Herb Richness Research Articles

Species abundance distribution models of Toona ciliata communities in Hubei Province, China

The study of plant species abundance distribution (SAD) in natural communities is of considerable importance to understand the processes and ecological rules of community assembly. With the distribution of tree, shrub and herb layers of eight natural communities of Toona ciliata as research targets, three different ecological niche models were used: broken stick model, overlapping niche model and niche preemption model, as well as three statistical models: log-series distribution model, log-normal distribution model and Weibull distribution model, to fit SAD of the different vegetation layers based on data collected. Goodness-of-fit was compared with Chi square test, Kolmogorov–Smirnov (K–S) test and Akaike Information Criterion (AIC). The results show: (1) based on the criteria of the lowest AIC value, Chi square value and K–S value with no significant difference (p > 0.05) between theoretic and observed SADs. The suitability and goodness-of-fit of the broken stick model was the best of three ecological niche models. The log-series distribution model did not accept the fitted results of most vegetation layers and had the lowest goodness-of-fit. The Weibull distribution model had the best goodness-of-fit for SADs. Overall, the statistical SADs performed better than the ecological ones. (2) T. ciliata was the dominant species in all the communities; species richness and diversity of herbs were the highest of the vegetation layers, while the diversities of the tree layers were slightly higher than the shrub layers; there were fewer common species and more rare species in the eight communities. The herb layers had the highest community evenness, followed by the shrub and the tree layers. Due to the complexity and habitat diversity of the different T. ciliata communities, comprehensive analyses of a variety of SADs and tests for optimal models together with management, are practical steps to enhance understanding of ecological processes and mechanisms of T. ciliata communities, to detect disturbances, and to facilitate biodiversity and species conservation.

Soil properties after forest rehabilitation by planting teak and mahogany in Java, Indonesia

We studied how rehabilitation of forests in Indonesia by planting teak, Tectona grandis (L.f.), and mahogany, Swietenia macrophylla (King), was associated with soil pH, organic matter, total nitrogen, total phosphorus, and total potassium. We also analyzed how soil properties and the environment (i.e. soil order, altitude, stand age) were associated with succession and compared rehabilitated stands with native forests. We found higher pH in teak compared to mahogany stands. The soil pH was lowest in the oldest stands (>70 years). Herb density was positively related to pH and to phosphorus, while density of seedlings and woody plants was positively related to nitrogen, potassium and phosphorus. Tree and herb species richness and tree density were positively associated with Oxisols, but negatively related to the proportion of native herbs. Species richness of herbs and density of seedlings decreased with time since rehabilitation, whereas species richness of woody plants increased. The proportion of native herbs and seedlings increased with stand age. We found few differences in soils between the planted stands and native forest. Our results demonstrated that successional vegetation of rehabilitated forests may play an important role in maintaining soil properties associated with soil order.

Conservation priorities and distribution patterns of vascular plant species along environmental gradients in Aberdare ranges forest.

Distribution patterns of biodiversity and the factors influencing them are important in conservation and management strategies of natural resources. With impending threats from increased human population and global climatic changes, there is an urgent need for a comprehensive understanding of these patterns, more so in species-rich tropical montane ecosystems where little is known about plant diversity and distribution. Vascular species richness along elevation and climatic gradients of Aberdare ranges forest were explored. A total of 1337 species in 137 families, 606 genera, 82 subspecies and 80 varieties were recorded. Correlations, simple linear regression and Partial least square regression analysis were used to assess richness and diversity patterns of total plants, herbs, shrubs, climbers, arboreal and endemic species from 2000–4000 m above sea level. Total plant species richness showed a monotonic declining relationship with elevation with richness maxima at 2000–2100 m a.s.l., while endemic species richness had a positive unimodal increase along elevation with peaks at 3600–3700 m a.s.l. Herbs, shrubs, climbers and arboreal had significant negative relationships with altitude, excluding endemism which showed positive relations. In contrast, both air and soil temperatures had positive relationships with taxa richness groups and negative relations with endemic species. Elevation was found to have higher relative influence on plant richness and distribution in Aberdare ranges forest. For effective conservation and management of biodiversity in Aberdare, localized dynamic conservation interventions are recommended in contrast to broad and static strategies. Establishment of conservation zones and migration corridors are necessary to safeguard biodiversity in line with envisaged global climatic vicissitudes.

