife killing or chasing away Moreover, appraisal of the extent of logging activities and and encroachment into opened forest by land grabbers. *Corresponding author. Email: adewoleolagoke@gmail.com ISSN 2151-3732 print/ISSN 2151-3740 online © 2010 Taylor & Francis DOI: 10.1080/21513732.2010.534976 http://www.infomaworld.com 132 V.A.J Adekunle and A.O. Olagoke the impact of logging on the residual plant species is Tree stem damage assessment required to promulgate and enforce operational and appro- The three damage measures used by Eroglu et al. (2009) priate logging policies in Nigeria. This study therefore and Weimin et al. (2008) were employed to quantify investigated the calamitous impacts of logging on residual stand-level damage severity. These are percentage of stems trees, neighbouring plant species and wildlings in the tropi- damaged, percentage of basal area lost and a ‘stand-level cal rain forest ecosystem in southwestern Nigeria. This can damage index’. As tree stems often suffered multiple dam- be achieved by assessing the causes and the colossal extent age types and events, we created an ‘integrated stem of damage to the trees and plant species during logging damage code’ by combining all information/indices of activities. Precautionary measures employed by the loggers uprooting, breakage, leaning and leaned on into a single to minimise damage to other non-targeted plants were also code ranging from 0 to 3. We defined a damaged stem explored and appropriate strategies for sustainable logging as code 3 if the tree sustained severe damage (i.e. com- practices in the state are recommend. pletely uprooted, ≥90% canopy lost or leaning towards the ground); code 2 if a tree sustained substantial dam- age (i.e. partially uprooted, 35–90% canopy loss, leaning Methods but supported by other trees or pinned on the ground by Study area fallen neighbours); and code 1 if a tree sustained mod- est damage (i.e. 10–35% canopy loss, leaning >10% or This research was carried out in the tropical rain forest bent with >10% crown displacement). Code 0 was used ecological zone of Owo Forest Reserve, Ondo State, south- for minor or no damage. The integrated stem damage code west Nigeria. Ondo State is an agrarian state spread over 2 ◦  ◦ ◦ reflects multiple damage attributes for a stem and therefore a land area of about 14,788,728 km (4 30 –6 E, 5 45 – o  ◦ should more accurately reflect tree damage status than the 8 15 N. Owo Forest Reserve lies at approximately 4 E and individual components assessed. 4.5 N. It is located within the rain forest ecological zone (Onyekwelu et al. 2005), which has been described in detail by Nwoboshi (1982), Okojie (1996) and Adekunle (2002). Logger experience and reports on causes of logging The climate is the humid sub-tropical, indicating that the damage to non-targeted plants reserve is basically within the tropical rain forest zone, which is dominated by broadleaf hardwood trees that form The questionnaire survey of 40 professional tree log- dense layered stands. gers, popularly referred to in Nigeria as ‘operators’, was designed to collect information on the demographic char- acteristic of the loggers, major causes of damage to other Data collection trees and seedlings during felling operations and precau- A total of 41 economic, indigenous and high value tim- tions to mitigate such damage. The questionnaires were ber species allocated to loggers and available for felling filled in by the loggers and retrieved on the spot. An inten- were selected, clearly marked and numbered before felling. sive interaction was carried out with key informants such as forest guards and government officials involved in logging Total heights and diameters at the base, middle, top and at activities and the enforcement of forest laws, especially breast height (DBH) of the selected trees were measured those involved in logging in the state. before felling. The surrounding residual plants and the con- dition of the environment were observed closely and noted prior to felling of marked trees. Post-felling damage to the Data analysis affected residual plants was assessed as follow: Tree species classification and frequency The botanical name of every living tree with a (1) Herbs: damaged herbs were identified and counted DBH ≥ 10 cm encountered in each field plot was recorded. according to species, noting the types and levels of