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1.
Understory herb communities in the Southern Appalachians are among the highest biodiversity plant communities in North America. In the mid-1990s, a debate began over whether understory herb communities recover to their pre-disturbance states following logging. Studies showing reduced herb-layer diversity in previously logged forests were criticized for not accounting for intersite environmental heterogeneity. More recent studies have addressed environmental heterogeneity, but have neglected long-term recovery by using “mature forests” as young as 80 years old as the benchmark for diversity comparison, even though old growth stands have disturbance return intervals exceeding 500 years. Here we address concerns clouding previous studies of high-diversity Appalachian herb communities and investigate their long-term recovery by comparing paired sites of old growth forest and forest logged 100–150 years ago. We found that species richness and individual abundance is greater in old growth forests than mature forests and that species composition differed significantly between the two. Turnover in species among old growth and mature forests accounted for 11% of the total species richness and was significantly greater than expected. Species turnover at intermediate (5–50 m) and landscape-scales (>10 km) contributed the most towards total species richness. Herb communities in rich cove forests have successional trajectories that exceed 150 years, with important community changes still occurring long after the forest returns to what has been previously termed a “mature” state. To conserve the diverse herb layer, we conclude that mature forest stands are too young to serve as baselines for recovery, landscape-scale preservation of multiple forest stands is needed to maximize species richness, and maintaining 100–150-year logging rotations will likely lead to loss of biodiversity.  相似文献   

2.
To examine the relationship between forest succession following fire and the composition of bird communities, we investigated the vegetation structure, bird population density, foraging behavior and guild structure in bamboo grasslands (11 years since the last fire), pine savanna (41 years), pine woodland (58 years), old-growth hemlock forest (never burned), and old-growth spruce forest (never burned) in the Tatachia area of central Taiwan. Canopy height, total foliage cover, tree density, total basal area of tree, total basal area of snags, foliage height diversity, and tree species richness all increased with successional age. However, shrub cover peaked in intermediate successional stages. The vertical profile of foliage cover was more diverse in later successional forests, which had more breeding bird species and ecological guilds. All the breeding bird species recorded in early and intermediate stages were also found distributed in the late successional forests. Because Taiwan has high precipitation and humidity, and most forest fires in Taiwan are caused by human activities, forest fires and large areas of early successional vegetation were probably rare in the mountain areas of Taiwan prior to the arrival of humans. Therefore, bird species have not had enough time to adapt to areas with early or intermediate successional vegetation. Moreover, late successional forests host all the major plant species found in the early and intermediate stages and have higher foliage height diversity index, which was positively correlated with the bird species richness and bird species diversity index in this study. As a result, all breeding bird species and guilds in the area can be found in late successional forests. Efforts for conserving avian diversity in Taiwan should focus on protecting the remaining native old-growth forests.  相似文献   

3.
The joint and independent effects of dominant tree species, forest patch spatial attributes, and forest structure and management as drivers of plant species richness and composition in small forest patches scattered within an intensive agricultural landscape were addressed.In a landscape with scattered urban and intensive dairy agricultural areas in north-west Portugal, within which small forest patches (dominated by pines, eucalypts, or both) represent semi-natural habitat islands, 50 small forest patches, with areas ranging between 0.3 and 3 ha, were selected and surveyed for vascular plant diversity, within dairy farming landscape mosaics dominated by annual forage crops. Explanatory variables were composed of three datasets derived either from GIS mapping or field observations: forest type (dominant tree species), forest patch spatial attributes (patch area and shape index), and measures of forest management and structure (diameter at breast height, tree density per hectare, and percentage cover of vegetation strata). Variations in these forest patch attributes were assessed across forest types, and related to measures of plant diversity (total, native, alien, woody, and herbaceous species richness). Redundancy analysis with variance partitioning was applied to evaluate the joint and independent effects of the three sets of variables on species assemblages. The recent shift in canopy dominance from pine to eucalypt observed in the region appears to be related to a (nonsignificant) tendency for the increase of patch area and to the decrease of patch complexity, as well as several changes in forest structure and management, expressed as a trend to denser tree canopies and lower cover of understory plants. Dominant tree species and attributes related to forest structure and management were the most important factors determining plant diversity. The joint effect of the dominant tree species and forest structure and management resulted in lower levels of plant species richness in eucalypt plantations. These were also more prone to invasion by alien species, probably due to decreased biotic resistance from unsaturated native plant assemblages. Our results draw attention to the importance of dominant tree species and management practices for the maintenance of plant diversity levels (species richness and composition) in dairy landscape mosaics, highlighting the importance of the remnants of semi-natural forests as refuges for plant diversity in the landscape context. Nonetheless, forest plant diversity could further be fostered by promoting naturalness of pine stands and the regeneration of native oak woodlands in some forest areas. This would also diversify the range of ecosystem services that could be provided by forest areas in these peri-urban farmlands.  相似文献   