Exclusion of large herbivores affects understorey shrub vegetation more than herb vegetation across 147 forest sites in three German regions.

BackgroundMany studies have analysed the effect of browsing by large herbivores on tree species but far fewer studies have studied their effect on understorey shrubs and herbs. Moreover, while many studies have shown that forest features and management intensity strongly influence understorey vegetation, the influence of such variation on the effect of large-herbivore exclusion is not known.This studyIn this study, we analysed changes of species richness, Shannon diversity, evenness and cover of understorey herbs and shrubs after excluding large herbivores for seven years on 147 forest sites, differing in management intensity and forest features, in three regions of Germany (Schwäbische Alb, Hainich-Dün, Schorfheide-Chorin). Further, we studied how the effect of large-herbivore exclusion on understorey vegetation was influenced by forest management intensity and several forest features.ResultsAs expected, exclusion of large herbivores resulted in highly variable results. Nevertheless, we found that large-herbivore exclusion significantly increased cover and Shannon diversity of shrub communities, while it did not affect herb communities. Forest management intensity did not influence the effect of large-herbivore exclusion while some forest features, most often relative conifer cover, did. In forests with high relative conifer cover, large-herbivore exclusion decreased species richness and cover of herbs and increased Shannon diversity of herbs and shrubs, while in forests with low relative conifer cover large-herbivore exclusion increased species richness and cover of herbs, and decreased Shannon diversity of herbs and shrubs.ConclusionWe suggest that browsing by large herbivores should be included when studying understorey shrub communities, however when studying understorey herb communities the effects of browsing are less general and depend on forest features.

Elevational changes in vascular plants richness, diversity, and distribution pattern in Abune Yosef mountain range, Northern Ethiopia

The aim of this research is to investigate the patterns of vascular plant species richness, diversity, and distribution along an elevation gradient in the Abune Yosef mountain range, Ethiopia. Preferential systematic sampling was employed to collect vegetation and environmental data along the elevation gradient. We found that plant species richness declines monotonically from low to high elevations. Specifically, vascular plant species richness and diversity were lower in the Afroalpine grassland (high elevation) than in the Dry evergreen Afromontane forest and Ericaceous forest (low elevations). In contrast, endemic vascular plant richness was significantly higher in the Afroalpine grassland than in the Dry evergreen Afromontane forest and Ericaceous forest. Elevation showed a significant impact on the richness, diversity, and endemism of vascular plants. According to Sørensen's coefficient, the similarity between Dry evergreen Afromontane forest and Ericaceous forest vegetation types is higher (32%) than the similarity between Ericaceous forest and Afroalpine grassland (18%). Only 5% similarity was recorded between the Dry evergreen Afromontane forest and Afroalpine grassland. Growth forms showed different elevational richness patterns. Trees and liana increased monotonically up to 3300 m. Shrub and herb richness patterns followed a hump-shaped and inverted hump-shaped pattern along the elevation gradient. The elevation patterns of vascular plant species richness, diversity, and growth form in the present study may be attributed to differences in management intensity, spatial heterogeneity, microclimatic variations, and anthropogenic disturbances.

Effects of eucalyptus plantations on avian and herb species richness and composition in North-West Spain

Eucalyptus plantations have been established in many areas of the world due to their fast growth and profitability. In NW Spain, Eucalyptus plantations now cover a larger area than native forests. Although Eucalyptus plantations have been shown to affect biodiversity, relatively few studies have compared their effect on multiple taxonomic groups and different aspects of biodiversity. We compared herb and bird species richness and bird abundance between 14 paired patches of native deciduous forest and Eucalyptus plantations in a heterogeneous agro-forest region of NW Spain. We also investigated whether Eucalyptus plantations contribute to shifts in community composition by analysing species nestedness and turnover. We found that species richness of both herbs and birds was consistently lower in Eucalyptus plantations compared to native forests. Furthermore, the abundances of bird species characteristic of agricultural, forest, scrubland and other habitats, were all much lower in Eucalyptus plantations than in native forests. Herb and bird communities were also significantly dissimilar between the two habitats, but as a result of different ecological processes. Species turnover explained variation between habitats in herb composition, such that species present in native forests were typical for both farmland and forest habitats, whereas those present in Eucalyptus plantations were typical for scrub and farmland habitats. In contrast, bird assemblages showed a significant nested subset pattern, with fewer species in Eucalyptus plantations compared to native forests. In total, the relative abundance of cavity-nesting forest birds was at least 64% higher in native forests. Our results show that Eucalyptus plantations cannot replace native forests as they harbour different herb species and only a subset of the bird species found in native forests. Considering the current rate of increase of Eucalyptus plantations and the fragmentation of native forests in NW Spain, a lack of conservation of native forests could result in future loss of biodiversity in general and forest specialist species in particular.

