| 摘要: |
| 青海玉树拥有典型的川西云杉树线，是开展树线种群结构与空间格局研究的理想场所。在青海玉树调查了3个受放牧干扰的川西云杉树线样地（30 m×200 m）。基于样地数据，分析了种群径级结构和更新状况；利用O-ring函数，在0—15 m尺度上，计算了种群的空间格局。结果表明：种群径级结构均呈增长型，但缺少≤10年树苗；树苗在0—4 m尺度上呈集群分布，在其余尺度上呈随机分布；成年树、老树主要呈随机分布。树木间空间关联主要发生在小尺度上：树苗与成年树在2—6 m为正相关，树苗与老树在9—14 m为正相关。本研究为理解藏东树线种群的空间分布特征和种内关系奠定了基础，同时为山地森林管理提供参考依据。 |
| 关键词: 空间格局 放牧干扰 树线 林线 青藏高原 |
| DOI：10.7515/JEE192064 |
| CSTR： |
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| 基金项目:南京林业大学南方现代林业协同创新中心 |
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| Size structure and spatial patterns of Balfour spruce treeline population in Yushu, Qinghai |
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ZHAN Kailu, LIU Bo, WANG Yafeng
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1. College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China
2. College of Urban and Environmental Sciences, Northwest University, Xi’an 710127, China
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| Abstract: |
| Background, aim, and scope Typical Balfour spruce (Picea likiangensis var. balfouriana) treelines were found in Yushu, Qinghai. It provides rare opportunity to explore the structure and spatial patterns of treeline population. The existing studies mainly focused on the variations in tree growth and altitudinal position of Balfour spruce treeline, however, little is known about the stand structure and spatial distribution patterns of Balfour spruce treeline population. Herein, this study aims to reveal the size structure and spatial patterns of Balfour spruce treeline population in Yushu, Qinghai. Materials and methods Using dendroecological methods, three rectangular plots (30 m×200 m) across grazing-disturbed Balfour spruce treelines were investigated in Yushu. Distributions of size structure of trees were analyzed within each plot. Using the O-ring statistics, we calculated the spatial patterns of different height classes of trees at the scales of 0—15 m. Results Population structure within three plots was characterized by reverse J-shaped distribution. Number of seedlings less than 10 years was rare or absent. Seedlings were clustered at the scale of 0—4 m, but were randomly distributed at the scale of 4—15 m. Both adults and old trees were randomly distributed at the scale of 0—15 m. Seedlings and adults were spatially positive correlated at the distance of 2—6 m, but were unrelated at other scales. Positive correlations between seedlings and old trees were detected at the distance of 9—14 m, but were unrelated at other scales. Discussion High regeneration potential and insufficient new recruit may indicate the combined effects of climate change and overgrazing disturbance. Clustering of trees was only detected at small scales. Intraspecific competition was found to be important within treeline population. Regional climate and local site conditions (e.g. grazing disturbance) jointly drove tree spatial patterns. Conclusions Disturbance regimes played an important role in driving structure and spatial patterns of population at treeline. Lack of new recruit may be a serious threat to the long-term survival of the spruce forest. Tree-tree interactions should be carefully considered in the studies of treeline population. Recommendations and perspectives This study laid a foundation for the understanding of spatial distributions and intraspecific interactions of treeline population on the eastern Tibetan Plateau. Ecological protection of spruce forest is urgently needed to achieve the sustainable development of mountainous ecosystems. |
| Key words: spatial pattern grazing disturbance treeline timberline Tibetan Plateau |
