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Li R.,Sichuan Academy of Forestry | Bennett J.,Australian National University | Wang X.,Australian National University
Land Use Policy | Year: 2013

The assessment of land use change (LUC) proposals aimed at improving environmental conditions requires information regarding the relationship between actions and outcomes. Yet such information is often limited in detail, especially in developing country contexts. This paper demonstrates an approach to the estimation of farm level biophysical relationships between proposed LUC activities and their impacts on soil erosion, air quality and biodiversity in the context of a payment for environmental services (PES) auction in Sichuan Province, China. Because data at the farm level are unavailable, the models are based on divergences of each farm's biophysical conditions from well-established regional averages. This paper focuses on the estimation of the farm-to-region divergence factors and the development of environmental outcome predictions that reflect the relative ecological significance of alternative LUC proposals. The strengths and weaknesses of the biophysical models are also discussed. © 2012. Source

Bu X.,Nanjing Forestry University | Ruan H.,Nanjing Forestry University | Wang L.,Fujian Academy of Agricultural science | Ma W.,Sichuan Academy of Forestry | And 2 more authors.
Applied Soil Ecology | Year: 2012

Density fractionation can be a useful means of separating soil organic matter (SOM) into light and heavy fractions. Our objective was to evaluate SOM storage in density fractions and the relative contribution of the light fraction to total SOM pool under four different vegetations, including evergreen broad-leaved forest (EBF), coniferous forest (CF), dwarf forest (DF) and alpine meadow (AM), along an altitude gradation in the Wuyi Mountains of southeastern China, and to investigate the factors controlling the pool size in density fractions. Here we separated light and heavy fractions using 1.7gcm-3 sodium iodide solution. The concentrations of C and N in light and heavy fractions were the highest in AM soils, while the C/N ratios in density fractions were the highest in CF soils across soil depths. The amounts of C and N in the heavy fractions increased with increasing silt plus clay content in the corresponding soil depth. Greater SOM storages in light and heavy fractions under AM suggested that the accumulation of SOM at higher altitude (lower soil temperature and higher soil moisture) mainly depends on slower decomposition rate despite lower organic matter inputs rate. The relatively larger contribution of the light fraction to total SOM under CF than that under the other three vegetation types is mainly attributed to its higher amount and quality of litterfall input and greater fine root biomass. Significant correlation existed between light fraction C and N, dissolved organic C, microbial biomass C and N, indicating considerable cycling of C and N between these pools. A stronger correlation between heavy fraction C and microbial biomass C suggested that the heavy fraction organic matter could be associated with most microbial biomass. © 2011 Elsevier B.V. Source

Su X.,Southwest University | Zeng B.,Southwest University | Huang W.,Sichuan Academy of Forestry | Xu S.,Southwest University | Lei S.,Southwest University
Ecological Engineering | Year: 2012

After the construction of the Three Gorges Dam (TGD) on Yangtze River, the preupland region and preriparian zone were submerged as a result of a substantial increase in the water level. To assess the overall effects of the Three Gorges Reservoir (TGR) impoundment on the drawdown zone vegetation, we compared the preupland drawdown zone (PU-DZ) vegetation with its adjacent upland and the preriparian drawdown zone (PR-DZ) vegetation with the natural riparian zone (NRZ) of the Yangtze River. Twelve sites were surveyed in each of these four habitats in September 2009. The results showed that the TGR impoundment had different effects on the PU-DZ and PR-DZ vegetation. The species composition of the PU-DZ vegetation changed substantially after the impoundment. The species number per 100m 2 increased significantly in the PU-DZ compared with the adjacent upland. Most of the species were forbs and ferns, especially annual and biennial species. However, the total cover in the PU-DZ was lower than that of the adjacent upland due to the destruction of tree and shrub communities. In contrast, the total cover and species composition of the PR-DZ did not change as seriously as the PU-DZ vegetation for the existing tolerant perennials. Significantly fewer species were found per 100m 2 in the PR-DZ than in the NRZ. Moreover, the species numbers per 100m 2 for trees and shrubs, forbs and ferns and graminoids decreased significantly, but the proportions of cover for these groups were unchanged, except for trees and shrubs decreased significantly. This result indicated that all species groups were extensively suppressed in the PR-DZ. © 2012 Elsevier B.V. Source

