物种多样性研究是认识群落物种组成、维持群落结构和功能稳定性的基础(汪殿蓓等, 2001; 刘旻霞等, 2021), 一直是生态学领域关注的热点问题。一般认为群落的物种多样性越高, 其风险抵抗能力越高, 生态系统稳定性也越强(Tilman, 1999)。草本层是森林生态系统的重要组成部分, 在维持森林生态系统稳定性方面发挥着重要作用。相较于乔木和灌木而言, 草本植物尽管植株矮小, 生物量占比低, 但在整个生态系统中通常具有较高的物种多样性(Hart & Chen, 2006; Gilliam, 2007, 2014; Wayman & North, 2007), 温带森林中的草本物种数可占其维管植物物种总数的80%以上(Gilliam, 2007; Spicer et al, 2020), 在热带森林中也占到45% (Linares-Palomino et al, 2009)。此外, 研究表明, 林下草本植物对森林生态系统的重要作用体现在多个方面: 影响木本幼苗更新(Thrippleton et al, 2018); 为节肢动物、大型食草动物和种子捕食者提供生存空间; 介导了许多重要的生态系统过程, 如养分循环和能量流动(Muller, 2014)。由于草本植物植株矮小, 不易辨识及其他认知的局限, 目前森林植被的研究多集中在对碳储存、生物量和经济价值贡献较大的树木(Braun, 1950; Richards, 1952; Condit, 1995; Linares-Palomino et al, 2009; Muller, 2014; Lutz et al, 2018)。针对林下草本的研究较少, 这不利于加深对整个森林生物多样性的认识(Murphy et al, 2016)。因此, 研究森林群落草本植物物种多样性及其影响因子, 对加强森林群落物种共存的理解、促进生物多样性和生态保护具有重要意义。
影响草本植物物种多样性分布的因子有生物因子(如木本植物竞争、食草动物与昆虫捕食、病原体等)和非生物因子(如生境因子等) (Warren & Bradford, 2011; Jia et al, 2022; Spicer et al, 2022)。其中, 地形是影响群落物种多样性的重要非生物因子(Bell et al, 2000), 其研究又可分为海拔、坡度、坡向和凹凸度等对物种组成和多样性的影响(王艳红等, 2020)。海拔是影响水热条件的主导因子(Gaston, 2000; 刘秉儒, 2021); 坡度在土壤养分分配、水分维持方面具有重要作用, 与凹凸度一起间接影响植物物种组成和多样性(McCool et al, 1987; Cielo-Filho et al, 2007); 坡向的方位对日照时数和太阳辐射强度有影响, 进而对其他环境因子产生影响, 在北半球, 阳坡的日照时数和太阳辐射强度均高于阴坡, 相较于阴坡, 阳坡的温度更高、更干旱(Xue et al, 2018)。林分结构是对林分发展过程的综合反映, 而林分因子(林分密度、平均胸径、胸径变异系数等)则是构成森林林分结构的重要要素。林冠是森林的主要光合作用层次, 也是与外界进行物质交换和能量流动的界面(李德志和臧润国, 2004), 其结构在很大程度上决定了下层植被的物种多样性(Wulf & Naaf, 2009; Chmura, 2013)。林分密度是指林木生长过程中单位面积上的立木株数, 被诸多研究者认为是影响林下植物物种组成和分布的重要因子, 它既可通过土壤理化性质直接影响林下植物多样性, 也可通过改变郁闭度影响光照的通透率而间接影响林下植物多样性(Zhang et al, 2021; 胡延辰等, 2022)。个体大小差异在植物种群中普遍存在, 常用胸径变异系数(DBHcv)表示种群内的个体大小不一致性。植物个体大小差异在群落发展中具有重要作用, 同一森林内不同大小的树木将导致群落具有更高的光资源利用率, 但是, 冠层树木对林下层树木的不对称竞争会导致生长在冠层以下的树木的透光率损失, 使得草本植物的生长和存活受到影响, 因此, 林分结构的胸径变异系数和物种丰富度与草本植物的生长状况关系紧密, 是维持群落物种多样性的重要因素(Clark, 2010; Jucker et al, 2014; Ali et al, 2016; 赵中华和惠刚盈, 2020)。因此, 研究不同地形因子以及林分因子对草本植物物种多样性的影响, 对了解植物资源的生态环境现状, 揭示物种多样性的环境梯度变化规律及生物多样性保护具有重要意义。
暖温带落叶阔叶林是暖温带地区最典型的地带性植被类型之一, 是与气候和土壤相适应的结果。但由于历史上人类活动干扰严重, 原生性的森林植被遭受了人类巨大的砍伐破坏, 现在该地区残存的天然林已经寥寥无几。东灵山山地森林是目前我国暖温带森林保存比较完好的天然次生林之一, 在我国暖温带森林植被中具有显著的代表性, 保存了暖温带地区丰富的物种资源(谢晋阳和陈灵芝, 1994)。但是, 截至目前, 关于暖温带落叶阔叶林的研究多存在于木本植物的生物量(桑卫国等, 2002)、群落结构(刘海丰等, 2011)、空间格局(马芳等, 2018; Gu et al, 2020)等方面, 而有关暖温带落叶阔叶林林下草本植物物种多样性与不同地形因子、林分因子的关联性研究鲜见报道。为此, 本研究以东灵山20 ha暖温带落叶阔叶林动态监测样地的草本植物调查结果为基础, 探讨了地形和林分结构对林下草本植物物种多样性的影响, 以期为暖温带落叶阔叶次生林群落生物多样性的保护和可持续发展提供理论依据。
1 研究区域概况
东灵山(40°00′-40°02′ N, 115°26′-115°30′ E)属于中国暖温带落叶阔叶林区域的北部亚带。东灵山20 ha暖温带落叶阔叶林动态监测样地位于北京市门头沟区小龙门国家级森林公园, 气候类型为暖温带大陆性季风气候, 四季分明, 年平均气温4.8℃, 最热月平均温18.3℃ (7月), 最冷月平均温-10.1℃ (1月) (侯继华等, 2004)。全年无霜期约195 d。年日照时间2,600 h。年均降水量500-650 mm, 主要集中在夏季(6-8月, 占全年降水量的78%), 7月多为暴雨。土壤类型以山地棕壤为主(马芳等, 2018)。植被为典型的暖温带落叶阔叶次生林, 主要树种有辽东栎(Quercus wutaishanica)、白桦(Betula platyphylla)、色木槭(Acer mono)、大叶白蜡(Fraxinus rhynchophylla)、胡桃楸(Juglans mandshurica)、山杨(Populus davidiana)、北京丁香(Syringa pekinensis)、六道木(Abelia biflora)等(刘海丰等, 2011)。
