A protocol to estimate epiphyte biomass in a forest management unit: case of Cameroon

Vascular epiphyte biomass is poorly studied in Congo Basin forest. The aim of this study was to develop a protocol to estimate epiphyte biomass. Epiphytes were collected on 77 phorophytes of diameter 57–169.5 cm, oven-dried for biomass. Allometric equations for epiphyte biomass were developed with diameter and phorophyte height as predictor variables using regression analysis. The mean epiphyte biomass was 24.48 kg/phorophyte with a standard deviation of ±49.99. Cylicodiscus gabunensis and Triplochiton scleroxylon hosted the greatest epiphyte biomass with a mean vascular epiphyte biomass of 71.65 and 62.3 kg/phorophyte, respectively. Kruskal–Wallis test (p = 0.005) showed that there was a significant difference between epiphyte biomass with respect to phorophyte species. The relationship found between epiphyte biomass and dendrometric variables of the phorophytes were intermediate (Adj.R² < 0.630) meaning epiphyte biomass increased with increasing tree diameter. However, models with diameter input variables had greater prediction than input variables of total height. Based on the Akaike Information Criterion (AIC), the allometry lnY = ?21.37 + 5.21 x ln(D) ?0.35 x ln(H) with AIC (183) was the best equation for the prediction of epiphyte biomass. These findings shall contribute to REDD+ (Reducing Emissions from Deforestation and Forest Degradation) strategy for climate change mitigation in Congo Basin.     

Response of vascular epiphyte diversity to different land-use intensities in a neotropical montane wet forest

Although vascular epiphytes contribute substantially to the biodiversity of tropical montane forests, it is unclear how their diversity and community composition is affected by forest alteration. We studied the response of vascular epiphyte assemblages to different intensities of land-use in a montane wet forest of northeastern Ecuador: (1) unmanaged mature forest; (2) mature forest with mid- and understorey opened for cattle grazing; and (3) isolated remnant trees in cattle pastures. The numbers of individuals and species of epiphytes per host tree did not differ significantly between land-use types, neither did total epiphyte species richness (n = 30 trees). However, total species richness of pteridophytes was significantly lower on isolated remnant trees compared to unmanaged forest, whereas several taxa rich in xerotolerant species (Bromeliaceae, Orchidaceae, Piperaceae) exhibited the opposite trend. An analysis of floristic composition using ordination (NMS) and randomisation techniques (MRPP) showed that epiphyte assemblages on isolated remnant trees were significantly distinct from unmanaged forest while managed forest was intermediate between those two vegetation types. Ordination analysis further indicated reduced floristic heterogeneity in disturbed habitats. These results suggest considerable, rapid species turnover since land-use change 6 years prior to study, with pteridophytes being replaced by more xerotolerant taxa. We attribute this floristic turnover primarily to changes in microclimate towards higher levels of light and desiccation stress associated with forest disturbance. Our results support the notion that community composition offers a more sensitive indicator of human disturbance than species richness.     

Community of vascular epiphytes on some phorophytes in the Babadjou Subdivision (Western Cameroon): Case of Bamelo

The environmental degradation of the western region of Cameroon has intensified over time and has contributed to the perturbation of the original floristic uniformity of pioneer vegetation. Epiphytes, which are very sensitive plants, have refuge mostly on phorophyte, hence permitting the evaluation of the conservation state of natural ecosystems. The present study aims to assess a floristic inventory of vascular epiphytes in the locality of Bamelo. Sampling was carried out on 100 individuals, 20 individuals for each of the five phorophyte species based on their abundance in the locality. A total of 36 species divided into eight families and 19 genera were recorded. Monocotyledons were the most abundant with 58.33% of community and represented only by the Orchidaceae family; pteridophytes and dicotyledons represent 22.22 and 19.44%, respectively. Persea amercina and Cola anomala were the most diversified phorophytes (19 species); Dacryodes edulis was the least diversified (eight). The principal component analysis revealed affinities between the epiphytic flora of Dacryodes edulis and Persea americana; Croton macrostachyus and Spathodea campanulata. At a time where the degradation of biodiversity occurs at an alarming rate, the conservation of such species becomes problematic. In view of the present results, epiphytes found refuge on fruit trees in plantations.     

