Unlogged Forest Research Articles

Selective logging alters allometric relationships of five tropical tree species in seasonal semi-deciduous forests

In selectively logged forests, trees are more likely to expand their diameters (D) at the expense of height (H) growth, resulting in variations in H:D relationships. This study examines how selective logging affects the H:D allometric relationships of five common tree species and whether the effects vary with functional groups (shade-intolerant or shade tolerant) in seasonal semi-deciduous forests. Individuals of five species in a 3000 m2 (0.3 ha) plot were marked and heights and diameters recorded. Most of the species, with one exception, showed greater investment in diameter per increment of height compared to an unlogged forest, possibly because of the greater light available. This study shows the effects of selective logging on species populations as evidenced by increases in H:D ratios. Comparison of forest fragments with different degrees of human impact is important because it allows us to understand the differences in architectural characteristics caused by selective logging.

From unburnt to salvage logged: Quantifying bird responses to different levels of disturbance severity

Abstract Forests world‐wide are increasingly subject to natural and human disturbances, including wildfires and logging of varying intensity and frequency. Understanding how biodiversity responds to different kinds and combinations of natural and human disturbance is critical to enhanced forest management. We completed an 8‐year study of bird responses across a spectrum of disturbance types in Australian mountain ash (Eucalyptus regnans) forests following wildfires in 2009. We found evidence of a gradient in bird species richness over the study duration. It was highest in unlogged and unburned (least disturbed) sites, decreasing through burnt unlogged forest (subject to high or low intensity fire), lower still in logged forest, and lowest in the most disturbed sites (subject to salvage logging without island retention). Retention of uncut islands within logged areas increased bird species richness above that found in areas that had been clearcut. The greatest rate of increase per year after disturbance in bird species richness was on sites burnt by high‐severity fire but which were not subject to any form of logging. The level of disturbance affected the composition of the bird assemblage. Sites that were unlogged and unburned were more likely to support species that were larger, more mobile, and nested at greater heights above the ground. Synthesis and applications. All forms of logging on burned sites impaired recovery in bird species richness relative to sites subject to high‐severity fire. Alterations in stand structure and plant species composition (and hence modification in bird habitat suitability) due to logging are the most likely reasons for reduced bird species richness and delayed patterns of recovery. This study highlights the importance for native bird species of retaining patches of unlogged forest not only within otherwise clearcut forest, but also in areas that are burned and subject to salvage logging. We therefore suggest that the adoption of retention harvesting be expanded to include stands disturbed by wildfires.

The combined impacts of experimental defaunation and logging on seedling traits and diversity.

Animals can have both positive (e.g. via seed dispersal) and negative (e.g. via herbivory) impacts on plants. The net effects of these interactions remain difficult to predict and may be affected by overhunting and habitat disturbance, two widespread threats to tropical forests. Recent studies have documented their separate effects on plant recruitment but our understanding of how defaunation and logging interact to influence tropical tree communities is limited. From 2013 to 2016, we followed the fate of marked tree seedlings (n = 1489) from 81 genera in and outside experimental plots. Our plots differentially excluded small, medium and large-bodied mammal herbivores in logged and unlogged forest in Malaysian Borneo. We assessed the effects of experimental defaunation and logging on taxonomic diversity and plant trait (wood density, specific leaf area, fruit size) composition of seedling communities. Although seedling mortality was highest in the presence of all mammal herbivores (44%), defaunation alone did not alter taxonomic diversity nor plant trait composition. However, herbivores (across all body sizes) significantly reduced mean fruit size across the seedling community over time (95% confidence interval (CI): -0.09 to -0.01), particularly in logged forest (95% CI: -0.12 to -0.003). Our findings suggest that impacts of mammal herbivores on plant communities may be greater in forests with a history of disturbance and could subsequently affect plant functional traits and ecological processes associated with forest regeneration.