Zhang C.,CAS Kunming Institute of Botany | Zhang C.,University of Chinese Academy of Sciences | Irwin R.E.,Dartmouth College | Wang Y.,CAS Kunming Institute of Botany | And 3 more authors.
New Phytologist | Year: 2011

• Self-pollination often provides plants with the benefit of reproductive assurance; thus, it is generally assumed that species' interactions that alter floral attractiveness or rewards, such as nectar robbing, will have little effect on the seed production of selfing species. We challenge this view with experimental data from Comastoma pulmonarium, a selfing annual experiencing a high ratio of nectar robbing in the Qinghai-Tibet Plateau. • We manipulated robbing (robbed or netted) and pollination mode (hand-selfed or hand-outcrossed) in a factorial design and measured the number of developing ovules and mature seeds, together with seed weight and seed germination, in each treatment. • Robbing decreased the number of mature seeds, but not the number of developing ovules, suggesting a negative influence of robbers through indirect effects via selective seed abortion. We found no evidence for early-acting inbreeding depression, but found later-acting inbreeding depression. Our data also suggested that later-acting inbreeding depression of progeny from robbed flowers could be reduced in comparison with that from unrobbed flowers. • We suggest that nectar robbing can have both negative and positive effects on the quantity and quality, respectively, of progeny produced in selfing plants, and challenge the view that robbing has no effect on selfing species. © 2011 New Phytologist Trust. Source

Wu P.,Southwest University for Nationalities | Liu S.,Chinese Academy of Forestry | Liu X.,Sichuan Academy of Forestry
Plant and Soil | Year: 2012

Aims: The aim of this study was to analyze the composition and spatio-temporal variation of soil macroinvertebrate communities in the northern Hengduanshan Mountains, Southwest China. Methods: The soil macroinvertebrates were investigated in April, August and November of 2008 in two deciduous broad-leaved forests: secondary shrub forest (SSF) and Betula albosinensis forest (BSF), two coniferous forests: Picea asperata plantation (PAP) and Abies fabri and Larix kaempferi mixed forest (ALF), a coniferous (A. fabri) and broad leaf (B. albosinensis) mixed forest (ABF) and a subalpine meadow (SM) at elevations of 2659 to 3845 m. Results: The soil macroinvertebrate community showed typical zonal characteristics compared with other localities in China. It comprised at least 113 taxa and was dominated by Insects (43. 33%, mainly Coleoptera and Diptera), followed by Diplopoda (16. 37%), Malacostraca (14. 31%), Oligochaeta (12. 71%) and Chilopoda (6. 67%). Abundances of each taxa showed clear differences among habitats. Community abundance ranged from 71. 56 individuals/m2 in the PAP to 148. 00 individuals/m2 in the SM. The composition and structure of the soil macroinvertebrate communities varied among the six habitats and changed with the sampling periods. The richness, abundance and Shannon index of soil macroinvertebrate communities were significantly different among habitats, but not between sampling periods. Significant temporal responses in abundance were recorded in the SSF and BSF and the Shannon index for the SM. Further analysis showed that the abundance of the seven taxonomic groups also differed significantly among habitats, but that sampling period only had significant effects on a few taxonomic groups. Patterns of temporal variation in abundance differed among the seven taxonomic groups, even when the same taxa also differed markedly among habitat types. On the whole, these temporal variations in abundance on community and taxa group levels were greater in the SSF and BSF than in the PAP, ABF, ALF and the SM. However, the habitat had a stronger effect on soil macroinvertebrates than the sampling period. Moreover, a significant correlation was found between the abundance, richness and Shannon index of soil macroinvertebrate community and plant species richness, but not with soil properties or elevation. Additionally, more taxonomic groups were significantly influenced by the litter mass and plant coverage, but few with soil properties. Conclusions: Plant community was the main environmental determinant influencing macroinvertebrate distribution in ecosystem of the northern Hengduanshan Mountains and presented a greater effect on the soil macroinvertebrates than soil properties or elevation. The temporal effects on soil macroinvertebrates were stronger in the deciduous broad-leaved forests than in the coniferous forests. © 2012 Springer Science+Business Media B.V. Source

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