Tree structure,regeneration and woody biomass removal in a sub-tropical forest of Mamlay watershed in the Sikkim Himalaya

This paper reports on the tree structure, tree dimension relationships and woody biomass production and removal of a sub-tropical natural forest in the Mamlay watershed of the Sikkim Himalaya. The forest provides fuel, fodder and timber to four villages. Only 11 tree species were found growing in the tree stratum despite the high diversity in the stand (32 tree species). The forest shows good regeneration potential with 5474 seedlings/ha and 1776 saplings/ha, but the population structure revealed a marked paucity of trees of higher diameter classes due to removal of trees of lower diameters. Standing wood biomass of 362 Mg/ha is mainly shared by 4 dominating species in the stand. The boles are removed mainly for timber and fuel purposes and about 22 Mg/ha wood biomass was removed in between 1987–1991. Net Primary productivity of woody biomass of the forest is recorded to be 18 Mg/ha/year. 3.85 Mg/ha of annual woody biomass production was removed in the form of tree boles apart from lopping of branches.     

Forest Pattern, Fire, and Climatic Change in the Sierra Nevada

In the Sierra Nevada, distributions of forest tree species are largely controlled by the soil-moisture balance. Changes in temperature or precipitation as a result of increased greenhouse gas concentrations could lead to changes in species distributions. In addition, climatic change could increase the frequency and severity of wildfires. We used a forest gap model developed for Sierra Nevada forests to investigate the potential sensitivity of these forests to climatic change, including a changing fire regime. Fuel moisture influences the fire regime and couples fire to climate. Fires are also affected by fuel loads, which accumulate according to forest structure and composition. These model features were used to investigate the complex interactions between climate, fire, and forest dynamics. Eight hypothetical climate-change scenarios were simulated, including two general circulation model (GCM) predictions of a 2 × CO₂ world. The response of forest structure,species composition, and the fire regime to these changes in the climate were examined at four sites across an elevation gradient. Impacts on woody biomass and species composition as a result of climatic change were site specific and depended on the environmental constraints of a site and the environmental tolerances of the tree species simulated. Climatic change altered the fire regime both directly and indirectly. Fire frequency responded directly to climate's influence on fuel moisture, whereas fire extent was affected by changes that occurred in either woody biomass or species composition. The influence of species composition on fuel-bed bulk density was particularly important. Future fires in the Sierra Nevada could be both more frequent and of greater spatial extent if GCM predictions prove true. Received 5 May 1998; accepted 4 November 1998.     

Trade‐offs between savanna woody plant diversity and carbon storage in the Brazilian Cerrado

Incentivizing carbon storage can be a win‐win pathway to conserving biodiversity and mitigating climate change. In savannas, however, the situation is more complex. Promoting carbon storage through woody encroachment may reduce plant diversity of savanna endemics, even as the diversity of encroaching forest species increases. This trade‐off has important implications for the management of biodiversity and carbon in savanna habitats, but has rarely been evaluated empirically. We quantified the nature of carbon‐diversity relationships in the Brazilian Cerrado by analyzing how woody plant species richness changed with carbon storage in 206 sites across the 2.2 million km² region at two spatial scales. We show that total woody plant species diversity increases with carbon storage, as expected, but that the richness of endemic savanna woody plant species declines with carbon storage both at the local scale, as woody biomass accumulates within plots, and at the landscape scale, as forest replaces savanna. The sharpest trade‐offs between carbon storage and savanna diversity occurred at the early stages of carbon accumulation at the local scale but the final stages of forest encroachment at the landscape scale. Furthermore, the loss of savanna species quickens in the final stages of forest encroachment, and beyond a point, savanna species losses outpace forest species gains with increasing carbon accumulation. Our results suggest that although woody encroachment in savanna ecosystems may provide substantial carbon benefits, it comes at the rapidly accruing cost of woody plant species adapted to the open savanna environment. Moreover, the dependence of carbon‐diversity trade‐offs on the amount of savanna area remaining requires land managers to carefully consider local conditions. Widespread woody encroachment in both Australian and African savannas and grasslands may present similar threats to biodiversity.     