Phytosociological characteristics and diversity of trees in a comanaged protected area of Bangladesh: Implications for conservation

ABSTRACT

The Chunati Wildlife Sanctuary (CWS), a degraded protected area in southeastern Bangladesh, had been under comanagement since 2004. This study examined phytosociological characteristics and diversity of trees in CWS and discussed villagers’ opinions on the impact of comanagement on forest conservation. Following a stratified and systematic sampling 140 circular plots, 17.84-m radius each, were laid out in seven forest beats for the assessment of phytosociological characteristics and tree diversity. Several key-informant interviews and 15 focus group discussions were held to explore the impact of comanagement on forest conservation and on villagers’ livelihood. A total of 93 tree species were identified having a diameter at breast height (dbh) of ≥ 5 cm in 36 plant families. The dominant species were Acacia auriculiformis, Dipterocarpus turbinatus, Ficus hispida, and Tectona grandis. The average density of trees was 239 trees/ha of which 60% was composed of planted exotic species. Nearly 90% trees were belonging to 5- to 15-cm dbh class and the Shannon-Wiener index was 3.15. The comanagement governance had brought positive changes in forest conservation. However, to sustain the engagement of poor villagers in the comanagement and conservation of degraded CWS, more collective efforts are needed to support their living.     

Mycorrhizal associations in the rain forest of South Cameroon

Mycorrhizal associations of important tree species were investigated within the research area of the Tropenbos Cameroon Programme (TCP), situated on the western portion of the Atlantic Biafrean forest of south Cameroon. Ninety-seven tree species of economic, social, and ecological importance, and three lianas were selected in three sites that differed in altitude, soil clay content, and soil pH. In each site plots were laid out in undisturbed forest. In each plot, seedlings, saplings, juvenile, and mature trees were identified to species level and counted; girth at breast height measured and basal area calculated; root samples were taken and examined for mycorrhizal type and extent of mycorrhizal colonization.

All 100 species investigated were mycorrhizal. Tree of 74 species formed exclusively arbuscular mycorrhizas (AM); 23 trees and three Gnetum species formed ectomycorrhizas (ECM). Five of these ECM plants also harbored AM structures. Extent of mycorrhizal root colonization showed large differences for various AM trees; however, colonization of more than half of these trees was less than 25%. Colonization of ECM trees was often higher than 75%. The contribution of ECM trees to basal area varied between 19 and 35%. ECM trees often occurred in small to large clumps. In sustainable forest management plans, existing ECM forest clumps should be given special conservation value.     

Woody plant species diversity and composition in and around Debre Libanos church forests of North Shoa Zone of Oromiya,Ethiopia

Dry afromontane forests are among the most poorly managed and endangered ecosystems.Therefore,we assessed the composition,diversity,and conservation status of woody plant species of the Debre Libanos church forests and surrounding forest lands in Oromiya Regional National State,central Ethiopia in 62 nested circular sample plots spaced 200 m apart along two transect lines.Large circular plots 314 m~2 were used to sample trees with DBH of at least 10 cm,and subplots of 28.26 m~2 were laid in each main plot were used to assess saplings and shrubs;a small subplot of 3.14 m~2 was used to assess seedlings.In total,70 woody plant species belonging to 62 genera and 43 families were recorded.Of these,59,28 and 32 were in the church,government and private forest types,respectively.The most dominant families were Fabaceae and Verbenaceae,each represented by five species.In the forests considered,trees accounted for 61%,and shrubs with diameter at breast height(DBH) of 1-10 cm accounted for ca.33%.Among growth forms of woody species,shrubs and seedlings,followed by trees constituted much of the density of woody species in all the three ownership types of forests.The church forest had the most species(59) and highest Shannon(3.12) and Simpson(0.92) species diversity indices,and the government and private forests had a nearly similar total number of species and Shannon and Simpson species diversity indices.Most of the species with higher importance value indices(IVI) were indigenous in origin within the church forest(Juniperus procera=82),government forest(J.procera=66) and private forest(Acacia abyssinica=84).The composition,diversity,and population structure of woody species in the church forest were significantly higher than in the other forest lands.However,interventions of the government and private sectors to conserve forest systems in the areas,particularly the government-owned forest and specific species such as Olea europaea need active enrichment plantings due to their limited natural regeneration.Without improved management interventions,livelihood income diversification and ecosystem services obtained from the forest will not be sustainable.     