Effects of boundary constraints and climatic factors on plant diversity along an altitudinal gradient

Despite the long-standing ecological interest in elevational-diversity gradients, it remains unclear whether different life forms (trees, shrubs and herbs) show the same diversity patterns along the gradient. The distribution of plants observed along an altitudinal elevation in the Lancang River Nature Reserve (Yunnan, China) was used to explore this question. We also explored the effects of boundary constraints and climatic factors on the distribution of plant diversity. Our results showed that: (1) All life forms (trees, shrubs and herbs) showed significant and similar elevational trends in richness, with the trend the most significant for trees (R2 = 0.708, p < 0.001), where species richness first increases and then decreases with increasing altitude. (2) Raw tree, shrub and herb richness are significantly correlated with each other, and shrub layer richness and herb layer richness have the greatest correlation (R2 = 0.715). (3) MAT (mean annual temperature), WMT (maximum temperature of the hottest month) and CMT (minimum temperature of the coldest month) better explained the richness patterns (raw and estimated) of different plant life forms along the elevational gradient than other climatic factors. (4) Estimated species (boundary constraint reduced) richness patterns along an elevational gradient can be better explained by climatic variables than by raw species richness for all life forms. Our findings reveal that the richness patterns of different life-forms were similar along the altitudinal gradient.

Assessment of tree diversity and above-ground biomass in coffee agroforest dominated tropical landscape of India’s Central Western Ghats

The purpose of this study was to quantify the changes in tree diversity and above-ground biomass associated with six land-use types in Kodagu district of India’s Western Ghats. We collected data on species richness, composition and above-ground biomass (AGB) of trees, shrubs and herbs from 96 sample plots of 0.1 ha. Totals of 83 species from 26 families were recorded across the land-uses. Tree species richness, diversity and composition were significantly higher in evergreen forest (EGF) than in other land-uses. Similarly, stem density and basal area were greater in EGF compared to other land-uses. Detrended correspondence analysis (DCA) yielded three distinct groups along the land-use intensities and rainfall gradient on the first and second axes, respectively. The first DCA axis accounted for 45% and second axis for 35% of the total variation in species composition. Together the first two axes accounted for over 2/3 of the variation in species composition across land-use types. Across the land-uses, AGB ranged from 58.6 Mg ha−1 in rubber plantation to 327.3 Mg ha−1 in evergreen forest. Our results showed that species diversity and AGB were negatively impacted by the land-use changes. We found that coffee agroforests resembled natural forest and mixed species plantation in terms of tree diversity and biomass production, suggesting that traditional coffee farms can help to protect tree species, sustain smallholder production and offer opportunities for conservation of biodiversity and climate change mitigation.

Ecological consequences of shrub encroachment in the grasslands of northern China