Each tree was recorded individually in the field forms; damage, and expressed as a percentage. palms and vines were not measured and efforts were (2) Shrubs, trees and tree branches: The species were made not to omit any eligible stem in a plot. All plants identified, enumerated and their height and diam- were classified to family and the number of species in eter at the base, middle, top and DBH measured. each family was obtained for tree diversity classification. Broken tree branches with a diameter ≥10 cm were Species relative densities were estimated and expressed as also measured and their frequencies noted. a percentage. Plant species identification Basal area and volume calculation The botanical names of the trees to be felled and those The basal area of each standing tree and of damaged trees affected by felling were recorded at the felling sites. In were estimated using the formula of Avery and Burkart cases where a botanical name was not known, it was iden- (2002): tified by its local name. The local names were translated to correct botanical names using Gbile (1984) and Keay πD Basal area m = . (1989). 4 International Journal of Biodiversity Science, Ecosystem Services & Management 133 The corresponding volumes were obtained using the Apocynaceae, Euphorbiaceae, Sapotaceae, Meliaceae, Newton formula of Husch et al. (2003): Mimosaceae and Moraceae) only one species was felled during the period of study. Khaya ivorensis had the highest mean DBH and mean volumes of 122 cm and 71.23 m , πH 3 2 2 2 while Ceiba pentandra had the highest total DBH and Volume m = D + 4D + D , b m t mean basal areas of 1017 cm and 1.19 m . The least mean and total DBH, basal area and volume were obtained for Mansonia altissima. The results of this study show that an where H is the height (m), D the DBH (m), D the diameter average of three trees was removed per species. The mean at base, D the diameter at middle, D the diameter at top m t DBH, basal area and volume of timber production in the and π = 3.142. 2 3 study area therefore was 93.12 cm, 0.79 m and 20.07 m . Data obtained for this study with the questionnaires The taxonomy and growth variables of damaged tree were subjected to descriptive statistical analysis in form species during logging activities are presented in Table 2. of frequency percentage distribution and ranking of The observation recorded during the study revealed that responses. The chi square non-parametric test was used to 154 standing stems belonging to 26 tree species were dam- test for association between respondents’ educational level aged in the process of logging. Cola gigantea had the high- and logging efficiency, respondents’ years of experience est frequency among the damaged species (47 trees), fol- and level of tree and seedling damage. lowed by Allophylus africanus (27 trees), and Terminalia superba (20 trees). Apart from Ricinodendron heudelotii, Results whose frequency was 11, other damaged species had a fre- quency of less than 10. Damage was done to only one stem The results enumerated in Table 1 show the taxonomy each of 11 tree species. A total of 38.00% of the affected and growth variables of the harvested 41 timber species. trees belonged to the Sterculiaceae, which was represented Among these, Ceiba pentandra had the highest frequency by five species, while 14.00% belonged to Combretaceae, (nine trees), followed by Cordia millenii (six trees), with represented by two species. Excluding Caesalpinaceae, minimum of one tree each of Ricinodendron heude- Mimosaceae and Ulmaceae, have two species each that lotii, Khaya ivorensis, Antiaris africana and Mansonia were also among the damaged tree species, only one altissima felled. The study revealed that two species species each of the other families was damaged during of Combretaceae, Sterculiaceae and Caesalpinaceae and the logging processes in the study area. While C. gigantea of eight other families (Bombacaceae, Boraginaceae, Table 1. Logged tree species and family, frequency, DBH, basal area (BA) and volume in a tropical rain forest ecosystem. Total Total Total DBH BA volume 2 3 Sl./No. Species Family Frequency (cm) (m ) (m ) 1. Afzelia africana Caesalpiniaceae 4 212 0.88 15.28 2. Alstonia boonei Apocynaceae 2 130 0.66 10.72 3. Antiaris Mimosaceae 1 70 0.38 4.88 africana 4. Brachystegia Caesalpiniaceae 5 480 3.65 80 eurycoma 5. Ceiba Bombacaceae 9 1017 10.71 