title: Trade-offs between the metabolic rate and population density of plants.
abstract: The energetic equivalence rule, which is based on a combination of metabolic theory and the self-thinning rule, is one of the fundamental laws of nature. However, there is a progressively increasing body of evidence that scaling relationships of metabolic rate vs. body mass and population density vs. body mass are variable and deviate from their respective theoretical values of 3/4 and -3/4 or -2/3. These findings questioned the previous hypotheses of energetic equivalence rule in plants. Here we examined the allometric relationships between photosynthetic mass (M(p)) or leaf mass (M(L)) vs. body mass (beta); population density vs. body mass (delta); and leaf mass vs. population density, for desert shrubs, trees, and herbaceous plants, respectively. As expected, the allometric relationships for both photosynthetic mass (i.e. metabolic rate) and population density varied with the environmental conditions. However, the ratio between the two exponents was -1 (i.e. beta/delta = -1) and followed the trade-off principle when local resources were limited. Our results demonstrate for the first time that the energetic equivalence rule of plants is based on trade-offs between the variable metabolic rate and population density rather than their constant allometric exponents.
authors: MOE Key Laboratory of Arid and Grassland, School of Life Science, Lanzhou University, Lanzhou, China.
authors: Jian-Ming
authors: JM
authors: Deng
authors: Tao
authors: T
authors: Li
authors: Gen-Xuan
authors: GX
authors: Wang
authors: Jing
authors: J
authors: Liu
authors: Ze-Long
authors: ZL
authors: Yu
authors: Chang-Ming
authors: CM
authors: Zhao
authors: Ming-Fei
authors: MF
authors: Ji
authors: Qiang
authors: Q
authors: Zhang
authors: Jian-Quan
authors: JQ
authors: Liu
mesh_terms: D004734:Energy Metabolism; D010788:Photosynthesis; D010944:Plants / Q000378:metabolism*; D013045:Species Specificity