Forest fragmentation in China and its effect on biodiversity.

Land-use change is fragmenting natural ecosystems, with major consequences for biodiversity. This paper reviews fragmentation trends - historical and current - in China, the fourth largest country on Earth, and explores its consequences. Remote sensing makes it possible to track land-use change at a global scale and monitor fragmentation of dwindling natural landscapes. Yet few studies have linked fragmentation mapped remotely with impacts on biodiversity within human-modified landscapes. Recent reforestation programs have caused substantial increases in forest cover but have not stopped fragmentation, because the new forests are mostly monocultures that further fragment China's remnant old-growth lowland forests that harbour the highest levels of biodiversity. Fragmentation - and associated biodiversity declines - is unevenly distributed in China's forests, being most problematic where agricultural expansion is occurring in the southwest and northeast, serious in the densely populated eastern regions where urbanisation and transport infrastructure are modifying landscapes, but less of a problem in other regions. Analyses of temporal trends show that the drivers of forest fragmentation are shifting from mainly agricultural expansion to urbanisation and infrastructure development. Most of China's old-growth forests persist in small, isolated fragments from which many native species have disappeared, on land unsuitable for human utilisation. Fragmentation throughout China is likely to have major consequences on biodiversity conservation, but few studies have considered these large-scale processes at the national level. Our review fills this research gap and puts forward a systematic perspective relevant to China and beyond.

Diversity and density patterns of large old trees in China.

Large old trees are keystone ecological structures that provide vital ecosystem services to humans. However, there are few large-scale empirical studies on patterns of diversity and density of large old trees in human-dominated landscapes. We present the results of the first nationwide study in China to investigate the patterns of diversity and density of large old trees in human-dominated landscapes. We collated data on 682,730 large trees ≥100 years old from 198 Chinese regions to quantify tree species diversity, tree density and maximum tree age patterns. We modelled the effects of natural environmental variables (e.g. climate and topography) and anthropogenic variables (e.g. human population density and city age) on these measures. We found a low density of large old trees across study regions (0.36 trees/km2), and large variation in species richness among regions (ranging from 1 to 232 species). More than 95% of trees were <500 years old. The best fit models showed that: (1) Species diversity (species richness adjusted by region size) was positively associated with mean annual rainfall and city age; (2) Density of clustered trees, which are mostly remnants of ancient woods, was negatively influenced by human population density and rural population (% of total population). In contrast, the density of scattered trees, which are mostly managed by local people, was positively correlated with mean annual rainfall and human population density. To better protect large old trees in cities and other highly-populated areas, conservation policy should protect ancient wood remnants, mitigate the effects environmental change (e.g. habitat fragmentation), minimize the negative effects of human activities (e.g. logging), and mobilize citizens to participate in conservation activities (e.g. watering trees during droughts).

[Expression of transforming growth factor-ß1 and its receptors in peripheral blood of patients with immune thrombocytopenic purpura].

This study was purposed to detect the expression of transforming growth factor ß1 (TGF-ß1) and its receptors (TGF-ßR) and to investigate their roles in pathogenesis of immune thrombocytopenic purpura (ITP). The expressions of TGF-ß1 and their receptors TGF-ßRI, TGF-ßRII and TGF-ßRIII in the peripheral blood of patients with ITP and healthy persons were detected by the real-time PCR, and differences of their expression levels were analysed. The results showed that the expression of TGF-ß1 and TGF-ßRII mRNA in ITP patients was significantly higher than that in the healthy controls, while the TGF-ßRI mRNA expression in ITP patient was significantly lower than that in the controls. The expression of TGF-ßRIII was not statistically different between the two groups. It is concluded that TGF-ß1 and its receptors including TGF-ßRI and TGF-ßRII express abnormally in the peripheral blood of ITP patients, which suggests that the TGF-ß signaling pathway probably play a vital role in the pathogenesis of the ITP.