301.59 pentandra 6. Cordia millenii Boraginaceae 6 588 4.62 89.28 7. Khaya ivorensis Meliaceae 1 122 1.17 71.23 8. Mansonia Sterculiaceae 1 50 0.20 3.00 altissima 9. Milicia excelsa Moraceae 2 126 0.68 12.24 10. Pachystela Sapotaceae 2 166 1.10 14.72 brevipes 11. Ricinodendron Euphorbiaceae 1 70 0.38 4.88 heudelotii 12. Terminalia Combretaceae 2 320 4.26 72.44 ivorensis 13. Terminalia Combretaceae 3 285 2.28 115.86 superba 14. Triplochiton Sterculiaceae 2 182 1.32 26.86 scleroxylon Total 14 11 41 3818 32.29 822.98 Mean 3 93.12 0.79 20.07 134 V.A.J Adekunle and A.O. Olagoke Table 2. Taxonomy and growth variables of damaged tree species in the tropical rain forest ecosystem. Total Total Total DBH BA volume 2 3 Sl./No. Species Family Frequency (cm) (m ) (m ) 1. Afzelia Africana Caesalpiniaceae 2 42.00 0.14 4.80 2. Albizia lebbeck Mimosaceae 3 246.00 1.59 21.96 3. Allophylus Sapindaceae 27 594.00 1.08 13.23 africanus 4. Aningeria Sapotaceae 1 10.00 0.01 0.07 robusta 5. Anopyxis Rhizophoraceae 1 53.00 0.22 3.28 klaineana 6. Antiaris Mimosaceae 2 70.00 0.28 2.70 africana 7. Brachystegia Caesalpiniaceae 3 285.00 2.10 25.77 eurycoma 8. Ceiba Bombacaceae 7 378.00 1.82 41.51 pentandra 9. Celtis zenkerii Ulmaceae 2 88.00 0.32 4.96 10. Cola gigantea Sterculiaceae 47 3102.00 17.39 313.96 11. Cordia millenii Boraginaceae 5 330.00 1.75 31.85 12. Enantia Annonaceae 1 16.00 0.02 0.84 chlorantha 13. Ficus capensis Moraceae 1 39.00 0.12 1.09 14. F. exasperata Moraceae 3 54.00 0.09 0.81 15. Grewia mollis Tiliaceae 1 30.00 0.07 0.97 16. Khaya ivorensis Meliaceae 1 54.00 0.23 3.21 17. Mansonia Sterculiaceae 6 294.00 1.20 14.22 altissima 18. Pycnanthus Myristicaceae 1 41.00 0.13 1.86 angolensis 19. Ricinodendron Euphorbiaceae 11 198.00 0.33 4.07 heudelotii 20. Spathodea Bignoniaceae 1 18.00 0.02 0.39 campanulata 21. Sterculia Sterculiaceae 4 176.00 0.60 9.56 rhinopetala 22. S. tragacantha Sterculiaceae 1 44.00 0.15 2.39 23. Terminalia Combretaceae 1 101.00 0.79 28.28 ivorensis 24. T. superba Combretaceae 20 1020.00 5.20 91.60 25. Trema orientalis Ulmaceae 1 19.00 0.03 0.18 26. Triplochyton Sterculiaceae 1 55.00 0.24 3.43 scleroxylon Total 26 17 154 7302.00 35.92 626.99 Mean 6 47.42 0.23 4.07 had the highest total DBH (3102 cm), T. ivorensis had the During the study, 1571 economic plants (four species) highest mean DBH (101 cm), mean basal area (0.79 m ) were destroyed on the felling sites during logging oper- and mean volume (28.28 m ), while Aningeria robusta had ations. These are the major plant species occupying the the least mean and total DBH, basal area and volume. The forest floor of tropical rain forest ecosystems of southwest total basal area of trees damaged by selectively logged was Nigeria, especially where there is good light penetration. 2 2 35.92 m and the mean damage per tree was 0.23 m . Chromolaena odorata, an invasive plant species in Nigeria, The basal area percentage index of stems damaged was common, followed by Pennisetum purpureum and was 54.00%. Palisota hirsute, while Thaumatococcus daniellii was least About 26.00% of the damaged trees had attained affected. merchantable size, with individual trees having a DBH The common causes of damage to residual plants dur- of >48.00 cm. The undergrowth damaged during tree ing logging activities were obtained from the respondents felling processes in the study area is presented in Table 3. (Table 4). All tree fellers claimed to be using power International Journal of Biodiversity Science, Ecosystem Services & Management 135 Table 3. Most damaged understory species during logging activities in the study area. Sl./No. Species Family Frequency Percentage Rank 1. Chromolaena odorata Asteraceae 629 40.03 1 2. Palisota hirsuta Commelinaceae 298 19.00 3 3. Pennisetum purpureum Graminae 539 34.33 2 4. Thaumatococcus daniellii Marantaceae 105 6.65 4 Total 4 4 1571 100 Table 4. Causes of damage to residual plant species during logging. %of S/N Causes of damage respondents Rank 1 Felling flaws/Incorrect determination of felling 35 1 direction 2 Illogical construction of skidding and 77 forwarding roads 3 Poor felling equipment 13 5 4 Incompetence of tree fellers (chainsaw 29 2 operators) 5 Non-removal of attached climbers prior to 96 felling 6 Wind prevalence while felling 25 3 7 Presence of obstructions 3 8 8 Felled trees bending/leaning towards dense 14 4 populations of other plant species Note: