Plant Functional Type Diversity In The Otindag Sandland

Plant has a series of corresponding adaptive and functional strategies morphologically, physiologically and ecologically with the change of environmental conditions. Plant Functional Types (PFTs) refer to a group of plants with similar characteristics (morphological and physiological characteristics), functions and response to environmental conditions. This definition connects reasonably the physiology and life history of the plant from the individual perspective and from the perspective of the whole ecological system. With the help of PFTs, we are able to summarize the complicated process of individuals and population into a relatively concise and periodical evolutionary mode. Recent researches have shown that diversity of functional types is more important than diversity of species. This paper focuses on the vegetation on the Otindag Sandland, divides PFTs of the Otindag Sandland according to life span (annual and perennial), photosynthetic pathway (C₃ and C₄), reproductive mode (clonal and non-clonal), and growth form (grass and herb), investigates the distribution of PFTs of the Otindag Sandland and the response of its ecological characteristics towards the sandland environment. The observation of soil factor, distribution of PFTs and community characteristic of five different habitats on the Otindag Sandland shows that annual C₄ non-clonal plant functional type invades the mobile sand dune first; perennial C₃ plant functional type starts to settle on the semi-mobile dune and gradually becomes the dominant species; all the plant functional types of the Otindag Sandland involved in this research appear on fixed dune when the diversity of plant functional types is the highest. Organic substance and nutrients in the soil of the meadows are the most abundant and perennial C₃ vegetation predominates. On the lakeside, the salt content and water moisture increases and perennial C₃ herb becomes dominant species. On the Otindag Sandland, annual C₄ non-clonal herbs all exist in the dune environment. There is no significant difference in environmental conditions of mobile dune, semi-mobile dune and fixed dune. What differs is the characteristic of vegetation. Therefore, so long as artificial influence and livestock disturbance are eliminated, the degraded sandy grassland of Otindag Sandland can get restored through natural force. Through research on the change of functional characteristics of the enclosed degraded meadow of the Otindag Sandland, consecutive four-year investigation shows that the community with the most diversifying functions may not be the community that is the most stable and costs the longest time to recover. In our research, PFT diversity is the highest in the first and the fourth year of recovery, while it lowers significantly in the second and the third year of recovery. However, phytomass of the second and the third year is higher than that of the first and the fourth year. Considering the function of ecosystem, the stability of the community is the temporary transitional type in the recovering process and the recovering process of the community was fluctuating periodically. In the four years of recovery, perennial C3 photosynthetically pathway clonal herb predominates in the community in density, coverage, number of species and phytomass. It plays a key role in the early natural recovery of the degraded sandy grassland. By analyzing consecutive four-year vegetation data recorded in the lowland meadow in the Otindag Sandland, we investigated: (1) characters of plant communities, including density, species number, coverage, phytomass, and relative importance of PFTs; (2) contribution of PFTs characters to community PFT diversity; and (3) correlation of primary productivity with both species diversity and PFT diversity of the community. Density, coverage, species number, phytomass, and relative importance of PFTs significantly depended on life span, photosynthetic pathway, reproductive mode and growth form. PFT diversity was significantly correlated with the species number of plant communities. The stepwise regression analysis showed that with restoration process the perennial C3 clonal grass became greatest contributor to PFT diversity. The correlation of community primary productivity (in terms of phytomass of the plant community) with the PFT diversity varied among the years.In order to investigate the adaption of the main PFTs to the sandland environment of the Otindag Sandland, we study the response of the perennial rhizome clonal grass Leymus secalinus and perennial non-clonal herb Artemisia intramongolica to the sand burial and wind erosion. The results showed that different plant functional types have different adaptive strategies to the sand burial and wind erosion. With certain depth of sand burial and wind erosion, Leymus secalinus defends the sand burial and wind erosion through the integration of the ramets and escapes the stress conditions through the investment to the biomass of rhizome. While Artemisia intramongolica defends wind erosion through amplifying the investment to the biomass of roots and defends the sand burial through amplifying the investment to the above-ground biomass.