贵州喀斯特区植被恢复过程中群落优势种适应性评价及其资源策略研究

Adaptability evaluation and resource strategy of community dominant species in the process of vegetation restoration in karst area of Guizhou

【目的】研究喀斯特区植被恢复过程中植物光、温、水环境资源策略及其变化规律,以期为该区域植被抚育管理提供理论依据。【方法】以贵州茂兰国家级自然保护区喀斯特植被为研究对象,采用空间替代时间的方法,以植物功能性状为切入点,分析由草灌群落—灌木群落—乔灌群落阶段恢复过程中的群落优势种适应性状变化过程,结合主成分分析与隶属函数法对植被恢复过程中的18个群落优势种进行光、温、水适应性评价;通过优势种适应性评价值(D)变化,阐明其资源策略,并采用K-means法划分适应功能群,揭示植被恢复过程中功能群结构变化规律及对策。【结果】群落优势种对光适应性状中,叶绿素a含量(1.213~1.851 mg/g)和叶绿素a/b(2.321~2.994)随植被恢复先降低后升高,比叶面积(125.491~215.580 cm^(2)/g)随植被恢复逐渐降低;对水适应性状中,叶干物质含量(0.272~0.386)和叶组织密度(0.060~0.151 g/cm^(3))随植被恢复逐渐增加,叶片相对含水量(0.671%~0.840%)随植被恢复先降低后升高;对温适应性状中,丙二醛含量(39.116~63.162 nmol/g)随植被恢复先降低后升高,过氧化氢酶活性[117.555~1618.869nmol/(g·min)]随植被恢复逐渐增加。主成分分析表明,D_(光)反映优势种光波长吸收的范围与光资源转换速率,D_(温)反映优势种对极端温度胁迫的耐受程度,D_(水)反映优势种在干旱环境下维持正常生长的能力;随植被恢复进行,群落优势种D_(光)呈先降后升的变化趋势,D_(水)由0.428逐渐升至0.612,D_(温)在各恢复阶段间无明显差异,群落优势种由开放型光资源获取策略转变为保守型水资源竞争策略。依据D划分出3个功能群,即FG1(低光—低温—低水适应功能群)、FG2(高光—高温—高水适应功能群)和FG3(低光—低温—高水适应功能群);随植被恢复进行,FG1的重要值占比逐渐降低,在草灌群落阶段达最高值(49.275%),在灌木群落阶段为36.931%,而乔灌群落阶段不存在该资源类型物种;FG2物种仅在草灌和乔灌群落阶段存在且重要值占比较小;FG3的重要值占比逐渐升高。【结论】低光合速率、低光资源捕捉面积、不耐水热胁迫的物种在恢复早期占据优势地位;自灌木群落阶段起,逐渐被低光合速率、低光资源捕捉面积、不耐极端温度、耐旱的物种替代。喀斯特区域植被抚育应在恢复早期保留光资源获取策略物种,且多种资源策略物种共存,恢复中后期主要保留水资源竞争策略物种。

【Objective】This paper studied the strategies of plant light,temperature and water environmental resources and their changing rules in the process of vegetation restoration in karst area,with a view to providing theoretical basis for vegetation nourishment management in the region.【Method】This paper took the karst vegetation in Maolan National Na-ture Reserve in Guizhou as the research object,used spatial substitution time method and plant functional traits as the en-try point,analyzed the adaptive trait change process of community dominant species during the restoration process from grass-shrub community stage to shrub community stage to arbor-shrub community stage,and combined principal compo-nent analysis and membership function method to evaluate the light,temperature,and water adaptability of 18 community dominant species during the vegetation restoration process;by analyzing the changes in the adaptive evaluation value(D)of dominant species,the resource strategy of dominant species was elucidated,and the K-means method was used to di-vide the adaptive functional groups,in order to reveal the structural changes and countermeasures of functional groups du-ring vegetation restoration.【Result】Among the light adaptation traits of the dominant species in the community,chloro-phyll a content(1.213-1.851 mg/g),chlorophyll a/b(2.321-2.994)decreased and then increased with vegetation restora-tion,and specific leaf area(125.491-215.580 cm^(2)/g)gradually decreased with vegetation restoration;among the water adaptation traits,leaf dry matter content(0.272-0.386),leaf tissue density(0.060-0.151 g/cm^(3))gradually increased with vegetation restoration,and leaf relative water content(0.671%-0.840%)decreased and then increased with vegetation res-toration;among the temperature adaptation traits,malonaldehyde content(39.116-63.162 nmol/g)decreased and then in-creased with vegetation restoration,and catalase activity[117.555-1618.869 nmol/(g·min)]gradually increased with vegetation restoration.Principal component analysis showed that D_(light) reflected the absorption range of light wavelengths and the strength of light resource conversion rate of the dominant species,D_(temperature) reflected the tolerance level of the dominant species to peroxidation produced by extreme temperature stress,and D_(water) reflected the ability of the dominant species to maintain normal growth under drought conditions;as vegetation restoration proceeded,D_(light) of the dominant species of the community showed a trend of decreasing and then increasing,D_(water) gradually increased from 0.428 to 0.612,D_(temperature) did not differ greatly among the restoration stages,and the dominant species of the community changed from an open light resource acquisition strategy to a conservative water resource competition strategy.In this paper,three func-tional groups were classified based on D,namely FG1(low light-low temperature-low water adaptation functional group),FG2(high light-high temperature-high water adaptation functional group)and FG3(low light-low temperature-high water adaptation functional group);the percentage of important values for FG1 gradually decreased with vegetation restoration,reaching the highest value(49.275%)in the grass-shrub community stage and 36.931%in the shrub community stage,whereas no species of this resource type existed in the arbor-shrub community stage;the species of FG2 existed in the grass-shrub and arbor-shrub community stages only and their percentage of important values was small;the percentage of important values for FG3 gradually increased with vegetation restoration.【Conclusion】Species with low photosynthetic rate,low light resource capture area,and intolerance to water and heat stress dominate in the early stages of recovery;since the shrub community stage,it has gradually been replaced by species with low photosynthetic rate,low light re-source capture area,intolerance to extreme temperatures and drought tolerance.Vegetation nurturing in karst areas should retain light resource acquisition strategy species in the early stages of restoration,with multiple resource strategy species coexisting,and mainly retain water resource competition strategy species in the middle and later stages of restoration.