中文摘要：

研究了长江上游低山丘陵区人为采伐形成的马尾松（Pinus massolbiana）人工林7种不同大小林窗（G1：100m^2、G2：225m^2、G3：400m^2、G4：625m^2、G5：900m^2、G6：1225m^2、G7：1600m^2）土壤微生物生物量磷（MBP）、有效磷（AP）及土壤全磷（TP）在一个生长季的变化。结果显示：林窗形成初期，林窗内土壤MBP对采伐干扰的响应十分敏感，AP次之，TP较为稳定。林窗大小对马尾松人工林土壤MBP、AP有显著影响，对TP影响不显著。土壤MBP在面积为625-900m^2林窗的中央较高；900-1600m^2林窗的中央及225～625m^2林窗的边缘AP较高；TP仅625m^2林窗的中央较高。MBP、AP在生长季不同时期有显著变化，TP变化较小。总体上，各林窗中央及小于625m^2林窗边缘MBP在初期相对较低，大于625m^2林窗的边缘为初期高中期低；林窗中央的AP为中期高初期低，边缘初期相对较低。另外，林窗大小与季节变化的交互作用显著影响了土壤MBP。林窗内不同位置MBP、AP和TP并没有显著变化，但与林下相比，各林窗土壤AP及TP在生长季中期和末期增高，而MBP仅较大的林窗在生长季中期较低，说明林窗形成后土壤磷含量有一定提高。相关分析结果表明，MBP与TP呈极显著正相关，MBP与土壤温度呈显著负相关，MBP、TP与土壤含水量呈极显著正相关。可见，土壤温度和含水量是林窗形成初期影响土壤磷含量的重要环境因子。

英文摘要：

The seasonal variations of soil microbial biomass phosphorus （MBP）, available phos- phorus （AP） and total phosphorus （TP） were observed in seven size gaps （GI： 100 m^2, G2： 225 m^2, G3：400 m^2, C,4：625 m^2, GS： 900 m^2, （;6：1225 m^2, G7：1600 m^2） ofa masson pine plantation in a hilly area of the upper reaches of Yangtze River. The results showed that the soil MBP in the forest gaps was most sensitive to cutting disturbance, followed by soil AP, while TP was relatively stable. The effects of gap size were significant on soil MBP and AP, but not on soil TP. The center of forest gap with a size of 625-900 m^2 was more conducive to increase soil MBP, the center of larger gap （900-1600 m^2） had a higher level of soil AP as well as the edge of medium-sized gap （225-625 m^2 ）, and the center of forest gap （625 m^2 ） had a high level of soil TP. MBP and AP had significant changes in different periods of the growing season, but TP had no significant changes. Soil MBP of the centers of all gaps and the edges of gaps less than 625 m^2 was lower in the early period, but that of other areas was higher in early and lower inmiddle of growing season. Soil AP in the gap center was higher in the middle and lower in the early of the growing season, while lower in the early stage of gap edge. In addition, the interac- tion of gap size and seasonal variation had significant impacts on soil MBP. The location within forest gap had no significant influence on MBP, AP and TP, but the soil AP and TP of all gaps in the middle and late growing season were higher than in the understory soil, while the soil MBP of large-sized gap was only lower in the middle growing season. It is suggested that soil phosphorus was improved in a certain degree after the formation of forest gaps. Correlation analyses showed that soil MBP was significantly positively correlated with TP, but significantly negatively correla- ted with soil temperature, and soil MBP and TP were significantly positively correlated with soi