Trade‐offs in berry production and biodiversity under prescribed burning and retention regimes in boreal forests

Abstract Green tree retention and prescribed burning are the practices used to mitigate negative effects of boreal forestry. Beside their effects on biodiversity, these practices should also promote non‐timber forest products (NTFPs). We assessed: (1) how prescribed burning and tree retention influence NTFPs by examining the production of bilberry, Vaccinium myrtillus and cowberry, Vaccinium vitis‐idaea; (2) if there are synergies or trade‐offs in the delivery of these NTFPs in relation to the delivery of species richness, focusing on five groups of forest‐dwelling species. We used a long‐term experiment located in eastern Finland, with three different harvesting treatments: clear‐cut logging, logging with retention patches and unlogged, which were combined with or without prescribed burning. Eleven years after the treatment application, we scored plant cover and berry production in different microhabitats within these treatments, while species richness data for five species groups (ground layer lichens and bryophytes, vascular plants, saproxylic beetles, pollinators—here bees and hoverflies) were collected at the stand level. Logging favoured cowberry production, particularly for plants growing in the vicinity of stumps. Logging was detrimental for cover and berry production of bilberry. Retention mitigated these negative effects slightly, but cover and berry production were still substantially lower compared to unlogged forests. Prescribed burning increased the cowberry production in retention patches and in unlogged forest. Bilberry production decreased with burning, except in unlogged forest where the effect was neutral. No single management treatment simultaneously favoured all values—NTFPs and richness—and trade‐offs among values were common. Only bilberry production and beetle diversity were higher under retention forestry, or in unlogged stands, compared to logged stands. Prescribed burning favoured many values when performed in combination with retention forestry, or in unlogged stands, but different treatment combinations favoured different species groups. Synthesis and applications. Our results demonstrate that widely applied conservation practices in managed boreal forests are unlikely to benefit all ecosystem values everywhere. If high multifunctionality is desired, managing at a landscape scale, countering the local trade‐offs among values, may be more appropriate than the stand‐scale conservation practices commonly practiced today.

Dynamics of Tree Species Diversity in Unlogged and Selectively Logged Malaysian Forests

Selective logging that is commonly conducted in tropical forests may change tree species diversity. In rarely disturbed tropical forests, locally rare species exhibit higher survival rates. If this non–random process occurs in a logged forest, the forest will rapidly recover its tree species diversity. Here we determined whether a forest in the Pasoh Forest Reserve, Malaysia, which was selectively logged 40 years ago, recovered its original species diversity (species richness and composition). To explore this, we compared the dynamics of secies diversity between unlogged forest plot (18.6 ha) and logged forest plot (5.4 ha). We found that 40 years are not sufficient to recover species diversity after logging. Unlike unlogged forests, tree deaths and recruitments did not contribute to increased diversity in the selectively logged forests. Our results predict that selectively logged forests require a longer time at least than our observing period (40 years) to regain their diversity.

RECOVERY OF RESIDUAL FOREST ECOSYSTEM AS AN IMPACT OF SELECTIVE LOGGING IN SOUTH PAPUA: AN ECOLOGICAL APPROACH

Papua has been experiencing heavy logging activity in its forests for decades . However, only several studies focused on the effect of logging in the forest ecosystem. This research was aimed to analyze recovery processes of the forest ecosystem. The research was conducted in the logged tropical rainforest in South Papua using ecological approach which used tree communities as biotic and soil condition as abiotic indicators. Data were collected in the logging area of PT Tunas Timber Lestari located in the tropical rainforest of South Papua. There were five groups of forests used in this research i.e. unlogged, one year post selectively-logged, five years post selectively-logged, ten years post selectively-logged and fifteen years post selectively-logged forests. Thirty nested plots were laid on each forest group. Canonical Correspondence Analysis (CCA) was applied to analyze the understory and upperstory plant communities. Understory and upperstory plant communities formed different patterns due to logging. Plant communities in the ten and fifteen years post-selectively logged forests were not similar to those in the unlogged forest. Soil organic matter (SOM) content in the selectively logged forests was lower than that in the unlogged forest. These occurrences indicated that the selectively logged forests were still recovering and required more than fifteen years to be fully recovered.

