Species spatial distributions in a warm-temperate deciduous broad-leaved forest in China

Spatial distribution is fundamental for understanding species coexistence mechanisms in forest communities.Here we comprehensively explored fine-scale spatial patterns of tree species in a secondary warm-temperate deciduous broad-leaved forest community in north China.Aggregated distribution patterns were predominant.Species functional traits had no significant effects on their spatial patterns.The aggregation intensity decreased with increasing DBH and abundance.The multivariate linear stepwise regression showed that abundance and maximum DBH were correlated with the aggregation intensity.Our results partially confirm that species attributes(abundance,DBH)and habitat heterogeneity may primarily contribute to spatial patterns and species coexistence in this secondary forest.

Community Dynamics of Seed Rain in Mixed Evergreen Broad-leaved and Deciduous Forests in a Subtropical Mountain of Central China

Seed dispersal is a key process within community dynamics. The spatial and temporal variations of seed dispersal and the interspecific differences are crucial for understanding species coexistence and community dynamics. This might also hold for the mixed evergreen broadleaved and deciduous forests in the mountains of subtropical China, but until now little existing knowledge is available for this question. In 2001, we chose to monitor the seed rain process of our mixed evergreen broad-leaved and deciduous forest communities in Mount Dalaoling National Forest Park, Yichang, Hubei Province, China. The preliminary analyses show obvious variations in seed rain density, species compositions and timing of seed rain among four communities. The average seed rain densities of the four communities are 2.43 ± 5.15, 54.13 ±182.75, 10.05 ±19.30 and 24.91 ± 58.86 inds/m^2, respectively; about one tenth the values in other studies in subtropical forests of China. in each community, the seed production is dominated by a limited number of species, and the contributions from the others are generally minor. Fecundity of evergreen broadleaved tree species is weaker than deciduous species. The seed rain of four communities begins earlier than September, and stops before December, peaking from early September to late October. The beginning date, ending date and peak times of seed rain are extensively varied among the species, indicating different types of dispersal strategies. According to the existing data, the timing of seed rain is not determined by the climate conditions in the same period, while the density of seed rain may be affected by the disturbances of weather variations at a finer temporal resolution.

Tree species influences soil microbial community diversity but not biomass in a karst forest in southwestern China

Aims The relationships between plant species and soil microorganisms remain indeterminable in different ecosystems worldwide.In karst ecosystems,soil microbial(SM)community structure and their environmental driving factors are poorly explored,and the relationships between plant species and soil microorganisms are unclear.This study aimed to characterize the general patterns of SM community composition and biomass,and to explore the specific tree species and soil physiochemical properties highly related to SM community diversity and biomass in a karst forest.Methods The effects of tree species on SM community composition and biomass were firstly investigated on the basis of 212 soil samples collected from five dominant tree species(Lithocarpus confinis Huang,Platycarya longipes Wu,Itea yunnanensis Franch.,Machilus cavaleriei H.Lév.and Carpinus pubescens Burkill)through phospholipid fatty acid(PLFA)analysis of a karst evergreen and deciduous broad-leaved mixed forest in central Guizhou Province,southwestern China.The relationships between SM community structure and tree species and soil physiochemical properties were statistically analysed.Important Findings A total of 132 SM-PLFA biomarkers were detected.The average number of SM-PLFA biomarkers and microbial biomass in each soil sample were 65.97 and 11.22µg g^(–1),respectively.Tree species influenced the number of SM-PLFA biomarkers but not the SM biomass.The number of SM-PLFA biomarkers of C.pubescens was significantly higher than that of other species(P<0.05);the numbers of SM-PLFA biomarkers amongst other species showed no significant difference.Microbial biomass showed no relationships with the soil physiochemical properties of nutrient-rich surface soils but positively correlated(P<0.05)with soil organic carbon,nitrogen and phosphorus concentrations in deeper soils.The karst forest in the plateau-surface terrain of central Guizhou Province presented a low fungal-to-bacterial ratio,low microbial biomass storage and high microbial community diversity.Specific tree species affect the SM community diversity in this kind of karst forest.