J Plant Ecol ›› 2013, Vol. 6 ›› Issue (4): 277-285 .

• Research Articles •

### Exogenous and endogenous determinants of spatial aggregation patterns in Tibetan Plateau meadow vegetation

Jiajia Liu1, Deyan Wu2, Xiaoyu Peng2, Shurong Zhou1,* and Corey J. A. Bradshaw3,4

1. 1 Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of life Sciences, Fudan University, Shanghai 200433, China; 2 State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China; 3 The Environment Institute and School of Earth and Environmental Sciences, The University of Adelaide, South Australia 5005, Australia; 4 South Australian Research and Development Institute, PO Box 120, Henley Beach, South Australia 5022, Australia
• Received:2012-07-11 Accepted:2012-11-10 Published:2013-07-19
• Contact: Zhou, Shurong

### Exogenous and endogenous determinants of spatial aggregation patterns in Tibetan Plateau meadow vegetation

Abstract: Aims We aim to quantify the relative importance of various endogenous and exogenous processes influencing the spatial distribution of the individuals of plant species at different temporal and spatial scales in a species-rich and high-cover meadow in the eastern Tibetan Plateau.
Methods We calculated Green's index of dispersion to infer the spatial distribution patterns of 73 herbaceous species at two scales (0.25 and 1.0 m 2). We constructed a series of generalized linear models to test the hypotheses that different species traits such as mean plant stem density, per capita dry biomass, maximum plant height and mean seed mass contribute to their spatial distribution. We used the first principal component of soil C, N and P to explain abundance variation across quadrats and sub-plots.
Important findings The individuals of the species studied were highly spatially aggregated. At both spatial scales, biomass and stem density explained the most variation in aggregation, but there was no evidence for an effect of mean seed mass on aggregation intensity. The effects of soil carbon, nitrogen and phosphorus at different depths affected plant abundance mostly at the broader spatial scale. Our results demonstrate that self-thinning and habitat heterogeneity all contribute to determine the spatial aggregation patterns of plant individuals in alpine meadow vegetation in the eastern Tibetan Plateau.

Aims We aim to quantify the relative importance of various endogenous and exogenous processes influencing the spatial distribution of the individuals of plant species at different temporal and spatial scales in a species-rich and high-cover meadow in the eastern Tibetan Plateau.
Methods We calculated Green's index of dispersion to infer the spatial distribution patterns of 73 herbaceous species at two scales (0.25 and 1.0 m 2). We constructed a series of generalized linear models to test the hypotheses that different species traits such as mean plant stem density, per capita dry biomass, maximum plant height and mean seed mass contribute to their spatial distribution. We used the first principal component of soil C, N and P to explain abundance variation across quadrats and sub-plots.
Important findings The individuals of the species studied were highly spatially aggregated. At both spatial scales, biomass and stem density explained the most variation in aggregation, but there was no evidence for an effect of mean seed mass on aggregation intensity. The effects of soil carbon, nitrogen and phosphorus at different depths affected plant abundance mostly at the broader spatial scale. Our results demonstrate that self-thinning and habitat heterogeneity all contribute to determine the spatial aggregation patterns of plant individuals in alpine meadow vegetation in the eastern Tibetan Plateau.