Twenty years monitoring growth dynamics of a logged tropical forest in Western Amazon

We performed a forest growth dynamics study in Acre State, Brazilian southwestern Amazon, where a 20 ha area was logged in 1992. The study was based permanent sample plots (1 ha) established in the logged area and in an unlogged forest immediately after logging operations finished. Forest dynamics parameters were assessed in terms of aboveground dried biomass (AGB). During the study period, three extreme climate events triggered a high impact on both logged and unlogged areas, producing AGB losses greater than those estimated for logging. Twenty years after logging, ingrowth and mortality rates were similar to those expected in an undisturbed forest, and AGB recovery was significantly faster in the logged areas. Forest management, when properly applied, can promote faster forest AGB recovery. We suggest that forest management could be considered as an alternative to adapt to extreme climate events, by promoting controlled disturbances, which should minimize tree mortality and biomass loss.

The conservation value of unlogged and logged forests for native mammals on the East Coast of Peninsular Malaysia

Tropical forests across the world provide important habitats for a diverse number of conservation priority species, yet are under threat from a range of anthropogenic impacts including logging. This study aims to quantify mammalian biodiversity in unlogged and logged forests in the adjoining Tembat and Petuang Forest Reserves, Terengganu, on the East Coast of Peninsular Malaysia. Data was collected over a series of surveys using direct and indirect observation methods from 2008 to 2014. A total of 30 medium and large sized mammals species were identified, with 27 of those species found in unlogged forests and 22 species in logged forests. Carnivores encompassed 11 species from 67 observations representing 15% of the total number of observations. The family Felidae had the highest number of species (six species), followed by Hylobatidae, Cercopithecidae and Suidae with three species each. A total of 17 species contributed to more than 90% of the mammal community in the unlogged and logged forests, while six species were uncommon and only observed once during the entire survey. Species abundance in the unlogged forest was significantly greater than the logged forests, but the difference was not significant for species richness. This study provides critical baseline information on the impact of unlogged and logged forests and the identification of threatened species warrant the establishment of conservation measures such as anti-poaching patrol and ranger stations in the study area.

Effects of selective logging on rodent-mediated seed dispersal

Abstract It is generally accepted that selective logging significantly influences the vegetation coverage and habitat structures, but little is known about whether and how low intensity selective logging affects seed dispersal mediated by small rodents. In this study, we compared the differences in seed disperser composition and abundance as well as primary and secondary seed dispersal and predation of Quercus aliena var. acuteserrata by scatter-hoarding rodents in different aged forest (i.e., unlogged stands, stands in the second and fifth year after low intensity logging 150 stems per ha) in Huoditang Forest in the Qinling Mountains, China. We found that the rodent composition of stands in the second year after logging (large-bodied disperser Sciurotamias davidianus was absent) differed conspicuously from that of the other two stands. Selective logging reduced the abundance of rodents, seed removal rate, scatter–hoarded proportion, and seed dispersal distance during the second year after selective logging. However, no significant differences were found in the composition and abundance of rodents as well as their seed dispersal services between the unlogged stands and in stands during the fifth year after logging. In addition, the proportions of initially buried acorns were significantly lower in stands in the second year after logging compared with the other two types of stands, but after seed caching, the seed revisiting rates were lower in stands in the second year after logging compared with the other two types of stands. Rodent–mediated seed dispersal was lower in the second year after selective logging but it recovered to its initial level within five years. The dispersal distance was significantly lower in stands in the second year after logging compared with the distances (3.12 ± 0.23 m) in the unlogged forest stands (5.75 ± 0.41 m) and in stands in the fifth year after logging (4.44 ± 0.36 m). Therefore, selective logging in forests is likely to temporarily alter the composition of rodent communities, change seed dispersal services, and the capacity for plant movements. Number of years after selective logging is important for determining whether seeds are removed rapidly by potential dispersers, which can lead to different rates of seed removal, seed predation, scatter–hoarding, and survival, and eventually influence forest recovery after selective logging.