4.
We examined patterns of variation in richness, diversity, and composition of understory vascular plant communities in mixedwood boreal forests of varying composition (broadleaf, mixedwood, conifer) in Alberta, Canada, before and for 2 years following variable-retention harvesting (clearcut, 20 and 75% dispersed green tree retention, control). Broadleaf-dominated forests differed from mixedwood or conifer-dominated forests in that they had greater canopy cover, litter depth, soil nitrogen, warmer soils, as well as greater shrub cover, herb and shrub richness and diversity (plot scale). In contrast, conifer, and to a lesser extent mixedwood, forest had greater β diversity than broadleaf forest. Overall, mixedwood and conifer forests were similar to one another, both differed from broadleaf forest. Several species were found to be significant indicators of broadleaf forest but most of these also occurred in the other forest types. Understory composition was related to canopy composition and edaphic conditions. Variable-retention harvesting had little effect on understory cover, richness, or diversity but resulted in reduced richness and β diversity at a larger scale. The clearcut and 20% treatments affected composition in all forest types. Early successional species and those common in disturbed sites were indicators of harvesting while evergreen, shade-tolerant understory herbs were indicators of the control forest and 75% retention harvest. We conclude that it is important to maintain a range of variation in canopy composition of mixedwood forests in order to conserve the associated understory communities. The presence of conifers in these forests has a particularly important influence on understory communities. The threshold for a lifeboat effect of variable-retention harvesting is between 20 and 75% retention. Examination of richness and β diversity at a variety of scales can provide interesting information on effects of harvesting on spatial reorganization and homogenization of understory plant communities.  相似文献   

5.
Simultaneous flowering caused a gregarious dieback of umbrella bamboo (Fargesia murielae) all over the world in 1993-2000. Mountain Shennongjia in Central China‘s Hubei Province is the only native home of umbrella bamboo, where it dominates the understorey of the farges fir (Abiesfargesii) forest between 2 400 and 3 100 m, covering the ground for more than one century before a periodically flowering death. Data from 20 quadrats along a vegetation sequence revealed that the density, coverage,and height of umbrella bamboo negatively affected the species richness, diversity, and evenness of vascular plants in the forest. Local climax community of fir-bamboo was the poorest in species diversity, while the bamboo-free communities (i.e. shrubs and meadows)were bearing a higher species diversity. The simultaneous dieback of umbrella bamboo is an ecological relcase, which can pcriodically promote the plant diversity in the fir forest.  相似文献   

6.

Elevated nitrogen (N) deposition is changing soil communities around the world and will have unknown consequences for terrestrial ecosystem functions. In this study, we investigated a field experiment that lasted for 13 years to explore the effect of simulated N deposition and seasonal variations on the soil faunal community structure in a temperate natural secondary forest. The experimental design included a control group (0 kg N ha?1 yr?1, CK), low N addition (25 kg N ha?1 yr?1, LN), and high N addition (50 kg N ha?1 yr?1, HN). The results showed that long-term high N addition reduced the soil pH, C/N ratio, and microbial biomass carbon (MBC) and increased the total phosphorus. The soil faunal community structure after high N addition was significantly different from those after the CK and low N addition treatments. The overall trend was that abundance and richness increased under low N addition and decreased under high N addition. Further analysis showed that the abundance of omnivores and detritivores was lowest after high N addition, significantly less than the CK and low N addition. The interaction of N addition and seasonal dynamics had a significant impact on herbivores. We found that these changes were driven by differences in ecological strategies such as food and environmental preferences. Furthermore, temperature, moisture, nutrients, and pH in the soil environment were the key factors driving ecological strategies and environmental factors. Seasonal variations significantly affected the soil faunal community structure, showing the highest abundance, richness, diversity, and functional group abundance and richness of the soil faunal community in September. Nitrogen addition and seasonal dynamics significantly affected the abundance and richness of soil fauna by changing soil nutrient concentrations, MBC, and plant diversity. Our study showed that long-term high N addition reduced the abundance and functional group abundance of the soil fauna in natural secondary forests, while low N addition had a positive effect on soil faunal community structure. Collectively, the results suggest that the seasonal balance of soil fauna is affected after long-term N addition, which increases the seasonal sensitivity of soil fauna.

