贵州普定喀斯特次生林乔灌层地上生物量

BIOMASS OF CANOPY AND SHRUB LAYERS OF KARST FORESTS IN PUDING, GUIZHOU, CHINA

生物量是植物群落最重要的特征之一,也是研究生态系统基本过程和功能的重要参数。我国西南喀斯特山地次生林是退化生态系统恢复过程中的重要阶段,其生境特殊,乔灌层种类繁杂且生长形态多样,物种间体积质量密度差异悬殊,生物量测定极为困难。所以,有关其生物量的基础资料极为缺乏。该文根据对普定喀斯特生态站的窄叶石栎(Lithocarpus confinis)+云南鼠刺(Itea yunnanensis)林、圆果化香(Platycarya longipes)+云南鼠刺林、圆果化香+槲栎(Quercus aliena)林3个主要次生森林类型的样地调查资料,采用样木回归模型法和收获法,研究了群落乔灌层地上生物量及其分配格局。利用172株样木数据建立了圆果化香、窄叶石栎、云南鼠刺、刺楸(Kalopanax septemlobus)、安顺润楠(Machilus cavaleriei)、槲栎、香叶树(Lindera communis)、川钓樟(Lindera pulcherrima var.hemsleyana)、异叶鼠李(Rhamnus heterophylla)、倒卵叶旌节花(Stachyurus obovatus)、薄叶鼠李(Rhamnus lepto-phylla)、贵州花椒(Zanthoxylum esquirolii)、竹叶椒(Zanthoxylum planispinum)、铁仔(Myrsine africana)和刺异叶花椒(Zanthoxylum dimorphophyllum var.spinifolium)15个主要树种的分种生物量回归模型。同时,利用这些样木建立了3个不同胸径(D)组(D<1cm、1cm≤D≤5cm和D>5cm)的生物量回归模型。通过进一步分种和分组的计算得出:这3个次生乔木林的乔灌层地上生物量分别为85.6×103、65.3×103和115.2×103kg·hm–2;层次分配上,3个样地的乔木层地上生物量占绝对优势,分别约占乔灌层地上生物量的98.5%、96.6%和99.0%;径级分配上,3个样地的生物量主要集中在大径级(D≥10cm)的个体上;物种分配上,3个样地的生物量排序前10位的物种分别约占乔灌层地上生物量的99.3%、97.3%和99.0%,并集中分配在少量优势树种中。

Aims Information on community biomass is very important for understanding the structure, function and productivity of ecosystems; however, the biomass of karst forests is difficult to measure because of high habitat heterogeneity, complex and irregular growth forms, etc., and it seldom has been studied. Our objective was to study the biomass ofkarst forests to learn the structure and function of the ecosystems. Methods We estimated biomass and allocation of tree and shrub layers in three karst forest communities at an ecological research station in Puding, Guizhou, using allometric analysis and sampling harvest methods. Important findings Biomass regression models were established for three diameter classes （〈1 cm, 1-5 cm and 〉5 cm） and 15 abundant species： Platycarya longipes, Lithocarpus confinis, 1tea yunnane- sis, Kalopanax septemlobus, Machilus cavaleriei, Quercus aliena, Lindera communis, Lindera pulcherrima var. hemsleyana, Rhamnus hetrophylla, Stachyurus obovatus, Rhamnus leptophylla, Zanthoxylum esquirolii, Zanthoxylum planispinum, Myrsine africana and Zanthoxylum dimorphophyllum var. spinifolium. Average biomass of canopy and shrub layers was 88.7×10^3 kg·hm^-2, with the tree layer ac-counting for about 98% of the total. Biomass allocation among different diameter classes was concentrated in the individuals 〉10 cm diameter at breast height. Ten species made up about 98% of the total biomass of canopy and shrub layers, and the total biomass was concentrated in the dominant trees.