Impact of logging on tree, liana and herb assemblages in a Bornean forest

ABSTRACTIn the present study, the impact of logging was assessed on the forest structure, richness, and composition of trees, lianas, and ground herbs in Indonesian Borneo. There were no significant differences in tree height, diameter, basal area, or abundance between unlogged and logged forest. Liana abundance was higher in logged than unlogged forest, but the difference was marginally nonsignificant. There was also no significant difference in the percentage cover of ground herbs. Tree species richness was similar between unlogged and logged forest, while liana species richness was higher in logged forest and herb species richness between unlogged forest. Tree and liana compositions differed significantly between unlogged and logged forest, but logging explained only a small part (<7%) of the variance in composition. In contrast to trees and lianas, ground herb composition did not differ significantly between unlogged and logged forest. Our findings indicate that the modest extraction intensity practiced did not have a severely adverse impact on forest structure or plant composition. This highlights the important role that logged forests may play in conserving biodiversity and the need to protect these forests from further disturbance.

Inter-den tree movements by Leadbeater's Possum

ABSTRACT Many species of arboreal marsupials move regularly between den sites in hollow-bearing trees. We show, based on short-term radio-tracking data, that the Critically Endangered Leadbeater's Possum (Gymnobelideus leadbeateri) can move 100 m (and sometimes up to 600 m) between den sites in hollow-bearing trees. These movement data have significant implications for the design of buffers of unlogged forest to protect colonies of Leadbeater's Possum as well as for crude estimates of the species' population size.

Defaunation and habitat disturbance interact synergistically to alter seedling recruitment

Vertebrate granivores destroy plant seeds, but whether animal-induced seed mortality alters plant recruitment varies with habitat context, seed traits, and among granivore species. An incomplete understanding of seed predation makes it difficult to predict how widespread extirpations of vertebrate granivores in tropical forests might affect tree communities, especially in the face of habitat disturbance. Many tropical forests are simultaneously affected by animal loss as well as habitat disturbance, but the consequences of each for forest regeneration are often studied separately or additively, and usually on a single plant demographic stage. The combined impacts of these threats could affect plant recruitment in ways that are not apparent when studied in isolation. We used wire cages to exclude large (elephants), medium, (sambar deer, bearded pigs, muntjac deer), and small (porcupines, chevrotains) ground-dwelling mammalian granivores and herbivores in logged and unlogged forests in Malaysian Borneo. We assessed the interaction between habitat disturbance (selective logging) and experimental defaunation on seed survival, germination, and seedling establishment in five dominant dipterocarp tree species spanning a 21-fold gradient in seed size. Granivore-induced seed mortality was consistently higher in logged forest. Germination of unpredated seeds was reduced in logged forest and in the absence of small to large-bodied mammals. Experimental defaunation increased germination and reduced seed removal but had little effect on seed survival. Seedling recruitment however, was more likely where logging and animal loss occurred together. The interacting effects of logging and hunting could therefore, actually increase seedling establishment, suggesting that the loss of mammals in disturbed forest could have important consequences for forest regeneration and composition.

Analysis of importance value index of unlogged and logged peat swamp forest in Nenasi Forest Reserve, Peninsular Malaysia

