黄河下游平原不同非农生境中植物多样性研究

Abstract

The well-being and survival of humanity depends upon the stability and sustainability of services provided by agricultural ecosystems. Natural and semi-natural habitats within agricultural landscapes,as well as the associated plant communities thereof, are of vital importance for preserving biodiversity in agro-ecosystems. Agricultural landscapes interspersed with forest and hedge patches dominate the lower reaches of the Yellow River Plain. In order to understand the characteristics and ecological functions of plant communities in non-agricultural habitats,a total of 54 plots were set up in Fengqiu county of Henan Province,reflecting landscape patterns. Within these plots,the vegetation in natural and seminatural habitats was investigated by using the Braun-Blanquet method. The surveyed habitats were mainly planted forests,hedges,field roads,and ditches. The results of this study are as follows:( 1) A total of 184 species belonging to 51 families and 157 genera( 1 species belonging to ferns) have been encountered in the study area,6 dominant families( Compositae,Gamineae,Leguminosae,Cruciferae,Labiatae,and Solanaceae) account for 48. 9% of all species. The plants are predominantly cosmopolitan( 26 families,148 species) and pantropic( 14 families,23 species) types,accounting for 80.0%( 40 / 50) of the total families and 93.4%( 171 / 183) of the total species. Ditches and field roads are primary habitats of the cosmopolitan types-respectively,88.5% and 86.0% of the plant species have been detected in these two habitats. The genera show complex patterns of geographical distribution type,comprising 13 of the 15 distribution types of Chinese seed plants. The temperate( 53 genera,56 species),cosmopolitan( 32 genera,48 species) and pantropic( 30 genera,34 species) are the dominant distribution types( 73.7% of all genera and 75.4% of all species). Overall,the study area is dominated by the widespread species,the dominant families and genera show marked superiority over the lesser taxa,and there is a distinct lack of endemic species.( 2) The planted forests and hedges have the highest species richness and diversity compared with the other non-agricultural habitats. The evenness and coverage in the ditches,planted forests and hedges are significantly higher than in the field roads. The field roads have the highest β-diversity.( 3) Community similarity analysis shows that the planted forests,hedges and field roads have high inter-community similarity,while the ditches have low inter-community similarity attributable mainly to species characteristics. Given the difference in community coverage and species importance value( IV) of the planted forests,hedges and field roads,we suggest that the results of the similarity analysis reflect the similarity of species occurrence rather than that of ecological functioning. Based on the results of this study,we believe that the planted forests and hedges have an important role in species conservation. The species diversity of planted forests is nearly equal to that of the hedges,indicating that the two habitats have similar abilities for protecting plant species in agro-landscapes. The ditches provide shelters for the hydrophytes and hygrophytes. In the future,we should concentrate on biodiversity characteristics controlling the ecosystem processes that underpin ecosystem functioning and services,investigate the ecological effects and mechanisms of the spatial configuration of the landscape elements,and explore appropriate regulation and management strategies. Furthermore,constructing hedge corridors may be an advisable approach for maintaining agricultural production and ecological functions in the study area. The ecological functions of planted forests may be enhanced by appropriately modifying the forests' structure and species composition to boost species diversity. Further studies are required to understand how agricultural landscapes can be configured to simultaneously maintain agricultural productivity and ecosystem functioning.