土地利用方式对岩溶山地土壤种子库的影响

本文从种类组成、种子数量、生态优势度、物种多样性、种子分布规律和物种相似性等方面比较了重庆市岩溶低山10种不同土地利用系统的土壤种子库特点，10种土地利用类型包括耕地、弃耕地、果园、灌草坡、人工林和次生林。结果表明，研究区种子以草本为主，随土利用强度增加，种子类和数量减少，与地面农田杂草相似性增加，土壤种子库出质和量方面的锐减。从土壤种子角度说明研究区生态退化严重。

The Soil Seed Banks in Karst Mountains as Affected by Land Use

Based on the analysis of species composition,amount and distribution,ecological dominance and species similarity,and its diversity,the properties of soil seed banks on 10 different land utilization systems in Chongqing Karst mountains were studied.The 10 land utilization systems comprised upland,old field (1 years abandoned dry field),orchard,shrub grassland,secondary forest and Robinia pseudoacacia(5 years).Five 0.1m 2 soil sample measured 15cm high from each of 10 lands were taken to laboratory to let seeds in the soil germinating.The results showed that:(1) Most of seeds in different land use soil banks are herb species,and the species composition between above ground vegetation and soil seed banks are nearly the same at the upland,old field,orchard,shrub grassland,but it is different in the woodland;(2)The amount of seeds and xylophyta species decreased with the increase in strength of land use,while as the amount of seeds increased,the bio diversity and the ecological dominance increased,the richness indices decreased;(3)Seed number decreased with depth within soil samples in most land use,but it is reverse in cropped land;(4)The seeds of herbaceous species distributed evenly,but the xylophyta species distributed patchily.