生物多样性 ›› 2016, Vol. 24 ›› Issue (1): 30-39.doi: 10.17520/biods.2015207

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喀斯特季节性雨林木本植物胸高断面积分布格局及其对地形因子的响应

郭屹立1, 2, 王斌1, 2, 向悟生1, 2, 丁涛1, 2, 陆树华1, 2, 黄甫昭1, 2, 文淑均1, 2, 李冬兴1, 2, 何运林1, 2, 李先琨1, 2, *()   

  1. 1 广西喀斯特植物保育与恢复生态学重点实验室, 广西壮族自治区/中国科学院广西植物研究所, 广西桂林 541006;
    2 广西友谊关森林生态系统国家定位观测研究站, 广西凭祥 532699
  • 收稿日期:2015-07-18 接受日期:2015-11-02 出版日期:2016-01-20
  • 通讯作者: 李先琨 E-mail:xiankunli@163.com
  • 基金项目:
    基金项目: 国家自然科学基金(31500342)、广西自然科学基金(2015GXNSFBA139050)和中国科学院西部之光项目(人字(2014) 91号)

Responses of spatial pattern of woody plants’ basal area to topographic factors in a tropical karst seasonal rainforest in Nonggang, Guangxi, southern China

Yili Guo1, 2, Bin Wang1, 2, Wusheng Xiang1, 2, Tao Ding1, 2, Shuhua Lu1, 2, Fuzhao Huang1, 2, Shujun Wen1, 2, Dongxing Li1, 2, Yunlin He1, 2, Xiankun Li1, 2, *()   

  1. 1 Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain, Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin, Guangxi 541006
    2 Guangxi Youyiguan Forest Ecosystem National Research Station, Pingxiang, Guangxi 532699
  • Received:2015-07-18 Accepted:2015-11-02 Online:2016-01-20
  • Contact: Li Xiankun E-mail:xiankunli@163.com

森林生态系统地上生物量的分布格局是物种分布格局的重要内容。局域尺度内因地形差异引起的生境异质性是地上生物量分布格局形成的环境基础。本文以弄岗北热带喀斯特季节性雨林15 ha动态监测样地2011年第一次普查数据中每木个体为研究对象, 尝试以每20 m × 20 m样方内所有个体及不同径级类群的胸高断面积之和为木本植物地上生物量的衡量指标, 利用广义可加模型对喀斯特季节性雨林中胸高断面积之和的空间分布格局进行研究, 定量分析了其对7个地形因子的响应。结果表明, 洼地、山坡和山脊3种生境类型中, 所有个体的胸高断面积之和山坡最高、山脊最低, 且山脊与山坡、洼地的差异均显著; 广义可加模型结果显示, 不同地形因子对胸高断面积之和的解释偏差差异明显, 其中海拔、坡向、凹凸度、岩石裸露率对胸高断面积之和的解释偏差依次降低, 而干旱度指数、坡度和地形湿润指数解释偏差相对较小。喀斯特季节性雨林木本植物胸高断面积之和空间分布的异质性及其与地形因子之间的关系, 反映了胸高断面积之和在地形因子对土壤、水分和光照等条件重分配影响下的多重响应机制及生长策略。

关键词: 格局, 胸高断面积, 地形因子, 贡献率, 弄岗动态监测样地, 北热带喀斯特季节性雨林

Spatial patterns of aboveground biomass are important aspect of species distribution patterns, whereas the environmental heterogeneity caused by the topographical differences in the scope of local scales is the environmental basis for the formation and evolution of this pattern in natural forest systems. In this study, we examined the spatial patterns of total basal area of woody plants, to quantitatively analyze the response mechanisms of the spatial patterns of total basal area to the seven topographic factors using a generalized additive model in a fully mapped 15 ha permanent plot in a northern tropical seasonal rainforest in a karst landscape in southern China. We used the total basal area of all the individuals and each DBH class in each 20 m × 20 m quadrat as a standard to measure the value of aboveground biomass of woody plants. Results showed that the hillside had the highest total basal area but the lowest was found at the ridge of the three habitat types. The total basal area of the ridge was significantly different between the hillside and the depression. Topographic factors had definite effects on the total basal area of woody plants, with the following sequence: elevation > aspect > convexity > rock-bareness rate (RBR) > altitude above channel (ACH) > slope > topographic wetness index (TWI). All topographical factors were statistically significant with the exception of the TWI and slope showing marginally significant. The relationships between the spatial variation of total basal area of woody plants and topographic factors reflected the response mechanisms and growth strategies of woody plants in a tropical seasonal rainforest under the effects of the redistribution of soil, water and light conditions.

