Knowledge Resource Center for Ecological Environment in Arid Area
| 中国灌丛生物量的组分分配和空间分布 | |
| 其他题名 | Biomass allocation and spatial distribution in shrubland ecosystems in China |
| 王杨 | |
| 出版年 | 2018 |
| 学位类型 | 博士 |
| 导师 | 谢宗强 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 中国灌丛植被类型繁多、分布广泛，在全球气候变暖和干旱的趋势下，灌丛的分布面积扩大、生长季植被指数升高、碳汇功能增强，成为我国陆地生态系统碳储量增加的主要原因。然而，当前陆地生态系统碳计量的相关研究中，灌丛植被的研究数据积累极少，估算方法相对单一，其生物量和空间分布成为我国陆地生态系统碳计量不确定性最大的因素。本研究基于中国灌丛生态系统1089个样地的生物量调查数据，分析环境因子、枝干形态、叶片习性和更新起源对灌木器官间相对生长和生物量分配的影响；在已发表的灌木生物量方程基础上，使用调查数据构建不同枝干形态的灌木优势种的单一物种方程，结合中国植被区划构建区域通用的混合物种方程，构建中国主要灌木生物量方程数据库；结合中国植被区划和土地覆被数据，整合多源数据和建模方法，构建区域尺度的灌丛地上生物量遥感估算模型，绘制灌丛地上生物量空间分布图。主要研究结果如下：（1）灌木地上-根、叶-茎、叶-根等器官间存在极显著的相对生长关系，大多符合或接近于等速生长，相对生长尺度系数的变异程度较小，回归常数的变异程度较大。总体上，灌丛生物量向叶、茎和根的分配比例分别为0.131、0.477、0.39，根冠比为0.87。灌木层高度和灌木层盖度与灌木器官间的相对生长和生物量分配显著相关，年平均气温、年降水量和坡度对灌木器官间的相对生长和生物量分配具有显著影响，灌木的生物量分配策略一定程度上支持了最优分配假说。枝干形态、叶片习性和更新起源不同的灌木，其相对生长和生物量分配存在差异，分析不同类型灌木的相对生长和生物量分配与环境因子之间的关系，能够揭示灌木响应气候变化的生长和分配策略。（2）通过文献收集共获取灌木生物量模型371条，90%以上的灌木生物量方程使用幂函数或线性函数构建，绝大多数为单一物种方程，通用方程不足3%，内蒙、山西、新疆和江西是灌木生物量方程的主要研究区域，全国灌木生物量方程的2/3源自这些区域。通过灌丛样地调查，共构建生物量方程480条，其中449条为单一物种方程，31条为混合物种通用方程。对分枝明确、枝干离散可数的灌木，方程的最佳自变量为基径平方与株高的乘积D2H；对分枝不明确、枝干成簇成团的灌木，最佳自变量为冠幅面积Ac或冠幅体积Vc；根系生物量方程以地上部分生物量为自变量。所建方程具有较高精度，其中单一物种方程解释度的均值为0.68，混合物种方程解释度的均值为0.57，33.5%的方程的解释度在0.8以上。估测值和实测值之间线性回归的斜率接近于1，且所有方程均无过度拟合。构建区域通用的混合物种方程至少应包含10个不同物种的样株，才能保证估算结果的可靠性；增加参与建模的物种数量，可进一步减小模型的估算误差，增强模型的普适性。（3）中国灌丛生态系统地上生物量密度平均值为7.64 Mg·ha-1，按照分布面积70.13×104 km2估算，地上生物量储量为0.54 Pg。灌丛的面积、分布和地上生物量密度，共同决定了地上生物量的储量和空间分布。灌丛的分布面积和地上生物量在不同的植被区域具有较大的异质性，地上生物量密度较高的灌丛主要分布于亚热带常绿阔叶林区域的东部、暖温带落叶阔叶林区域的东北部、温带荒漠区域的东南部以及西南部的塔里木盆地周边。亚热带常绿阔叶林区域的灌丛分布面积占到全国灌丛总面积的51.16%，地上生物量密度最大，平均值为10.72 Mg·ha-1，局部区域可达28.98 Mg·ha-1，其地上生物量储量占全国灌丛地上生物量的71.81%。寒温带针叶林区域的灌丛分布面积最小，仅占全国灌丛总面积的0.16%，地上生物量密度最小，为0.10 Mg·ha-1，其地上生物量储量占全国灌丛地上生物量的0.002%。平均生物量密度法是一种较为粗略的估算方法，容易掩盖生物量密度在较小空间尺度上的变异性，在估算区域尺度的灌丛生物量时容易产生不同程度的高估。以上结果表明：灌木层高度可能通过影响灌木对光照和空间资源的竞争影响其生长和分配策略；根据灌木的枝干形态特征和植被区划构建生物量方程，有利于区域尺度灌丛生物量的准确估算；通过整合植被指数、气候、地形和人为干扰等数据，采用最近更新的灌丛分布信息，可有效减小陆地生态系统碳计量的不确定性。本研究在总结和分析前人主要研究成果的基础上，分析了不同尺度上灌丛类型和环境因子对灌丛植被生物量的组分分配和空间分布的影响。研究结果为动态监测灌丛生态系统碳收支提供了科学方法，为多样性和生产力关系、陆地生态系统养分循环以及全球气候模型等研究提供了关键参数和科学依据。 |
| 英文摘要 | Shrubland is widely distributed in China and containing a variety of shrub types. With the distribution expansion, growing season greenness increment and strengthened function as carbon sinks, this sink is estimated to be the most important component in terrestrial ecosystem carbon stocks under global warming and projected drying trend. However, in terrestrial ecosystem carbon accounting studies, shrubland biomass is identified as the most important uncertain component in terrestrial carbon balance, due to limited research data and relative poorer estimating methods. Based on the inventory data of 1089 shrub sites, we analyzed the influence of environmental factors, stem forms, leaf habits and regeneration origin on the relative growth and biomass allocation pattern of shrubs. We synthesized former published shrub biomass equations, and created species-specific and regional generic equations for dominant shrub species with different stem forms, to build a database of biomass equations for common shrub species. By integrating vegetation regionalization map, land cover map, as well as multi-source data, we also developed remote sensing-based aboveground biomass models and mapped the spatial distribution of shrubland aboveground biomass. The main results were as follows:(1) Different shrub organs showed significant relative growth relationships, and these patterns were isometric or near isometric in most cases. The variation in scaling exponents was relatively small while the variation in regression constants was relatively large. In general, the percentages of biomass allocated to leaves, stems and roots were 0.131, 0.477 and 0.39 respectively, and the root-to-shoot ratio of shrubs was 0.87. The relative growth and biomass allocation patterns were significantly correlated with the height and coverage of shrub layer, and were significantly influenced by mean annual temperature, annual precipitation and slope. The biomass allocation strategies of shrubs partially supported the optimal partitioning theory. The relative growth and biomass allocation patterns varied between different shrub types with respects to morphology of branches and stems, leaf habits and shrub regeneration origin. Divide shrubs into different types according to stem forms, leaf habits and shrub regeneration origin could facilitate understanding the growth and allocation strategy of shrubs in response to climate change.