YANG Yong1,2, XU Xin1,2, XU Yue1, NI Jian1,3
(1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
2. Chinese Academy of Sciences, Beijing 100049, China;
3. College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, China)
Abstract: Three dominant woody species (Platycarya strobilacea, Pinus massoniana and Viburnum utile) were selected to determine plant functional traits and C, N, P, Ca and Mg contents of leaves, twigs and roots along an elevation gradient in the Langxi Watershed of northern Guizhou Province, southwestern China. The key features of functional traits and ecostoichiometry among different plant organs and their correlations were analyzed, the adaptive strategies of three dominant species to the trough-valley karst environment were further explored. Results showed that: (1) The leaf dry-matter contents (LDMC) of three dominant species had no significant interspecific variation, but specific leaf area (SLA), twig dry-matter content (TDMC), twig tissue density (TTD), coarse root tissue density (CRTD) and medium root tissue density (MRTD) had significant interspecific variation. The highest interspecific variation occurred in SLA (32.13%) and the lowest one in LDMC (12.76%). (2) SLA and LDMC, CRTD and MRTD had significant negative correlations, but LDMC, TDMC, TTD, CRTD and MRTD had parallel positive correlations. (3) The distribution of C contents in leaves, branches and roots was relatively uniform. N, P and Mg contents had the same trend of leaf > twig > root in three plants, the trend of C/N and C/P was root > twig > leaf, and the leaf N/P ranged from 10.89 to 27.39 with an average of 17.75. (4) In the corresponding plant organs, N was significantly and positively correlated with P and N/P, C was significantly and negatively correlated with Ca and Mg, Ca was significantly and positively correlated with Mg, while Ca was significantly and negatively correlated with P in leaves. (5) SLA had significant and positive correlations with contents of leaf N, P and Mg, but had a significant and negative correlation with leaf content of C. Ca contents in coarse and medium roots had very significant and positive correlations with the tissue densities of roots, indicating that the dominant plants in karst areas of northern Guizhou trough valley differentiated in their functional traits to reduce the overlap of niches and such to reduce the resource competition. In order to adapt the arid and infertile environment, on the one hand, karst plants developed multiple functional traits of lower specific leaf area, higher dry matter content and higher tissue density, on the other hand, they re-allocated the element distribution among organs and increased investments of twig and root.
Key words: trough-valley karst; plant functional traits; ecostoichiometry; adaptive strategy
EARTH AND ENVIRONMENT Vol.48, No.4, Tot No.336, 2020, Page 413-423