Ismail MH, Fuad MFA, Zaki PH, Jemali NJN. 2017. Analysis of importance value index of unlogged and logged peat swamp forest in Nenasi Forest Reserve, Peninsular Malaysia. Bonorowo Wetlands 1: 74-78. Peat swamp forests are highly significant globally, both for their diverse and threatened species and as a representative of unique wetland ecosystems. Apart from its critical role in providing habitat for wildlife, the tropical peat swamp forest also acts as a gene bank that harbors potentially useful varieties of plant species. The composition of trees of the peat swamp forest in Nenasi Pahang State, Peninsular Malaysia were investigated especially in un-logged and logged over forests. The objectives of this study are two folds; (i) to identify and compare the dominant tree species in the two types of forests and (ii) to calculate the importance value index (IVI) of the vegetation in the study areas. Two plots of 50 m by 20 m were established in different forest type. At each site this quadrate was in turned subdivided using a 25 m by 20 m, and 5 m by 5 m, respectively. The results showed that the unlogged peat swamp forest is higher in tree species compared to logged peat swamp forest. There were 10 species distributed among 9 families in the unlogged forest and 7 species in 7 families in the logged forest. The most dominant species identified in unlogged peat swamp forest were Litsea sp., Syzygium sp. and Santiria laevigata. The IVI for these species were 71.21, 51.13 and 42.49. In logged peat swamp forest the dominant species are Shorea platycarpa, followed by Pometia pinnata, and Xylopia fusca. The IVI of these species were 87.38, 52.66 and 47.55, respectively. The study concludes that in the logged peat swamp forests about 40 percent of the tree composition has declined compared to unlogged peat swamp forest.

The effects of restoring logged tropical forests on avian phylogenetic and functional diversity.

Selective logging is the most prevalent land-use change in the tropics. Despite the resulting degradation of forest structure, selectively logged forests still harbor a substantial amount of biodiversity leading to suggestions that their protection is the next best alternative to conserving primary, old-growth forests. Restoring carbon stocks under Reducing Emissions from Deforestation and Forest Degradation (REDD+) schemes is a potential method for obtaining funding to protect logged forests, via enrichment planting and liberation cutting of vines. This study investigates the impacts of restoring logged forests in Borneo on avian phylogenetic diversity, the total evolutionary history shared across all species within a community, and on functional diversity, with important implications for the protection of evolutionarily unique species and the provision of many ecosystem services. Overall and understorey avifaunal communities were studied using point count and mist netting surveys, respectively. Restoration caused a significant loss in phylogenetic diversity and MPD (mean pairwise distance) leaving an overall bird community of less total evolutionary history and more closely related species compared to unlogged forests, while the understorey bird community had MNTD (mean nearest taxon distance) that returned toward the lower levels found in a primary forest, indicating more closely related species pairs. The overall bird community experienced a significant loss of functional strategies and species with more specialized traits in restored forests compared to that of unlogged forests, which led to functional clustering in the community. Restoration also led to a reduction in functional richness and thus niches occupied in the understorey bird community compared to unlogged forests. While there are additional benefits of restoration for forest regeneration, carbon sequestration, future timber harvests, and potentially reduced threat of forest conversion, this must be weighed against the apparent loss of phylogenetic and functional diversity from unlogged forest levels, making the biodiversity-friendliness of carbon sequestration schemes questionable under future REDD+ agreements. To reduce perverse biodiversity outcomes, it is important to focus restoration only on the most degraded areas or at reduced intensity where breaks between regimes are incorporated.

Logging and indigenous hunting impacts on persistence of large Neotropical animals

AbstractAreas allocated for industrial logging and community‐owned forests account for over 50% of all remaining tropical forests. Landscape‐scale conservation strategies that include these forests are expected to have substantial benefits for biodiversity, especially for large mammals and birds that require extensive habitat but that are susceptible to extirpation due to synergies between logging and hunting. In addition, their responses to logging alone are poorly understood due to their cryptic behavior and low densities. In this study, we assessed the effects of logging and hunting on detection and occupancy rates of large vertebrates in a multiple‐use forest on the Guiana Shield. Our study site was certified as being responsibly managed for timber production and indigenous communities are legally guaranteed use‐rights to the forest. We coupled camera‐trap data for wildlife detection with a spatially explicit dataset on indigenous hunting. A multi‐species occupancy model found a weak positive effect of logging on occupancy and detection rates, while hunting had a weak negative effect. Model predictions of species richness were also higher in logged forest sites compared to unlogged forest sites. Density estimates for jaguars and ocelots in our multiple‐use area were similar to estimates reported for fully protected areas. Involvement of local communities in forest management, control of forest access, and nesting production forests in a landscape that includes protected areas seemed important for these positive biodiversity outcomes. The maintenance of vertebrate species bodes well for both biodiversity and the humans that depend on multiple‐use forests.