2 研究方法
2.1 样地设置与植被、地形因子数据收集
2015年在样地内均匀设置了150个种子雨收集器, 在每个收集器的3个方向(西、北、南)距其2 m处分别设立1个1 m × 1 m样方, 共设立了450个1 m2小样方。于每年的7-8月对小样方内的维管草本植物及木本幼苗进行系统调查, 记录物种名称、高度、盖度、株(丛)数, 本研究采用2022年的草本调查数据。同时根据每个20 m × 20 m样方的4个顶点的海拔, 计算每个样方的海拔、坡度、凹凸度、坡向等基本信息(Legendre et al, 2009)。其中, 海拔为每个20 m × 20 m样方4个顶点处的海拔平均值; 坡度为样方的任意3个顶点形成的4个不同三角形平面偏离水平面角度的平均值; 凹凸度是样方的平均海拔减去与该样方相邻的所有样方平均海拔的平均值, 对于边缘的样方, 凹凸度是该样方中心点的海拔值减去4个顶点处海拔的平均值; 坡向为样方的任意3个顶点形成4个不同的三角形平面, 这4个平面与正北方向偏差角度的平均, 以正北方向为起点(0°)。以种子雨收集器为中心, 10 m为半径, 采用10 m范围内胸径 ≥ 1 cm的林木数据计算每个调查样点里面的林分指标。地形与林分因子基本概况见附录1。
2.2 数据处理及分析
2.2.1 物种多样性指数
选用物种丰富度指数、Shannon-Wiener多样性指数、Simpson优势度指数和Pielou均匀度指数表示林下草本植物物种多样性水平, 采用Pearson相关系数判断地形及林分结构指标与各物种多样性指标之间的相关性。各指数计算公式如下(马克平等, 1995):
Shannon-Wiener多样性指数(H′):
式中, S为样方内出现的物种数, pi = Ni/N, Ni为第i个物种的多度, N为所有物种的多度值之和。
2.2.2 林分结构参数
林地物种丰富度(richness): 为胸径 ≥ 1 cm的林木物种数;
式中, Na为样方内林木总株数, F为样方单元的面积(100π m2), di为第i株林木的胸径, D为样本标准差,
2.2.3 回归分析
采用Pearson相关系数判断各环境因子与各物种多样性指数之间的单因素相关性, 然后以环境因子为自变量, 各物种多样性指数为因变量进行线性关系拟合曲线分析。
2.2.4 冗余分析
首先将草本植物物种多样性数据-样方进行去趋势对应分析(detrended correspondence analysis, DCA), 4个排序轴的梯度长度最大值为1.6, 所以本研究排序方法采用线性模型, 即冗余分析(redundancy analysis, RDA)。计算各环境变量的方差膨胀因子(VIF), 发现其值均小于10, 说明无明显的共线性问题(附录1)。对草本植物的4个物种多样性指数矩阵与环境因子矩阵进行排序, 分析物种多样性指数与地形因子、林分因子之间的关系。排序图中, 各因子的箭头长度表示其与物种多样性指数的关系强弱, 箭头连线与排序轴的夹角大小表示其与排序轴的相关性, 夹角越大, 该因子与排序轴相关性越低。本文基于R软件的vegan软件包实现冗余分析(Oksanen et al, 2020)。
2.2.5 通过层次分割解析单个解释变量的相对重要性
本文的数据分析和图形输出均使用R 4.1.1 (
3 结果
3.1 地形因子与物种多样性之间的关系
地形因子与物种多样性指数相关性分析结果表明, Shannon-Wiener多样性指数与坡向呈显著负相关(P < 0.05), 而物种丰富度指数、Simpson优势度指数和Pielou均匀度指数与坡向无显著关系; 各物种多样性指数与海拔、坡度和凹凸度均无显著相关性(表1)。
表1 东灵山20 ha暖温带落叶阔叶林动态监测样地地形和林分结构与草本植物物种多样性指数之间的相关系数
Table 1
| 参数 Parameters | 物种丰富度 Species richness | Shannon-Wiener多样性指数 Shannon-Wiener diversity index | Simpson优势度指数 Simpson dominance index | Pielou均匀度指数 Pielou evenness index | |
|---|---|---|---|---|---|
| 海拔 Elevation | -0.017 | -0.102 | -0.119 | -0.130 | |
| 坡度 Slope | 0.042 | 0.043 | 0.075 | 0.017 | |
| 凹凸度 Convexity | 0.087 | 0.047 | 0.051 | -0.028 | |
| 坡向 Slope aspect | -0.148 | -0.187* | -0.153 | -0.111 | |
| 林分密度 Stand density | -0.280** | -0.224* | -0.163 | 0.065 | |
| 平均胸径 Mean of diameter at breast height (DBH) | 0.295** | 0.243** | 0.181 | 0.032 | |
| 胸径变异系数 Coefficient of variation of DBH (DBHcv) | -0.154 | -0.107 | -0.07 | 0.021 | |
| 林地物种丰富度 Forest species richness | -0.234** | -0.180* | -0.163 | -0.032 | |
* P < 0.05, ** P < 0.01.
