Undersampling correction methods to control γ-dependence for comparing ß-diversity between regions.

Measures of ß-diversity are known to be biased by differences in γ-diversity (i.e., γ-dependence), making it challenging to compare ß-diversity across regions. Undersampling corrections have been designed to reduce effects of γ-dependence on ß-diversity arising from the problem of incomplete sampling. However, no study has systematically tested the effectiveness of these corrections or examined how well they reflect ß-diversity patterns across ecological gradients. Here, we conduct these tests by comparing two undersampling corrections with the widely used individual-based null model approach, using both simulated communities along an ecological gradient and empirical data across a wide range of γ-diversity and sample sizes. We found that undersampling corrections using diversity accumulation curves were more effective than the null-model approaches in removing γ-dependence. In particular, the corrected ß-Shannon diversity index was least dependent on γ-diversity, and was the most reflective of the ß-diversity pattern along a simulated ecological gradient. Moreover, a corrected Jaccard-Chao index applied to null model results removed γ-dependence more effectively than either the correction alone or the null model alone. Undersampling corrections are effective tools for removing γ-dependence bias, thus facilitating comparisons of ß-diversity across regions.

Environmental and evolutionary drivers of diversity patterns in the tea family (Theaceae s.s.) across China.

Subtropical forest is recognized as an important global vegetation type with high levels of plant species richness. However, the mechanisms underlying its diversity remain poorly understood. Here, we assessed the roles of environmental drivers and evolutionary dynamics (time-for-speciation and diversification rate) in shaping species richness patterns across China for a major subtropical plant group, the tea family (Theaceae s.s.) (145 species), at several taxonomic scales. To this end, we assessed the relationships between species richness, key environmental variables (minimum temperature of the coldest month, mean annual precipitation, soil pH), and phylogenetic assemblage structure (net related index) by using non-spatial and spatial linear models. We found that species richness is significantly related to environmental variables, especially soil pH, which is negatively related to species richness both across the whole family and within the major tribe Theeae (116 species). Family-level species richness is unrelated to phylogenetic structure, whereas species richness in tribe Theeae was related to phylogenetic structure with U-shaped relationship, a more complex relation than predicted by the time-for-speciation or diversification rate hypotheses. Overall, these results suggest that both environmental and evolutionary factors play important roles in shaping species richness patterns within this subtropical plant family across China, with the latter mainly important at fine taxonomic scales. Most surprisingly, our findings show that soils can play a key role in shaping macro-scale diversity patterns, contrary to often-stated assumptions.

Diversity of woodland communities and plant species along an altitudinal gradient in the Guancen Mountains, China.

Study on plant diversity is the base of woodland conservation. The Guancen Mountains are the northern end of Luliang mountain range in North China. Fifty-three quadrats of 10 m × 20 m of woodland communities were randomly established along an altitudinal gradient. Data for species composition and environmental variables were measured and recorded in each quadrat. To investigate the variation of woodland communities, a Two-Way Indicator Species Analysis (TWINSPAN) and a Canonical Correspondence Analysis (CCA) were conducted, while species diversity indices were used to analyse the relationships between species diversity and environmental variables in this study. The results showed that there were eight communities of woodland vegetation; each of them had their own characteristics in composition, structure, and environment. The variation of woodland communities was significantly related to elevation and also related to slope, slope aspect, and litter thickness. The cumulative percentage variance of species-environment relation for the first three CCA axes was 93.5%. Elevation was revealed as the factor which most influenced community distribution and species diversity. Species diversity was negatively correlated with elevation, slope aspect, and litter thickness, but positively with slope. Species richness and heterogeneity increased first and then decreased but evenness decreased significantly with increasing elevation. Species diversity was correlated with slope, slope aspect, and litter thickness.

Effects of tourism and topography on vegetation diversity in the subalpine meadows of the Dongling Mountains of Beijing, China.

