Phylogeographic Structure of a Tethyan Relict Capparis spinosa (Capparaceae) Traces Pleistocene Geologic and Climatic Changes in the Western Himalayas, Tianshan Mountains, and Adjacent Desert Regions.

Complex geological movements more or less affected or changed floristic structures, while the alternation of glacials and interglacials is presumed to have further shaped the present discontinuous genetic pattern of temperate plants. Here we consider Capparis spinosa, a xeromorphic Tethyan relict, to discuss its divergence pattern and explore how it responded in a stepwise fashion to Pleistocene geologic and climatic changes. 267 individuals from 31 populations were sampled and 24 haplotypes were identified, based on three cpDNA fragments (trnL-trnF, rps12-rpl20, and ndhF). SAMOVA clustered the 31 populations into 5 major clades. AMOVA suggests that gene flow between them might be restricted by vicariance. Molecular clock dating indicates that intraspecific divergence began in early Pleistocene, consistent with a time of intense uplift of the Himalaya and Tianshan Mountains, and intensified in mid-Pleistocene. Species distribution modeling suggests range reduction in the high mountains during the Last Glacial Maximum (LGM) as a result of cold climates when glacier advanced, while gorges at midelevations in Tianshan appear to have served as refugia. Populations of low-altitude desert regions, on the other hand, probably experienced only marginal impacts from glaciation, according to the high levels of genetic diversity.

[Effects of microbial agents on litter decomposition in urban protective greenbelts of arid zone].

In order to explore the ways for promoting litter decomposition in urban protective greenbelts of arid zone, litter falls were collected from the protective greenbelts in north suburb of Karamay, Xinjiang, and a composting experiment with the inoculation of three kinds of microbial agents, i.e., Qingzhu, Jiegan, and Sufu, was carried out for 198 days in late October 2007. At the early stage (0-30 d) of composing, inoculating microbial agents promoted the decomposition of the litter falls, and the effect of Sufu agent was significant, compared with CK. The N, P, and Ca concentrations in the composing litter falls increased persistently with time. By the end of the experiment, the nutrient concentrations in the composed litter falls were 14.2%-252.9% higher than their initial values. During the whole composing process, the decomposition rate of the litter falls organic C increased continuously, and the C/N ratio decreased gradually. It was suggested that inoculating microbial agents could accelerate the composting process, and increase the nutrient concentrations in composted litter falls. Among the three test microbial agents, Jiegan agent was the best one.

[Contribution of soil seed bank to the regeneration of damaged vegetation on floodplain].

A field germination experiment of soil seed bank was carried out on two typical floodplains in the lower reaches of Tarim River, and a comparison was made between the soil seed banks and corresponding seedling banks on the two floodplains, aimed to assess the contribution of soil seed bank to the regeneration of damaged vegetation. The results showed that there were 12 plant species in the soil seed banks, and the life forms were mainly perennial herbs and shrubs. The soil seed banks had a density of 282.5 seeds m(-2) and 173.2 seeds x m(-2), and the seeds in top soil (0-2 cm) accounted for 76.9% and 71.0% of the total, respectively. The soil seed banks had significant effects on the seedlings species composition and density, and 84.7% and 99.4% of the seedlings on the two floodplains were emerged from corresponding soil seed banks. The similarity coefficient between soil seed bank and seedling bank of the two floodplains was 0.72 and 0.63, respectively, and there existed significant positive correlation between seedling density and soil seed bank density, illustrating that soil seed bank made important contribution to the natural regeneration of vegetation.