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Scientia Silvae Sinicae ›› 2015, Vol. 51 ›› Issue (8): 1-7.doi: 10.11707/j.1001-7488.20150801

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Biomass Change of Middle Aged Forest of Qinghai Spruce along an Altitudinal Gradient on the North Slope of Qilian Mountains

Zhang Lei1, Yu Pengtao1, Wang Yanhui1, Wang Shunli2, Liu Xiande2   

  1. 1. Key Laboratory of Forestry Ecology and Environment of State Forestry Administration Research Institute of Forest Ecology, Environment and Protection, CAF Beijing 100091;
    2. Academy of Water Resources Conservation Forests in Qilian Mountain of Gansu Province Zhangye 734000
  • Received:2015-03-10 Revised:2015-07-06 Online:2015-08-25 Published:2015-09-10

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Abstract:

[Objective] In this study, biomass changes in Qinghai spruce (Picea crassifolia) forests along an altitudinal gradient (from 2 700-3 300 m) were studied. The results will be helpful to the prediction of water yield in Qilian Mountains and the integrated management of vegetation, soil and water in Heihe Basin. [Method] In Pailugou small watershed, located in the middle section of the northern slope of Qilian Mountains, vegetation was investigated by setting up sample plots in selected representative stands with good growth along the altitude gradients. A total of 15 plots in a size of 20 m×20 m were set up at the altitudes of 2 700-2 800, 2 800-2 900, 2 900-3 100, and 3 100-3 300 m. The forest biomass and its distribution among different size classes were calculated using the existing equations on the relationship among biomass, tree height and tree diameter on breast height (DBH), which were built up for the study area. Key factors attributing to the forest biomass and its changes along the altitudinal increase were analyzed. [Result] The total biomass of Qinghai spruce forest was (128.61±50.25) t·hm-2, which came from the middle-sized trees (12.5 cm22.5 cm). The biomass of the middle-sized trees (12.5 cm22.5 cm) evenly accounted for 44% and 35% of total forest biomass, respectively. The contribution of saplings (5 cm-2, respectively. Along the altitudinal increase, key contributors to forest biomass shifted among tree size classes. At the altitudes of 2 700-2 800 m, middle tree size class was key contributor to the total biomass of spruce forest with the biomass of 63.54 t·hm-2, which accounted for 48% of the total forest biomass. At the altitudes of 2 800-2 900 m, the biomass of middle-sized trees increased and reached 90.53 t·hm-2 (accounting for 59% of the total). Nevertheless, at the altitudes of 2 900-3 100 m, the key contributor to forest biomass shifted to big tree size class with a biomass of 54.46 t·hm-2 (45% of the total). At the altitudes of 3 100-3 300 m, the biomass of big trees reached 71.46 t·hm-2 (71% of the total). The forest biomass (128.61 t·hm-2) in the study area was close to that in Haxi Forest Farm of Qilian Mountains (132.90 t·hm-2), the average biomass in Qilian Mountains (169.80 t·hm-2) and the national average of forest biomass (156.66 t·hm-2). However, it was less than the biomass of forests at Sunan County, Gansu Province (282.54 t·hm-2), Sidalong Forest Farm of Qilian Mountains (217.41 t·hm-2), and the average forest biomass of 209.24 t·hm-2 at the northern slope of Qilian Mountains. [Conclusion] The change of forest biomass along altitudinal gradients strongly relies on stand density, temperature and precipitation. The altitudes of 2 800-2 900 m is the most suitable area for Qinghai spruce forests in the study area.

Key words: Botryosphaeria dothidea, Trichoderma aureoviride, Fusarium equiseti, biocontrol strains, inhibitory effect

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