Informant-based valuation of use and conservation preferences of savanna trees in Burkina Faso

Use and conservation preferences for woody savanna species among the Gourounsi people in south-central Burkina Faso were investigated using a new informant-based valuation system. Two hundred informants from 10 villages evaluated the importance of 20 preselected woody species for nine different uses: edible fruits, vegetable sauce, construction, firewood, medicine, commerce, field trees, and conservation. The study identified eight key species: Parkia biglobosa, Vitellaria paradoxa, Tamarindus indica, Adansonia digitata, Vitex doniana, Detarium microcarpum, Bom-bax costatum, and Strychnos spinosa. They all had high commercial and nutritional value. The local knowledge about the selected woody species was similar between men and women, and between young and old, but it differed between villages. The results indicate that knowledge erosion does not take place among the Gourounsi, but considerable local differences exist. Conservation management should focus on the key species, and for these, assisted regeneration, tree planting, and further ecological research is recommended.     

Influence of urbanization on riparian forest diversity and structure in the Georgia Piedmont, US

Riparian forests are increasingly threatened by urban expansion and land use change worldwide. This study examined the relationships between landscape characteristics and woody plant diversity, structure, and composition of small order riparian corridors along an urban-rural land use gradient in the Georgia Piedmont, US. Riparian plant diversity, structure, and composition were related to landscape metrics and land use. Species richness was negatively associated with impervious surfaces and landscape diversity, and positively associated with forest cover and largest forest patch index. Shannon species diversity was strongly related to the biomass of non-native species, especially for the regeneration layer. Urban sites were characterized by high richness of non-native and pioneer species. Developing sites were dominated by the non-native shrub, Ligustrum sinense Lour., and several native overstory trees, mainly Acer negundo L. While agricultural and managed forest sites were composed of ubiquitous species, unmanaged forest sites had a structurally distinct midstory indicative of reduced disturbance. Urban and agricultural land uses showed decreased native stem densities and signs of overstory tree regeneration failure. Results from this study highlight the impact of the surrounding landscape matrix upon riparian forest plant diversity and structure.     

Carbon Accumulation in Neotropical Dry Secondary Forests: The Roles of Forest Age and Tree Dominance and Diversity

Tropical secondary forests are important sinks for atmospheric carbon, yet C uptake and accumulation rates are highly uncertain, and the mechanisms poorly understood. We evaluated the recovery of C stocks in four pools (aboveground biomass, litter, roots and topsoil) during dry forest regrowth by combining a space for time replacement (that is, a chronosequence) with a repeated measurements approach (that is, a resampling). We fit nonlinear models to chronosequence data to test whether forest age could explain differences in C stocks across sites, and to changes in aboveground biomass calculated from resampling over two 3-year periods, to test the predictive potential of forest age. We combined data from both approaches into structural equation models (SEM) to assess forest age and tree community attributes (diversity and dominance) as drivers of C stocks and changes in aboveground biomass. Forest age explained differences across sites in C stocks for aboveground biomass, litter and live roots, but not for the remaining pools. Observed C stock changes in aboveground biomass were poorly predicted by forest age. SEM revealed that aboveground biomass C was consistently and positively related to forest age and to the community weighted mean of maximum tree height (H _max CWM), but not to tree diversity. Observed C stock changes were related only to H _max CWM, although not consistently across the two 3-year periods. Our results highlight that the chronosequence approach can yield reasonable insights into long-term C accumulation trends, but erroneous estimates of C change over specific time periods. They also show that, in addition to age, dominance by tall statured species, but not tree species diversity, plays a significant role in C accumulation.     

Woody Debris in the Mangrove Forests of South Florida1

Woody debris is abundant in hurricane‐impacted forests. With a major hurricane affecting South Florida mangroves approximately every 20 yr, carbon storage and nutrient retention may be influenced greatly by woody debris dynamics. In addition, woody debris can influence seedling regeneration in mangrove swamps by trapping propagules and enhancing seedling growth potential. Here, we report on line‐intercept woody debris surveys conducted in mangrove wetlands of South Florida 9–10 yr after the passage of Hurricane Andrew. The total volume of woody debris for all sites combined was estimated at 67 m³/ha and varied from 13 to 181 m³/ha depending upon differences in forest height, proximity to the storm, and maximum estimated wind velocities. Large volumes of woody debris were found in the eyewall region of the hurricane, with a volume of 132 m³/ha and a projected woody debris biomass of approximately 36 t/ha. Approximately half of the woody debris biomass averaged across all sites was associated as small twigs and branches (fine woody debris), since coarse woody debris >7.5 cm felled during Hurricane Andrew was fairly well decomposed. Much of the small debris is likely to be associated with post‐hurricane forest dynamics. Hurricanes are responsible for large amounts of damage to mangrove ecosystems, and components of associated downed wood may provide a relative index of disturbance for mangrove forests. Here, we suggest that a fine:coarse woody debris ratio ≤0.5 is suggestive of a recent disturbance in mangrove wetlands, although additional research is needed to corroborate such findings.     

