RESUMO
The decline in species richness at higher latitudes is among the most fundamental patterns in ecology. Whether changes in species composition across space (beta-diversity) contribute to this gradient of overall species richness (gamma-diversity) remains hotly debated. Previous studies that failed to resolve the issue suffered from a well-known tendency for small samples in areas with high gamma-diversity to have inflated measures of beta-diversity. Here, we provide a novel analytical test, using beta-diversity metrics that correct the gamma-diversity and sampling biases, to compare beta-diversity and species packing across a latitudinal gradient in tree species richness of 21 large forest plots along a large environmental gradient in East Asia. We demonstrate that after accounting for topography and correcting the gamma-diversity bias, tropical forests still have higher beta-diversity than temperate analogues. This suggests that beta-diversity contributes to the latitudinal species richness gradient as a component of gamma-diversity. Moreover, both niche specialization and niche marginality (a measure of niche spacing along an environmental gradient) also increase towards the equator, after controlling for the effect of topographical heterogeneity. This supports the joint importance of tighter species packing and larger niche space in tropical forests while also demonstrating the importance of local processes in controlling beta-diversity.
Assuntos
Biodiversidade , Árvores , Ecologia , Ásia OrientalRESUMO
To explore the distribution of fungal community in soil of brown coniferous forest in Daxing'anling and its relationship with soil characteristics, soil fungal community structure and diversity in three forest types, light brown coniferous forest, grass brown coniferous forest, and typical brown coniferous forest, were analyzed by high-throughput sequencing technology. The relationship between soil fungal community and soil characteristics was analyzed by R and SPSS 17.0 software. The results showed that soil physical and chemical characteristics differed significantly across the three brown coniferous forests. A total of 111 species belonged to six phyla, 23 class, 46 orders, 74 families and 88 genera were recorded in this study. Ascomycetes and basidiomycetes were dominant phyla. There were significant differences in relative abundance of phyla among three forest types. There was no significant difference in the Ace and Chao1 diversity indices among three brown coniferous forests, whereas there were significant differences in the Shannon and Simpson indices. Results from canonical correlation analysis and correlation analysis showed that both α and ß diversity were significantly correlated with soil moisture, soil pH, soil organic matter, soil total nitrogen, and soil total potassium. The results indicated that soil characteristics were important factors affecting soil fungal diversity of brown coniferous forest in Xing'an larch forest in Daxing'anling.
Assuntos
Solo , Traqueófitas , China , Florestas , FungosRESUMO
By the method of runoff determination in large basin combined with contrast experiment in small watershed, and based on the runoff and forest resources data in past 35 years, this paper studied the serial changes of river runoff in Xiaoxing'anling after forest harvesting. The results showed that the river flow was increased in the early 10 years after forest harvesting, but decreased gradually with the growth and crown closure of artificial larch forest, tended towards or even lower than the level before harvesting. The river runoff had a close correlation with annual rainfall and the areas of forest harvesting and regeneration. Significant positive correlation was observed between annual flow and forest harvesting area, which resulted in the increase of river runoff after forest harvesting. Forest harvesting could also significantly increase the peak flood and snowmelt runoff. There was a negative correlation between regenerated forest area and annual flow, and thus, forest regeneration would decrease annual