基于树木年轮定量重建过去50年贵州典型森林优势树种的地上生物量与生产力变化

利用树木年轮宽度结合树木生物量方程,重建了贵州3个地区典型森林(2个常绿与落叶阔叶混交林和1个典型常绿阔叶林)6个优势树种(天龙山:化香树Platycarya strobilacea、安顺润楠Machilus cavaleriei;茂兰:化香树、马尾松Pinus massoniana;雷公山:华山松Pinus armandii、白梓树Pterostyrax psilophyllus)以树木个体为单元的地上生物量(AGB)与地上净初级生产力(ANPP);比较了喀斯特与非喀斯特地区树木AGB与ANPP的差异;并研究了近50年气候变化对ANPP的影响。结果显示,针叶树的平均年轮宽度大于阔叶树,喀斯特地区针叶树和阔叶树的平均树木年轮宽度,分别小于非喀斯特地区针叶树和阔叶树的平均树木年轮宽度。喀斯特地区树木的AGB及其变异幅度均小于非喀斯特地区树木。近50年来,喀斯特地区阔叶树与针叶树的ANPP平均分别为(2.4±1.2) kg a~(-1)株~(-1)和(4.6±4.1) kg a~(-1)株~(-1),显著低于非喀斯特地区阔叶树与针叶树的(5.6±4.8) kg a~(-1)株~(-1)和(12.4±7.7) kg a~(-1)株~(-1)。喀斯特地区树木ANPP的增长趋势与年均温的相关性高于生长季降水,非喀斯特地区树木ANPP与年均温和生长季降水均显著相关,且不管是在喀斯特还是在非喀斯特地区,针叶树ANPP对气候指标的变化比阔叶树更敏感。

Reconstruction of above-ground biomass and net primary productivity of dominant tree species in Guizhou forests over past five decades based on tree-ring data

Tree-ring widths and allometric functions were used to reconstruct above-ground biomass (AGB) and net primary productivity (ANPP) of six dominant tree species (Tianlongshan Mt.: Platycarya strobilacea, Machilus cavaleriei; Maolan: Platycarya strobilacea, Pinus massoniana; Leigongshan Mt.: Pinus armandii, Pterostyrax psilophyllus) in three typical forests of Guizhou Province (karst evergreen and deciduous broadleaved mixed forests in two sites and another site of typical evergreen broadleaved forest). Similarity and dissimilarity of AGB and ANPP of different tree species, as well as the effects of climate change in the past five decades on ANPP were compared between karst and non-karst regions. The results showed that coniferous trees presented wider mean tree-ring widths than broadleaved trees. The mean ring-widths of coniferous trees and broadleaved trees in karst regions were narrower than those in non-karst region. The trees in karst regions indicated higher AGB and larger variation ranges than those in non-karst region. The ANPP of broadleaved trees and coniferous trees in karst regions were 2.4 ±1.2 kg a^-1 individual^-1 and 4.6 ±4.1 kg a^-1 individual^-1, respectively in the past five decades, which were significantly lower than those in non-karst region (5.6 ±4.8 kg a^-1 individual^-1 and 12.4±7.7 kg a^-1 individual^-1, respectively). Tree ANPP increase in karst regions was more related to mean annual temperature than growing season precipitation, and tree ANPP increase in non-karst region showed significant relationships with both mean annual temperature and growing season precipitation. ANPP of coniferous trees was more sensitive to climate change than that of broadleaved trees in both karst and non-karst regions.