Influence of Forest Management on the Species Richness and Composition of Wood-inhabiting Basidiomycetes in Swiss Forests

In order to investigate the diversity of wood-inhabiting aphyllophoroid basidiomycetes in Swiss forests, 86 plots of 50 m ² were established. They harboured a total of 3339 samples of woody debris, classified according to three categories (coarse, fine, and very fine woody debris), yielding 238 species of wood-inhabiting fungi. The selected sites cover the main forest types of Switzerland and various degrees of management intensity. A multiple linear regression analysis showed that substrate variation, i.e. differences in the quality of dead wood, including volume, age, degree of decomposition and host tree species, are the most important factors influencing diversity of wood-inhabiting fungi. In addition, a Principle Coordinate Analysis highlighted differences in the fungal communities in the different forest types. The greatest fungal species richness is found on thermophilic deciduous tree and woody shrub species. Fine and very fine woody debris, even present in intensively managed forests, often serve as important refuges for many species. Forests with a recent management intervention were found to be either species poor or species rich. Possible reasons for these differences may lay in forest size and landscape fragmentation, the distance to the nearest species pool or microclimatic factors. In Switzerland intensively managed forests harbour significantly less wood-inhabiting, aphyllophoroid fungi than non-managed or extensively managed forests. This is the case in both deciduous forests and in conifer forests. However, occasionally intensively managed forest will also harbour rare and endangered species.     

Does designation of protected areas ensure conservation of tree diversity in the Sudanian dry forest of Burkina Faso?

The importance of conservation status of the forest (protected versus unprotected) at two sites with differing human population density (high versus low) on the tree diversity of a Sudanian dry forest in Burkina Faso was studied. All woody species were recorded in 127 circular plots (area = 456.16 m²), and density, dominance, frequency, importance value indices and a variety of diversity measures were calculated to assess the species composition, structure and heterogeneity. A total of 69 species, representing 26 families and 52 genera, were found. Combretaceae, Leguminosae subfamily Caesalpinioideae and Rubiaceae were the dominant families. Neither human pressure nor forest conservation status significantly influenced the tree species richness. Stem density and basal area were significantly higher at the site with high population density than otherwise. Fisher’s diversity index revealed the unprotected forest at the site with low population density as the most diverse. We identified species with high conservation importance that should be enriched to maintain a viable population size. In conclusion, the current designation of protected areas seems inefficient at ensuring the conservation of tree diversity in the forest reserve. Thus, participatory conservation programme should be initiated.     

Rapid Simultaneous Estimation of Aboveground Biomass and Tree Diversity Across Neotropical Forests: A Comparison of Field Inventory Methods

A standardized rapid inventory method providing information on both tree species diversity and aboveground carbon stocks in tropical forests will be an important tool for evaluating efforts to conserve biodiversity and to estimate the carbon emissions that result from deforestation and degradation (REDD). Herein, we contrast five common plot methods differing in shape, size, and effort requirements to estimate tree diversity and aboveground tree biomass (AGB). We simulated the methods across six Neotropical forest sites that represent a broad gradient in forest structure, tree species richness, and floristic composition, and we assessed the relative performance of methods by evaluating the bias and precision of their estimates of AGB and tree diversity. For a given sample of forest area, a ‘several small’ (< 1 ha) sampling strategy led to a smaller coefficient of variation (CV) in the estimate of AGB than a ‘few large’ one. The effort (person‐days) required to achieve an accurate AGB estimate (< 10% CV), however, was greater for the smallest plots (0.1 ha) than for a compromise approach using 0.5 ha modified Gentry plots, which proved to be the most efficient method to estimate AGB across all forest types. Gentry plots were also the most efficient at providing accurate estimates of tree diversity (< 10% CV of Hill number). We recommend the use of the 0.5 ha modified Gentry plot method in future rapid inventories, and we discuss a set of criteria that should inform any choice of inventory method.     