Shrub encroachment is a critical environmental issue in arid and semi-arid landscapes. However, due to the complicated effects of shrub characteristics and environmental variables, ecological consequences of shrub encroachment significantly differ in different regions. As a result, although the phenomenon of shrub encroachment is widespread in the grasslands of northern China, its ecological consequences and associated drivers have not been well documented at the regional scale. We explored the effects of shrub encroachment on ecosystem structures (herb richness and abundance) and functioning (above- and belowground biomass, and soil carbon and nitrogen content) and evaluated the relative importance of climatic variables (temperature and precipitation) and shrub characteristics (cover, area, and height) as drivers of these effects. Based on field data from 53 sites that stretch across approximately 3000 km in northern China, we conducted the relative interaction intensity (RII) of the response variables between shrub patches and grassy matrix, and then used the structural equation modeling (SEM) to assess the relative importance of chosen drivers on the ecological consequences. Shrub encroachment increased the landscape heterogeneity by decreasing the richness, abundance and aboveground biomass of herbs, while by increasing the soil carbon and nitrogen content. The SEM explained 25–43% of the variation in shrub characteristics and 5–34% of the variation in the effects of shrub encroachment. Shrub height had greater effects on the RII of herb richness, soil carbon and soil nitrogen content, and the standardized total effects were 0.48, 0.25 and 0.18, respectively. Precipitation and temperature positively affected the impacts of shrub encroachment on herb richness, abundance, biomass, and multi-indexes. However, the direct effects of climate could be partially mediated by indirect effects via shrub characteristics. The height, size and cover of shrub patches significantly influenced the community structures and functioning of grassland ecosystems. The increasing aridity could potentially exacerbate the negative consequences of shrub encroachment in arid regions. Our results also demonstrated that the effects of climate variables on grassland ecosystems could be mediated by shrub management.

A trait‐based approach reveals the importance of biotic filter for elevational herb richness pattern

AbstractAimTo evaluate how a biotic filter (overstorey cover [OC]) shapes an elevational herb richness pattern and to test whether intermediate elevations represent more suitable habitats for herb species due to the minimal biotic and moderate abiotic filtering that occured there.LocationDongling Mountain, China.TaxonHerbs.MethodsWe sampled herb richness along a 1,000‐m vertical transect (OC and elevation covary) and four horizontal transects (across the OC gradient with no change in elevation). Functional traits related to shade (leaf mass per area [LMA] and leaf stem ratio [LSR]) and freezing tolerance (leaf thickness [LT] and hair density [HD]) were collected based on vegetation sampling plots. We divided the richness data into below‐ and above‐timberline groups and then assessed the most important driver for each group. By estimating the variations in species richness and functional diversity along horizontal transects, we examined how these parameters responded to OC while controlling for associated differences in elevation.ResultsHerb richness showed a unimodal relationship with elevation, with a peak around the timberline. Below the timberline, herb richness was better predicted by OC and showed a positive relationship with the functional diversity of LMA and LSR. The frost period performed better in predicting herb richness above the timberline, and herb richness was positively related to the functional diversity of HD.Main conclusionsThe results support our hypothesis and highlight the importance of OC in shaping herb richness patterns. Below the timberline, OC acts as a filter, sorting species based on their ability to tolerate shade, whereas the frost period limits richness above the timberline and favours species that can tolerate low temperatures. Therefore, we suggest that biotic interactions, as well as environmental and geographical factors, should be considered the main drivers of elevational plant richness patterns.

Fire rather than nitrogen addition affects understory plant communities in the short term in a coniferous-broadleaf mixed forest.

Increasing fire risk and atmospheric nitrogen (N) deposition have the potential to alter plant community structure and composition, with consequent impacts on biodiversity and ecosystem functioning. This study was conducted to examine short‐term responses of understory plant community to burning and N addition in a coniferous‐broadleaved mixed forest of the subtropical‐temperate transition zone in Central China. The experiment used a pair‐nested design, with four treatments (control, burning, N addition, and burning plus N addition) and five replicates. Species richness, cover, and density of woody and herbaceous plants were monitored for 3 years after a low‐severity fire in the spring of 2014. Burning, but not N addition, significantly stimulated the cover (+15.2%, absolute change) and density (+62.8%) of woody species as well as herb richness (+1.2 species/m2, absolute change), cover (+25.5%, absolute change), and density (+602.4%) across the seven sampling dates from June 2014 to October 2016. Light availability, soil temperature, and prefire community composition could be primarily responsible for the understory community recovery after the low‐severity fire. The observations suggest that light availability and soil temperature are more important than nutrients in structuring understory plant community in the mixed forest of the subtropical‐temperate transition zone in Central China. Legacy woody and herb species dominated the understory vegetation over the 3 years after fire, indicating strong resistance and resilience of forest understory plant community and biodiversity to abrupt environmental perturbation.

