Rule of organic phosphorous and microbial on phosphorous supply for vegetation in forest soil

为了阐明森林植被的磷素特征和磷素供应特征，采用赫德利法和微生物量磷（MBP）对日本普通森林、热带森林和喀斯特地区森林土壤中的磷素进行了研究。研究结果如下：1.土壤中有效磷（离子态磷+碳酸氢盐态磷）含量极低（低于30 μg P/g），低于森林植被对磷的年吸收量.可矿化磷在日本森林中普遍存在。有机磷的矿化速率对森林植被的磷素供应具有重要意义.在印度尼西亚东加里曼丹强风化的热带森林土壤中，全磷量、有效磷率和可矿化磷率随森林植被的减少而降低. MBP含量大于活性磷（有效磷加可矿化磷）含量，因此MBP库对热带森林磷的供应具有重要意义.长江上游岩溶区森林土壤有效磷和可矿化磷与土壤pH和全碳呈极显著正相关。赫德利法测定的土壤有效磷浓度与Bray II法和Olsen法测定的土壤有效磷浓度呈正相关。赫德利的可解P几乎等于布雷II-P。MBP浓度与活性磷浓度基本相当，可作为评价喀斯特地区森林供磷能力的指标.在三宅岛厚而坚硬的火山灰沉积区，由于火山灰层氮素供应不足，赤杨带着根瘤大量生长.氮素供应丰富的热带天然林和日本关东地区的森林，与氮素供应相比，存在磷素限制条件。在三宅岛的热带退化林和酸性土壤中，根贵的磷供应是森林恢复的关键。

Phosphorus fractions by Hedley method and microbial biomass P (MBP) have been investigated in general Japanese forest, tropical forest and karst region forest soils to clarify the characteristics of P and P supply to forest vegetation. The results are summarized as follows.1. Available-P (Ion fraction-P + Bicarb-P) concentrations were remarkable low (under 30 μg P/g), and their values were lower than the annual uptake P by forest vegetation.2. Mineralizable-P is much in general Japanese forest. Phosphorus mineralization rate from organic P is important for P supply to forest vegetation.3. In tropical forest soil with strong weathering in East Kalimantan in Indonesia, total-P amount, available-P ratio and mineralizable-P ratio decreased with decreases of forest vegetation.4. MBP concentrations were greater than labile-P (available plus mineralizable-P) concentrations, so MBP pool is important for P supply to tropical forest.5. In forest soils in a karst region of the upper Yangtze River in China, both available-P and mineralizable-P have strong positive correlation with soil pH and total-C.6. Available-P concentrations by Hedley method have positive correlation with P concentrations by Bray II and Olsen methods. Available-P by Hedley is nearly equal to Bray II-P.7. MBP concentrations were nearly equal as labile-P concentrations, so MBP is index of P supply evaluation in karst region forest.8. In the region of the thick and very hard volcanic ash sedimentation in Miyake Island, Alnus sieboldiana grew a lot with their root nodule because of poor N supply in the ash layer.9. The tropical natural forest and Kanto region forest in Japan, which have rich N supply, had P limit condition compared to N condition.10. We discuss that P supply to root noble is the key to forest recovery in tropical degradation forest and in acid soil on Miyake Island.