Comparison of microhabitat use in young regrowth and unlogged forest by the eastern pygmy-possum (Cercartetus nanus)

We describe microhabitat use and response to disturbance by the eastern pygmy-possum (Cercartetus nanus) in heathy dry sclerophyll forest using spool-and-line-tracking. We compared unlogged forest with forest regenerating four years after selective logging. Structural and floristic attributes were scored along spool lines and compared with a random line for each possum. We found that possums (n = 23) selected areas based on both structural and floristic attributes. Possums selected dense understorey, especially that comprising flowering hairpin banksia (Banksia spinulosa) and Gymea lily (Doryanthes excelsa). Fallen logs were not selected by nocturnally active possums. Spool lines in regrowth forest had less eucalypt cover and more understorey cover (e.g. D. excelsa and B. spinulosa) than unlogged forest. Conversely, cover of Banksia serrata was less in regrowth than unlogged forest. Spool lines were commonly found both at ground level (mean = 52–57% of lengths) and above the ground (43–48% of lengths). There was no difference in the mean spool height between the logging treatments (regrowth: 0.47 ± 0.14 m; unlogged: 0.49 ± 0.10 m; ± s.e.). Overall, our results suggest that the dense, flowering understorey that regenerates after selective logging is suitable for use and is the primary attribute selected by active pygmy-possums.

Quantifying uncertainty about forest recovery 32-years after selective logging in Suriname

The inclusion of managed tropical forests in climate change mitigation has made it important to find the sustainable sweet-spot for timber production, carbon retention, and the quick recovery of both. Here we focus on recovery of aboveground carbon and timber stocks over the first 32years after selective logging with the CELOS Harvest System in Suriname. Our data are from twelve 1-ha permanent sample plots in which growth, survival, and recruitment of trees ≥15cm diameter were monitored between 1978 and 2012. We evaluate plot-level changes in basal area, stem density, aboveground carbon, and timber stock in response to average timber harvests of 15, 23, and 46m3ha−1. We use a linear mixed-effects model in a Bayesian framework to quantify recovery time for aboveground carbon and timber stock, as well as annualized increments for both. Our statistical models accounted for the uncertainty associated with the height and biomass allometries used to estimate aboveground carbon and increased precision of annualized aboveground carbon increments by including data from forty-one plots located elsewhere on the Guiana Shield. The probabilities of aboveground carbon recovery to pre-logging levels 32years after harvests of 15, 23 and 46m3ha−1 were 45%, 40%, and 24%, respectively. Net aboveground carbon increment for logged forests across all harvest intensities was 0.64MgCha−1yr−1, more than twice the rate observed in unlogged forests (0.26MgCha−1yr−1). The probabilities of timber stock recovery at the end of the 32-year period were highest after harvest intensities of 15 and 23m3ha−1 (with 80% probability) and lowest after the harvest of 46m3ha−1 (with 70% probability). Timber stock recovery across all harvest intensities was driven primarily by residual tree growth. Application of the legal cutting limit of 25m3ha−1 will require more than 70 and 40years to recover aboveground carbon and timber stocks, respectively, with 90% probability. Based on the low recruitment rates of the twelve species harvested, the 25year cutting cycle currently implemented in Suriname is too short for long-term timber stock sustainability. We highlight the value of propagating uncertainty from individual tree measurements to statistical predictions of carbon stock recovery. Ultimately, our study reveals the trade-offs that must be made between timber and carbon services as well as the opportunity to use carbon payments to enable longer cutting rotations to capture carbon from forest regrowth.