Benefits of thinning and burning for understory diversity vary with spatial scale and time since treatment

Fuel-reduction treatments have been used effectively in dry, fire-adapted forests to reduce risk of high-severity crown fire, but it is less certain whether they achieve ecological objectives such as promoting understory diversity. Using long-term data from a fuel-reduction experiment, we tested how conclusions about treatment effectiveness are related to the spatial and temporal scales over which ecological responses are evaluated. We modeled the richness of herbs and shrubs at smaller (1–50 m2) and larger (1000 m2) spatial scales as functions of pre-treatment richness, thinning intensity, burning, and time since treatment (2–3 vs. 10–13 years). Pre-treatment richness was the strongest predictor of post-treatment richness, reflecting high rates of species survival, irrespective of treatment. Richness was enhanced by burning and, to a lesser extent, by thinning, although the timing and strengths of these effects varied with spatial scale. Among herbs, annuals showed an early and persistent increase after burning at the larger scale, but a lagged response at the smaller scale—the latter enabled by limited competition from perennial herbs and shrubs. In contrast, perennials showed lagged responses to thinning at smaller scales and to burning at larger scales, suggesting slow recruitment via seed or vegetative spread. Non-natives were unresponsive to treatments but were also uncommon before treatment, suggesting limited propagule pressure from the surrounding landscape. Rates of colonization were unrelated to pre-treatment richness; thus, the potential for understory enrichment was not constrained by initial diversity. The low cover and lagged responses of woody and herbaceous perennials suggest that further enrichment is possible, particularly at smaller spatial scales. Our results illustrate that uncertainty about the ecological effectiveness of fuels treatments can relate to the spatial and temporal scales over which responses are measured. They underscore the value of long-term, multi-scale assessments in defining the spatial and temporal contexts of ecological outcomes, and in evaluating the necessity for, or timing of, further intervention.

Species diversity, pollinator resource value and edibility potential of woody networks in the countryside in northern Belgium

Woody networks of hedgerows, tree lines and forest patches can harbour a high biodiversity and may serve as an important species refuge in agricultural landscapes. In order to protect the biodiversity and associated potential ecosystem services of woody networks, we need to understand their drivers. We surveyed the plant diversity and calculated the pollinator resource value and edibility value of 831 woody elements in 47 landscape windows of 1 km2 in the countryside in northern Belgium. The woody network hosted approximately 45% of the plant diversity in the studied countryside, and forest species, grassland species, tall herbs as well as pioneer species coexisted successfully within the woody elements. The pollination resource value showed the highest correlation with the species richness and abundance of the forest species, whereas for edibility the species richness and abundance of the tall herbs were determinative. The number of forest species mainly depended on the presence of forests in the surrounding landscape and the link was even stronger in historical woody elements. For grassland species, tall herbs and pioneers, we found that structural variables of the woody element itself were the most important driver. We argue that by protecting existing woody elements and thoughtfully designing and locating new ones, intrinsic and functional diversity in the countryside can benefit well.

Influence of nitrogen fertilization on abundance and diversity of plants and animals in temperate and boreal forests

Aerial and land-based applications of nitrogen-based fertilizers to enhance forest growth makes nutrients potentially available to all trees, plants, and wildlife in a given ecosystem and, therefore, may have direct and indirect effects on wildlife and biodiversity. A scientific review of these potential effects was conducted with 106 published studies covering vascular and nonvascular plants, amphibians, birds, mammals, terrestrial invertebrates, and soil animals associated with fertilization in temperate and boreal forests, primarily in North America and Scandinavia. In terms of direct effects, amphibians and domestic mammals appear to be the most sensitive to urea used in fertilization programs. The avoidance behaviour and (or) mortality of amphibians in laboratory studies was species dependent. Ruminant animals, including wild ungulates, rapidly convert urea to ammonia and are susceptible to toxicity following ingestion of large amounts of urea. Feeding on urea pellets by small mammals or gallinaceous birds appears to be minimal as granules are unpalatable. In terms of indirect effects, the majority of responses of understory herbs to nitrogen fertilization showed an increase in abundance. Some shrubs in repeatedly fertilized stands eventually increased in abundance in long-term studies, whereas dwarf shrubs and abundance of bryophytes (mosses and terrestrial lichens) declined. In general, species richness and diversity of understory herbs and shrubs declined, or were unaffected, in fertilized stands. Response in abundance and species richness-diversity of vascular plants to a single application of nitrogen showed either an increase or no change. Repeated applications (2–5 and &gt;5) usually resulted in declines in these responses. Relative abundance of mule deer (Odocoileus Rafinesque spp.), moose (Alces alces L.), and hares (Lepus L. spp.), and forage quantity and quality were usually increased by fertilization. Small mammal species generally showed increases or no change in abundance; decreases may be related to fertilizer-induced changes in food sources. Forest fertilization may provide winter feeding habitat for coniferous foliage-gleaning insectivorous birds in some cases. Six species of forest grouse showed no response to fertilizer treatments. Responses of soil animals to nitrogen fertilization appeared to be species- and dose-specific and are ameliorated by surrounding micro- and macro-habitat characteristics.

