鼎湖山黄果厚壳桂、鼎湖钓樟群落主要营养元素的分配和生物循环

较系统地研究了鼎湖山黄果厚壳桂(Cryptocaryaconcinna)-鼎湖钓樟(Linderachunii)群落植物主要营养元素(P、K、Ca、Mg)的分配和生物循环特征。营养元素含量随群落层次、组分(器官)和元素不同而异。群落植物营养元素贮量为(kghm-2):P61.253,K928.764,Ca1212.771和Mg79.349。各元素贮量在不同层次中的大小分布序列为:乔木(94.3%-97.8%)>藤本(1.3%-4.1%)>灌木(0.8%-1.4%)>草本(0.05%-0.15%)。在乔木层,元素贮量则主要分布在树干和树枝两组分(38.6%-61.7%)。各元素在植物组分中的贮量序列为:Ca>K>Mg>P(根、干和皮)和K>Ca>Mg>P(其余器官)。群落植物营养元素年积累量为(kghm-2):P2.677,K41.550,Ca63.309和Mg3.693,其在群落植物中的分配格局与贮量的相类似。群落植物营养元素利用系数为:P0.18,K0.11,Ca0.09和Mg0.28;循环系数:P0.76,K0.61,Ca0.41和Mg0.84;周转期(a):P7.36,K15.12,Ca28.05和Mg4.30。

Distribution and Biological Cycle of Nutrients in Cryptocarya concinna/Lindera chunii Community in Dinghushan

Studies of the distribution and contents of nutrients in40-yr-old Cryptocarya concinna/Lindera chunii community of lower subtropical evergreen broadleaved forest in Dinghushan Biosphere Reserve showed that the total nutrient standing stock in the community was estimated to be61.253for P,928.764for K,1212.771for Ca,and79.349kg hm -2 for Mg.Nutrient allocation in different layers in the community was in the order of trees>lians>shrubs>herbs.In tree layer,38.6%-61.7%of nutrient elements was in tree trunks and branches.Standing stock of nutrients in roots,trunks and barks was Ca >K>Mg >P,and that in other organs was K>Ca >Mg >P.Annual nutrient accumutations of P,K,Ca and Mg were2.677,41.550,63.309and3.693kg hm -2 ,respectively.Nutrient use coefficients in the community were0.18(P),0.11(K),0.09(Ca)and0.28(Mg),the nutrient cycling coefficients being0.76(P),0.61(K),0.41(Ca)and0.84(Mg).Nutrient cycling period for P,K,Ca and Mg was7.36,15.12,28.05and4.30years,respectively.It is concluded that the community had greater nutrient reserve ability but lower nutrient use efficiency as compared to the previous study on Pinus massoniana community.