Total figure can be higher than 100% because some respondents made more than one choice. Table 5. Types of damage inflicted on residual plants during felling operations. %of %oftotal respondents’ Sl./No. Type of damage damaged trees responses 1. Clearing of vegetation 41.98 56.22 2. Breaking of branches and boles 25.30 30.50 3. Leaning and leaned into 5.34 10.55 4. Uprooting of surrounding trees and shrubs 27.38 2.73 chainsaws for felling of trees. The majority of them (35%) to residual plants was total removal and clearing of trees reported felling flaws or incorrect determination of felling and vegetation on the route and close to trees to be felled. direction as the first causes of damage to non-target plants This affected about 42% of total trees that were logged during felling. This was followed by 25% who lamented (Table 5). Uprooting of trees by the loggers during skidding that some tree fellers (chainsaw operators) are not compe- and road construction and by the felled logs accounted for tent enough to handle felling machinery. These are the set about 27.5% of total damage. Another important type of of operators without training or skill. Other reported causes damage is falling on other trees of the felled trees (25.3%) of damage to plant species include a lack of control over and in the process, breaking the boles and branches. Trees the wind and the falling force of trees, which make con- that were leaning and leaned on as a result of felling were trolling the direction of fall very difficult to control, and less pronounced (5.3%). As tree stems often suffered mul- non-removal of climbers and lianas attached to trees to be tiple damage types and events, the integrated stem damage felled. The presence of obstructions, such as rocks, river code was used by combining all information/indices of courses, etc. close to the trees to be felled was also reported uprooting, breakage, leaning and leaned on. The results by a few respondents (3%) as a cause of damage to plant show that the highest proportion (52%) of total damaged species. Table 5 shows the types and severity of damage trees was in scale 3, followed by 34% in scale 2, 10% in caused by the felled trees on other trees and seedlings dur- scale 1 and only 4% in scale 0. ing this study. The observation and assessment of felling The frequency with which the respondents mention a sites was corroborated by the respondents’ (tree loggers certain type of damage (%) to non-targeted trees and under- and forest guards) reports on the types and levels of dam- growth from each of the logging operations is ranked and age to residual plants. The commonly encountered damage presented in Table 6. Highest damage, as observed in the 136 V.A.J Adekunle and A.O. Olagoke Table 6. Logging operations and their damage to residual most common (37.5%), with a range of ages from 20 to 60 plants. years involved in logging. Only 2.5% of loggers did not have some formal education. Among loggers, 52.5% have Number of been loggers for 10 years and only 25% were skilled in Logging operation respondents Percentage timber felling. The remaining loggers came to the profes- Felling 15 33.33 sion through their friends (37.5%) and through wood-based Skidding and loading 7 15.56 industries (17.5%). The results of this study also show that Gantry construction 5 11.11 the majority of the operators (95%) had no training; their Road construction 18 40.00 skills increased according to the time spent on the job. Generally, the performance efficiency on a particular job strongly depended on the number of years of experience, field, occurred during road construction. This was corrob- their age and education level. orated by the majority of the respondents (40%) and by government agents in charge of log control. This was fol- lowed by the huge damage attributed to felling, as observed Discussion and reported by 33.33% of respondents and forest guards. Minimal damage was recorded during skidding/loading The flourishing timber industry has evidently grown and gantry construction according to the remaining respon- beyond the forests’ regeneration capacity, with poor con- dents. Loggers’ perception of the deleterious impacts of ventional harvesting practices and the wanton destruction logging activities to the forest ecosystem is presented in of forest ecosystems during logging operations, which are Table 7. The highest