Large‐scale distribution patterns of mangrove nematodes: A global meta‐analysis

Mangroves harbor diverse invertebrate communities, suggesting that macroecological distribution patterns of habitat‐forming foundation species drive the associated faunal distribution. Whether these are driven by mangrove biogeography is still ambiguous. For small‐bodied taxa, local factors and landscape metrics might be as important as macroecology. We performed a meta‐analysis to address the following questions: (1) can richness of mangrove trees explain macroecological patterns of nematode richness? and (2) do local landscape attributes have equal or higher importance than biogeography in structuring nematode richness? Mangrove areas of Caribbean‐Southwest Atlantic, Western Indian, Central Indo‐Pacific, and Southwest Pacific biogeographic regions. We used random‐effects meta‐analyses based on natural logarithm of the response ratio (lnRR) to assess the importance of macroecology (i.e., biogeographic regions, latitude, longitude), local factors (i.e., aboveground mangrove biomass and tree richness), and landscape metrics (forest area and shape) in structuring nematode richness from 34 mangroves sites around the world. Latitude, mangrove forest area, and forest shape index explained 19% of the heterogeneity across studies. Richness was higher at low latitudes, closer to the equator. At local scales, richness increased slightly with landscape complexity and decreased with forest shape index. Our results contrast with biogeographic diversity patterns of mangrove‐associated taxa. Global‐scale nematode diversity may have evolved independently of mangrove tree richness, and diversity of small‐bodied metazoans is probably more closely driven by latitude and associated climates, rather than local, landscape, or global biogeographic patterns.     

Seasonal occurrence and diel locomotor activity in littoral Cladocera in a mesohumic lake in Norway

The community structure and standing crop biomass of a mangrove forest in Futian Nature Reserve, Shenzhen, the People's Republic of China was studied. This mangrove, located towards the northern latitudinal limit of the mangrove development (22°N), had relatively simple structure and low diversity (the Shannon-Wiener index was 0.78). The three dominant species, namely Aegiceras corniculatum, Kandelia candel and Avicennia marina, possess importance values of 72, 19 and 9%, respectively. The average height of the mangrove community was 4.5 m with no vertical stratification. The values of tree density of A. corniculatum and A. marina were found to be 5290 and 260 ha^–1, respectively. The biomass of both A. corniculatum and K. candel was best estimated from regression equations using a combination of height and diameter at breast height as the independent variables. For Avicennia marina, there was no simple correlation between biomass and height or diameter. The regression models suggested by previous workers did not give satisfactory estimation of biomass of A. marina in this mangrove forest. The total biomass of this mangrove forest was 12.1 kg m^–2, with 73% of such production contributed by A. corniculatum and 8% by A. marina. Because of its small percentage, the inaccuracy in estimating biomass of A. marina did not affect the overall determination of biomass of the whole community. Average above-ground biomass was 8.7 kg m^–2 (72% of the total biomass) and the major components were aerial woody tissues, stems and branches. The root:shoot ratio of this plant community was 0.4:1.     

Plant community structure, soil properties and microbial characteristics in revegetated quarries

Quarries are an important type of degraded land in southern China requiring ecological improvement and rehabilitation. In this study, plant community structure, soil properties, and microbial biomass and community function were examined at different rehabilitated phases in three quarries, namely Turret Hill Quarry, Lam Tei Quarry and Shek O Quarry, in Hong Kong. Results show that plant species richness and the percentage of native species increased with rehabilitated ages in the three quarries. The highest coverage of woody species was found at older phases, while the lowest woody coverage occurred at younger phases. Soils were strongly to moderately acidic in reaction, and more acidic soils were found in the older than in the younger sites. Organic C as well as total N and P accumulated in soil along with secondary succession in the three quarries, which were positively correlated with woody species richness. Older phases had higher total microbial biomass C and N which were positively correlated with soil organic C, total N and extractable NO₃-N, as well as woody species coverage and native species richness as shown by the biplot of redundancy analysis. Diversity of utilized carbons suggested that metabolic abilities developed gradually with rehabilitation ages in Shek O Quarry, but Turret Hill Quarry and Lam Tei Quarry had similar patterns of carbon source utilization. Principal component analysis further revealed consistent differences in metabolic diversity. Woody coverage and native species richness were significantly correlated with carbon source utilization and functional diversity.     

Pantropical trends in mangrove above-ground biomass and annual litterfall

A major paradigm in biosphere ecology is that organic production, carbon turnover and, perhaps, species diversity are highest at tropical latitudes, and decrease toward higher latitudes. To examine these trends in the pantropical mangrove forest vegetation type, we collated and analysed data on above-ground biomass and annual litterfall for these communities. Regressions of biomass and litterfall data show significant relationships with height of the vegetation and latitude. It is suggested that height and latitude are causally related to biomass, while the relationship with litterfall reflects the specific growing conditions at the respective study sites. Comparison of mangrove and upland forest litterfall data shows similar trends with latitude but indicates that mangrove litterfall is higher than upland forest litterfall. The regression equations allow the litterfall/biomass ratio to be simulated, and this suggests that the patterns of organic matter partitioning differ according to latitude.     

