晋西黄土区天然次生林营养元素分配与积累研究

在山西省吉县蔡家川流域内设置天然次生林样地，对其生态系统内各层生物量及其分配和各层各器官中N、P、K、Ca和Mg 5种营养元素的含量、分配格局、积累规律均进行了研究。结果表明，天然次生林系统总生物量为36.087 t/hm2，乔木层、灌木层、草本层、枯落物层的生物量分别占总生物量的46.02％、28.99％、12.76％、12.23％；5种营养元素积累总量为1 089.82 kg/hm2（不包括土壤层），其中，乔木层储量最多，占天然次生林营养元素总储量的4082％，灌木层、草本层和枯落物层分别占31./27％、12.55％、15.36％；乔木层各器官营养的积累量为枝根干皮叶。5种营养元素在土壤中的积累总量为634.97 t/hm2，天然次生林土壤中各养分储量占其元素总储量的比例为:95.32％ (N)、99.64％ (P)、99.91％ (K)、99.84％ (Ca)和99.95％(Mg)；从乔木层的各器官富集系数来看，叶枝根皮干；从各层对土壤营养元素的富集系数来看，总的变化趋势为灌木层乔木层草本层，NPCa KMg。 

Nutrient distribution and accumulation patterns of natural secondary forests on the Loess Plateau of Shanxi Province

The biomass and allocation of natural secondary forests and the content,accumulation and distribution of nutrient elements(N,P,K,Ca,Mg) are studied in sample plot of the Loess Region in Shanxi Province.The results show that natural secondary forest biomass reaches 36.087 t/hm~2,in which the arborous layer biomass occupies 46.02%,shrub layer 28.99%,herb layer 12.76%,litter layer 12.23%.The total storage of 5 nutrient elements is 1 089.82 kg/hm~2,the storage in the arborous layer is the largest and reaches 40.82%.The sequence in which storage elements vary among different layers is as follows:shrub layer 31.27%,herb layer 12.55%,litter layer 15.36%.In the accumulation of arborous layer,the order of different organs is: branch > root > stem > bark> leaf.The total storage of 5 nutrient elements in soil is 634.97 t/hm~2,and the accumulative nutrients account for 95.32%(N),99.64%(P),99.91%(K),99.84%(Ca) and 99.95%(Mg) of total amount.The accumulation coefficients of different organs in arborous layer are leaf > branch > root > bark> stem wood > leaf.The accumulation coefficients of different layers are shrub layer>arborous layer >herb layer and N>P>Ca >K>Mg.