通过对地形因子与物种多样性指数进行线性关系拟合曲线分析, 发现暖温带落叶阔叶林林下草本植物的Shannon-Wiener多样性指数整体随坡向的增大(由阳坡转向阴坡)呈下降的变化趋势(图1; 附录2)。
图1
图1
东灵山20 ha暖温带落叶阔叶林动态监测样地地形和林分结构与草本植物物种多样性指数的回归拟合。灰色表示95%置信区间。
Fig. 1
Regression fitting between topography and forest stand structure and herbaceous species diversity index in a 20 ha warm temperate deciduous broad-leaved forest dynamics plot in Donglingshan. DBHcv, Coefficient of variation of DBH. Gray represent 95% confidence interval.
3.2 林分因子与物种多样性之间的关系
由暖温带落叶阔叶林林下草本植物物种多样性指数与林分因子相关性分析结果可知, 物种丰富度指数与林分密度呈极显著负相关(P < 0.01), Shannon-Wiener多样性指数与林分密度呈显著负相关(P < 0.05); 物种丰富度指数和Shannon-Wiener多样性指数与平均胸径呈极显著正相关(P < 0.01); 物种丰富度指数与林地物种丰富度呈极显著负相关(P < 0.01), Shannon-Wiener多样性指数与林地物种丰富度呈显著负相关(P < 0.05); Simpson优势度指数和Pielou均匀度指数与林分密度、平均胸径和林地物种丰富度均无显著相关性; 各物种多样性指数与胸径变异系数均无显著相关性(表1; 附录2)。
通过对林分因子与物种多样性指数进行线性关系拟合曲线分析发现, 暖温带落叶阔叶林林下草本植物的物种丰富度指数和Shannon-Wiener多样性指数随林分密度、林地物种丰富度的增大呈下降的变化趋势, 而随平均胸径的增大呈上升的变化趋势(图1)。
3.3 环境因子与物种多样性的排序分析及其相对贡献
冗余分析排序结果中, 特征根总量为0.012, 其中解释量为0.0013, 解释率为10.56%。排序计算结果显示前两个排序轴累计包含了物种多样性指数-环境因子关系10.51%的解释率, 故采用前两轴的数据作冗余分析二维排序图(图2)。层次分割结果表明,地形因子及林分因子对东灵山暖温带落叶阔叶林林下草本植物物种多样性的解释率大小为: 林分密度 > 平均胸径 > 胸径变异系数 > 海拔(图3)。从排序图可以明显看出, 样地内林分密度和平均胸径与草本植物物种多样性的相关性较强。对于草本植物而言, 林分密度与其物种丰富度指数和Shannon-Wiener多样性指数显著负相关, 平均胸径与其物种丰富度指数和Shannon-Wiener多样性指数显著正相关。林分密度与平均胸径呈显著负相关, 但与林地物种丰富度呈显著正相关。
图2
图2
东灵山20 ha暖温带落叶阔叶林动态监测样地地形和林分结构与草本植物物种多样性指数的冗余分析(RDA)排序图。R: 物种丰富度指数; H′: Shannon-Wiener多样性指数; D: Simpson优势度指数; E: Pielou均匀度指数。
Fig. 2
Redundancy analysis (RDA) biplot of topography and forest stand structure and herbaceous species diversity index in 20 ha warm temperate deciduous broad-leaved forest dynamics plot in Donglingshan. R, Species richness; H′, Shannon-Wiener diversity index; D, Simpson dominance index; E, Pielou evenness index; DBHcv, Coefficient of variation of DBH.
图3
图3
通过rdaca.hp解析东灵山20 ha暖温带落叶阔叶林动态监测样地地形和林分结构各变量的相对重要性
Fig. 3
The relative importance of individual variable of topography and forest stand structure in 20 ha warm temperate deciduous broad-leaved forest dynamics plot in Donglingshan by rdacca.hp. DBHcv, Coefficient of variation of DBH.