(2) A total of 371 biomass equations were obtained by synthesizing former published shrub biomass equations. More than 90% of the biomass equations were developed with power models or simple linear models. Most equations were species-specific, while no more than 3% of them were generic multi-species models. Two-thirds of shrub biomass equations were created in Neimenggu, Shanxi, Xinjiang and Jiangxi. 480 equations were developed with field inventory data, among which, 449 were species-specific equations and 31 were generic equations for multi-species. D2H was the optimal predictor for shrubs with explicit and dispersed branch structure, while crown area Ac or crown volume Vc was the optimal predictor for shrubs with implicit and clustered branch structure. Root biomass was estimated from corresponding aboveground biomass. Equations created here were of high predictive accuracy, the mean value of variation explained by specific and generic equations were 68% and 57% respectively, and 33.5% of the biomass equations explained more than 80% of the variation in biomass. The slopes of linear regression between predicted and measured values were around one, and no significant overfits exist in all cases. Samples of at least ten different shrub species should be used in creating regional generic multi-species equations. With more species used in modeling, the error in biomass estimation further reduced; meanwhile the universality of the equations increased.(3) The mean value of aboveground biomass density of shrublands in China was 7.64 Mg·ha-1, and the aboveground biomass stock was estimated to be 0.54 Pg according to an area of approximately 70.13×104 km2. The area, spatial distribution and aboveground biomass density jointly determined the aboveground biomass stock and its spatial distribution. The area and aboveground biomass density of shrublands varied significantly among vegetation regions. The aboveground biomass density were relatively higher in east parts of Subtropical evergreen broadleaf forest region, northeast parts of Warm temperate deciduous broadleaf forest region, southeast parts of Temperate desert region and the periphery of the Tarim Basin. In terms of area occupied, 51.16% of the shrublands were distributed in Subtropical evergreen broadleaf forest region. The mean value of aboveground biomass density was 10.72 Mg·ha-1 in this region, and in Northern subtropical broadleaf evergreen and deciduous forest zone within the Eastern humid broadleaf evergreen forest subregion, the aboveground biomass density reached as high as 28.98 Mg·ha-1. The aboveground biomass stocks in this region occupied 70.81% of the national total. Only 0.16% of the shrublands were distributed in Cold-temperate needleleaf deciduous forest region. The mean value of aboveground biomass density was 0.10 Mg·ha-1 in this region, and the aboveground biomass stocks shared only 0.002% of the national total. Average biomass density method was relatively coarse in regional shrub biomass estimation, and might fail to reflect small-scale variations but cause overestimation to some extent.Results indicate that, the height of shrub layer may affect the competition of light and space, and ultimately alter the growth patterns and biomass allocation stratergies of shrubs. Grouping shrubland sites according to the vegetation regionalization and categorizing shrubs with respect to differences in morphology of branches and stems could facilitate accurate biomass estimation at regional scales. By integrating multi-source data, such as vegetation indices, climatic variables, topographic data and human disturbance, and utilizing the recently updated information on shrubland spatial distribution, the uncertainties in terrestrial ecosystem carbon accounting could be reduced.Former published studies were summarized and analyzed firstly. The research analyzed the effects of shrub types and environmental factors on shrub biomass allocation and spatial distribution at different scales. The results provided scientific methods for the dynamic monitoring of carbon budgets of shrubland ecosystems, meanwhile provided critical parameters and scientific foundations for researches on biodiversity - productivity relationships, nutrient cycling of terrestrial ecosystems and the global climate model. |
| 中文关键词 | 异速生长 ; 最优分配 ; 植被区划 ; 生物量模型 ; 遥感估算 |
| 英文关键词 | Allometry Optimal partitioning Vegetation regionalization Biomass model Remote sensing-based estimation |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院植物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288056 |
| 推荐引用方式 GB/T 7714 | 王杨. 中国灌丛生物量的组分分配和空间分布[D]. 中国科学院大学,2018. |
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