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7.
武夷山国家级自然保护区植物物种多样性研究   总被引:44,自引:0,他引:44  
兰思仁 《林业科学》2003,39(1):36-43
以植物群落调查样地资料为基础,从不同类型、不同层次的物种丰富度、多样性指数及均匀度指数对武夷山国家级自然保护区植物群落多样性进行了分析。本区植物群落多样性的变化规律为:物种丰富度、多样性指数及均匀度随该区植被演替趋势从针叶林、针阔叶混交林到常 阔叶林而增加,群落间变幅较大;植物生长型在物种丰富度、多样性指数及均匀度等多样性指数上均表现出灌木层>乔木层的规律。毛竹林作为一种重要的植被类型,其灌木层物种多样性高于其它3种森林类型,但由于毛竹是无性繁殖,其在林分中占绝对优势,故乔木层物种多样性明显低于其它3种森林类型。  相似文献   

8.
采用典型抽样的方法对昆明昙华寺公园中的前园与中园、后园的园林植物群落进行物种结构、水平结构、垂直结构和季相的调查与分析。前园共有植物73种,分属于40科、63属。中园共有植物73种,分属于38科、53属。前园树种丰富度为6.32,树种多样性指数为3.45。中园树种丰富度为5.56,树种多样性指数为3.39。后园树种丰富度为5.94,树种多样性指数为3.34。中园胸径超过3 cm,冠幅超过9 m所占总数的百分比远比其它园区多的多。前园与中园乔木树高主要集中在10.7 m以上,后园树高在4.6~10.7 m的最多。3个园区的园林植物群落季相变化都不是很明显。  相似文献   

9.
采用典型样方法,对武汉市10个具有代表性的城市公园的165个植物群落进行调查,结果表明,所调查植物群落中共有植物219种,分属74科156属;运用组平均法(UPGMA)对165个植物群落进行聚类分析,分为21种植物群落类型;利用Partrick物种丰富度指数、Shannon-Wiener多样性指数、Simpson多样性指数和Pielou均匀度指数,比较不同群落类型的物种多样性特征,其中群落类型紫玉兰-杜鹃-小苜蓿的物种丰富度和物种多样性最高,圆柏-八角金盘+山茶的物种丰富度最低,水杉-杜鹃+洒金桃叶珊瑚-早熟禾+车前的多样性指数最低,植物群落的多样性程度表现为乔木层 ≈ 草本层 > 灌木层。在城市公园绿地中人工配置决定了植物群落物种多样性特征,其他环境和人为干扰因素也影响植物群落的物种多样性。建议适当增加观赏价值高的乡土植物,构建物种丰富、层次复杂、结构稳定的近自然植物群落。  相似文献   

10.
Understanding how soil fertility changes due to environmental conditions and stand-age-dependent for-est attributes is important for local-scale forest restoration.We evaluated the effects of stand-age-dependent forest attributes (plant community composition and litter stock)on soil and technosol fertility across two second-growth Atlantic forests (SGF) after the deposition of mining tail-ings in Mariana,southeastern Brazil.We hypothesized that technosol fertility in the SGF tailings is positively affected by plant community composition variability,stand age,and litter stock.We used total exchangeable bases and organic matter as fertility indicators for technosol and soil,and spe-cies composition and litter stock as stand-age-dependent forest attributes.Our results showed significant differences in the stand-age-dependent forest attributes and soil chemi-cal properties between the two forest patches (SGF tailing and SGF non-tailing) evaluated.Thus,there was a marked gradient of litter storage and fertility between soil and tech-nosol that can be important forest recovery indicators for the affected plant communities.Furthermore,according to the tested models,we corroborated the hypothesis that techno-sol fertility is positively affected by stand age,plant com-munity composition variability,and litter stock,which may contribute considerably to forest recovery on tailings.Our results demonstrate that the fertility predictors analyzed to explain the forest recovery on tailings can also be considered as ecological indicators for assessing forest restoration in areas impacted by mining tailings in Mariana.  相似文献   

