Balance between facilitation and resource competition determines biomass-density relationships in plant populations.
Theories based on competition for resources predict a monotonic negative relationship between population density and individual biomass in plant populations. They do not consider the role of facilitative interactions, which are known to be important in high stress environments. Using an individual-based 'zone-of-influence' model, we investigated the hypothesis that the balance between facilitative and competitive interactions determines biomass-density relationships. We tested model predictions with a field experiment on the clonal grass Elymus nutans in an alpine meadow. In the model, the relationship between mean individual biomass and density shifted from monotonic to humped as abiotic stress increased. The model results were supported by the field experiment, in which the greatest individual and population biomass were found at intermediate densities in a high-stress alpine habitat. Our results show that facilitation can affect biomass-density relationships.
Chu
Cheng-Jin
CJ
MOE Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou 730000, ChinaÁrea de Biodiversidad y Conservación, Departamento de Biología y Geología, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, SpainNational Center for Ecological Analysis and Synthesis, Santa Barbara, CA 93101-5504, USACold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China.
Maestre
Fernando T
FT
MOE Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou 730000, ChinaÁrea de Biodiversidad y Conservación, Departamento de Biología y Geología, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, SpainNational Center for Ecological Analysis and Synthesis, Santa Barbara, CA 93101-5504, USACold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China.
Xiao
Sa
S
MOE Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou 730000, ChinaÁrea de Biodiversidad y Conservación, Departamento de Biología y Geología, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, SpainNational Center for Ecological Analysis and Synthesis, Santa Barbara, CA 93101-5504, USACold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China.
Weiner
Jacob
J
MOE Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou 730000, ChinaÁrea de Biodiversidad y Conservación, Departamento de Biología y Geología, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, SpainNational Center for Ecological Analysis and Synthesis, Santa Barbara, CA 93101-5504, USACold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China.
Wang
You-Shi
YS
MOE Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou 730000, ChinaÁrea de Biodiversidad y Conservación, Departamento de Biología y Geología, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, SpainNational Center for Ecological Analysis and Synthesis, Santa Barbara, CA 93101-5504, USACold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China.
Duan
Zheng-Hu
ZH
MOE Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou 730000, ChinaÁrea de Biodiversidad y Conservación, Departamento de Biología y Geología, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, SpainNational Center for Ecological Analysis and Synthesis, Santa Barbara, CA 93101-5504, USACold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China.
Wang
Gang
G
MOE Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou 730000, ChinaÁrea de Biodiversidad y Conservación, Departamento de Biología y Geología, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, SpainNational Center for Ecological Analysis and Synthesis, Santa Barbara, CA 93101-5504, USACold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China.
D018533:Biomass; D017753:Ecosystem; D008954:Models, Biological; D010944:Plants; D011156:Population Density