The role of complex agroforestry systems in the conservation of forest tree diversity and structure in southeastern Ghana

The role of different agroforestry systems in the conservation of plant diversity and forest structure has not been directly compared in many agricultural dominated landscapes. In this study, we investigated tree diversity and forest structure in a complex agroforestry landscape traditionally grown for cocoa and mixed food crops and compared these to the natural forest in southeastern Ghana. The study was carried out using 36 25 m × 25 m plots. There was significant difference [95% Confidence Interval (95% CI)] in the native forest/non-crop tree species richness between the natural forest and the agroforest farmlands but species richness was similar between the cocoa and mixed food crops agroforests. The density of native forest/non-crop trees was significantly higher (P < 0.05) in the natural forest but similar between cocoa and mixed food crops agroforest. Similarly, the basal area of native forest/non-crop trees was significantly higher (P < 0.05) in the natural forest but comparable between cocoa and food crops agroforest. Of the 20 most abundant native forest/non-crop trees recorded, 12 of them showed significant responses (P < 0.05) to land use change with nine of the species significantly abundant in the natural forest relative to the agroforest systems. Eighteen native forest/non-crop trees species in the agroforestry systems were commonly recorded as being used; 100% of them being used as fuel wood with 83.3 and 77.8%, respectively, used as medicines and materials. The findings of this study suggests that although complex agroforestry systems are a poor substitute for the natural forest the heterogeneous mosaic landscape in which complex agroforestry forms part can be strategically managed to maximize the benefits of both sustainable agriculture production and conservation of plant diversity by acting as buffer between protected areas and intensively managed areas.     

Carbon storage and density dynamics of associated trees in three contrasting Theobroma cacao agroforests of Central Cameroon

In Central Cameroon cocoa is mainly produced by household farming systems based on complex associations between cocoa and companion trees. Setup either on native/remnant forest or savannah, these agroforestry systems (AFS) are managed according their geographical position and local pedoclimatic conditions. In this paper, we investigated the effects of local management strategies on carbon (C) storage of live trees in three different cocoa production zones of Central Cameroon. In the 58 fields studied, 8,996 cocoa trees and 1,258 companions were surveyed. Tree sampling was non-destructive and to estimate C storage we used allometric models for above- and belowground biomasses. We measured abundance, height, diameter at breast height and determined species of companion trees. We distinguished between four cocoa plantation age categories (immature, young, mature and senescent) and three preceding systems (forest, forest gallery and savannah). We surveyed farmers’ use of each associated tree, allocated it to a functional category and asked if it had been introduced or conserved. Total C content of live trees was on average close to 70 t ha^?1. We found that it mostly relied on associated trees—cocoa trees contribution being ac. 2–12 % of live trees total C. The level of contribution to C storage of companions from different use categories differed between sites—trees producing food had contributed most in Bokito and Obala while trees used for shading or fertility contributed most in Ngomedzap. Dynamics of C storage in live trees was found to be independent from cocoa trees growth and age. When aging, AFS continuously lost companion trees and especially conserved ones putatively because of farmers’ selective logging. Yet, AFS apparently maintained equivalent C storage abilities with time. Hence, even if cocoa do not contribute significantly to C storage in our study, the systems into which they are included are able to significantly store C and may also contribute to other ecological services such as conservation.     

Individual legacy trees influence vertebrate wildlife diversity in commercial forests

