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Carbon cycle
Biomass
Boreal conifer forest
Dryland
Forest management
High mountains
Net primary productivity
Northwestern china
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Abstract:
Biomass and net primary productivity (NPP) of coniferous forests in the Allay Mountains (AM) and Tianshan Mountains (TM), which are located in the dryland of northwestern China, were estimated using intensive data derived from a national forest inventory. Conifer forests in these two mountains have total biomass of 9.1-771.7 t ha(-1) (mean = 312.6) and total NPP of 2.2-18.3 t ha(-1) year(-1) (mean = 9.6) at 21 sampling sites with elevations mostly from 1600 to 2400 m. Forest biomass and NPP have linear (positive and negative) relationships with their geographic location (longitude and latitude), but these relationships are not significant. However, forest biomass has non-linear relationship with elevation and forest NPP has significant negative linear relationship with elevation. Comparison between these two mountains showed that forest NPP in the Altay Mountain is higher than in the Tianshan Mountain (by approximately 0.9 t ha(-1) year(-1)), while biomass in the Allay Mountain is lower than in the Tianshan Mountain (by approximately 42 t ha(-1)), although the Altay Mountain is located north to the Tianshan Mountain. Biomass and NPP of different forest types in these two mountains also have differences. Spruce forest has higher biomass, larch and larch-spruce forests have median biomass, and larch- spruce-fir and larch-spruce-birch forests have lower biomass. However, larch forest has higher NPP than other four types of forests that have median and similar NPP values. Compared to other studies, forest biomass in the Altay and Tianshan Mountains are higher than that of both zonal and mountainous boreal forests in northern China and all over China, but forest NPP in these two mountains is in the reasonable ranges with both Chinese and global boreal forests. This study of forest productivity in high mountains has practical significance in local environmental protection and biodiversity conservation in dryland of northwestern China, and also has theoretical significance in involving mountainous vegetation in the study of global carbon cycle. (C) 2004 Elsevier B.V. All rights reserved. [References: 41]
