The Relationship Between Species Diversity And Productivity And The Affecting Factors At The Forest-Grassland Transect Daxing’an Mountain

Ecological transition zone is response to the environmental sensitive area, biologicaldiversity decreases or rare species endangeres as a result of overgrazing，increasing grazingcapacity, excessive deforestation and killing the wildlife even other environmental factorsincluding the hole in the ozone layer, acid rain, serious soil erosion, the greenhouse effect andtoxic gases emissions and so on in recent years, so protecting the biodiversity has beenreceived the widespread attention in the ecosystem. Understanding the relationship betweenbiodiversity and ecosystem function is the hotspot issues by human research, it provides areasonable basis in order to ecosystem restoration and management or utilization of transitionzone, which is beneficial to the sustainable development of environment and resources evenhuman beings.This study was carried out in Naji forest statition along a Forest-Grassland transects inInner Mongolia, northern DaXing’an Mountain. We elected the typical grassland section (G),three forest steppe ecotone sections (Ta, Tb and Tc), forest grassland section (M) and forestsection (F). We investigated the plant characteristic values (species, height, coverage, density)and the habitat factors (elevation, slope, longitude, latitude, soil type, rainfall) in plantcommunity and picked up the above ground of plant and soil samples, then determined theplant biomass and soil water content, pH, soil organic matter, total nitrogen, availablephosphorus and available potassium, etc. It aims at discussing the relationships among speciesdiversity, productivity and stability and the key ecological factors which affect productivityand species diversity.The main results of this experiment are:①From the grasslands to the forest communitytransition zone,267species of vascular plants belonging to153genera and39families wererecorded in2008year;250species of vascular plants belonging to142genera and43familieswere recorded in2009year;223species of vascular plants belonging to130genera and38families were recorded in2010year, there is small changes every year.②Species richnesswas significantly different along the transect, as the distribution of plant species showed adouble-humped trend, the species increased in Ta section and adjacent to the forest grasslandTc section, which was in the peak two vertices; Tb section was in the cavity between the twopeaks, it conforms to the characteristics of positive edge effect.③With respect to thefunctional group, perennial forbs was the dominant species. In relation to water ecotone,Mesophyte was the main form when considerding their Raunkiear life form, Chamaephyteswas dominated along the transition zone. Aboveground productivity, species richness index and Shannon-Weiner index were also from low to high then low, the biggest productivity andspecies diversity index were in M section.④There were no relationship between productivityand species richness index or Shannon-Weiner index, which conforms to the redundancytheory hypothesis. Also, there were no linear correlation among stability, productivity andspecies diversity index.⑤There was a significantly positive correlation between productivityand soil water content, available phosphorus potassium ratio, while the pH and availablepotassium was negative correlation relative to the productivity. Soil moisture content was thekey factor which determined the productivity distribution. Through the theoretical analysis tothe study area, we can be clearer of the time and space distribution pattern of the speciesdiversity along the transitional zone, it provides a certain theoretical basis for the next step ofthe protection and planning management.