4 讨论
林下草本植物物种多样性的维持机制始终是植物生态学研究的核心问题之一, 明确影响林下草本植物物种多样性的主导因素有助于维持和保护区域生物多样性(Cook, 2015)。特别是在生物多样性破坏较为严重的暖温带地区, 相较于热带和亚热带地区, 其草本植物物种比木本植物的比例更高, 在暖温带森林开展相关研究尤其重要。暖温带落叶阔叶林是暖温带地区典型的地带性植被类型, 北京东灵山20 ha森林动态监测样地是暖温带森林保存比较完好的天然次生林, 在暖温带森林植被中具有显著的代表性。本研究选择地形因子中的海拔、坡度、坡向和凹凸度等, 用林分密度、平均胸径、胸径变异系数和林地物种丰富度表征林分结构因子, 采用Pearson相关分析、回归分析、冗余分析及层次分割方法, 探讨了不同地形和林分结构下东灵山暖温带落叶阔叶林草本群落的物种多样性特征, 揭示了草本群落物种多样性与地形、林分因子的相互关系。发现随坡向增大(由阳坡转向阴坡), 林下草本植物的Shannon-Wiener多样性指数呈下降趋势; 物种丰富度指数和Shannon-Wiener多样性指数随林分密度和林地物种丰富度的增大呈下降的变化趋势, 而随平均胸径的增大呈上升的变化趋势。林分密度是影响东灵山暖温带落叶阔叶林林下草本植物物种多样性的主要因子。我们的发现将为暖温带落叶阔叶林草本生物多样性未来的研究提供参考, 为暖温带森林草本多样性保护和植被修复提供理论基础。
4.1 地形因子对林下草本植物物种多样性的影响
目前有关研究发现, 海拔对暖温带落叶阔叶林林下草本植物物种多样性的影响效应不同。张丽霞等(2000)对山西芦芽山植物群落物种多样性进行研究发现, 随着海拔高度的增加, 植物群落物种丰富度指数整体上呈下降的趋势; 张凡兵(2018) ① ( ① 张凡兵 (2018) 北京松山森林群落植物物种多样性格局及其环境解释. 硕士学位论文, 北京林业大学, 北京.)发现在北京松山草本层植物物种多样性随海拔升高呈递减趋势; 张世雄等(2020)发现山西吕梁山森林中海拔与林下草本植物物种多样性为单峰型曲线关系。但本研究发现林下草本植物随海拔梯度的升高而无明显变化规律, 这主要与本研究区域海拔梯度范围较小(1,330-1,470 m)有关, 因为海拔高差较小导致海拔梯度上环境因子的变化不大。而Jiang和Ma (2015)在北京东灵山其他区域设置10条样带, 衔接形成1,020-1,770 m的海拔梯度, 从低海拔段一直延伸至树线附近, 发现林下草本植物物种多样性随海拔升高而升高, 其受光照、温度和水分等因子的综合作用, 从而形成林下草本植物到亚高山草甸群落的转变。
凹凸度可反映地形的起伏程度, 小地形的起伏造成小气候的变化(王达力, 2011② (②王达力 (2011) 浙江天童20 ha常绿阔叶林动态样地群落特征及其与地形关系. 硕士学位论文, 华东师范大学, 上海.)), 坡度在垂直方向上影响着水分和土壤养分的流向, 进而影响植物群落的生长与分布(朱强等, 2019)。本研究发现暖温带落叶阔叶林林下草本植物的Shannon-Wiener多样性指数、Simpson优势度指数、Pielou均匀度指数与坡度和凹凸度均无显著相关性, 表明草本植物可以在不同坡度、凹凸度上生长。这与刘贵峰等(2021)的研究结果相似, 即坡度和凹凸度并不一定会影响林下草本多样性的分布。
地面草本植物占据森林中最底层这一事实使它们高度依赖于空间变化和短暂的太阳事件, 如太阳黑子(Chazdon & Pearcy, 1991), 而不同坡向的光照、土壤含水量等存在差异, 从而影响植物群落的物种组成和分布(Xue et al, 2018)。有关研究发现坡向对长白山阔叶红松林林下草本植物空间分布影响较大, 但其不同坡向的物种丰富度在早春、夏末和秋季的差异极显著, 在早春阶段北坡和东坡的丰富度高于南坡和西坡, 而在夏末和秋季却截然相反(李步杭等, 2008)。本研究结果与上述研究结果相似, 本研究中林下草本植物Shannon-Wiener多样性指数随坡向的增大而减小, 坡向范围从东南坡到北坡(110.55°-356.00°), 林下草本植物从阳坡到阴坡物种多样性呈下降趋势。阳坡由于光照条件好, 样地内林下草本植物接收光照更多, 有利于更多的喜阳耐干旱草本植物生长, 如细叶薹草(Carex duriuscula subsp. stenophylloides)等。但本次草本调查仅涉及7-8月, 仍可能有些早春草本植物未被调查到, 坡向对其物种多样性的影响是否随季节而发生变化, 有待进一步探究。
4.2 林分因子对林下草本植物物种多样性的影响
林分密度与平均胸径呈极显著负相关关系(附录3)。林分密度对于林木的胸径具有直接影响: 随着密度的增大, 由于林木之间相互遮蔽, 影响了林木的光合作用, 从而影响林木生长; 其次林地透光性变差, 林内光照减少, 影响土壤中酶的活性, 导致凋落物的分解速率降低, 进入土壤中的有效养分减少(Zhang et al, 2019), 且林分密度与林地物种丰富度呈极显著正相关关系(附录4), 使得对养分的竞争也随之增加, 造成单株可利用的养分含量减少, 林木的胸径减小(杨晓毅, 2019① (①杨晓毅 (2011) 黄土高原沟壑区人工刺槐林林分结构及林下植物多样性研究. 硕士学位论文, 西北农林科技大学, 陕西杨凌.))。
本研究发现林地物种丰富度与胸径变异系数呈极显著正相关关系(附录5), 这与其他热带和亚热带的结果不一致。在热带和亚热带森林中林木胸径变异系数与林地物种丰富度呈负相关关系, 胸径变异系数越大, 优势物种多度越丰富, 冠层树木对林下层树木的不对称竞争会导致生长在冠层以下的树木的透光率损失, 使得林下层物种丰富度下降(Jucker et al, 2014; Ali et al, 2016)。造成这样的差异与气候密切相关, 相较于热带和亚热带森林, 暖温带森林气候相对干旱, 植物为了减少蒸腾作用, 叶片相对较小, 即使随着胸径变异系数的增大, 优势物种多度增加, 林下透光率依然较大。这就印证了我们的发现: 胸径变异系数与林下草本植物物种多样性无显著相关性, 林木优势种组成对草本植物物种多样性无显著影响。
通过层次分割方法发现林分密度是制约林下草本植物物种多样性的主要因子, 且与林下草本植物物种丰富度指数和Shannon-Wiener多样性呈显著负相关关系, 这与张林等(2022)在北京山区侧柏(Platycladus orientalis)林和张柳桦等(2019)在新津文峰山马尾松(Pinus massoniana)林研究发现林分密度是决定林下植物多样性的主导因子, 且随着林分密度的增加, 林下草本植物物种多样性逐渐降低的研究结论基本一致。林分密度通过控制林冠层的透光性以及彼此之间的竞争来影响林下草本植物的生存环境(Machado & De Almeida, 2019), 一方面, 林下草本植物丰富度与光能利用率呈正相关(Radhamoni et al, 2023), 而高密度的林木抑制了草本植物对光的吸收效率, 使得一些喜阳草本植物难以存活(雷相东等, 2018), 另一方面, 当草本群落内竞争水平较高时, 由于竞争排斥效应, 具有较强竞争力的物种占据绝对优势, 竞争能力较弱的物种难以生存, 将导致群落物种多样性降低(Grime, 1973), 高密度林下养分竞争激烈, 加剧了林下草本植物生态位竞争, 从而影响一些劣势草本植物生长(Zhang et al, 2021)。此外, Jia等(2022)在温带长白山森林样地的研究发现, 真菌和植食性昆虫对林下草本植物物种多样性的影响强度与林冠树种组成有关。而目前有关暖温带森林林下草本植物与微生物和食草动物相关性等方面的研究鲜见报道, 未来可进一步加强。
本研究以地形、林分结构因素为主线, 对暖温带落叶阔叶林草本植物物种多样性与海拔、坡度、凹凸度、坡向、林分密度、平均胸径、胸径变异系数和林地物种丰富度的关系进行研究, 发现东灵山20 ha暖温带落叶阔叶林动态监测样地中不同地形、林分结构条件下草本植物物种多样性具有较大差异。其中坡向是显著影响东灵山暖温带落叶阔叶林林下草本植物物种多样性的地形因子; 林分密度、平均胸径、林地物种丰富度是显著影响草本植物物种多样性的林分结构因子。所有因子中, 林分密度是林下草本植物物种多样性的主要影响因子。本研究着重分析了地形因子及林分因子对林下草本植物物种多样性的影响, 下一步将具体研究光照、水分、土壤等其他环境因子对林下草本植物物种多样性的影响, 以期为更好地理解暖温带落叶阔叶林林下草本植物物种多样性的维持机制提供依据。
