关键词: 桃园, 动物群落, 物种多样性, 群落均匀性, 季节动态

Abstract: Based on the data from MODIS (Moderate-resolution Imaging Spectroradiometer) and meteorological observatories, and by using improved CASA (Carnegie-Ames-Stanford Approach) model, the vegetation net primary productivity (NPP) and its spatiotemporal distribution on the North Shaanxi Loess Plateau in 2005 were simulated and analyzed. Comparing with the traditional CASA model which only uses a universal mean annual maximum light use efficiency (LUE), the estimated regional NPP by the improved CASA model was more precise, because this improved model used the LUE parameters of different vegetation covers. The detailed land cover classification also contributed to the increase of the precision via introducing the time-series Normalized Different Vegetation Index (NDVI) and ground survey data to modify and adjust the original classification system based on vegetation map (1:1000000). The testing of the simulation results from different models with the ground survey data in North Shaanxi showed that the estimation by the modified CASA model was much closer to the real survey data, implying the potential practical significance of this model in estimating the vegetation NPP in North Shaanxi Loess Plateau and its adjacent areas. In 2005, the NPP in North Shaanxi was estimated as 4.76×10¹³ g C, accounting for about 1.5% of China’s terrestrial total NPP, and the mean NPP was 447.3 g C·m ^-2·a^-1, being much higher than that of China’s terrestrial vegetation (323.8 g C·m^-2·a^-1) in 1982-2000. The spatial distribution pattern of the vegetation NPP showed an apparently declining trend from the southeast to the northwest, with the highest value of 1087 g C·m^-2·a^-1 occurred in the broadleaved and conifer mixed forests of Huanglong Mountain in southeast part of the region. The mean NPP of desert vegetation in the whole region was the lowest, only about 205.0 g C·m^-2·a^-1. An obvious seasonal variation of the NPP was observed. The NPP in growth season (from April to October) took about 91.5% of the total in the year, and the peak occurred in mid-July to mid-August, amounting to 37.8% of the total.

Key words: Peach orchards, Arthropod communities, Species diversity, Community evenness, Seasonal dynamics