王朗自然保护区地栖脊椎动物群落结构和生境类型的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 王朗自然保护区地栖脊椎动物群落结构和生境类型的关系 DOI: 10.5846/stxb201606071094 作者: 作者单位: 中国科学院成都生物研究所,北京大学,王朗国家级自然保护区;王朗国家级自然保护区,王朗国家级自然保护区;王朗国家级自然保护区,北京大学,中国科学院成都生物研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 保护国际基金项目；中国生物多样性监测与研究网络项目 The relationship between community structure of ground-dwelling vertebrates and habitat types in the Wanglang Natural Reserve Author: Affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences,,,,Peking University, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:2006年8-11月，采用围栏陷阱法对四川省王朗自然保护区地栖脊椎动物的群落结构进行了研究，结合森林砍伐、旅游和植被恢复方式等干扰因子所推动的动物栖息生境变化，探讨了动物群落结构和生境类型的关系。监测历时75 d，8个样地共捕获3纲6目17科21种778只地栖脊椎动物，物种组成包括3种两栖类、1种鸟类和17种哺乳类。每百陷阱日的捕获率为32.4%；以普通鼩鼱、高山姬鼠、纹背鼩鼱、高原林蛙等4种为优势种，占全部捕获数的76.9%；其余17种的个体数均较少，物种多度和其分布区域呈显著线性相关（P < 0.001）。动物群落多样性指数，以干扰相对弱的原生针叶林物种多样性指数和均匀度指数为最高，而优势度指数最低；其次为旅游干扰的原生林灌丛和自然更新的次生林灌丛；人工种植的次生针叶林多样性指数和均匀度指数最低，而优势度指数最高。以动物群落相似性指数进行系统聚类，8个样地的动物群落聚为3类：即干扰相对弱的原生针叶林动物群落、严重干扰的人工针叶林动物群落、部分干扰的原生林灌丛和次生林灌丛动物群落。 Abstract:The community structure of grand-dwelling vertebrates in the Wanglang Natural Reserve, Sichuan Province, was examined in relation to a wide range of habitat changes associated with logging, tourism, and restoration measures. Eight sampling sites from a range of habitats were monitored using drift-fences and pitfall traps from August to November 2006. A total of 778 individuals representing 21 species of vertebrates were captured in 75 d, including three species of amphibians, one species of bird, and 17 species of mammals. The capture rate of vertebrates was 32.4%. The vertebrate community was dominated by four species with high abundance. The relative abundance of the species was correlated with their distribution ranges (P < 0.001). Each species was trapped on different dates. Fifteen species were captured within 14 d, no new species were captured from day 15 to 30, and rest of the six species were captured after 30 sampling days. For long-term investigations, 15-30 days interval is enough to encounter vertebrate species from this method. The cumulative number of species at the sampling site exhibited a logarithmic growth curve. After 40-60 specimens were trapped, 70% of the overall species richness in one sampling site was monitored. In general, changes in the quality of habitat resulted in considerable differences in species composition, abundance, and distribution pattern of community structure, with a marked decline in diversity and evenness indices, and a substantial increase in the proportion of dominant species. The diversity of vertebrates in different habitats indicated that species diversity index (2.099) and evenness index (0.875) was highest, but the species dominance index (0.149) was lowest in weakly disturbed primary forest. Both primary shrubland with tourism and secondary shrubland experiencing spontaneous recovery from logging had moderate indices. In contrast, the secondary forest with artificial recovery had the lowest species diversity index (1.337) and evenness index (0.520), but the highest species dominance index (0.454). Based on the similarity index of community structure, a phenogram was reflected in three assemblages representing weakly disturbed, partially disturbed, and heavily disturbed habitats. Among three disturbance factors, timber harvest accounted the high level of disturbance and 42.9% difference in species composition between logged and un-logged forest communities after 50 years of clear cutting. Species most affected by tourism were associated with primary forest under an intermediate level of disturbance, whereas after 50 years of regeneration, the spontaneous recovery produced a mixed community structure that had recovered and exhibited higher species diversity. 参考文献 相似文献 引证文献

Recruitment, growth and recovery of commercial tree species over 30 years following logging and thinning in a tropical rain forest

