• 研究简报 •

### 祁连山青海云杉中龄林混交度对细根形态特征的影响

1. 1. 青海大学农林科学院 西宁 810016
2. 西北农林科技大学林学院 杨凌 712100
3. 西北农林科技大学水土保持研究所 杨凌 712100
4. 中国科学院水利部水土保持研究所 杨凌 712100
5. 德国马克斯-普朗克学会生物地球化学研究所 耶拿 07745
6. 青海省高原林木遗传育种重点实验室 西宁 810016
• 收稿日期:2018-04-04 出版日期:2020-01-25 发布日期:2020-02-24
• 通讯作者: 关晋宏
• 基金资助:
国家重点研发计划"高寒丘陵区林草植被的结构优化与功能提升技术"(2017YFC0504604);中国博士后科学基金(2015M580877);青海省农林科学院创新基金(2017-NKY-02)

### Effects of Mingling Intensity on Morphological Characteristics of Fine Roots of a Middle-Aged Picea crassifolia Natural Forests in Qilian Mountains

Lei Deng1,6,Chunyun Zhu1,6,Shichuan Yu2,Yinyan Qi1,6,Wenhui Zhang2,Sheng Du3,4,Jinhong Guan2,5,*

1. 1. Academy of Agriculture and Forestry Sciences, Qinghai University Xining 810016
2. College of Forestry, Northwest A&F University Yangling 712100
3. Institute of Soil and Water Conservation, Northwest A&F University Yangling 712100
4. Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources Yangling 712100
5. Max Planck Institute for Biogeochemistry, Germany Jena 07745
6. Qinghai Plateau Key Laboratory of Tree Genetics and Breeding Xining 810016
• Received:2018-04-04 Online:2020-01-25 Published:2020-02-24
• Contact: Jinhong Guan
• Supported by:
国家重点研发计划"高寒丘陵区林草植被的结构优化与功能提升技术"(2017YFC0504604);中国博士后科学基金(2015M580877);青海省农林科学院创新基金(2017-NKY-02)

Abstract:

Objective: Picea crassifolia is the dominant native species in the northeast Qinghai-Tibetan Plateau, and thus is believed to be important in regulating regional soil and water conservation and carbon cycle. The objective of this research was to investigate the effects of mingling intensity on the dynamics of fine root biomass, morphological characteristics and their impact mechanism in P. crassifolia mixed natural forests. The result would provide a theoretical basis for forest rehabilitation and management in the eastern Tibetan Plateau. Method: A suite of mixed middle-aged P. crassifolia natural forests representing different mingling intensities (0, 0.2, 0.4, and 0.6) were selected in Datong, Xining, eastern Qinghai-Tibetan Plateau of China. Fine root biomass density, specific root length, specific root surface area, root surface area density, and root length density were analyzed from two soil depths (0-20 and 20-40 cm) by taking soil cores. Result: In the P. crassifolia forest of mingling intensity 0.4, the diameter class of 10-25 cm (63.72%), height classes of 24-32 cm (48.72%) and 16-20 cm (11.18%), accounted for the largest proportion of all trees, which are significantly higher than the forests with other 3 mingling intensities. Fine root biomass density was mainly distributed in 0-20 cm soil depth, accounting for 68.31%-83.49% of the total. Values of fine root biomass density in the soil depth of 0-20 cm increased with the increasing mingling intensity and peaked at the mingling intensity of 0.4 (616.26 g·m-3) and then decreased in the mingling intensity of 0.6. Fine root biomass density in the soil depth of 20-40 cm increased with increasing mingling intensity, which peaked at the intensity of 0.6 (227.17 g·m-3). Changes of morphological characteristics of fine root highly depended on the mingling intensity. Specifically, in the soil depth of 0-20 cm, root length density and root surface area density showed as mingling intensity of 0.4 > 0.2 > 0 > 0.6, while specific root length and specific root surface area showed as mingling intensity of 0.4 > 0.2 > 0.6 > 0. In contrast, in the soil depth of 20-40 cm, root length density, root surface area density and specific root length showed the same pattern as mingling intensity of 0.6 > 0.4 > 0.2 > 0, while specific root surface area showed as the mingling intensity of 0.6 > 0.2 > 0.4 > 0. With the increase of mingling intensity, contribution of P. crassifolia to fine root biomass density and morphology such as specific root length, specific root surface area, root surface area density, and root length density gradually reduced, whereas the contribution of Betula platyphylla to that increased in the soil depth of 0-40 cm. The effect of mingling intensity on fine root length density and root surface area density was mainly focused on the finest diameter fine roots (0-1 mm). Conclusion: In the study region of eastern Qinghai-Tibet Plateau, P. crassifolia mixed forest of mingling intensity 0.4 was characterized by proper ratio of height class and diameter class. Meanwhile, uneven-aged and multi-storied forest is benefit to reduce the competition among neighbor trees overlapping and promote the using of forest resources, and thus believed to improve the stability of the forest community in the long run. The amount of fine root biomass density, specific root length, specific root surface area, root surface area density, and root length density maximized at the mingling intensity of 0.4. The result suggested that future management of middle-aged P. crassifolia forest should appropriately control the mingling intensity of 0.4, at which growth of fine roots can be maximized and the utilization of forest resource can be promoted and thus achieving the goal of sustainable development of forest.