PARENT SESSION
Contributed Oral Session 51: Arid Land Management, Vegetation, and Nutrient Dynamics
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 522 A, Level 5, Palais des congrès de Montréal

The rule of self-crowding with relative density in sparse vegetation.

Wang, Gen-Xuan^*,1, Wei, Xiao-Ping², Li, Shu-Ping ³, ¹ Institute of Ecology, College of life sciences, Zhejiang University, Hangzhou 310029, China, Hangzhou, Zhejiang, China² MOE laboratory of Arid and grassland ecology, College of life sciences, Lanzhou University, Lanzhou 730000, China, Lanzhou, Gansu, China³ College of resource and environment, Lanzhou University, Lanzhou 730000, China, Lanzhou, Gansu, China

ABSTRACT- The knowledge on the sparse vegetation is important to improve the management of desert and the restoration of ecosystem, but it is poorer than that in crowded vegetation. Almost all of rules such as the rule of self-thinning and scaling law was applicable in the crowd population or communities, which based on the theory of negative interaction or competition among organisms. Why the positive interaction was found in plants facing stress and negative in suitable conditions? Is it contradictory to the scaling law? A general field of signals (St) with negative and positive elements surround plants had been hypothesized to integrate the positive and negative interaction and understand its mechanism. We get a quantitative rule that the relative augment (Wc/Wt-1) increased with relative density (dr) following a 1/3 power rule in the sparse vegetation (dr<<1): Wc/Wt-1=kd^1/3 Where, W is an estimation of plant weight in the presence (c) or in the absence (t) of neighbors, k is constant. While, the function of scaling law was got from the theory when St =0. The predictions were strongly supported by the data got from a series of field observations and experiments. The threshold of dr could be determined for stopping grazing or cutting to prevent desertification.

Key words: signal ecology, Interaction, vegetation, desert