基于生物量回归方程估算黔中喀斯特常绿落叶阔叶混交林木本植物的根系生物量

常规根系生物量研究方法在我国西南喀斯特森林地区实施困难,根系挖掘法所得研究结果不确定性高,导致目前根系生物量数据匮乏。选择贵州中部喀斯特常绿落叶阔叶混交林为对象,建立常规的根系生物量回归方程,结合群落调查数据,以期研究该森林木本植物的根系生物量特征及其空间分布格局。利用106株乔木、34株灌木和34株藤本标准木根系数据,构建了5种优势乔木(安顺润楠Machilus cavaleriei、化香树Platycarya strobilacea、云贵鹅耳枥Carpinus pubescens、云南鼠刺Itea yunnanensis和窄叶石栎Lithocarpus confinis)、3种优势灌木(刺异叶花椒Zanthoxylum dimorphophyllum、倒卵叶旌节花Stachyurus obovatus和异叶鼠李Rhamnus heterophylla)和2种优势藤本(藤黄檀Dalbergia hancai Benth和小果蔷薇Rosa cymosa)以及乔木通用、灌木通用和藤本通用共13个根系生物量回归方程。利用这些方程计算得到该喀斯特森林木本植物总根系生物量为22.72Mg/hm2。乔木根系生物量(22.57 Mg/hm2)远高于灌木和藤本,占森林总根系生物量的99.30%。5个优势乔木树种的根系生物量(19.67 Mg/hm2)占森林总根系生物量的86.54%。物种根系发达程度是影响根系生物量空间分布格局的重要因素。研究可为喀斯特地区植被地下生物量与碳储量的全面估算提供一个新途径。

Allometric function-based root biomass estimate of woody plants in a karst evergreen and deciduous broadleaf and mixed forest in central Guizhou Province, southwestern China

Traditional methods of root biomass field investigation are difficult to implement in karst forests, and root excavation methods cause high uncertainties, thereby resulting in a lack of data. In the present study, root biomass and spatial distribution patterns of woody plants in a karst evergreen and deciduous broadleaf and mixed forest in central Guizhou Province, southwestern China were analyzed by building root biomass allometric functions and using vegetation plot surveys. Root biomass regression models were established based on the root data of 106 trees of five dominant species (Machilus cavaleriei, Platycarya strobilacea, Carpinus pubescens., Itea yunnanensis, and Lithocarpus confinis.), 34 shrubs of three dominant species (Zanthoxylum dimorphophyllum, Stachyurus obovatus, and Rhamnus heterophylla), and 34 lianas of two dominant species (Dalbergia hancei Benth. and Rosa cymosa). The estimated root biomass of woody plants in the karst forest was 22.72 Mg/hm². Trees with 22.57 Mg/hm² root biomass accounted for 99.30% of the total forest root biomass and were the major root biomass contributors, with the five dominant tree species comprising 86.54% (19.67 Mg/hm²) of the total forest root biomass. The root development level of different species is a significant factor that influences spatial distribution patterns of root biomass. This study provides a new way to comprehensively estimate belowground vegetation biomass and carbon storage in karst regions.