Old-growth forests provide important habitat elements for many species of wildlife. These forests, however, are rare where lands are managed for timber. In commercial forests, large and old trees sometimes exist only as widely-dispersed residual or legacy trees. Legacy trees are old trees that have been spared during harvest or have survived stand-replacing natural disturbances. The value of individual legacy trees to wildlife has received little attention by land managers or researchers within the coast redwood (Sequoia sempervirens) region where 95% of the landscape is intensively managed for timber production. We investigated the use of individual legacy old-growth redwood trees by wildlife and compared this use to randomly selected commercially-mature trees. At each legacy/control tree pair we sampled for bats using electronic bat detectors, for small mammals using live traps, for large mammals using remote sensor cameras, and for birds using time-constrained observation surveys. Legacy old-growth trees containing basal hollows were equipped with ‘guano traps’; monthly guano weight was used as an index of roosting by bats. The diversity and richness of wildlife species recorded at legacy trees was significantly greater than at control trees (Shannon index=2.81 versus 2.32; species=38 versus 24, respectively). The index of bat activity and the number of birds observed was significantly greater at legacy trees compared to control trees. We found no statistical differences between legacy and control trees in the numbers of small mammals captured or in the number of species photographed using remote cameras. Every basal hollow contained bat guano and genetic methods confirmed use by four species of bats. Vaux’s swifts (Chaetura vauxi), pygmy nuthatches (Sitta pygmaea), violet-green swallows (Tachycineta thalassina), and the long-legged myotis (Myotis volans) reproduced in legacy trees. As measured by species richness, species diversity, and use by a number of different taxa, legacy trees appear to add significant habitat value to managed redwood forests. This value probably is related to the structural complexity offered by legacy trees. The presence of a basal hollow, which only occur in legacy trees, was the feature that appeared to add the greatest habitat value to legacy trees and, therefore, to commercial forest stands. The results of our study call for an appreciation for particular individual trees as habitat for wildlife in managed stands. This is a spatial resolution of analysis that, heretofore, has not been expected of managers. The cumulative effects of the retention of legacy trees in commercial forest lands could yield important benefits to vertebrate wildlife that are associated with biological legacies.     

Epiphyte diversity and biomass loads of canopy emergent trees in Chilean temperate rain forests: A neglected functional component

We document for the first time the epiphytic composition and biomass of canopy emergent trees from temperate, old-growth coastal rainforests of Chile (42°30′S). Through tree-climbing techniques, we accessed the crown of two large (c. 1 m trunk diameter, 25–30 m tall) individuals of Eucryphia cordifolia (Cunoniaceae) and one large Aextoxicon punctatum (Aextoxicaceae) to sample all epiphytes from the base to the treetop. Epiphytes, with the exception of the hemi-epiphytic tree Raukaua laetevirens (Araliaceae), were removed, weighed and subsamples dried to estimate total dry mass. We recorded 22 species of vascular epiphytes, and 22 genera of cryptogams, with at least 30 species of bryophytes, liverworts and lichens. The dominant vascular epiphytes were Fascicularia bicolor (Bromeliaceae), Raukaua laetevirens, Sarmienta repens (Gesneriaceae), and filmy ferns (Hymenophyllaceae). Epiphyte loads per tree ranged between 134 and 144 kg dry mass, with 60–70% water. The hemi-epiphytic tree R. laetevirens added between 1 and 2.6 t of dry mass to each host tree. A main component of epiphyte biomass, making 70% of the weight, was detritus and roots, while leaves, stems, and fronds made up the remaining 30%. Emergent trees hold a high proportion of the regional diversity of epiphytes: 33% of all flowering epiphytes, and 50% of all filmy ferns described for Chilean temperate forests. Dry epiphyte biomass associated only with the emergent E. cordifolia trees in coastal forests was estimated in 10 t/ha. Epiphyte biomass may store up to 300 l of water in each emergent tree, and add 40–150% of photosynthetic biomass to the tree crowns. Based on this evidence, epiphytes may play key but generally neglected roles in ecosystem carbon uptake, water storage, and nutrient cycling. Moreover, emergent trees represent nuclei of biodiversity and ecosystem functions distributed throughout mature forests. Forest management should recognize large trees as significant management units for the preservation of biodiversity and ecological functions.     

Fine-scale analysis reveals a potential influence of forest management on the spatial genetic structure of Eremanthus erythropappus

Forest management may have significant effects on forest connectivity and natural population sizes.Harvesting old-growth single trees may also change natural patterns of genetic variation and spatial genetic structure.This study evaluated the impacts of forest management using a silvicultural system of seed trees on the genetic diversity and spatial genetic structure of Eremanthus erythropappus(DC.)MacLeish.A complete survey of 275 trees on four plots was undertaken out to compare the genetic variation of a managed stand with an unmanaged stand.We genotyped all adult and juvenile individuals 60 months after the management and compared the genetic diversity and the spatial genetic structure parameters.Genetic diversity was considered high because of an efficient gene flow between stands.There were no genetic differences between stands and no evidence of inbreeding.Genetic clustering identified a single population(K=1),indicating no genetic differentiation between managed and unmanaged stands.Adult and juvenile individuals of the unmanaged stand were more geographically structured than individuals from the managed one.There was a tendency of coancestry among juveniles at the first class of distance of the managed stand,suggesting a drift of genetic structure possibly caused by management.Understanding early responses to management on genetic diversity and stand structure is a first step to ensuring the effectiveness of conservation practices of tree species.The sustainability of forest management of E.erythropappus on genetic diversity,and more accurately,on spatial genetic structure needs evaluation over time to promote effective conservation of the population size and genetic variability.     