Drought differentially affects the post-fire dynamics of seeders and resprouters in a Mediterranean shrubland

In fire-prone ecosystems, changes in rainfall after fire could differentially affect seeders and resprouters, thus leading to long-lasting impacts on the vegetation. Climate change in the Mediterranean region is projected to reduce precipitation, expand the summer drought and increase fire danger. Understanding the sensitivity to changes in rainfall during the post-fire regeneration stage is critical to anticipate the impacts of climate change on Mediterranean-type areas of the world.Here, we investigated how species differing in post-fire regeneration strategy (seeders vs resprouters) responded to rainfall changes in a Cistus-Erica shrubland of central Spain. Drought treatments were implemented using a system of automatic rainout shelters with an irrigation facility before (one season) and after (four years) burning a set of experimental plots. Treatments applied were: environmental control (natural rainfall), historical control (mimicking the long-term rainfall), moderate drought (−25% rainfall), and severe drought (−45% rainfall). Plant demography and vigour (main woody shrubs), as well as abundance (shrubs and herbs) were monitored during the first four years after fire.The first post-fire year was the key period for the recovery of seeders (Cistus ladanifer and Rosmarinus officinalis), and their recruitment, cover and size significantly decreased with drought. However, density four years after fire was larger than unburned and it was significantly correlated with emergence during the first year, indicating that population controls were more on emergence than on establishment. In contrast, resprouters (Erica arborea, Erica scoparia and Phillyrea angustifolia) were hardly affected by drought. Plant community dynamics in the burned control plots progressively converged with the unburned ones, while that in the drought-treated plots lagged behind them, maintaining a higher cover, richness and diversity of herbs. This post-fire “herbalization” due to drought might facilitate an untimely fire, before seeders would reach sexual maturity, which could have major implications for the maintenance of the community.

