喀斯特地区不同退耕林地的生物量及其评价——以广西平果县为例

为了揭示喀斯特地区退耕还林后生境的演变和特征,以广西壮族自治区平果县自然封育7年的天然草地为对照,调查当地板栗纯林、桉树纯林、马尾松纯林、任豆纯林、早熟桃纯林和八角纯林6种纯林的退耕林地生物量,计算不同退耕林地的群落生产力,并用统计模型对不同退耕林地进行生物量评分.结果表明：1）广西平果县各退耕林地的生物总量按从大到小的顺序排列表现为板栗＞桉树＞八角＞马尾松＞早熟桃＞任豆;2）各树种生物量均表现为地上部分大于地下部分,其中八角、桉树、板栗的地下部分比例较大,更有利于保持水土;3）各退耕林地林下草本层的生长状况明显优于灌木层,但林下草本层的生物量仍低于天然草地;4）枯落物干质量平均值表现为板栗＞桉树＞早熟桃＞任豆树＞八角＞马尾松;5）生物量综合评分值表现为八角＞板栗＞桉树＞马尾松＞早熟桃＞任豆.通过研究得出：退耕还林工程有助于对当地脆弱环境的修复,因此需要长期建设和维护;林地生物量的调查统计对于客观、全面分析退耕还林工程的生态效益具有重要意义.

Biomass allocation of the returning farmland to forest project in karst region： A case study of Pingguo County,Guangxi Zhuang Autonomous Region in China

In order to reveal the evolution of karst region after the returning farmland to forest project,six types of restored plantations including Castanea mollissima,Eucalyptus robusta Smith,Pinus massoniana Lamb,Zenia insignis Chun,Amygdalus persica Linn,and lllicium verum in Pingguo County of Guangxi Zhuang Autonomous Region were studied,and a seven-year grassland under enclosure was taken as control.The biomass allocations of different plantations were compared and biomasses were scored.Results showed that：1） Total biomass per unit area ordered from high to low as C.mollissima ＞ E.robusta ＞ I.verum ＞ P.massoniana ＞ A.persica ＞ Z.insignis.2） For each type of restored plantation,the biomass of aboveground part is larger than that of the underground part.3） The biomass of the herb layer is larger than that of the shrub layer in most of plantation types,but lower than the biomass of the seven-year grassland; 4） The dry litter weight per unit area ranked from large to small as C.mollissima ＞ E.robusta ＞ A.persica ＞ Z.insignis ＞ I.verum ＞ P.massoniana; 5） Biomass composite scores ordered from high to low as I.verum ＞ C.mollissima ＞ E.robusta ＞ P.massoniana ＞ A.persica ＞ Z.insignis.This project of returning farmland to forest can maintain ecological safety and promote the harmony between human and the nature,and still requires a long-term construction.Analysis of the ecological benefits of returning farmland to forest project has great significance to the nature and human.