为探明喀斯特地区次生林优势种群竞争关系,以贵州省紫云苗族布依族自治县格凸河国家级风景名胜区中洞景区撂荒30余年的典型喀斯特次生林作为研究对象,基于1.68 hm²的固定样地,在实地调查的基础上,采用Hegyi竞争指数对样地内优势种群种内种间竞争关系进行定量分析。结果表明:1)株数统计显示,共计调查胸径≥1 cm的林木2 805株,其中亮叶桦、化香树、马尾松、枫香树和山杨共2 455株,占总株数87.52%,为优势种群;2)林木间的竞争压力主要来自其周围5 m范围内的竞争木,除亮叶桦和枫香树的种间竞争大于种内竞争外,其余3个种群均为种内竞争大于种间竞争,表明次生林的竞争压力基本以种内竞争为主。5个优势种群种内竞争压力依次为化香树>山杨>马尾松>枫香树>亮叶桦;3)竞争模型预测表明,优势种群的胸径与竞争强度之间呈现幂函数关系,揭示了随着林木个体胸径的逐渐增大,竞争强度减弱,当林木个体胸径在3~5 cm时,竞争最为激烈,而当胸径达到10 cm后,竞争强度的变化趋于平稳。因此,建议在林木胸径达到10 cm之前,及时进行抚育管理,以减缓竞争压力,提高林分的稳定性。

This study explored the competitive relationships among dominant populations in secondary forests in karst areas.A typical karst secondary forest in the Zhongdong Scenic Spot of the Getu National Scenic Areas in Ziyun Miao and Buyi Autonomous County,Guizhou Province,abandoned for over 30 years,was selected as the study area.Based on 1.68 hm² fixed sample plots,the Hegyi Competition Index was used to quantitatively analyze competitive relationships through field surveys.1)Based on the number of plants,a total of 2 805 trees with a diameter at breast height(D_BH)more than 1 cm was investigated.Among these,the species consisting of Betula luminifera,Platycarya strobilacea,Pinus massoniana,Liquidambar formosana,and Populus davidiana collectively account for 2 455 individuals,constituting 87.52% of the total number of plants,and are thus identified as the dominant populations.2)The competitive pressure among trees was mainly exerted by those within 5 meters.However,for Betula luminifera and Liquidambar formosana,interspecific competition exceeded the intraspecific competition.The other three populations had more intraspecific than interspecific competition,which indicated that the competitive pressure of the secondary forests was mainly dominated by intraspecific competition.The intraspecific competitive pressures of the five dominant populations were ranked as follows:Platycarya strobilacea>Populus davidiana>Pinus massoniana>Liquidambar formosana>Betula luminifera.3)Competition model predictions showed a power function relationship between D_BH and competition intensity in dominant populations,revealing that competition intensity tended to weaken with the gradual increase in D_BH of individual trees in the population.The competition was most intense when D_BH of individual trees in the population stands was in the range of 3 to 5 cm.After D_BH reached 10 cm,the change in competition intensity tended to stabilize.Timely nursery management is recommended to reduce competitive pressure and enhance the stability before the D_BH reaches 10 cm.