林下草本植物是森林生态系统的基本组成要素,对森林的更新、生态系统结构、功能的维持和提升具有重要作用,理解林下草本层群落特征及其影响因素,有助于构建理想的林-草结合模式.本研究以宁南山区泾源县无人为干扰的华北落叶松林人工林、间伐处理的华北落叶松林人工林和华北落叶松与白桦自然混交林为研究对象,探究林下草本层群落特征(物种多样性和地上生物量)及其与土壤理化特性(土壤容重、含水量、全碳含量、全氮含量及全磷含量)和林分结构(密度和郁闭度)的关系.结果表明:(1)与人工林相比,自然混交林林下草本植物组成最丰富(34种),且物种多样性和地上生物量也最高;(2)自然混交林林下土壤特性均优于人工林,但间伐处理的人工林林下土壤特性较无人为干扰的人工林土壤特性有显著提高;(3)冗余分析表明,林下草本层物种多样性主要与土壤含水量、土壤全碳、全氮和全磷含量呈正相关,与土壤容重、林分密度和郁闭度呈负相关,且林分密度、0～20 cm 土层含水量对林下草本物种多样性有显著影响(P＜0.05);(4)回归分析结果表明,0～20 cm 土层的土壤特性、物种丰富度和优势度、林分密度及郁闭度显著影响林下草本地上生物量的积累(P＜0.05);随机森林模型及方差分解进一步得出:土壤因子对地上生物量积累的解释率为30.99％,其中0～20cm 土层土壤容重、全碳含量、全氮含量、土壤含水量为最重要的解释因子;林分结构的解释率为12.74％,其中林分密度是最重要的解释因子,而物种多样性的解释率仅为3.42％.研究表明,自然混交林作为理想的林-草结合模式,有利于林下草本的健康发育和林下生态环境的改善,且林下草本层物种多样性、地上生物量分别受不同环境因子所控制.研究结果对于人工林的近自然化管理(抚育间伐、补植等)和林下经济的高质量发展具有一定的参考价值和指导意义.
Community characteristics and influencing factors of herbaceous layer under Larixe gmelinii var.principis-rupprechtii forests in a south mountainous area of Ningxia
Understory herbs are the basic components of forest ecosystem,which play a vital role in forest regenera-tion,as well as in the maintenance and improvement of ecosystem structure and function.Understanding the com-munity characteristics and influencing factors of herbaceous layer in the understorey is helpful to construct an ideal forest-grass combination model.In this study,the undisturbed Larix gmelinii var.principis-rupprechtii plantations,the thinned L.gmelinii var.principis-rupprechtii plantations,and the natural mixed forest of L.gmelinii var.princip-is-rupprechtii and Betula platyphylla in Jingyuan County of the south mountainous area of Ningxia were examined.We explored the relationship between community characteristics(i.e.,species diversity and community biomass)of understory herbs,soil properties(i.e.,soil bulk density,water content,total carbon content,total nitrogen content and total phosphorus content)and stand structure(i.e.,stand density and canopy density).The results showed that:(1)Compared with the monoculture plantations,the natural mixed forest had more herbaceous species(34 species),higher species diversity and aboveground biomass;(2)Soil properties under the natural mixed forest were better than those under the plantations,but soil properties under the thinned plantation were significantly improved than those under plantation without human disturbance;(3)Redundancy analysis showed that species diversity of herbaceous layer was positively correlated with soil water content,soil total carbon content,total nitro-gen content,and total phosphorus content,but negatively correlated with soil bulk density,stand density and cano-py density.Stand density and soil water content of 0-20 cm soil layer significantly affected species diversity of understory herbs(P＜0.05);(4)The regression analysis showed that soil properties of 0-20 cm layer,species richness and dominance,stand density and canopy density significantly affected aboveground biomass of herbaceous species(P＜0.05).The random forest model and variance decomposition further showed that the explanation rate of soil factors on aboveground biomass was 30.99％,among which soil bulk density,total carbon content,total nitro-gen content and soil water content of 0-20 cm layer were the most important ones.The explanation rate of stand structure was 12.74％,of which stand density was the most important explanatory factor.The explanation rate of species diversity was only 3.42％.The natural mixed forests as the most ideal model of forest-grass combination were conductive to the healthy development of understory herbs and the improvement of understory ecological environ-ment.Species diversity and aboveground biomass of herbaceous layer were affected by different environmental fac-tors.Our results provide references for the near-natural management of plantations(such as thinning and replan-ting)and the high-quality development of understory economy.
万方数据
维普