Woody species patterns at forest–grassland boundaries in southern Brazil

Vegetation mosaics of grassland/savanna and forest can be found in tropical and subtropical regions of the world, as in southern Brazil, where climate conditions are suitable for forest. Changes in intensity or frequency of disturbances could enable woody species encroachment in grassland communities; however, the processes are related to site conditions and life history of pioneer species. In this paper, we study transition patterns of forest to grassland in the absence of grazing, but under different site conditions related to aspect (landscape position) and time since the last burn. Data are based on shrub and tree species composition and soil variables at forest–grassland boundaries. We found 119 woody species of 42 families along transects of 27 m into the forest and 31.5 m into the grassland. Gradients from forest to grassland were analysed as compositional trajectories in ordination space and differences in the spatial patterns depicted between distinct site aspects. The time since the last fire did not influence these patterns. Inside the forest, tree species diversity was significantly higher close to the edge, independent of the density of individuals. Two main mechanisms may promote forest expansion into the grassland. First, a gradual tree encroachment near the edge and, second, a mechanism linked to the recruitment of isolated pioneer trees within the grassland matrix, most frequently near rocky outcrops, where a decrease in grass biomass leads to low-intensity fires. Despite vegetation patterns at boundaries differing according to aspect, the most important explanatory factor was the distance from the forest border, not just by itself, but with all correlated parameters that are changing along the gradient.     

Characteristics of Old-Growth and Secondary Forests in Relation to Age and Typhoon Disturbance

Many properties of forest ecosystems, such as species composition and forest structure, naturally vary with forest age. However, in regions prone to cyclone disturbances, both forest age and cyclone severities can play a role shaping these properties. To evaluate potential effects of an altered cyclone regime on forest ecosystems, it is necessary to disentangle the roles of cyclones and forest age on different forest characteristics. In this study, we compared species composition and forest structure at plot level across sites with similar climate and topographic backgrounds, yet differing in age and typhoon severities in northeastern Taiwan. We found shorter tree stature, higher wood density, higher tree species diversity, and lower typhoon-induced tree mortality in the sites with more severe typhoon disturbances. On the other hand, regardless of typhoon severity, the sites of younger ages had a considerably smaller amount of woody debris, suggesting that it takes time for the accumulation of woody debris. More typhoon-induced canopy gaps at sites with more severe typhoon influences highlights a role of typhoons in canopy dynamics. However, the lack of gaps prior to typhoon disturbances in the less severely affected forest is likely related to the low background mortality associated with the relative young age of the forest. Our results indicate that frequent or severe typhoon disturbances can homogenize some of the structural differences among forests of different ages. If the frequency or severity of cyclones increase in the future, many forests, including old-growth forests, may gradually lose large trees.     

Contrasting effects of habitat quantity and quality on moth communities in fragmented landscapes

Habitat loss is commonly identified as a major threat to the loss of global biodiversity. In this study, we expand on our previous work by addressing the question of how lepidopteran species richness and composition vary among remnants of North American eastern deciduous forest located within agricultural or pastoral landscapes. Specifically, we tested the relative roles of habitat quantity (measured as stand area and percent forest in the greater landscape) and habitat quality (measured as tree species diversity) as determinants of moth species richness. We sampled >19 000 individuals comprising 493 moth species from 21 forest sites in two forested ecoregions. In the unglaciated Western Allegheny Plateau, the species richness of moths with woody host plants diminished as forest stand size and percent forest in the landscape decreased, but the total species richness and abundance of moths were unaffected by stand size, percent forest in the landscape, or tree species diversity. In contrast, the overall species richness and abundance of moths in the glaciated North Central Tillplain were affected primarily by tree species diversity and secondarily by forest size. Higher tree species diversity may reduce species loss from smaller forest stands, suggesting that small, diverse forests can support comparable numbers of species to those in less diverse, large stands. Smaller forests, however, contained a disproportionate number of moth species that possess larvae known to feed on herbaceous vegetation. Thus, although woody plant feeding moths are lost from forests with changes in stand area, new species appear capable of recolonizing smaller fragments from the surrounding habitat matrix. Our study further suggests that when species replacement occurs, local patch size and habitat quality may be more important than landscape context in determining the community structure of forest Lepidoptera.     