附录 Supplementary Material
附录1 东灵山20 ha暖温带落叶阔叶林动态监测样地地形与林分因子基本概况
Appendix 1 Basic information of topography and stand factors in a 20 ha warm temperate deciduous broad-leaved forest dynamics plot in Donglingshan
附录2 东灵山20 ha暖温带落叶阔叶林动态监测样地地形和林分结构与草本植物物种多样性指数的回归拟合
Appendix 2 Regression fitting between topography and stand structure and herbaceous species diversity index in a 20 ha warm temperate deciduous broad-leaved forest dynamics plot in Donglingshan
附录3 东灵山20 ha暖温带落叶阔叶林动态监测样地林分密度与平均胸径相关性
Appendix 3 Correlation between stand density and mean DBH in a 20 ha warm temperate deciduous broad-leaved forest dynamics plot in Donglingshan
附录4 东灵山20 ha暖温带落叶阔叶林动态监测样地林分密度与林地物种丰富度相关性
Appendix 4 Correlation between stand density and forest species richness in a 20 ha warm temperate deciduous broad-leaved forest dynamics plot in Donglingshan
附录5 东灵山20 ha暖温带落叶阔叶林动态监测样地胸径变异系数与林地物种丰富度相关性
Appendix 5 Correlation between coefficient of variation of DBH (DBHcv) and forest species richness in a 20 ha warm temperate deciduous broad-leaved forest dynamics plot in Donglingshan
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PMID:19341137
[本文引用: 1]
The classical environmental control model assumes that species distribution is determined by the spatial variation of underlying habitat conditions. This niche-based model has recently been challenged by the neutral theory of biodiversity which assumes that ecological drift is a key process regulating species coexistence. Understanding the mechanisms that maintain biodiversity in communities critically depends on our ability to decompose the variation of diversity into the contributions of different processes affecting it. Here we investigated the effects of pure habitat, pure spatial, and spatially structured habitat processes on the distributions of species richness and species composition in a recently established 24-ha stem-mapping plot in the subtropical evergreen broad-leaved forest of Gutianshan National Nature Reserve in East China. We used the new spatial analysis method of principal coordinates of neighbor matrices (PCNM) to disentangle the contributions of these processes. The results showed that (1) habitat and space jointly explained approximately 53% of the variation in richness and approximately 65% of the variation in species composition, depending on the scale (sampling unit size); (2) tree diversity (richness and composition) in the Gutianshan forest was dominantly controlled by spatially structured habitat (24%) and habitat-independent spatial component (29%); the spatially independent habitat contributed a negligible effect (6%); (3) distributions of richness and species composition were strongly affected by altitude and terrain convexity, while the effects of slope and aspect were weak; (4) the spatial distribution of diversity in the forest was dominated by broad-scaled spatial variation; (5) environmental control on the one hand and unexplained spatial variation on the other (unmeasured environmental variables and neutral processes) corresponded to spatial structures with different scales in the Gutianshan forest plot; and (6) five habitat types were recognized; a few species were statistically significant indicators of three of these habitats, whereas two habitats had no significant indicator species. The results suggest that the diversity of the forest is equally governed by environmental control (30%) and neutral processes (29%). In the fine-scale analysis (10 x 10 m cells), neutral processes dominated (43%) over environmental control (20%).