Assessment of plant species diversity of ancient tea garden communities in Yunnan, Southwest of China

Ancient tea garden has existed in Lancang County, Yunnan Province for more than 1,300 years, and is regarded as the provenance of Pu’er Tea’s seed source. The ancient tea garden ecosystem is a typical model that integrates conservation biodiversity and utilization of natural resources. In order to reveal the role of biodiversity conservation of this ecosystem, plant diversity and application value of ancient tea gardens, normal tea gardens and secondary forestry communities in Lancang County were surveyed and compared. 360 households investigation were also conducted by using household-based agro-biodiversity assessment (HH-ABA). The results showed: (1) Ancient tea garden communities have high biodiversity, whose plant species diversity (H = 3.03) is lower than that of secondary forestry (H = 4.59) and higher than that of normal tea garden (H = 2.62); (2) Life forms analysis of plant species showed the vertical structure of the ancient tea garden communities are intact, herbs, trees, shrubs, vines, epiphytes are included, which is similar to that of secondary forest, while normal tea garden is dominant by herbs and no trees; (3) A large number of protected species, including five endangered, seven vulnerable and three rare, is well conserved in the ancient tea garden, while no protected species were found in secondary forest and normal tea garden; (4) The analysis of agro-biodiversity revealed that 56 % of plant species in the ancient tea garden are effectively used by households, while no plant except tea trees is used in normal tea garden; (5) The integrated values of ancient tea garden and normal tea garden illustrated that both biodiversity conservation and economic income of ancient tea garden are higher than that of normal tea garden. We suggest that the local peoples’ knowledge and experience on resource management and utilization should be well documented and encouraged, and effective conservation and reasonable utilization of ancient tea garden would be achieved through training and demonstration with the participation of the local government, research institution and farmer.     

Plant and bird diversity in rubber agroforests in the lowlands of Sumatra,Indonesia

Plant and bird diversity in the Indonesian jungle rubber agroforestry system was compared to that in primary forest and rubber plantations by integrating new and existing data from a lowland rain forest area in Sumatra. Jungle rubber gardens are low-input rubber (Hevea brasiliensis) agroforests that structurally resemble secondary forest and in which wild species are tolerated by the farmer. As primary forests have almost completely disappeared from the lowlands of the Sumatra peneplain, our aim was to assess the contribution of jungle rubber as a land use type to the conservation of plant and bird species, especially those that are associated with the forest interior of primary and old secondary forest. Species-accumulation curves were compiled for terrestrial and epiphytic pteridophytes, trees and birds, and for subsets of ‘forest species’ of terrestrial pteridophytes and birds. Comparing jungle rubber and primary forest, groups differed in relative species richness patterns. Species richness in jungle rubber was slightly higher (terrestrial pteridophytes), similar (birds) or lower (epiphytic pteridophytes, trees, vascular plants as a whole) than in primary forest. For subsets of ‘forest species’ of terrestrial pteridophytes and birds, species richness in jungle rubber was lower than in primary forest. For all groups, species richness in jungle rubber was generally higher than in rubber plantations. Although species conservation in jungle rubber is limited by management practices and by a slash-and-burn cycle for replanting of about 40 years, this forest-like land use does support species diversity in an impoverished landscape increasingly dominated by monoculture plantations.     