Subalpine meadows in the Dongling Mountains (located at E115º26'-115º40', N40º00'-40º05') of Beijing, China are important for tourism and the provision of ecosystem services. However, because of poor management serious degradation has occurred on these subalpine meadows. The aim of this paper is to present a quantitative analysis of effects of tourism disturbance and topography on the status and diversity of montane meadow communities and to provide direction for improved management. Sixty quadrats of 2 × 2 m(2) along 10 transects were set up to collect data on site characteristics and vegetation status. The relationships between community composition and structure, species diversity, and tourism disturbance and topographic variables were analyzed by multivariate methods (TWINSPAN and CCA). The results showed that eight meadow communities were identified by TWINSPAN. Most of them were seriously degraded. The first CCA axis identified an elevation and tourism disturbance intensity gradient, which illustrated that tourism disturbance and elevation were most important factors influencing meadow types, composition and structure. Some resistant species and response species to tourism disturbance were identified and can be used as indicator species of tourism disturbance. Species richness, heterogeneity and evenness were closely related to tourism disturbance and elevation. It is concluded that tourism disturbance must be controlled to enable grassland rehabilitation to occur in the meadows. Measures of effective management of the meadows were discussed.

Soil biota reduce allelopathic effects of the invasive Eupatorium adenophorum.

Allelopathy has been hypothesized to play a role in exotic plant invasions, and study of this process can improve our understanding of how direct and indirect plant interactions influence plant community organization and ecosystem functioning. However, allelopathic effects can be highly conditional. For example allelopathic effects demonstrated in vivo can be difficult to demonstrate in field soils. Here we tested phytotoxicity of Eupatorium adenophorum (croftonweed), one of the most destructive exotic species in China, to a native plant species Brassica rapa both in sand and in native soil. Our results suggested that natural soils from different invaded habitats alleviated or eliminated the efficacy of potential allelochemicals relative to sand cultures. When that soil is sterilized, the allelopathic effects returned; suggesting that soil biota were responsible for the reduced phytotoxicity in natural soils. Neither of the two allelopathic compounds (9-Oxo-10,11-dehydroageraphorone and 9b-Hydroxyageraphorone) of E. adenophorum could be found in natural soils infested by the invader, and when those compounds were added to the soils as leachates, they showed substantial degradation after 24 hours in natural soils but not in sand. Our findings emphasize that soil biota can reduce the allelopathic effects of invaders on other plants, and therefore can reduce community invasibility. These results also suggest that soil biota may have stronger or weaker effects on allelopathic interactions depending on how allelochemicals are delivered.

Testing the genotoxicity of coking wastewater using Vicia faba and Hordeum vulgare bioassays.

The coking wastewater induces severe environmental problems in China, however, its toxicity has not been well known. In the present study, the genotoxicity of coking wastewater was studied using Vicia faba and Hordeum vulgare root tip cytogenetic bioassays. Results show that the tested coking wastewater decreased the mitotic index, and significantly enhanced the frequencies of micronucleus, sister chromatid exchange and pycnotic cell in concentration-dependent manners. Exposure to the same concentration wastewater, the increasing ratios of above genetic injuries were higher in V. faba than that in H. vulgare. The results imply that coking wastewater is a genotoxic agent in plant cells and exposure to the wastewater in environment may pose a potential genotoxic risk to organisms. It also suggests that both bioassays can be used for testing the genotoxicity of coking wastewater, but the V. faba assay is more sensitive than H. vulgare assay during the process.

[Species diversity and community structure of forest communities in Lishan Mountain].

Lishan Mountain is belonged to the Zhongtiao Ranges in Southeast Shanxi, and situated between 35 degrees 16'30" - 35 degrees 27'20" N and 111 degrees 51'-- 112 degrees 5'35" E. The climate is cool and arid in winter, but warm and rainy in summer. This paper studied the species diversity and community structure of forest communities there, based on field investigation data and by using diversity, richness and evenness indices. The results showed that the species diversity and evenness of the communities were in the order of Acer davidii + Acer mono > Acer davidii + Carpinus turczaninouii > Quercus liaolugensis > Quercus varibilis > Pinus armandii + Betula albo-sinensis > Pinus tabulaeformis + Quercus glandulifera > Betula platyphylla > Platycladus orientalis + Quercus variabilis > Betula albo-sinensis > Pinus armandii > Platycladus orientalis > Pinus tabulaeformis > Populus davidiana + Betula albo-sinensis. The diversity and richness of shrub layer were higher than those of herb layer and arbor layer, but the evenness of arbor, shrub and herb layers had no significant difference. There were positive correlations (P < 0.05) between Shannon-Wiener index, Hill index, and species richness from 1 000 m to 1 920 m above sea level, but negative correlations (P < 0.05) from 1920 m to the top of the Mountain. The species diversity showed a "mid-altitude bulge" pattern with the change of altitude, and the reason was that the combination of temperature and moisture conditions from 1000 m to 1920 m above sea level was improved, and human disturbance was decreased gradually.

