京北山区刺槐林主要养分元素积累与分配的研究

Nutrient distribution and accumulation pattern of the Robinia pseudoacacia forests in the mountainous area of north Beijing.

对北京北部山区刺槐林主要养分元素的积累与分配进行了研究 .结果表明 ,刺槐林生态系统的总生物量 (包括乔木层、灌木层、草本层和枯落物层 )为 2 1 81 5～ 2 92 85kg hm2 .刺槐林不同器官中各养分元素的含量差异较大 ,在叶、枝和干中各养分元素的含量顺序相同 ,根系中的养分元素除Ca随着根系直径的增加呈升高的趋势外 ,其余的养分元素的含量随着根系直径的增加而降低 .刺槐林生态系统 5种养分元素的贮存量为 4 0 7 35～ 5 91 82kg hm2 ,其中乔木层中的养分贮存量占总贮存量的 83 4 2 %～ 89 83% .若以各养分元素在生态系统生物层中的贮存量来计 ,则Ca的贮存量最大 ,P的最小 ,不同养分元素贮存量的顺序为Ca >N >K >Mg >P .刺槐林生态系统乔木层对N元素的富集能力最强 ,不同元素的富集系数排序为N >P >Ca >K >Mg ,刺槐林每积累 1t干物质需N、P、K、Ca和Mg等养分元素共计约 1 4kg .

The Robinia pseudoacacia is the mainly afforested tree in North China and it is mainly distributed in the gully and hilly area. The paper studied the nutrient accumulation and distribution pattern of the Robinia pseudoacacia forest ecosystem in the mountainous area of north Beijing. The results show that the total biomass of the Robinia pseudoacacia forest ecosystem is 21 815～29 285 kg/hm 2 , the arboreal layer biomass is 20 132～26 874 kg/hm 2 , the shrub layer biomass is 599～983 kg/hm 2 , the herb layer biomass is 386～502 kg/hm 2 , the debris layer biomass is 698～1 007 kg/hm 2 , respectively. They account for 91 68%～92 28%, 2 74%～3 36%, 1 50%～1 80%, and 3 47%～3 95% of the total biomass, respectively. The concentrations of nutrient elements nitrogen (N), phosphors (P), potassium (K), calcium (Ca) and magnesium (Mg) were analyzed in different organs of Robinia pseudoacacia . The content of five kinds of nutrients in different organs aboveground shows that the order of different nutrient element concentrations in the different organs is: leaf > branch > stem. And in different diameters of the root, the N, P, K, and Mg content show that the concentration reduces with the increase of root diameter, the Ca shows the reversed trends. The total storage of the five kinds of nutrient elements in the Robinia pseudoacacia forest ecosystem is 470 35～591 82 kg/hm 2 , and the tree layer nutrient element storage amount accounts for 83 42%～89 83% of total storage. Sum up the total nutrient amount according to different nutrient elements, then the storage amount of nutrient elements N, P, K, Ca and Mg in the Robinia pseudoacacia forest ecosystem is 144 26～204 53 kg/hm 2 , 8 90～11 78 kg/hm 2 , 32 48～46 27 kg/hm 2 , 204 27～302 31 kg/hm 2 and 17 44～25 81 kg/hm 2 , respectively. The order of nutrient storage of five kinds of nutrient elements is: Ca > N > K > Mg > P. The accumulation coefficient of nutrient element N is higher than that of others, and the order of accumulation coefficient of different elements is: N>P>Ca>K>Mg. The net production of organic matter per ton needs about 14 kg of five elements, and the order of demand amount is: Ca > N > K > Mg > P.