Differences of above-ground biomass and comparisons of its effect on soil moisture between natural vegetation and artificial vegetation in Yanhe basin

【Objective】 Above-ground biomass and soil moisture between natural and artificial vegetation,were compared to explore the reason of artificial vegetation degeneration,vegetation restoration planning and decision support in Yanhe basin.【Method】 We collected climate data of 57 meteorological stations from the year 1980-2000,and divided the Yanhe basin into 17 environmental gradient units according to rainfall and temperature changes.Above-ground biomass of the natural vegetation and 0-500 cm soil moisture content were measured.The spatial variation of natural vegetation and its influence factors were analyzed,and the changes of above-ground biomass and soil moisture content between the natural vegetation and artificial vegetation were compared.【Result】 The results showed that above-ground biomass of natural vegetation in space had significant differences,and above-ground biomass increased gradually from northwest to southeast in Yanhe basin.Above-ground biomass of natural vegetation had a positive correlation with annual total precipitation(P0.05),and it showed a negative correlation with growing seasonal temperature;the above-ground biomass changed significantly with the different terrain or slope in the same climate.With natural vegetation as reference,the maximum overloading of artificial vegetation above-ground biomass was 30 425.83 g/m2,the minimum 118.93 g/m2,and the average 6 668.00 g/m2,artificial vegetation above-ground biomass significantly exceeded the extent of natural vegetation carrying capacity.Compared with natural vegetation,the biggest deficit of artificial vegetation's soil moisture could reach 80.5 g/kg,so it indicated that average of artificial vegetation was significantly lower than the natural vegetation(P0.05),appearing different degrees of dry soil layer which led the artificial vegetation communities to decline or death.【Conclusion】 Finally,the main reason for soil moisture depletion and vegetation degeneration was overloaded biomass.When restoring and reconstructing vegetation,we must consider the potential biomass restriction under specific site conditions,rather than choose blindly unsuitable species.