小南海天坑群外围次生林植物叶片化学计量特征研究

Leaf Stoichiometry Characteristics of Plants in Secondary Forest of Xiaonanhai Tiankeng Group

为探讨汉中天坑群及其外围植物生长过程中的养分循环和生态适应性,采用常规采样和化学测定法,对南郑区小南海天坑群外围主要林分类型——天然次生林不同植被层(草本、灌木、乔木)植物叶片C、N、P、K含量,化学计量比及其相关性进行了分析。结果表明:(1)植物叶片N、P、K含量随植被层级正向变化呈降低趋势,C呈升高趋势;(2)N∶P平均值为11.89±0.55,且灌木层(12.80)>草本层(12.28)>乔木层(10.78);(3)N、P、K元素之间呈显著正相关(P<0.01),C与N、P呈负相关,不显著(P>0.05),C与K呈显著负相关(P<0.01);植物体内N、P、K营养元素含量需求变化相对一致。研究区植物虽然具有相对较高的N、P利用效率,但仍受限制,反映了植物对生长环境的适应性。

The paper studied the stoichiometric characteristics of plant leaves in different vegetation layers of secondary forests in the karst area of Xiaonanhai Tiankeng Group,and discussed the nutrient cycling and ecological adaptability of plants in the growth process,which could provide theoretical basis for maintaining the ecological environment stability in the karst area.The content,stoichiometric ratio and correlation of C,N,P and K of different vegetation layers(herbs,shrubs and trees)in the Xiaonanhai Tiankeng Group were analyzed by the method of"space replacing time".The results showed that:(1)the contents of N,P and K in plants decreased and C increased with the change of vegetation level;(2)the mean N:P was 11.89±0.55,with the order:shrub layer(12.80)>herb layer(12.28)>tree layer(10.78);(3)there was a significant positive correlation between N,P and K(P<0.01),there was no significant negative correlation between C and N,P(P>0.05),and there was a significant negative correlation between C and K(P<0.01),which reflected the relative consistency of content changes in N,P and K of plants.Although the N and P utilization efficiency of plants in the study area is relatively high,it is still limited,which reflects the adaptability of plants to the growth environment.