Response of plant species and life form diversity to variable fire histories and biomass in the jarrah forest of south‐west Australia

Frequent fires reduce the abundance of woody plant species and favour herbaceous species. Plant species richness also tends to increase with decreasing vegetation biomass and cover due to reduced competition for light. We assessed the influence of variable fire histories and site biomass on the following diversity measures: woody and herbaceous species richness, overall species richness and evenness, and life form evenness (i.e. the relative abundance or dominance among six herbaceous and six woody plant life forms), across 16 mixed jarrah (Eucalyptus marginata) and marri (Corymbia calophylla) forest stands in south‐west Australia. Fire frequency was defined as the total number of fires over a 30‐year period. Overall species richness and species evenness did not vary with fire frequency or biomass. However, there were more herbaceous species (particularly rushes, geophytes and herbs) where there were fewer shrubs and low biomass, suggesting that more herbaceous species coexist where dominance by shrubs is low. Frequently burnt plots also had lower number and abundance of shrub species. Life form evenness was also higher at both high fire frequency and low biomass sites. These results suggest that the impact of fire frequency and biomass on vegetation composition is mediated by local interactions among different life forms rather than among individual species. Our results demonstrate that measuring the variation in the relative diversity of different woody and herbaceous life forms is crucial to understanding the compositional response of forests and other structurally complex vegetation communities to changes in disturbance regime such as increased fire frequency.     

Are the eucalypt and non-eucalypt components of Australian tropical savannas independent?

Eucalypts (Eucalyptus and Corymbia spp.) dominate (>60%) the tree biomass of Australia's tropical savannas but account for only a fraction (28%) of the tree diversity. Because of their considerable biomass and adaptation to environmental stressors, such as fire, the eucalypts may drive tree dynamics in these savannas, possibly to the exclusion of non-eucalypts. We evaluated whether the eucalypt and non-eucalypt components in tropical savannas are dependent so that changes in one component are matched by opposite trends in the other. Using tree inventory data from 127 savanna sites across the rainfall and fire frequency gradients, we found that eucalypt and non-eucalypt basal area and species richness had a negative relationship. This relationship was maintained across the rainfall gradient, with rainfall having a positive effect on the basal area and species richness of both components, but with a greater effect in non-eucalypts. Fire frequency negatively affected basal area, but not species richness, although basal area and species richness of eucalypts and non-eucalypts did not differ in their response to fire. Rainfall appears to set the upper bounds to woody biomass in these mesic savannas, while fire maintains woody biomass below carrying capacity and facilitates coexistence of the components. The magnitude of the component responses, particularly for non-eucalypts, is determined by rainfall, but their dependence is likely due to their differential response to both rainfall and fire, but not to competition for resources. Thus, while eucalypts dominate biomass overall, at high rainfall sites non-eucalypt basal area and diversity are highest, especially where fire frequency is low.     

广东黑石顶南亚热带森林幼苗的区系和生态研究（英文）

 本文研究了自然林下和深入林内2km新开公路的斜坡(当作特殊的林窗)的幼苗的种类组成、多样性、分布格局和生长。林下幼苗种丰富度(99种)和Shannon-Wiener多样性指数(5.43)与所在林分立木种的丰富度(117种)和多样性指数(5.42)相当,而比公路斜坡相近面积上幼苗的相应值(59种,多样性指数4.21)高。林下幼苗的乔木种类占的比例(46％)较公路斜坡幼苗的乔木种类的比例(34％)高,而草本种类占的比例(23%)较后者(32％)低。林下幼苗的木本种类和林分立木的S ф rensen相似系数(0.500)较公路斜坡幼苗木本种类和林分的相似系数(0.171)高得多,林下幼苗的种类组成和公路斜坡幼苗的种类组成的相似性很低(S ф rensen 系数(0.247)。两个生境中大多数优势种群都表现为集群分布。公路斜坡上的幼苗种群似乎集群程度更高。先锋树种的幼苗在公路斜坡较瘦瘠的土壤条件下1～5年生幼苗的平均相对生长率为：0.944～1.555g·g-1·a-1,比在林下耐阴树种幼苗的相对生长率(0.765～1.402)高或相当,但生物量积累较后者慢。在森林中,耐阴树种的幼苗未显出休眠的特性。先锋树种的幼苗有较高比例的叶生物量,而演替后期树种的幼苗则有较高比例的生物量分配给根。