11.
以湖南桑植县石漠化区为研究对象,采用样方调查法对3个不同石漠化等级样地进行植被调查,分析不同石漠化等级植物物种组成结构及植物多样性指数差异,并根据Jaccard群落相似性原理进行不同石漠化等级植物群落间的相似度评价分析.结果表明:调查区共出现草本植物23科39种、木本植物26科38种,优势科为菊科、蔷薇科、百合科、禾本...  相似文献   

12.
根据64个植被样方调查资料,分析卧龙自然保护区大熊猫栖息地植物群落多样性特征.结果表明:卧龙自然保护区大熊猫栖息地不同植被类型的物种多样性指数值H'、D和均匀度指数Jsi基本表现出一致的变化趋势:常绿落叶阔叶林>温性针阔混交林>落叶阔叶林>温性针叶林>亚高山针叶林,而物种丰富度S变化为温性针叶林>落叶阔叶林>常绿落叶阔叶林>亚高山针叶林>温性针阔混交林.在不同的植物群落中,由于地形地势、坡度、土壤、水热条件等原因,其物种多样性指数不同,但其多样性测度指标除物种丰富度外均呈现出基本一致的变化趋势.随海拔的升高,大熊猫栖息地物种丰富度、多样性指数和均匀度变化先增加,然后下降,最后趋于平稳.坡度不是影响卧龙野生大熊猫栖息地生物多样性的关键因子.不同的坡向其物种丰富度S变化为西>北>东>南,物种多样性指数H'、D呈现西>南>北>东的递降格局,均匀度指数Jsi呈现南>西>东>北的递降格局.在不同的群落中,物种丰富度变化表现为灌木层>乔木层>草本层,且42.9%群落中乔木层大于灌木层、64.3%群落中乔木层大于草本层、92.9%群落中灌木层大于草本层,落叶针叶林乔木层树种丰富度小于灌木层和草本层,但其灌木层物种丰富度大于草本层.在同一或不同生长型中,物种多样性指数和均匀度指数变化大体一致.  相似文献   

13.
Simultaneous flowering caused a gregarious dieback of umbrella bamboo (Fargesia murielae) all over the world in 1993–2000. Mountain Shennongjia in Central China’s Hubei Province is the only native home of umbrella bamboo, where it dominates the understorey of the farges fir (Abies fargesii) forest between 2 400 and 3 100 m, covering the ground for more than one century before a periodically flowering death. Data from 20 quadrats along a vegetation sequence revealed that the density, coverage, and height of umbrella bamboo negatively affected the species richness, diversity, and evenness of vascular plants in the forest. Local climax community of fir-bamboo was the poorest in species diversity, while the bamboo-free communities (i.e. shrubs and meadows) were bearing a higher species diversity. The simultaneous dieback of umbrella bamboo is an ecological release, which can periodically promote the plant diversity in the fir forest.  相似文献   