基于林龄的滨海盐碱地杨树刺槐混交林土壤理化性质及草本植物多样性动态

PDF HTML阅读 XML下载 导出引用 引用提醒 基于林龄的滨海盐碱地杨树刺槐混交林土壤理化性质及草本植物多样性动态 DOI: 10.5846/stxb201801220172 作者: 作者单位: 山东农业大学,山东农业大学,滨州学院,山东农业大学,山东省黄河三角洲农业高新技术产业示范区管理委员会 作者简介: 通讯作者: 中图分类号: S725.1 基金项目: 国家自然科学基金项目（31770668）；山东省重大科技创新工程（2017CXGC0316）；山东省重点研发计划（2015GNC111026） Soil physiochemical properties and diversity of herbaceous plants dynamic on the different ages mixed forests of Populus×Euramercana ‘Neva’ and Robinia pseucdoacacia in coastal saline-alkali area Author: Affiliation: Shandong Agricultural University, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以黄河三角洲滨海盐碱地不同林龄的杨树（Populus×Euramercana ‘Neva’）、刺槐（Robinia pseucdoacacia）人工混交林及相应的纯林为研究对象，采用空间代时间的方法，研究了其不同林龄人工林林下植被特征与土壤理化性质变化。结果表明：（1）白茅（Imperata cylindrica）、猪毛菜（Salsola collina）、刺儿菜（Cirsium setosum）是滨海盐碱地人工林林下群落的优势种。（2）随着林分年龄（3年、7年、18年）的增加，杨树刺槐混交林及相应纯林Patrick指数及Margalef指数、Shannon-Wiener指数、Simpson指数及Pielou指数均表现出低-高-低的变化趋势，7年生时丰富度、草本多样性、均匀度最高。（3）杨树刺槐混交提高了林下草本物种组成及重要值，就纯林而言，刺槐林下植被物种多样性显著高于同龄杨树。（4）随着林龄的增大，杨树刺槐混交林及其纯林林下土壤pH值逐渐降低，杨树刺槐纯林土壤含盐量先增后减，杨树×刺槐混交林土壤含盐量依次递减；杨树刺槐混交林及其纯林林下土壤全磷含量呈先增加后减小趋势；杨树纯林及杨树×刺槐混交林全氮含量呈先减小后增加的趋势，刺槐纯林林下土壤全氮量呈连续增长的趋势；林龄间土壤pH、含盐量、全氮及全磷含量差异显著。（5）草本植物多样性相关指数与土壤含盐量呈极显著负相关，与土壤全磷量呈极显著正相关。 Abstract:Using the variable of spatial instead of time, the dynamics of soil physiochemical properties and undergrowth vegetation characteristics of Populus×Euramercana ‘Neva’ and Robinia pseucdoacacia artificial mixed and the corresponding pure forests in different ages in the coastal saline-alkali area of the Yellow River Delta were addressed in this research. The results showed that:(1) Imperata cylindrica, Salsola collina, and Cirsium setosum were the dominant species in the undergrowth community of plantations. (2) With increasing plantation ages (3 a, 7 a, and 18 a), the Patrick index, Margalef index, Shannon-Wiener index, Simpson index, and Pielou index of Populus×Euramercana ‘Neva’ and Robinia pseucdoacacia artificial mixed forests and their pure forests appeared a low-high-low variation trend; 7 a artificial forests had the highest richness, uniformity, and diversity of herbs. (3) Populus×Euramercana ‘Neva’ and Robinia pseucdoacacia mixed forest had more species of understory herbs and higher importance values. As far as pure forests are concerned, the species diversity of the understory vegetation of the Robinia pseucdoacacia forest was significantly higher than that of the Populus×Euramercana ‘Neva’ forest. (4) With stand age increased, the soil pH value of mixed and the corresponding pure forests decreased gradually. The soil salinity of pure forests increased first and then decreased, and that of the mixed forests decreased gradually. The total phosphorus content of mixed and the corresponding pure forests first increased and then decreased. The total nitrogen content of the Populus×Euramercana ‘Neva’ pure and mixed forests first decreased and then increased. Soil total nitrogen content in the Robinia pseucdoacacia pure forests exhibited a continuously increasing trend. Soil pH value, salinity, total nitrogen, and total phosphorus among the three age stands were significantly different. (5) There was a significant negative correlation between the index of herbaceous diversity and soil salinity, and a significant positive correlation with soil total phosphorus. 参考文献 相似文献 引证文献

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

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

How long should the fully hillside-closed forest protection be implemented on the Loess Plateau, Shaanxi, China?

BackgroundRestoration of degraded forest ecosystem is crucial for regional sustainable development. To protect the country’s fragile and fragmented environment, the Chinese government initiated an ecological engineering project, the Natural Forest Protection Program, in seventeen provinces in China beginning in 1998. Fully hillside-closed forest protection (vegetation restoration naturally without any artificial disturbance) was one of vital measures of the Natural Forest Protection Program applied nation wide. Whether plant diversity, biomass and age structure of dominant tree species and soil nutrients in protected stands may become better with increase of protected period are still open problems.MethodsWe investigated community diversity, biomass of dominant tree species, age structures, and analyzed soil chemical properties of a Pinus tabulaeformis population at protected sites representing different protected ages at Huanglongshan Forest Bureau on the Loess Plateau, Shaanxi, China.ResultsPlant species richness of Pinus tabulaeformis community was significantly affected (p < 0.05) by forest protection and the effect attenuated with protection age. Shannon evenness index of plant species generally increased with protection age. Stands protected for 45 years had the highest tree biomass and considerable natural regeneration capacity. Contents of organic carbon, available phosphorus and available potassium in top soil increased in protected stands less than 45 years, however decreased significantly thereafter. Long-term forest protection also decreased the content of mineral nitrogen in top soil.DiscussionWe found that the richness of shrubs and herbs was significantly affected by forest protection, and evenness indices of tree, shrub and herb increased inconsistently with protected ages. Forest protection created more complex age structures and tree densities with increasing age of protection. Content of soil mineral nitrogen at 0–20 cm soil depth showed a decreasing trend in stands of up to 30 years. Soil available phosphorus and potassium contents were higher in stands with greater proportions of big and medium trees. Long-term protection (>45 years) of Pinus tabulaeformis stands in southeast Loess Plateau, China, may be associated with decreasing plant species richness, proportion of medium to large trees, dominant biomass of Pinus tabulaeformis and soil nutrients.

