黄土高原不同纬度下刺槐林土壤生态化学计量学特征研究

ECOLOGICAL STOICHIOMETRY CHARACTERISTICS OF ROBINIA PSEUDOACACIA FOREST SOIL IN DIFFERENT LATITUDES OF LOESS PLATEAU

为了阐明黄土高原不同纬度地区刺槐林土壤的生态化学计量学特征,对黄土高原由南向北13个县区刺槐林下的土壤碳、氮、磷化学计量学特征进行了测定与分析。结果表明:(1)阳坡0～10 cm土壤C∶N比、C∶P比、N∶P比的变化范围分别为9.48～15.33、8.93～59.79、0.77～5.11,10～20 cm土壤分别为9.13～13.57、7.85～37.69、0.44～3.19;阴坡0～10 cm土壤C∶N比、C∶P比、N∶P比分别为8.58～13.75、9.46～47.71、0.76～3.63,10～20 cm土壤分别为7.60～13.41、5.99～31.28、0.54～2.65。(2)土壤全氮的空间分布与有机碳具有一致性,均随纬度的升高呈指数减小的趋势,表层大于表下层,且随着纬度的升高该差异逐渐减小;全磷的空间变异性低于有机碳和全氮,研究区内土壤全磷含量随纬度的升高呈先增加后减小的趋势。(3)土壤C∶N比随纬度的升高无明显的变化趋势,而C∶P比和N∶P比随纬度的升高显著减小;土壤C∶N∶P比均随着土层增加而减小,但差异不显著。

To explore effect of latitude on ecological stoichiometry characteristics of Robinia pseudoacacia forest soil on the Loess Plateau, soil samples were collected from Robinia pseudoacacia forests in 13 counties distributed from south to north in Northern Shaanxi for analysis of soil C, N and P stoichiometry. Results show that （ 1 ） on sunny slopes, the ran- ges of soil C： N, C： P, N： P ratios varied in the range of 9.48 - 15.33, 8.93 -59.79 and 0.77 ~5.11 respectively, in the 0 ~ 10cm soil layers and in the range of 9.13 - 13.57, 7.85 ~ 37.69 and 0.44 - 3.19, respectively, in the 10 - 20cm soil layer, while on shady slopes, they did in the range of 8.58 -13.75, 9.46 -47.71 and 0.76 - 3.63, respectively, in the top soil layers and in the range of 7.60 - 13.41, 5.99 - 31.28 and 0.54 - 2.65, respectively, in the 10 ~ 20cm soil layers. （2） Soil organic carbon and soil total N were quite consistent in spatial distribution, showing the same trend of declining exponentially with rising latitude and they were higher in the surface layers than in the subsurface lay- ers, and the difference narrowed with rising latitude; Total P was lower than SOC and total N in spatial variability, show- ing a trend of rising first and then declining with latitude in the studied area. （3） Soil C： N ratio did not change much with latitude, while soil C： P and N： P ratios decreased significantly with rising latitude; and soil C： N： P ratio was higher in the topsoil layers than in the subsurface soil layer, but the difference was not significant.