14.
Much research effort is being devoted to developing forest management practices with limited impacts on biodiversity. While the impact of poplar Populus sp. plantations on biodiversity is relatively well-known at the landscape scale, the impact of alternative management practices at the plantation scale has received much less attention. Yet biodiversity is likely to be impacted by the choice of the poplar clone, stem density at plantation, type and duration of the understory control, and age at which the poplars are harvested. In this study, we investigated the impact of these factors on herbaceous plant communities with data from plant surveys conducted in 85 young (2–5 years) and 96 mature (11–17 years) hybrid poplar high-forest plantations in northern France. On average, ruderal or generalist plants contributed to 40.5% of the plot species richness; tall herbs (60.2%), forest (26%) and meadow plants (13.8%) contributed to the remaining 59.5% more specialised species. Soil moisture and soil nitrogen were major determinants of plant communities: wet soils were favourable to tall herbs, while meadow and forest species preferred moist soils; a significantly lower diversity of the three species groups was reported in the nutrient richer soils (in mature plantations only for forest plants). Mean species richness decreased with plantation age except for forest species. Plant communities in young plantations showed little differences in composition according to the type of understory control (chemical, mechanical or both). The development of a shrubby layer in mature plantations was restricted to the drier soils and was detrimental to both meadow plants and tall herb species. Effects of previous land use on forest and tall herb species were found only in young plantations, suggesting a rapid reset of plant communities for these two groups. This may not be the case for meadow species as the influence of previous land use was significant in mature plantations only. Finally, clone type and stem density at plantation had no significant impact on plant communities. Adjusting age at which the poplars are harvested seems the only effective way to drive plant communities in high-forest poplar plantations: delaying poplar harvest (probably beyond 15–20 years) would benefit forest plants, while advancing poplar harvest (about 10 years) would benefit tall herbs, especially in wet soil conditions.  相似文献   

15.
霍妍  郑云龙 《防护林科技》2013,(1):15-17,20
以大黑山水土保持生态修复工程示范区为研究区域,运用典型植物群落物种组成和群落物种多样性指数方法,对大黑山水土保持生态修复区典型植物群落物种多样性变化特征进行了研究,结果表明,生态修复区内天然次生林植物群落形成了乔灌草相结合的稳定的植物群落结构。人工林植物群落按生长型可以划为明显的乔木层和草本层2层群落结构类型;典型植物群落物种多样性指数的排序为:蒙古栎+蒙椴植物群落(Ⅱ)>山杏+黄榆植物群落(Ⅰ)>蒙古栎植物群落(Ⅲ)>油松+山杏混交植物群落(Ⅴ)>油松纯林植物群落(Ⅳ)>油松+沙棘混交植物群落(Ⅵ)>油松疏林植物群落(Ⅶ)。天然次生林植物群落的物种多样性要大于人工林植物群落。天然次生林植物群落由于远离人类活动区,长期以来受人为干扰较小,逐渐形成了相对比较发达的草本层植物群落。  相似文献   

16.
Forest management regimes dictate the composition and structure of large parts of the Fennoscandian boreal forest region. The understanding of thinning impacts on understorey plant communities is considerably lower compared to the effects of final felling. We studied the response of bryophyte assemblages to second commercial thinning in spruce-dominated stands sampled to be representative of the dominant forest type of south-central Sweden. Eighteen stands were analysed 6–12 years after second commercial thinning, and were compared with six stands commercially thinned only once, at two spatial scales (0.1 and 0.01?ha), with stand ages varying between 52 and 66 years. We found few strong differences in bryophyte species richness and no differences in bryophyte species composition between stands thinned once or twice. More pioneer species were found in stands thinned only once, a result that needs further study. Species richness declined significantly with time since thinning on both investigated spatial scales. Canopy cover significantly affected the composition of forest floor species. Thinning effects over longer time periods need further study, and also effects in different forest types along productivity gradients. For nature conservation, studies targeted towards thinning response of uncommon species connected to specific habitats and substrates will be essential.  相似文献   

17.
文章对苏州穹窿山植物群落的物种重要值、多样性、群落内温湿度和空气颗粒物浓度等进行研究,并评价其体感舒适度。研究结果表明,在紫楠林、栎类林、松林、毛竹林的乔木层中,栎类林和松林的物种丰富度指数(S)最高;栎类林的Simpson多样性指数(D)、Shannon-Wiener多样性指数(H)和Pielou均匀度指数(J)均最高;毛竹林的S、D、H和J均为最低;4类群落的体感舒适度等级均为很舒适,栎类林的体感舒适度最佳;通过相关性分析,植物群落的丰富度指数与其体感舒适度指数呈极显著负相关(体感舒适度指数越高,表明体感舒适度越低),群落丰富度越高,其体感舒适度越好;研究结果可为管理穹窿山森林资源和提升森林的保健功能提供一定理论依据。  相似文献   

18.

