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土地利用方式变化是影响陆地生态系统碳储量的重要因素。试验以黄土高原沟壑区王东沟小流域杜家坪坡地果园和邻近农田为对象,分析了坡地退耕还果20年后,地上植被生物量、地下根系生物量以及0—100 cm土层有机碳氮储量的变化及其影响因素。结果表明,坡地果园0—100 cm土层有机碳(SOC)储量为C 50.7 t/hm2低于农田(C 57.3 t/hm2),但0—20 cm土层,果园SOC储量为C 16.7 t/hm2高于农田(C 15.3 t/hm2),增幅为9.2%;而在20—100 cm土层,SOC含量基本呈现出农田>果园的趋势。果园土壤1 m剖面各层次全氮(TN)含量都低于农田,但未达到显著水平。农田退耕为果园20年后,坡地果园植株和根系碳储量(C 19.7 t/hm2)、氮储量(N 165.9kg/hm2)约为农田作物(C 3.4 t/hm2、N 96.8 kg/hm2)的5.8和1.7倍。果树主干、枝条和根部的新增生物量是导致果园生态系统碳、氮储量积累的主要因素。
Changes in land use patterns are important factors affecting the terrestrial ecosystem carbon stocks. The experiment was conducted to analyze the orchard and adjacent farmland on the slope of Dujianping in the Wangdonggou watershed of the gully region of the Loess Plateau. After 20 years of conversion of returning farmland to farmland, the aboveground biomass of vegetation, underground root biomass and organic carbon Nitrogen storage changes and their influencing factors. The results showed that the SOC of 0-100 cm soil layer in sloping field orchard was C 50.7 t / hm2 lower than that of farmland (C 57.3 t / hm2), but the SOC storage in 0-20 cm soil layer was 16.7 t / hm2 was higher than that of farmland (C 15.3 t / hm2), with an increase of 9.2%. In 20-100 cm soil layer, SOC content showed a trend of farmland> orchard. The total nitrogen (TN) content at 1 m section of orchard soil was lower than that of farmland, but did not reach significant level. After 20 years of farmland conversion to orchard, the plant or root carbon storage (C 19.7 t / hm2) and nitrogen storage (N 165.9 kg / hm2) in the orchard were about 3.4 times of the cropland (N 96.8 kg / hm2) 5.8 and 1.7 times. The newly increased biomass of the trunk, branches and roots of fruit trees is the main factor leading to the accumulation of carbon and nitrogen reserves in the orchard ecosystem.