Relationship between tourism development and vegetated landscapes in Luya Mountain Nature Reserve, Shanxi, China.

The relationship between tourism development and vegetated landscapes is analyzed for the Luya Mountain Nature Reserve (LMNR), Shanxi, China, in this study. Indices such as Sensitive Level (SL), Landscape Importance Value (LIV), information index of biodiversity (H'), Shade-tolerant Species Proportion (SSP), and Tourism Influencing Index (TII) are used to characterize vegetated landscapes, the impact of tourism, and their relationship. Their relationship is studied by Two-Way Indicator Species Analysis (TWINSPAN) and Detrended Correspondence Analysis (DCA). TWINSPAN gives correct and rapid partition to the classification, and DCA ordination shows the changing tendency of all vegetation types based on tourism development. These results reflect the ecological relationship between tourism development and vegetated landscapes. In Luya Mountain Nature Reserve, most plant communities are in good or medium condition, which shows that these vegetated landscapes can support more tourism. However, the occurrence of the bad condition shows that there is a severe contradiction between tourism development and vegetated landscapes.

Effects of vegetation and fertilization on weathered particles of coal gob in Shanxi mining areas, China.

Combined application of sewage sludge and chemical fertilizer in weathered particles of coal gob (WPCG) was studied by pot-scale trials. The accumulation of available nutrients and weathering process of coal gob piles were also investigated by field trial. It was showed that combined application of sewage sludge and chemical fertilizer increased yields of tall fescue, improved WPCG fertility especially its biological fertility. After application of sewage sludge, the microbial biomass carbon, urease activity and total microorganism population were, respectively, increased by 0.3-2.4, 1.8-2.8 and 34-150 times. Heavy metals did not accumulate in tall fescue after application of sewage sludge in WPCG. Available nutrients were accumulated in topsoil eight years after reclamation in the field trial. Moreover, the effects of biological weathering exceeded that of natural weathering in coal gob piles. The percentage of coal gob particle diameter smaller than 3mm in the reclamation sites was increased by 85-203%, but 30% in the un-reclaimed sites. While that of greater than 10 mm in the un-reclaimed sites was decreased by 19%, however, 62-74% in the reclamation sites. It was concluded that combined application of sewage sludge and chemical fertilizer could help quickly establishing a self-maintaining vegetation system in the primary process of reclamation.

[Ecological relationships among artificial vegetations during their restoration in Antaibao mining area].

By the methods of TWINSPAN, DCA and DCCA, and from the aspects of the relations between plant species, communities and environmental factors, this paper studied the ecological relationships among artificial vegetations during their restoration in Antaibao mining area. 63 collected quadrates were classified into 12 community types by TWINSPAN, and the distribution of the communities could comprehensively reflect the influence of environmental factors. DCA ordination indicated that soil water content, which was increased with restoration time, was the main factor restricting the distribution of the communities. DCCA ordination showed that soil organic matter content was the decisive factor to the development of communities.

[Emergy evaluation of power plant eco-industrial park].

In this paper, new emergy indices for the material circulation utilization and energy cascade utilization were presented to evaluate the emergy of power plant eco-industrial park. The common contribution of the members in power plant eco-industrial park should be accounted for emergy yield ratio (PEYR) and emergy investment ratio (PEIR), namely, PEYR = sigma(i = 1)6 (Fi + Ri + Ni)/sigma(i = 1)6 Fi and PEIR = sigma(i = 1)6 Fi/sigma(i = 1)6 (Ni + Ri). Saved renewable and nonrenewable resources and purchased resources and decreased environmental load should be accounted for environmental loading ratio (PELR) and index of sustainability (PESI), namely, PELR = sigma(i = 1)6 Fi/F' and PESI = PEYR/PELR. Case analysis on the Shuozhou power plant eco-industrial park showed that new emergy indices were practical in evaluating the power plant eco-industrial park.