Key message

In tree communities, tree size inequality reduces productivity and interacts with tree shade tolerance to modulate stand productivity, with a higher productivity in stands where shade-intolerant species dominate shade-tolerant species in size.

Context

Positive diversity–productivity relationships have been reported in different plant communities, including tree communities. These effects may be strongly related to both structural diversity and functional diversity, but also to their interactions if there is a non-random distribution of species functional characteristics among canopy layers.

Aims

We explore the relative effects on forest productivity of tree species diversity, tree size inequality, and species shade tolerance diversity, as well as the effect of the distribution of tree shade tolerance in the canopy.

Methods

We used 11,054 mixed-species forest plots from the French Forest Inventory (IGN) distributed throughout France (2006–2011). We analyzed the effects of species richness, shade tolerance diversity, and height inequality on forest plot productivity, represented by basal area annual increment over a period of 5 years, while controlling for first-order structure characteristics (basal area and quadratic mean diameter) and environmental factors (soil water budget and sum of growing degree days). Using the covariance between tree height and shade tolerance in mixed species canopies, we also explored the effect of the distribution of species’ shade tolerance among canopy layers.

Results

The results showed a positive effect of species richness (effect size, 0.02) and a negative effect of height inequality (??0.05) on mixed-forest productivity. We also showed that a negative covariance between shade tolerance and height (e.g., higher proportion of shade-tolerant species in lower height classes) increased productivity (0.01). Shade tolerance diversity did not affect productivity.

Conclusion

In tree communities, as shown previously in monospecific forest stands, tree size inequality reduces productivity. This effect is modulated by the distribution of shade tolerance among canopy layers. Previous studies on species diversity effect have generally overlooked the importance of the size structure and the size hierarchy of functional characteristics. These effects are, however, crucial and deserve to be explored in greater detail.
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19.
本文对胡家林场天然林早春植物多样性进行研究,结果显示:科、属和物种的丰富度指数和Shannon—Wiener多样性指数逐年降低;优势度升高。物种丰富度指数和Shannon—Wiener多样性指数明显差异大,而生态优势度D变化不明显。  相似文献   

20.
Silvicultural practices that provide a wide variety of vegetative composition and structure (habitats) in young stands should help manage for biological diversity across forested landscapes. This study was designed to test the hypotheses that: (i) abundance and diversity of stand structure attributes (species diversity and structural diversity of herb, shrub and tree layers) and forest floor small mammal communities, and (ii) relative habitat use by large herbivores, will increase from unthinned to conventionally thinned to chemically thinned stands of young lodgepole pine (Pinus contorta) forest. Replicate study areas were located near Summerland, Kelowna and Williams Lake in south-central British Columbia, Canada. Each study area had three treatments: a conventionally thinned, a chemically thinned and an unthinned stand. Pre-commercial thinning was conducted in 1993. Coniferous stand structure and understory vegetation were measured prior to thinning in 1993 and 5 years later in 1998. Small mammal populations were sampled intensively from 1993 to 1998. Relative habitat use by large herbivores was sampled in 1998.

Our results indicate that chemical thinning of young lodgepole pine stands produced an aggregated pattern of crop trees compared with stands subjected to conventional thinning. Diameter growth of crop trees in the chemically thinned stands was similar to that in the conventionally thinned, but also to that in unthinned stands. Although horizontal stratification (aggregates of trees) was enhanced, vertical stratification (structural diversity of vegetation) was less in the chemically than conventionally thinned stands. Abundance and diversity of understory vegetation and small mammal communities were generally unaffected by stand thinning in these particular installations. Relative habitat use by mule deer (Odocoileus hemionus) occurred in a gradient from highest in the conventionally thinned stand to lowest in the unthinned stand. Habitat use by snowshoe hares (Lepus americanus) tended to have the opposite trend. Moose (Alces alces) exhibited no difference in habitat use among stands. Thus, although there were few differences among treatment stands, chemical thinning could be used to develop an aggregated pattern of crop trees in pre-commercially thinned stands to maintain habitat for herbivores such as snowshoe hares and mule deer. Understory plant and forest floor small mammal communities would be maintained in these stands as well.  相似文献   


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