Key words: pattern, basal area, topographic factors, contribution rate, Nonggang Dynamics Forest Plot, tropical karst seasonal rainforest

图1

弄岗喀斯特季节性雨林胸高断面积之和(m2)的分布格局"

图2

广义可加模型(GAM)所揭示的不同地形因子对弄岗喀斯特季节性雨林胸高断面积之和分布格局的影响。S(地形因子)为光滑样条函数的拟合值, 表示其对胸高断面积之和的影响。实线表示胸高断面积之和的期望值, 上下两侧虚线表示方程的95%置信区间。"

表1

喀斯特季节性雨林胸高断面积之和与地形因子的广义可加模型(GAM)检验"

径级 DBH
Class (cm)
环境参数
Environmental parameters
r2adj 累计解释偏差
Cumulative explained deviation (%)
赤池信息准则Akaike Information Criterion (AIC)
所有个体
All individuals
海拔 Elevation 0.148 16.1 -88.071
坡向 Aspect 0.256 28.4 -130.984
凹凸度 Convexity 0.291 33.1 -142.770
岩石裸露率 Rock-bareness rate 0.313 36.0 -148.860
地形湿润指数Topographic wetness index 0.314 36.4 -149.909
坡度 Slope 0.322 37.4 -152.044
干旱度指数 Altitude above channel 0.336 39.4 -156.461
DBH < 2.5 海拔 Elevation 0.113 12.6 -2,416.026
坡向 Aspect 0.153 18.4 -2,425.371
凹凸度 Convexity 0.193 22.8 -2,441.038
岩石裸露率 Rock-bareness rate 0.266 29.7 -2,477.055
地形湿润指数Topographic wetness index 0.303 34.0 -2,492.105
坡度 Slope 0.311 34.9 -2,495.940
干旱度指数 Altitude above channel 0.328 36.3 -2,506.965
2.5 ≤ DBH < 7.5 海拔 Elevation 0.412 42.1 -1,340.583
坡向 Aspect 0.432 44.7 -1,348.138
凹凸度 Convexity 0.462 48.9 -1,360.737
岩石裸露率 Rock-bareness rate 0.481 51.1 -1,371.831
地形湿润指数Topographic wetness index 0.505 53.1 -1,390.343
坡度 Slope 0.540 57.6 -1,407.893
干旱度指数 Altitude above channel 0.540 57.8 -1,410.145
7.5 ≤ DBH < 22.5 海拔 Elevation 0.194 21.0 -448.036
坡向 Aspect 0.267 29.5 -476.660
凹凸度 Convexity 0.305 34.4 -490.249
岩石裸露率 Rock-bareness rate 0.316 36.2 -492.008
地形湿润指数Topographic wetness index 0.334 38.0 -498.367
坡度 Slope 0.339 38.5 -507.223
干旱度指数 Altitude above channel 0.381 43.6 -522.046
22.5 ≤ DBH 海拔 Elevation 0.263 27.4 -193.325
坡向 Aspect 0.321 34.7 -216.574
凹凸度 Convexity 0.326 35.4 -216.982
岩石裸露率 Rock-bareness rate 0.335 36.5 -220.844
地形湿润指数Topographic wetness index 0.345 37.8 -225.257
坡度 Slope 0.392 42.8 -250.109
干旱度指数 Altitude above channel 0.398 43.7 -251.184

表2

不同地形因子间的Spearman秩相关性分析"

坡度 Slope (SLO) 凹凸度 Convexity (CON) 坡向 Aspect (ASP) 地形湿润指数Topographic wetness index (TWI) 干旱度指数 Altitude above channel (ACH) 岩石裸露率 Rock-bareness rate (RBR) 胸高断面积之和
Total basal area
海拔 Elevation (ELE) 0.578** 0.466** 0.052 -0.701** 0.289** 0.450** -0.147*
SLO 0.336** 0.205* -0.631** 0.220** 0.509** -0.080
CON 0.025 -0.564** 0.518** 0.300** 0.051
ASP -0.098 -0.159* 0.140* 0.134*
TWI -0.629** -0.326** 0.035
ACH -0.016 0.083
RBR 0.044
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