Methodology and applications of site quality assessment based on potential mean annual increment
基于林分潜在生长量的立地质量评价方法与应用
Seasonal dynamics and spatial distribution patterns of herbs plant diversity in broad-leaved Korean pine (Pnus koraiensis) mixed forest in Changbai Mountains
长白山阔叶红松林草本植物多样性季节动态及空间分布格局
The research advances on the structure and function of forest canopy, as well as their temporal and spatial changes
森林冠层结构与功能及其时空变化研究进展
Progress in the study of elevational patterns of soil microbial diversity
土壤微生物多样性海拔格局研究进展
Non-woody life-form contribution to vascular plant species richness in a tropical American forest
DOI:10.1007/s11258-008-9505-z URL [本文引用: 2]
Recent advances in altitudinal distribution patterns of biodiversity
生物多样性的海拔分布格局研究及进展
DOI:10.16258/j.cnki.1674-5906.2021.02.025
[本文引用: 2]
可下载PDF全文。
Species diversity of understory herbaceous plants in four typical natural secondary forests in Hanshan Nature Reserve
罕山自然保护区4种典型天然次生林林下草本植物物种多样性
Species composition and community structure of the Donglingshan forest dynamic plot in a warm temperate deciduous broad-leaved secondary forest, China
DOI:10.3724/SP.J.1003.2011.11319
[本文引用: 3]
<p>Community structure is one of the key features in the process of vegetation succession. Warm temperate mixed deciduous broad-leaved secondary forest is the main forest vegetation type in China’s warm temperate zone. In order to better study the mechanisms of succession and species coexistence in this forest type, we established the Donglingshan 20-ha forest plot (DLS plot) in 2009 and 2010 using the same protocol as the well-established plot on Barro Colorado Island in Panama. In the plot, all free-standing woody plants with DBH (diameter at breast height) ≥1 cm were mapped, tagged, and identified to species. Here, we address preliminary results on floristic characteristics, community composition, and size-class, vertical, and spatial structure of the DLS plot. These datasets will serve as baseline information accessible to a wide range of future studies. We tagged a total of 52,136 genotype individuals (103,284 individuals including branches of genotype individuals), belonging to 58 species, 33 genera and 18 families. All of these tree species were deciduous. Floristic characteristics of the community suggested a temperate flora, including some subtropical and tropical elements. There were very obvious dominant species in the plot. Five species comprised 61% of all individuals, and 20 species comprised 92% of all individuals, while the other 38 species comprised only 8% of all individuals. Vertical structure was composed of an overstory layer (19 species), midstory layer (18 species), and a shrub layer (21 species). The DBH size-class structure of all species in the plot generally fitted a “reverse J” distribution, indicating good regeneration across the community. The size-class structure of the main species in the overstory layer showed a bimodal or nearly normal distribution, while the most abundant species in the midstory and shrub layers showed “reverse J” or even “L” distributions. Spatial distribution patterns of the dominant species varied with size-class and scale and shifted from closer aggregation to looser aggregation from small to adult or old trees. The size-class spatial distribution patterns of the dominant species showed the different diameter levels of their own individuals occupied different spatial positions in the plot.</p>
东灵山暖温带落叶阔叶次生林动态监测样地: 物种组成与群落结构
DOI:10.3724/SP.J.1003.2011.11319
[本文引用: 3]
群落结构状态是植被演替进程中的重要体现之一, 同时也是下一步演替过程发生的基础。暖温带落叶阔叶次生林是中国暖温带森林植被的主要类型。为了更好地研究其演替动态、生物多样性维持机制, 我们参照巴拿马Barro Colorado Island (BCI) 50 ha热带雨林样地的技术规范, 于2009年11月至2010年9月在北京门头沟区小龙门森林公园的暖温带落叶阔叶次生林内建立了一块20 ha的固定样地(简称DLS), 对样地内胸径≥1 cm的所有木本植物进行了鉴定、调查及定位, 分析了群落的组成和结构。结果表明, 样地内木本植物有58种, 隶属于18科33属。独立个体的总数为52,136, 包括独立个体分枝的总数为103,284, 全部为落叶树种。群落的区系类型以北温带成分居多, 同时混有一些亚热带和热带成分, 属典型的温带森林类型。群落优势种明显, 个体数最多的前5个种的个体数占到总个体数的61%, 前20个种占到92%, 而其余38个种只占8%。群落成层现象明显, 垂直结构由主林层(19个种)、次林层(18个种)和灌木层(21个种)组成。样地所有木本植物个体总径级分布呈倒“J”型, 群落更新良好。主林层树种的径级结构近似于双峰或正态分布, 而次林层和灌木层树种则表现出倒“J”型或“L”型。几个主要树种的空间分布表现出不同的分布格局, 随着径级增大, 聚集程度降低。空间分布格局显示主要优势种自身个体在其径级大小的空间分布上互补, 不同径级的个体占据了样地内不同的空间位置。
Relationship between species diversity and functional diversity of plant communities on different slopes in alpine meadow
高寒草甸不同坡向植物群落物种多样性与功能多样性的关系
Application of “rdacca.hp” R package in ecological data analysis: Case and progress
DOI:10.17521/cjpe.2022.0314
[本文引用: 1]
Quantitative estimation of the contribution of predictary variables to community composition is a hotspot in community ecology. However, multicollinearity and joint contributions among predictors make it difficult to estimate the importance of predictor in specific analysis scenarios. To address this issue, the “rdacca.hp” package provides a new quantitative indicator by introducing the concept of hierarchical partitioning (HP) to assign individual effects for individual predictors (or groups of predictors) across all possible model subsets. The package solves the problem of estimating the relative importance of predictors with multicollinearity in canonical analysis. The “rdacca.hp” package has become an important tool for community ecological analysis. To further promote users’ understanding and use of the “rdacca.hp” package, we demonstrate the general steps for using this package in canonical analysis with an example analyzing the important environmental and spatial drivers that shape the oribatid mites (Oribatida) community. Subsequently, we conduct a bibliometric analysis of recent studies using “rdacca.hp” package. The results show that, since its launch, the package has been widely used as a fundamental quantitative framework in ecology, environmental science and related disciplines. Finally, we discuss the further application and extension of the “rdacca.hp” package. In conclusion, this paper aims to advocate the understanding and application of the “rdacca.hp” package for domestic researchers.