proportion of respondents (63%) indi- undoubtedly inimical to sustainability of forest resource cated that they were aware that logging operations could management. Most of the seedlings and saplings are result in soil compaction, erosion and infertility. A total severely damaged (when cut, trampled or uprooted) during of 55% were conscious that logging could cause defor- logging operations, reducing their natural ability to succes- estation and ecosystem destruction and 43.00% expressed sively replace the harvested trees in the future. This present their knowledge of severe injuries caused to neighbour- study has clearly revealed that major damage is done to ing trees, seedlings and understorey plants during logging the remaining trees during felling and transportation of operations. About 23% of loggers reported the implications the targeted tree species. Clatterbuck (2006) corroborated of logging activities on wildlife. the occurrence of such damage and further stressed that The loggers suggested some measures for reducing residual tree species are devalued and may not recover logging damage to untargeted trees and the entire forest to become better grade timber. Limbeck-Lilienau (2003) ecosystem (Table 8). The results show that 80% of respon- noted that fungal infections and decay are common when dents favoured proper determination of felling direction, trees are wounded. Hence, logging damage, especially particularly in areas with sparse tree populations, as the bole-breakage, stem splitting and debranching, could lead most important damage-reducing measure during tree to fungi infections and decay of damaged tree species and felling. The second proposal was the use of competent open the door for other pathogens to infest the trees. Some and well-trained tree fellers (73%) and stopping felling tree species that are mildly injured could recover from the when the wind is strong and weather conditions are not stress inflicted during logging activities. favourable (63%). The remaining 55% considered that The socio-economic characteristics of the loggers show engaging experienced skidding operators and prohibition that the majority have good experience, education and are of the use of heavy log evacuation equipment (40%) were mature, attributes that have contributed to their present other common measures that could be used to minimise expertise. Nevertheless, adequate training could improve logging damage. The demographic characteristics of the their competence and further reduce the destruction of loggers are shown in Table 9. The majority of tree log- the ecosystem during logging activities. The results of this gers (92.5%) were married. The age group 31–40 years was study also revealed that the loggers are aware of the damage Table 7. Effects of logging on forest ecosystems according to the loggers. Number of Logging damage to forest ecosystems respondents Percentage It leads to destruction of neighbouring trees and forest understory 17 42.5 It results in deforestation and ecosystem destruction 22 55 It results into soil compaction, erosion and loss of soil fertility 25 62.5 It may result in destruction of soil fauna and exposure of wildlife to direct attacks from predators and hunters 9 22.5 It results in destabilisation of the forest ecosystem 10 25 It may deprive wildlife of their habitats 16 40 It may cause extinction of some plant and animal species 14 35 Note: Figures are more than 100% because some respondents made more than one choice. International Journal of Biodiversity Science, Ecosystem Services & Management 137 Table 8. Respondent opinion of various logging damage reduction measures. Number of Logging damage reduction measures respondents Percentage During Use of appropriate felling machine 20 50 felling Employment of competent tree fellers with adequate 29 72.5 training Proper determination of felling direction, especially 32 80 in areas with a low plant populations Felling should be stopped during high winds or not 25 62.5 carried out while wind is blowing During log Skidding and transportation should be done by an 22 55 evacuation experienced skidding operator Timber evacuation route must be constructed in areas 11 27.5 with low plant populations Prohibition of the use of heavy log evacuation 16 40 equipment caused to the forest ecosystem during logging. This is in highest number of respondents considered road