Seasonal changes of the Hazel Grouse Tetrastes bonasia habitat requirements in managed mountain forests (Western Carpathians)

We studied the differences between spring and winter sites of Hazel Grouse Tetrastes bonasia in a managed, temperate forest in the Beskid Mountains (Western Carpathians, Poland). The study of seasonal requirements of this species in this type of habitat was innovatory. Spring territories must provide birds with appropriate conditions for breeding and winter ones must give good habitat for wintering. The environmental variables of spring and winter sites were collected in three layers in a 100 m radius from the place of recording of the Hazel Grouse: canopy, understory and undergrowth. According to our study, the proportion of deciduous trees was greater in spring territories in comparison to winter territories in all studied layers. Conversely, greater species richness in the undergrowth and understory in spring sites of Hazel Grouse was found in comparison to winter sites. Moreover, a greater proportion of birch, poplar, willow, wild cherry and bird cherry were found in the spring sites of Hazel Grouse in comparison to winter sites. Generalized Linear Model models showed that the occurrence of overgrown clearings, clearfellings with deadwood and higher richness of grass and herbs and their cover in the forest were important habitat factors for Hazel Grouse in both spring and winter sites. Sites of Hazel Grouse were strongly affected by the proportions of beech, sycamore, fir, spruce and larch in the canopy layer in both seasons. Moreover, a greater proportion of tree species producing nuts, drupes or winged seeds was important in both spring and winter sites. Bush cover was important for winter sites of the Hazel Grouse. Food resources, mainly in winter sites are important factors for habitat selection. Summarizing, we found habitat differences between spring territory and winter sites of Hazel Grouse. In both seasons, higher habitat heterogeneity was an important factor for occurrence of this species.

Phytosociology and ecology of treeline ecotone vegetation in Rolwaling Himal, Nepal

Questions: Species composition and ecology of treeline vegetation types in the Rolwaling Valley is largely unknown to date. The aim of this study is to differentiate plant communities along the elevational gradient in the treeline ecotone, and to identify site factors which cause the differentiation of the treeline ecotone vegetation. Study area: Rolwaling Valley (27 degrees 52' N;86 degrees 25' E) in the central Himalaya, Nepal. Methods: We included 91 phytosociological releves along three elevational transects in this analysis, ranging from 3745 to 4300 m a.s.l. Plant communities were differentiated and vegetation-environment relationships analysed using cluster analysis and ordination. For each community and higher ranked unit, we detected diagnostic species according to their fidelity index (phi coefficient). Ecological preferences of each community were examined using one-way analysis of variance (ANOVA). Results and conclusions: We identified five communities, belonging to two different classes: the Synotis alata-Abies spectabilis and Ribes glaciale-Abies spectabilis communities occupy the upper part of the subalpine forest zone, representing the uppermost forest stands below treeline. These communities are primarily comprised of Abies spectabilis and Betula utilis in the tree layer, with varying cover of several tree species and distinct differences within the herb layer. Above treeline, the mixed forest stands are replaced by the species-poor Boschniakia himalaica-Rhododendron campanulatum community, forming a dense krummholz belt. We assigned the forest and krummholz communities to the class Betula utilis-Abies spectabilis forests. In the alpine zone two communities were classified and assigned to the class Dasiphora arbuscula-Rhododendron anthopogon dwarf shrub heaths.The species-poor Pedicularis cf. micro calyx-Rho dodendron anthopogon community has a less developed herbaceous layer, whereas the Anaphalis royleana-Rhododendron anthopogon community is characterized by higher cover and higher species richness of herbs and grasses. Species composition of identified communities is mainly differentiated by soil temperature, nitrogen supply and availability, and soil moisture content.