不同菌根类型森林净初级生产力对降水的响应

Responses of Net Primary Productivity to Precipitation in Forests Dominated by Different Mycorrhizal Types

基于全球森林数据库,建立了包括全球森林的菌根类型、净初级生产力(NPP)和年平均降水量等指标的新数据库,分析了6种菌根类型森林的各组分NPP对年平均降水量变化的响应。结果表明,在所有菌根类型的森林中,森林总NPP、地上NPP和树叶NPP都随年平均降水量的升高呈现上升的趋势;地下NPP、树木主干NPP以及细根和粗根NPP则因菌根类型的不同,对年平均降水量的增加呈现出降低或升高的趋势。从全球森林总NPP随年平均降水量变化的响应程度来看,年平均降水量对丛枝菌根+外生菌根类型森林总NPP变异的解释率最高,为31.79%;而对外生菌根+内外生菌根类型森林的解释率则最低,仅为4.85%。可见,菌根影响着森林NPP对降水量变化的响应程度,表明菌根类型是预测降水变化对森林NPP影响的重要指标。

A new database was established, including the indexes such as different mycorrhizal types, net primary production（NPP） and average annual precipitation（MAP） of forests, based on the global forest data- base. The new database was used to study the responses of NPP of the forests to MAP change. Of all forests dominated by six different mycorrhizal types, the total NPP, aboveground NPP and tree leaf NPP increased with increasing MAP. However, the belowground NPP, stem NPP, and fine and coarse NPP presented a trend of either increase or decrease with the enhancement of MAP in the forests. As far as the responses of forest total NPP to MAP change concerned, the highest explanation（31.79%） of MAP change to the variation of total NPP was observed in the forest dominated by arbuscular mycorrhiza ＋ ecto-mycorrhiza type. Contrarily, the MAP change only explained the 4.85% of the variation of total NPP in the forest dominated by ecto-mycorrhiza＋ ectendomycorrhiza type, which was the lowest explanation in all the six forests. We conclude that different mycorrhizas affect the extent of response of forest NPP to MAP change. Mycorrhizal type is an important index for accurate prediction of future change of forest NPP with change of precipitation.