Chin J Plan Ecolo ›› 2017, Vol. 41 ›› Issue (8): 872-881.

• Research Articles •

### Trade-off relationship between vein density and vein diameter of Achnatherum splendens in response to habitat changes in Zhangye wetland

Ling HAN, Cheng-Zhang ZHAO*(), Wei FENG, Ting XU, Hui-Ling ZHENG, Bei-Bei DUAN

1. College of Geography and Environmental Science, Northwest Normal University, Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, Lanzhou 730070, China
• Online:2017-09-29 Published:2017-08-10
• Contact: Cheng-Zhang ZHAO E-mail:zhaocz601@163.com
• About author:

KANG Jing-yao(1991-), E-mail: kangjingyao_nj@163.com

Abstract:

Aims The coevolution between vein traits has influences on water use strategies of plant and the formation of leaf economic spectrum, and therefore is important for understanding the trade-off between carbon input in leaf vein construction and the functional feedback from leaf veins. Our aim is to study the allometric relationship between vein density and vein diameter of Achnatherum splendens populations at three natural microhabitats (subcanopy, transitional and open areas) in Zhangye wetland. Methods According to the shade condition of the arbor canopy and the distance to arbor, the A. splendens community were divided into three microenvironments: subcanopy, transitional and open areas. We sampled 10 (4 m × 4 m) A. splendens plots from each microenvironment and investigate the biological characteristics of the plots and leaf traits of the plants within the plots. Then the soil physical and chemical properties, and community photosynthetically active radiation (PAR) were investigated at three gradients. Six individual of A. splendens were selected in each plot and the leaf length, leaf width, vein density and vein diameter of two or three healthy and complete leaves from four directions of each individual were measured in laboratory. The SMA estimation method and correlation analysis were then used to examine the allometric relationship between vein density and vein diameter. Important findings Along the gradient from subcanopy, transitional zone to open areas, soil moisture displayed a pattern of initial decrease of plant community, and soil electric conductivity displayed increase changing trends. Photosynthetically active radiation (PAR), vapor pressure deficit (VPD), vein density (1.28-1.59 mm·mm-2), leaf width and water use efficiency (WUE) increase gradually, while the leaf length, vein diameter (0.21-0.16 mm) of A. splendens decrease. The average value of plasticity indexes of leaf characteristics was 0.19. Leaf net photosynthetic rate (Pn), transpiration rate (Tr) and bundle density increase first and them decrease. The vein density and vein diameter of A. splendens were negatively correlated with each other in subcanopy environment (p < 0.01), transitional and open areas (p < 0.05). The SMA (0.54-1.50) slope of regression equation in the scaling relationships between vein density and vein diameter decrease gradually from subcanopy to open areas.