construc- conformity with reports of other authors (Ogbonnaya 2002; tion as the chief contributor to damage to other plants Eroglu and Acar 2007; Eroglu et al. 2009), which indicated and the ecosystem during logging operations. In addition, that damage to residual stands due to timber harvesting logging roads open up the forests to shifting cultivation, involve tree felling, hauling of logs, road construction encroachment and permanent settlement. Bruenig (1996) and log transportation. Bruenig (1996) and Dykstra and stated that excessive skidding and log transportation could Heinrich (1996) noted that between 30% and 75% of lead to excessive soil compaction and erosion. This leads to logged areas can be seriously affected by roads, tractor unsustainability of felling cycles of 25–50 years, and cycles trails, landings or just through bulldozers. A similar trend of 60–100 years are more realistic. Nonetheless, skid trails was found in the present study, which revealed that the and skidding cannot be dispensed with during log extrac- tion, although skidding damage could be minimised by Table 9. Demographic characteristics of the tree fellers in planning the trails and utilising optimum trail spacing. Ondo State, Nigeria. Now that timber harvesting has become a very lucra- Characteristics Percentage tive venture, damage can only be abated by taking pre- cautions and through adequate training of loggers. The Marital status Married 92.5 working practises and experience of chainsaw operators Single 7.5 and skidders can considerably minimise logging damage. Total 100 Maintaining a minimum number of straight skidding trails Age (years) 20–30 20.0 31–40 37.5 and directional felling of trees towards skidding trails 41–50 32.5 and away from areas of dense plant species are critical 51–60 22.5 among the suggested measures to avert logging damage. In Total 100 addition, proper forest harvesting, especially well-planned Education status No former logging techniques are required to maintain site productiv- education 2.5 Primary school 27.5 ity and ensure sustainable management of forest resources Secondary school 50 (Dykstra and Heinrich 1992). Eltz and Bruhl (2001) have Tertiary education 20 confirmed that reduced impact logging causes less direct Number of years as damage to the environment compared to conventional prac- power saw operator 1–3 0 4–6 25 tices, and this should be promoted, especially in developing 7–9 22.5 countries such as Nigeria. >10 52.5 Total 100 Route into this job Learning 25 Conclusions Environmental influence 20 The results of this study show that logging activities are Employed by a causing obvious damage to neighbouring plant species. wood industry 17.5 Damage was recorded during felling, skidding gantry and Through a friend 37.5 road construction. Most of the damage was attributed to Total 100 Training received Yes 5 excessive and indiscriminate logging, use of inexperienced No 95 tree fellers and skidders and lack of adequate training. Total 100 Forest clearance during road construction causes more 138 V.A.J Adekunle and A.O. Olagoke havoc to the environment than the fallen trees. Bole break- Eroglu H, Acar HH. 2007. The comparison of logging techniques for productivity and ecological aspects in Artvin, Turkey. J age and splitting, leaf removal, suppression of herbs and Appl Sci. 14:1973–1976. soil compaction are the dominant types of damage to resid- Eroglu H, Öztürk UO, Sönmez T, Tilki F, Akkuzu E. 2009. The ual plants and the ecosystem during logging. Loggers are impacts of timber harvesting techniques on residual trees, fully aware of the adverse impacts of continuous log- seedlings, and timber products in natural oriental spruce ging activities on the ecosystem. However, skill and taking forests. Afr J Agric Res. 4(3):220–224. Gbile ZO. 1984. Vernacular names of Nigerian plants – Yoruba. all necessary precautions during logging operations could Ibadan (Nigeria): Forestry Research Institute of Nigeria. potentially reduce the amount of damage associated with Husch B, Charles IM, Thomas WB. 2003. Forest mensuration. timber harvesting. 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Journal

International Journal of Biodiversity Science, Ecosystem Services & Management – Taylor & Francis

Published: Dec 1, 2010

Keywords: logging; reduced impact logging; Ondo State

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