基于森林生态系统管理的森林经营与传统森林经营的比较研究

通过长期定位观测研究,对基于森林生态系统管理的经营方法与传统森林经营方法进行了对比研究。结果表明:与传统森林经营方法相比,基于森林生态系统管理的经营方法可有效提高林分年蓄积增长量,采取基于森林生态系统管理经营的林分单位面积年蓄积增长量分别是择伐林分、抚育采伐及对照林分年蓄积增长量的1.20、1.17和1.49倍;林内物种多样性及丰富度指数较传统森林经营方法(抚育、择伐)明显增大,优势种相对明显,个体数在不同种类间的分布较为集中;林内土壤含水量及凋落物输入量增大,土壤肥力明显提高。     

Trees and farming in the dry zone of southern Honduras II: the potential for tree diversity conservation

The potential of the dry zone agro-ecosystem of southern Honduras to contribute to the conservation of Mesoamerican dry forest tree diversity is evaluated. Four rural communities containing eight land uses were surveyed using rapid botanical sampling resulting in the identification of 241 tree and shrub species. As a result of ordination analysis, it is concluded that the land uses are relatively similar in their species composition, particularly maize fields (milpas), fallows, pastures and woodlots, because of the predominance of natural regeneration. Therefore all land uses might contribute to local tree diversity conservation. Those land uses in which planting also contributes to diversity, home gardens (solares) and orchards, are more distinct; however the tree species found there are widespread and often exotics and thus not the usual focus of conservation measures. Across the landscape the total complement of species considered a global priority for biodiversity conservation is very low and therefore this agro-ecosystem does not represent a good place in which to implement dry forest tree diversity conservation programmes. Instead its value is likely to be in the contribution that tree diversity makes to rural livelihoods. Particular consideration is given to Swietenia humilis Zucc. (small leaved mahogany) and its status as a threatened species is questioned because of its abundance within this landscape and its wide distribution. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of bark harvest and other human activity on populations of the African cherry (Prunus africana) on Mount Oku, Cameroon

Bark extracts from the African cherry, Prunus africana (Rosaceae), are a popular treatment for enlarged prostates. Harvests of the bark began in Cameroon in the 1970s. Because of concerns regarding the sustainability of the trade, the species is included on the IUCN Red List and in CITES Appendix II. This study followed five P. africana populations in the Kilum-Ijim Forest Preserve on Mount Oku, Cameroon, examining growth, mortality and reproductive parameters, as well as response to harvest and other human activities. During the first part of the study (1998–1999), the forest had limited human activity; by the second part (2007–2008), more activity was apparent, including wildfires, grazing and a forest-wide bark harvest in 2005/2006. Over the study period, population structure differed from a typical J-shaped frequency curve for long-lived species, which may reflect past harvesting. After the 2005/2006 harvest, the population structure had shifted slightly toward the smaller size classes. In addition, the number of surviving trees was reduced in all size classes. About half of the reproductive trees died during the study. Size class was not a significant predictor of death, but the location of the harvest (plot) was. All trees affected by wildfires died, suggesting that the species is not adapted to fire. Trees that were harvested without disrupting the vascular cambium survived better and had minimal loss of crown. Thus, the fate of the trees in a given plot may lie in the care taken by an individual harvester. Average growth (0.34 cm per year) was not significantly different among the size classes. Crown die-back significantly reduced fruit production, obscuring the asynchronous alternating fruiting pattern. Seedling numbers followed a similar alternating pattern, but survival was negligible due to grazing. The combined factors of mortalities of a large percentage of reproductive trees (especially the largest ones), highly reduced fruit production and poor seedling survival offer a bleak prognosis for future regeneration and long-term persistence of the species in this forest. Only after decades of harvest are existing standing crop inventories and scientifically based annual quotas now being determined. It is known that the trees are easily domesticated. Efforts have been intensified to train villagers and community forest managers in vegetative propagation techniques and nursery practices, offering some hope that the species can be successfully managed to provide for sustainable harvests and dependable rural livelihoods.     