rdacca.hp包在生态学数据分析中的应用: 案例与进展
DOI:10.17521/cjpe.2022.0314
[本文引用: 1]
定量评估不同变量对群落组成的贡献是群落生态学分析的热点问题。但在具体的分析情景中, 因子间的共线性与解释率的重叠对评估不同因子重要性造成了较大困难。基于这一问题, R程序包“rdacca.hp”通过引入层次分割法(HP)的理念, 在所有可能的模型子集下为各解释变量(或解释变量组)分配单独效应, 为典范分析中共线性解释变量的相对重要性评估提供了新的定量指标。目前, “rdacca.hp”包已经成为群落生态学分析的重要工具。为进一步促进用户对“rdacca.hp”包的理解与运用, 该文通过引入一个分析塑造甲螨(Oribatida)群落的重要环境和空间驱动因素的实例, 重点展示了使用该程序包进行典范分析的一般步骤。随后对近期应用“rdacca.hp”包开展分析的相关研究进行文献计量学分析, 结果表明该程序包自上线以来已被广泛用作解决生态学、环境科学及相关学科问题的基本定量框架。最后, 该文对“rdacca.hp”包的未来应用和升级进行了展望。总之, 该文旨在使国内学者们进一步加深对“rdacca.hp”包的认识和应用。
Global importance of large-diameter trees
Spatial distribution patterns of snag and standing trees in a warm temperate deciduous broad-leaved forest in Dongling Mountain, Beijing
北京东灵山暖温带落叶阔叶林枯立木与活立木空间分布格局
Plant community diversity in Dongling Mountain, Beijing, China. II. Species richness, evenness and species diversities
北京东灵山地区植物群落多样性的研究. II. 丰富度、均匀度和物种多样性指数
Spatial structure, diversity, and edaphic factors of an area of Amazonian coast vegetation in Brazil
DOI:10.3159/TORREY-D-18-00025.1 URL [本文引用: 1]
Revised slope steepness factor for the universal soil loss equation
DOI:10.13031/2013.30576 URL [本文引用: 1]
Nutrient relations of the herbaceous layer in deciduous forest ecosystems
In: The Herbaceous Layer in Forests of Eastern North America, 2nd edn (ed. Gilliam FS), pp.
Higher beta-diversity observed for herbs over woody plants is driven by stronger habitat filtering in a tropical understory
DOI:10.1890/15-1801.1 URL [本文引用: 1]
Local- and landscape-scale drivers of terrestrial herbaceous plant diversity along a tropical rainfall gradient in western Ghats, India
DOI:10.1111/jec.v111.5 URL [本文引用: 1]
Coupling biomass and energy in warm temperate deciduous broad-leaved oak (Quercus liaotungensis) forest ecosystem
东灵山暖温带落叶阔叶林生物量和能量密度研究
研究了辽东栎（Quercus liaotungensis）林生物量、能量分配和能量密度过程，结果表明，辽东栎林的生物量在60~200 t·hm<sup>-2</sup>之间，乔木层的生物量在50~160 t·hm<sup>-2</sup>之间，在林分中所占比例为80%~98%，辽东栎生物量在林分中所占比例从40%到100%，净初级生产力从, 5 t·hm<sup>-2</sup>·a<sup>-1</sup>到24 t·hm<sup>-2</sup>·a<sup>-1</sup>。辽东栎群落能量现存密度为83000 kcal·m<sup>-2</sup>，其中乔木层占96.65%、灌木层占3.12%、草本层占0.23%。乔木层中各器官能量密度排列顺序是树干> 树根> 树枝> 树叶，比例是4：3：2：1，灌木层中，各器官能量密度顺序是干> 枝> 根> 叶。最后给出了该类森林生态系统变化的生物量和能量概念模式，为下一步建立抽象的数学模型，建立可操作能实用的计算机模拟模型打下了基础。
Spatial pattern analysis and topographical interpretation of species diversity in the forests of Dalaoling in the region of the Three Gorges
三峡大老岭森林物种多样性的空间格局分析及其地形解释
Effects of stand density on understory vegetation and soil properties of Cunninghamia lanceolata plantation
林分密度对杉木人工林林下植被和土壤性质的影响
Seeing beyond the trees: A comparison of tropical and temperate plant growth forms and their vertical distribution
Herbaceous plant diversity in forest ecosystems: Patterns, mechanisms, and threats
DOI:10.1007/s11258-021-01202-9 [本文引用: 1]
A review on the elevational patterns of plant species diversity
DOI:10.17520/biods.2004004 URL [本文引用: 1]
植物物种多样性的垂直分布格局
DOI:10.17520/biods.2004004
[本文引用: 1]
生物多样性沿环境梯度的变化趋势是生物多样性研究的一个重要议题，而海拔梯度包含了多种环境因子的梯度效应，因此研究生物多样性的海拔梯度格局对于揭示生物多样性的环境梯度变化规律具有重要意义。在不同的研究尺度，植物多样性沿海拔梯度具有不同的分布格局，而形成这种格局的因素有很大差异。本文从α多样性，β多样性和γ多样性三个尺度总结了植物物种多样性沿海拔梯度分布格局及其环境解释。α多样性沿海拔梯度的分布格局在不同生活型的物种之间差异很大，但对于木本植物来说，虽然也存在其他格局，但α多样性随海拔升高而降低是被广泛接受的一种格局。在一般情况下，β多样性随着海拔的升高而降低，并且对于不同生活型的物种，β多样性沿海拔梯度具有相似的分布格局。γ多样性沿海拔梯度具有两种分布格局： 偏峰分布格局和显著的负相关格局； 特有物种数往往随着海拔的升高而减少，而特有度则随着海拔的升高而增加。
Overstorey-understorey interactions intensify after drought-induced forest die-off: Long-term effects for forest structure and composition
DOI:10.1007/s10021-017-0181-5 URL [本文引用: 1]
The ecological consequences of changes in biodiversity: A search for general principles
A review on the species diversity of plant community
植物群落物种多样性研究综述
Effects of topographic heterogeneity on species diversity in a monsoon ever green broad-leaved forest in Pu'er, Yunnan, China
DOI:10.17521/cjpe.2020.0148 URL [本文引用: 1]
地形异质性对云南普洱季风常绿阔叶林物种多样性的影响
The shape of things to come:Woodland herb niche contraction begins during recruitment in mesic forest microhabitat
Initial response of a mixed-conifer understory plant community to burning and thinning restoration treatments
DOI:10.1016/j.foreco.2006.11.011 URL [本文引用: 1]
Herb layer response to broadleaf tree species with different leaf litter quality and canopy structure in temperate forests
DOI:10.1111/jvs.2009.20.issue-3 URL [本文引用: 1]
Species diversity characteristics of deciduous forests in the warm temperate zone of North China
暖温带落叶阔叶林的物种多样性特征
Slope aspect influences plant biomass, soil properties and microbial composition in alpine meadow on the Qinghai-Tibetan Plateau
