关键词: 陆地生态系统, 干旱地区, 磷素循环, 生物有效性, 影响因素

Abstract: Phosphorus (P) is a key element of all life and the limiting nutrient in many ecosystems of the world. P biogeochemistry partly controls ecosystem structure and function. Over the past couple of decades, the importance of P biogeochemistry in controlling terrestrial ecosystem processes has received increasing attention. Advances in P cycling in terrestrial ecosystems were reviewed in this paper. Characteristics of P cycling in ecosystem were attributed to factors such as the source of P, the chemical form, traits in soils and the complexity of its controlling factors. P in terrestrial ecosystems is derived mainly from weathering of apatite, and biological and chemical processes, such as microbial absorption, precipitation and adsorption by Fe and Al oxides and CaCO3, easily immobilize P in soil. Transformations of P between different chemical forms in the ecosystem, especially in the soil, and its controlling factors were discussed in detail. P cycling in terrestrial ecosystems is mainly intra-ecosystem cycling which is controlled mainly by the genotype of plant and soil properties, especially pH and ion concentration. The relative importance of different controlling factors differs among ecosystems and across temporal and spatial scales. Also, methods for studying P cycling in terrestrial ecosystems were reviewed. Pot experiments, fertilization trials and sequential extraction procedures were commonly used to test for the bioavailability of different forms of soil P; however, in situ field experiments that used resin bags, litter bags, new isotope tracer methods using 32P and 33P, and NMR spectroscopy to study P dynamics and the chemical structure of soil P were more useful for understanding P cycling and plant availability. Additionally, the significance of P cycling in arid regions was analyzed. P cycling in arid regions, where vegetation is sparse and soil is infertile, are very different from humid regions, and ecosystems there are more easily limited by P. Finally, the trends and hotspots of P cycling in terrestrial ecosystems are summarized for different temporal and spatial scales, different study areas and contents.

Key words: Terrestrial ecosystem, Arid regions, P cycling, Bioavailability, Controlling factors