Chin J Plant Ecol ›› 2017, Vol. 41 ›› Issue (10): 1081-1090.DOI: 10.17521/cjpe.2016.0393

Special Issue: 生态化学计量

• Research Articles • Previous Articles     Next Articles

Edge effects of forest gap in Pinus massoniana plantations on the ecological stoichiometry of Cinnamomum longepaniculatum

Si-Meng SONG1, Dan-Ju ZHANG1,2, Jian ZHANG1,2,*(), Wan-Qin YANG1,2, Yan ZHANG1, Yang ZHOU1, Xun LI1   

  1. 1Monitoring Station for Eco-environments in the Rainy Zone of Southwest China, Institute of Ecology & Forestry, Sichuan Agriculture University, Chengdu 611130, China;

    2Collaborative Innovation Center of Ecological Security in the Upper Reaches of Yangtze River, Chengdu 611130, China
  • Online:2017-10-10 Published:2017-12-24
  • Contact: Jian ZHANG

Abstract:

Aims Pinus massoniana is one of the major plantation tree species in the low hilly lands along the upper reaches of the Yangtze River Valley in China’s “Grain for Green” project. The objective of this study was to explore the edge effects of forest gap on the ecological stoichiometry of dominant tree species in a P. massoniana plantation forest.Methods We collected Cinnamomum longepaniculatum leaves in a 39-year-old P. massoniana plantation forest with seven forest gap sizes (G1: 100 m2; G2: 225 m2; G3: 400 m2; G4: 625 m2; G5: 900 m2; G6: 1 225 m2; G7: 1 600 m2, and the control: closed canopy) located in Gao County, south Sichuan Province during different seasons. The contents of C, N and P in leaves were measured, and the effects of edges, seasons and their interaction on leaf C, N and P contents and C:N:P stoichiometry were evaluated.Important findings The leaf C content, C:N and C:P of C. longepaniculatum at the edge of forest gaps in different seasons were all significantly higher than those of understory plants in P. massoniana plantation. With increasing size of forest gaps, leaf C content and C:N ratio, C:P and N:P of C. longepaniculatum increased initially and then decreased with the maximum at medium size (400-900 m2). From spring to winter, leaf N and P contents of C. longepaniculatum increased after an obvious decrease; and the C:N and C:P increased first but then decreased. However, the inflection point all appeared in the summer. The nutrient utilization of C. longepaniculatum at the edge of forest gaps was more efficient in summer and autumn than in spring and winter, indicating significant edge effects. The results of principal component analysis (PCA) suggested that gap size, relative light intensity and monthly average air temperature were the main environmental factors affecting the stoichiometry of C. longepaniculatum at the different edge of forest gaps in the P. massoniana plantation. These results indicated that forest gap with size 625 m2 had the highest organic matter storage and nutrient utilization efficiency in the edge areas in all seasons, and therefore had the most significant edge effect on leaf element stoichiometry.

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Key words: gap size, edge effect, stoichiometry, Cinnamomum longepaniculatum, Pinus massoniana plantation