Spatial and historical distribution of organic phosphorus driven by environment conditions in lake sediments

The chemistry of sedimentary organic phosphorus（OP） and its fraction distribution in sediments are greatly influenced by environmental conditions such as terrestrial inputs and runoffs. The linkage of OP with environmental conditions was analyzed on the basis of OP spatial and historical distributions in lake sediments. The redundancy analysis and OP spatial distribution results suggested that both Na OH-OP（OP extracted by Na OH） and Re-OP（residual OP） in surface sediments from the selected 13 lakes reflected the gradient effects of environmental conditions and the autochthonous and/or allochthonous inputs driven by latitude zonality in China. The lake level and salinity of Lake Hulun and the runoff and precipitation of its drainage basin were reconstructed on the basis of the geochemistry index. This work showed that a gradient in weather conditions presented by the latitude zonality in China impacts the OP accumulation through multiple drivers and in many ways.The drivers are mainly precipitation and temperature, governing organic matter（OM）production, degradation rate and transportation in the watershed. Over a long temporal dimension（4000 years）, the vertical distributions of Re-OP and Na OH-OP based on a dated sediment profile from HLH were largely regulated by the autochthonous and/or allochthonous inputs, which depended on the environmental and climate conditions and anthropogenic activities in the drainage basin. This work provides useful environmental geochemistry information to understand the inherent linkage of OP fractionation with environmental conditions and lake evolution.

Historic distribution and recent loss of tigers in China

Historical records can provide important evidence of changes in distributions of wildlife species.Here we discuss the distribution of the tiger(Panthera tigris Linnaeus,1758)over the past 2000 years in China based on 2635 historical records.We also compare tiger distributions outlined in these records with ecosystem type maps.Throughout this time period,tigers maintained a broad distribution across 7 biomes(from forests to deserts).However,in recent decades the range has been significantly condensed.Today,only 2 populations remain,neither of which is independently viable.Tigers have completely disappeared from the temperate broadleaf and mixed forests of central China,a region that was traditionally their most important biome in China.The continued presence of wild tigers in China is highly dependent on significant conservation measures.