Sustainable production of timber from commercial species across felling cycles is a core challenge for tropical silviculture. In this study, we analysed how the intensity and type (harvesting and thinning) of silvicultural interventions affect: (a) recruitment of small stems (5cm⩽DBH<15cm), (b) increment of future crop trees (15cm⩽DBH<50cm) and (c) recovery of harvestable growing stocks (DBH⩾50cm) of 52 commercial timber species in the Tapajós National Forest, Brazil. Intervention intensities comprised logging (on average 61m3ha−1) and associated damage to remaining trees (1982) and thinning (refinement) to reduce basal area at the stand level (1993/1994). These interventions together resulted in a gradient of reduction in basal-area from 19 to 53% relative to pre-logging stocks. Trees (DBH⩾5cm) were measured on eight occasions in 41 permanent sample plots of 0.25ha each. The dynamics were analysed at the stand level over 30years and compared among treatments (including unlogged forest) and to pre-logging stands. Recruitment and growth temporarily increased following interventions and recovery of harvestable growing stock decreased with intervention intensity. Harvesting substantially increased recruitment of small stems relative to the unlogged forest, but recruitment rates decreased over time and did not increase following thinning. Gross increment of future crop trees was higher in logged than in unlogged forest and increased over time with high intensity of follow-up thinning, where it remained significantly higher than in control plots over time. Increased recruitment rates and volume increments were mainly driven by long-lived pioneer species, changing the composition of the growing stock. In 2012, recovery of harvestable growing stock of the 22 species harvested in 1982 varied between 19% and 57% in logged treatments relative to pre-logging levels. When considering an additional group of 30 species that were not harvested in the permanent sample plots but are now potentially commercial, relative recovery increased enough to support a second harvest under the present regulations (maximum harvest of 30m3ha−1), except for treatment with high thinning intensity where stocks were still less than 30% relative to pre-harvest levels. In contrast, light and medium thinning intensity promoted recovery of harvestable growing stock. These findings indicate that intensive thinning should be avoided and silvicultural interventions oriented towards future crop trees of target species should be adopted. This may enhance recovery and reduce unintended changes in composition of the commercial growing stock.

Aboveground biomass variability across intact and degraded forests in the Brazilian Amazon

AbstractDeforestation rates have declined in the Brazilian Amazon since 2005, yet degradation from logging, fire, and fragmentation has continued in frontier forests. In this study we quantified the aboveground carbon density (ACD) in intact and degraded forests using the largest data set of integrated forest inventory plots (n = 359) and airborne lidar data (18,000 ha) assembled to date for the Brazilian Amazon. We developed statistical models relating inventory ACD estimates to lidar metrics that explained 70% of the variance across forest types. Airborne lidar‐ACD estimates for intact forests ranged between 5.0 ± 2.5 and 31.9 ± 10.8 kg C m−2. Degradation carbon losses were large and persistent. Sites that burned multiple times within a decade lost up to 15.0 ± 0.7 kg C m−2 (94%) of ACD. Forests that burned nearly 15 years ago had between 4.1 ± 0.5 and 6.8 ± 0.3 kg C m−2 (22–40%) less ACD than intact forests. Even for low‐impact logging disturbances, ACD was between 0.7 ± 0.3 and 4.4 ± 0.4 kg C m−2 (4–21%) lower than unlogged forests. Comparing biomass estimates from airborne lidar to existing biomass maps, we found that regional and pantropical products consistently overestimated ACD in degraded forests, underestimated ACD in intact forests, and showed little sensitivity to fires and logging. Fine‐scale heterogeneity in ACD across intact and degraded forests highlights the benefits of airborne lidar for carbon mapping. Differences between airborne lidar and regional biomass maps underscore the need to improve and update biomass estimates for dynamic land use frontiers, to better characterize deforestation and degradation carbon emissions for regional carbon budgets and Reduce Emissions from Deforestation and forest Degradation (REDD+).