刺槐林地土壤水分与林下植物群落生物量的关系

Relationship Between Soil Moisture of Robinia pseudoacacia Forests and Aboveground Biomass of Understory Vegetation

通过样地调查,对比研究了不同林龄刺槐林地和撂荒地土壤水分年际变化特征及样地生物量特征。结果表明,刺槐林地土壤水分含量及储水量随林龄增长降低,过熟林的剖面含水率接近凋萎湿度;0—140 cm土层生长季土壤水分变异系数遵循过熟林>成熟林>幼龄林>撂荒地的规律,而140—500 cm土层则基本与上述规律相反。成过熟刺槐林下植物群落地上部生物量略高于撂荒地,土壤水分与地上部生物量仅存在微弱的负相关关系。说明刺槐生长虽然消耗了大量土壤储水,但未显著降低林下植物群落的生产力。研究表明,将刺槐作为先锋树种用于黄土高原森林草原区的植被恢复有助于迅速形成植被覆盖,发挥刺槐林的水土保持功能。同时,林下植物群落的健康发育可以保证刺槐衰退后的生态系统持续稳定地发挥其生态功能。

In order to understand the relationship between soil moisture and aboveground biomass of understory vegetation in Robinia paeudoacacia forests in Loess hilly region, 20 plots were sampled, including 16 Robinia pseudoacacia Forest plots at different age and 4 abandoned field plots over 25 years. The results showed that soil moisture of all Robinia pseudoacacia forest plots was significantly lower than that of abandoned fields and soil moisture reduced with age of trees increasing. The variation of soil moisture in 0-40 cm profile in growth season followed a law. overmature forest〉 mature forest〉 young forest〉 abandoned field, but reversed in 140-500 cm soil layer. Aboveground biomass of understory vegetation in overmature and mature forests was slightly higher than that in abandoned fields. Soil moisture content was almost not correlated with aboveground biomass. We concluded that Robinia pseudoacacia did not effect the productivity of land, although it consumed much water in soil and make it dryer and dryer. So, Robinia pseudoacacia should be used as a pineer tree spieces to restore degraded ecosystem in Loess hilly region.