Effects of Different Management Practices on Stand Composition and Species Diversity in Subtropical Forests in Nepal: Implications of Community Participation in Biodiversity Conservation

In this article, we compared the structure, composition, and diversity of trees, shrubs and saplings, seedlings and herbaceous species of community- and government-managed forests in the lowlands of eastern Nepal. Results suggest that among the trees, the community forest was dominated by a single species, Shorea robusta. However, Shorea robusta and Terminalia myriocarpa were codominant in the government forest. Tree density and basal area were higher in the government forest, but shrub/sapling density and basal area were higher in the community forest, suggesting a positive effect of community management on tree regeneration. Overstory species assemblages showed an obvious compositional difference between the forests, but understory species assemblages were less obvious. Plot-level tree and shrub/sapling species richness was higher in the government forest than the community forest. However, seedling-herbaceous species richness was higher in the community forest. The dominance of Shorea robusta trees in the community forest suggests that people involved in managing forests may be more interested in a limited number of economically valuable species while removing less important trees. Such preferential management practices may increase resource heterogeneity within a forest and maintain species diversity in the understory. Thus, community participation in forest management should be encouraged, with guided management techniques and exercises, to achieve maximum forest recovery, provide sustainable ecosystem services, and maintain forest diversity.     

History matters: Impact of historical land use on butterfly diversity in clear-cuts in a boreal landscape

In Swedish boreal landscapes, the loss of species-rich semi-natural grasslands is largely due to a long history of agricultural abandonment. Large areas historically managed as meadows have become mature coniferous forest. This study focused on the potential biological legacy following a long period of grassland abandonment. The butterfly fauna in clear-cuts which was historically meadows and abandoned long enough to allow a generation of conifers to mature (70-90 years) was compared with clear-cuts which were historically coniferous forest. The results showed that clear-cuts historically managed as meadows were: (i) much richer in individuals, (ii) more species-rich, and (iii) contained many more grassland specialists than clear-cuts with a history as forest, with many of these species threatened in other parts of Europe.The results from our study demonstrate for the first time, to our knowledge, that the legacy of historical land-use in remnant plant communities can affect butterfly diversity in clear-cuts and hence the large-scale dynamics over a timescale of a full tree rotation. The results of this study have implications for forest management practices. Replanting clear-cuts on land that was previously meadows with deciduous trees or allowing the forest to regenerate naturally instead of planting conifers would make it possible to preserve a greater diversity of habitats for butterflies and other organisms.     

生态疏伐对华北落叶松林分结构和生物多样性的影响

森林抚育对调整林分结构、促进林木生长都具有极大作用。为了解抚育对华北落叶松林分结构和林下物种多样性的影响,以承德市第三乡林场华北落叶松—白桦混交林为研究对象,采用对比分析的方法,对生态疏伐前后的林分结构、径阶分布和生物多样性进行了探讨。结果表明:生态疏伐后林分平均胸径增加2.1cm,平均树高稍有变化,林分密度从疏伐前的1 365株/hm~2下降到900株/hm~2;生态疏伐前,直径分布曲线呈左偏,6~16径阶林木数量占总数的42.6%;疏伐后,6~16径阶林木株数占总株数的21.3%,直径分布稍向右偏,更趋于正态分布;疏伐后,林下物种的Simpson和Shannon-Wiener指数均有所增加,Pielou均匀度指数在1号、4号、5号样方内有所下降,2号、3号样方内呈增加趋势,且3号样方的Simpson、Shannon-Wiener和Pielou均匀度指数涨幅均最大,分别比抚育前增加了0.373、0.834和0.203。     

Diversity and structural composition of species in dipterocarp forests: a study from Fasiakhali Wildlife Sanctuary,Bangladesh

Fasiakhali Wildlife Sanctuary is a protected area composed of tropical remnant rainforest that harbor substantial number of large,old Garjan(Dipterocarpus spp.)trees.The present study assessed composition,structure and diversity of the species in this protected area.A total of 32 trees species were recorded with DBH ≥ 11 cm belonging to 24 genera and 19 families.The forest is low in plant diversity as represented by Shannon–Wiener diversity and Simpson Dominance indices.Dipterocarpus turbinatus was the most dominant species with maximum relative density,frequency,dominance,and importance value index.Syzygium firmum and Tectona grandis followed in terms of dominance.The structural composition indicated higher number of individuals in the medium growth classes(41 to 511 cm DBH and 16–20 m height ranges),whereas D.turbinatus was the only species that dominated most of the growth classes.Poor stem density in lower growth classes indicated meager recruitment of regeneration which may be due to lower annual precipitation,increased grazing and encroachments.This study will help to understand the patterns of tree species composition and diversity in the remnant dipterocarp forests of Bangladesh.It will also contribute to identifying threatened plants to undertake D.turbinatus based conservation and sustainable management of the Fasiakhali Wildlife Sanctuary.