Primary production and resource use efficiency in relation to resource acquisition in deciduous and coniferous forest ecosystems

资源有效性的变化会影响植物对养分的利用效率。研究了林分特征、土壤养分有效性、气候条件和间伐对杉木林分氮素利用策略的影响。研究区域为气候条件差异较大的本州岛太平洋一侧（高知县）、日本海一侧（京都北部地区）和内陆地区（京都神模市）；林分年平均气温9.1 ~ 16.3℃，年平均降水量1500 ~ 3300 mm。在高知和神igamo的每个森林中，我们定位了两个研究样地：在一个样地进行间伐，在另一个样地不砍伐树木作为对照。我们发现对杉木氮素状况的显著影响如下。疏植试验中，疏植样地氮吸收效率高于对照样地。高知林凋落叶氮素浓度在3月至10月太阳辐射较高的情况下较低。结果表明，氮素利用效率（NUE）随光照利用率的增加而增加。相反，年降水量高的森林凋落叶中氮浓度并不低，说明氮素利用效率不随水分有效度的增加而增加。在较温暖的气候条件下，年落叶量达到50%的时间较晚。凋落叶后期凋落叶N浓度较低。结果表明，当气候条件有利时，氮肥利用效率增加。此外，在海拔较高的林分，台风强风对植物的影响更大。在这些林分中，年落叶50%的时间提前，白木落叶的氮浓度较高。结果表明，白木柏树的NUE与落叶物候密切相关，落叶物候受气温和台风的影响。研究结果表明，气候条件和资源可利用性影响着白木的氮肥利用效率。少

Changes in resource availability can affect nutrient use efficiency of plants. We investigated the effects of stand characteristics, soil nutrient availability, climatic condition and thinning on nitrogen use strategy in hinoki cypress stands. The study areas were Pacific side of Honshu (Kochi prefecture), Japan Sea side (northern region of Kyoto prefecture) and inland region (Kamigamo, Kyoto city) where climate conditions differ substantially; the means of annual temperature and mean annual precipitation in the stands ranged from 9.1 to 16.3℃ and from 1500 to 3300 mm, respectively. In each forest in Kochi and Kamigamo, we located two study plots: in one plot thinning was conducted and in the other plot no trees were cut as the control. We found the significant effects on nitrogen status of hinoki as following. Nitrogen resorption efficiency was larger in the thinned plots than in the control plots in the thinning experiments. The nitrogen concentration in the leaf litter was lower whe … More n solar radiation from Mardi to October was higher in Kochi forest for 13 years. The results suggest that nitrogen use efficiency (NUE) increases with increasing light availability. By contrast, nitrogen concentration in leaf-litter was not lower in forests with higher annual precipitation, suggesting that NUE does not increase with higher water availability. The time of 50 % annual leaf-fall was later in the warmer climatic condition. Leaf-litter N concentration was lower when leaf-fall occurred later. The results suggest that NUE increases when the climatic conditions are favorable. In addition, the effects of strong wind in typhoons on plants are greater in the stands at higher elevation. In these stands, the time of 50 % annual leaf-fall was earlier and hinoki trees shed their leaves with higher nitrogen concentration. The results indicate that NUE of hinoki cypress is closely related with leaf-fall phenology that is affected by temperature and typhoon. The results of the study suggest that the climatic condition as well as resource availability affects NUE of hinoki cypress. Less