黄土丘陵区油松人工林植物器官—凋落物—土壤化学计量特征的季节变化

为了解黄土丘陵区油松人工林植物器官—凋落物—土壤的化学计量特征随季节的变化规律,通过时空替代法、野外调查取样与室内试验的手段,以陕西省延安市安塞区纸坊沟流域中林龄油松（Pinus tabuliformis）人工林为对象,分析了4—10月油松不同器官—凋落物—土壤的碳（C）、氮（N）、磷（P）生态化学计量学特征。结果表明：（1）从4—10月,叶片C、P含量逐渐上升,在10月最高,叶片的N含量和N：P及枝的N、P含量均先减小后增大,且均在8月最低,而枝的C：N及C：P和细根的C：P、N：P均先增大后减小,且均在8月最高。土壤C、N含量、C：P、N：P先增大后减小,在8月最高。凋落物N含量、C：P和N：P均呈先降后升的趋势,在6月最低,P含量变化不显著;（2）除叶片4—6月、细根4—8月N：P>14外,其他各器官4—10月均N：P<14,该区域油松生长主要受N限制;（3）叶片与凋落物的C、N含量及C：N之间均呈显著正相关,C：N、C：P与N：P之间均呈显著正相关（p<0.05）。叶片N：P与土壤C：N呈极显著负相关（p<0.01）,其他化学计量特征之间均无显著相关性。凋落物C含量与土壤P含量呈显著正相关（p<0.05）。研究结果使人工林生态化学计量学的研究更加系统性,为黄土丘陵区植被良好生长提供参考依据。

Seasonal Variation of Plant Organ-Litter-Soil Stoichiometry in Pinus Tabulaeformis Plantation in Loess Hilly Region

To understand the seasonal variation of plant organs-litter-soil stoichiometry in Pinus tabulaeformis plantation in Loess Hilly region, the field investigation and laboratory experiments were used by means of spatio-temporal substitution method in Zhifanggou Watershed, Ansai District, Yan''an City, Shaanxi Province, China. The ecological stoichiometry characteristics of carbon (C), nitrogen (N) and phosphorus (P) in different organs-litter-soil of Pinus tabulaeformis from April to October were analyzed. The results showed that:(1) From April to October, the contents of C and P in leaves increased gradually, and reached the highest in October. The contents of N and N:P in leaves and branches decreased first and then increased, and reached the lowest in August. While the contents ofC:N and C:P in branches and C:P and N:P in fine roots increased first and then decreased, and reached the highest in August. Soil C and N contents, C:P and N:P increased first and then decreased, and reached the highest value in August. Litter N content, C:P and N:P all showed a trend of decreasing first and then increasing, and reached the lowest in June, while P content had no significant change. (2) Except for N:P>14 in leaves from April to June and fine roots from April to August, N:P<14 in other organs from April to October, the growth of Pinus tabulaeflorus in this region was mainly restricted by N. (3) There were significant positive correlations between C and N contents and C:N of leaf and litter, and there were significant positive correlations between C:N, C:P and N:P (p<0.05). There was a significant negative correlation between leaf N:P and soil C:N (p<0.01), but no significant correlation between other stoichiometric characteristics. There was a significant positive correlation between litter C content and soil P content (p<0.05). The results make the study of ecological stoichiometry of plantation more systematic and provide reference for vegetation growth in loess hilly region.