陆地生态系统磷素循环及其影响因素

 磷是生命系统的重要组成成分，其在生态系统内的迁移转化是生态系统结构和功能的决定性因素之一。近20年来，磷在陆地生态系统内的重要性受到越来越多的关注。该文总结了国内外磷循环研究的成果，从磷的来源、在土壤中的存在形态和固定特性、影响因素的复杂性等方面分析了磷素循环的特点；系统阐述了磷在陆地生态系统各库之间及其内部，主要是植被-土壤亚系统内的迁移转化规律及影响因素。陆地生态系统磷素循环主要是系统内部的生物化学循环，由植物自身的遗传特性和土壤的生物、理化性质共同控制，不同控制因素的相对重要性因生态系统类型、时间和空间尺度而异。文章简述了磷循环研究方法的发展及存在的局限性；另外，分析了干旱、半干旱地区磷循环研究的重要性和意义；干旱区生态系统的脆弱性及其植被、土壤特性决定了其磷素循环有其自身的特点及研究的必要性。最后指出了当前陆地生态系统磷循环研究的发展趋势。

PHOSPHORUS CYCLING IN TERRESTRIAL ECOSYSTEMS AND ITS CONTROLLING FACTORS

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 e-cosystem, especially in the soil, and its controlling factors were discussed in detail. P cycling in terrestrial e-cosystems 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.