川西亚高山5种森林生态系统的碳格局

采用样方法研究了川西亚高山白桦(Betula platyphylla)林(BF)、针阔混交林(MF)、岷江冷杉(Abies faxoniana)林(FF)、紫果云杉(Picea purpurea)林(SF)和方枝柏(Sabina saltuaria)林(CF)的碳贮量、组成及其分布格局。结果表明: 1)在5种森林生态系统中, 土壤碳含量和碳贮量都随土壤深度的增加而极显著地降低, 且与土壤深度之间有较好的线性关系; 2)地被物碳贮量分别为SF(23.97±1.77)>FF(21.35±3.64)>MF(11.78±1.21)>CF(9.09±0.91) >BF(8.16±1.34) 10³kgC·hm^-2, 对生态系统总碳贮量的贡献率差异不显著, 约占3%~4%; 3)乔木层对植物碳贮量贡献最多, 根系碳贮量占植物碳贮量的比例在13%~19%之间; 4)SF和FF的碳贮存以植物为主, MF、BF和CF的碳贮存则以土壤为主; 5)整个生态系统的碳贮量依次为SF(729.92±43.49)>FF(618.86±53.97)>MF(353.88±21.76)>BF(247.79± 17.15)>CF(244.52±18.70) 10³ kgC·hm^-2, 差异显著, 对应的短期碳固定能力则依次为2.97、3.80、5.15、3.33和4.84 10³ kgC·hm^-2·a^-1。在没有破坏性干扰前提下, 川西亚高山次生林恢复是大气中碳沉降的潜在碳汇。合适的树种及其搭配比例、造林模式和森林生态系统管理对策, 是促进该区域植被快速恢复和增加碳贮存的关键。

CARBON STOCK AND ITS ALLOCATION IN FIVE FOREST ECOSYSTEMS IN THE SUBALPINE CONIFEROUS FOREST ZONE OF WESTERN SICHUAN PROVINCE, SOUTHWEST CHINA

Aims Forest ecosystems are important carbon pools of the global terrestrial ecosystem and play a key role in sequestrating and reserving greenhouse gases. Our objectives were to quantify the carbon stock of different forest ecosystems in the subalpine coniferous forest in western Sichuan Province (SCFS) and identify short-term carbon sequestration potential. Methods We investigated the forests of Wanglang National Natural Reserve, located in Pingwu County, Sichuan Province. Five similar altitude and slope ecosystems dominated by Betula platyphylla (BF), Betula spp. and Abies faxoniana (MF), Abies faxoniana (FF), Picea purpurea (SF) and Sabina saltuaria (CF) were selected to quantify ecosystem carbon stock and its allocation. We sampled eight replicate plots in each ecosystem. All plants in each plot were surveyed and sorted into three groups: tree layer (DBH ≥5 cm), understory (DBH <5 cm), and herb layer. We surveyed the carbon stock of the tree layer using standard tree sampling methods, in which biomass and carbon stock of three newly up-rooted trees were measured. Carbon stock of understory, herb, ground cover (including litter, lichens and coarse woody debris <2 cm diameter) and soil was measured by destructive sampling. Important findings Soil organism carbon (SOC) decreased significantly with increased soil depth (p<0.01). Carbon stock contributions of ground cover were similar (3%–4% of the total). The tree layer had the largest plant carbon pool, and root carbon reached 13%–19% of plant carbon. The main carbon stock was in plants in SF and FF and in soil in MF, BF and CF. Ecosystem carbon stock was SF (729.92±43.49) > FF (618.86±53.97) > MF (353.88±21.76) > BF (247.79±17.15) > CF (244.52±18.70 10³ kg C·hm^–2), and the difference was significant (p<0.05). Plant recent carbon stock potentials were 2.97, 3.80, 5.15, 3.33 and 4.84 10³ kg C·hm^–2·a^–1, respectively. Therefore, the SCFS could play a key role in CO₂ sequestration. This provides insight into forest carbon sequestration capacity and, hence, into understanding global carbon balance.