Driving effects of forest stand structure of a subtropical evergreen broad-leaved forest on species composition variation: From local to regional scales
DOI:10.17520/biods.2022139
[本文引用: 1]
<p id="p00005"><strong>Aim:</strong> The variation of species composition can be partitioned into two components which are explained by environment and space, and can be used to further explore the niche process and neutral process of community assembly. Forest stand structure characterizes the light availability and heterogeneity under forest canopies, and it is a major driving factor in the variation of species composition for forest communities. However, few studies have applied forest stand structure to explain the variation of species composition within forest communities. In this study, we sampled 19 separate 1-ha forest dynamics plots established among grids of 1 km<sup>2</sup> (regional scale) near the 20 ha subtropical mid-mountain moist evergreen broad-leaved forest dynamics plot (local scale, less than 1 km<sup>2</sup>) in Ailao Mountains as a research platform. Using forest stand structure, environmental factors, and spatial structure variables as the explanatory variables for the species composition variation. We resolved the driving forces of species composition variation at local and regional scales, with an emphasis on the role of forest stand structure in driving the variation of species composition.</p> <p id="p00006"><strong>Methods: </strong>Based on a long-term community survey and airborne LiDAR data, we used redundancy analysis (RDA) and variance partitioning to analyze how environment, spatial structure, and forest stand structure were related to species composition variation in a subtropical evergreen broad-leaved forest at both local and regional scales. To explore the main factors driving the variation of species composition, we analyzed the relative importance of individual explanatory variables using commonality analysis and hierarchical partitioning method.</p> <p id="p00007"><strong>Results:</strong> Inclusion of forest stand structure as an explanatory variable increased the response rate of the variation of species composition at both local and regional scales. However, inclusion of forest stand structure as an explanatory variable resulted in a significant decrease in the rate of spatial structure at the local level. The cumulative contribution of forest stand structure and environment to the variation in species composition was 41.0% at the local level. At the regional scale, forest stand structure and environment contributed a cumulative explanatory rate in species composition was 23.0%.</p> <p id="p00008"><strong>Conclusions: </strong>This study confirms that, for subtropical broad-leaved evergreen forests, forest stand structure characterizing the light environment is an important driver of the variation in species composition, which deepens our understanding of the role of environmental filtering in driving the variation in species composition and remedies the traditional under-consideration of environmental factors. From local to regional scales, the role of purely spatial structure declines sharply to negligible levels. However, the relative importance of environmental filtering is significantly enhanced from the local to the regional scale. Light availability may have a strong effect shaping species composition below the forest canopies. This new relationship between forest stand structure on species composition warrants future studies to explore the causal mechanisms of how forest stand structure drives species composition variation in subtropical broad-leaved evergreen forests.</p>
亚热带常绿阔叶林林分结构对物种组成变异的驱动作用: 从局域到区域尺度
DOI:10.17520/biods.2022139
[本文引用: 1]
林分结构可以表征森林群落光的可利用性和光环境的异质性, 对群落物种组成的变异具有重要驱动作用。然而, 目前还鲜有研究将林分结构用于解释群落物种组成的变异。本研究以哀牢山亚热带中山湿性常绿阔叶林20 ha森林动态监测样地及其周边区域按公里网格设置的19个1 ha森林动态样地为研究对象, 将林分结构参数、环境因子和空间结构变量共同作为解释变量, 采用基于冗余分析的变差分解和层次分割方法, 在局域和区域尺度上同时解析群落物种组成变异的驱动因素。结果表明, 在局域和区域尺度上, 纳入林分结构后均提高了对物种组成变异的解释率。在局域尺度上, 加入林分结构作为解释变量后, 单纯的空间结构的解释率明显下降, 林分结构与环境因子累计贡献了41.0%的解释率。在区域尺度上, 林分结构与环境因子累计贡献了23.0%的解释率。从局域到区域尺度, 环境过滤的相对作用明显增强。林分结构指示的光的可利用性对林冠下方的树种组成具有较强的塑造作用, 今后的研究应进一步探讨林分结构对亚热带常绿阔叶林物种组成变异的驱动机制。
Analysis of influencing factors on the understory herbaceous plant diversity of Platycladus orientalis forest in Beijing mountainous areas
北京山区侧柏林下草本植物多样性的影响因素分析
DOI:10.11733/j.issn.1007-0435.2022.08.032
[本文引用: 1]
为分析和比较林分结构和环境因子对侧柏林下草本物种多样性的影响，以北京山区侧柏林为研究对象，采用多元逐步回归分析和结构方程模型解析了林分结构和环境因子与林下草本物种多样性的耦合关系。结果表明：多元线性回归显示海拔、林分密度和土壤有机质是影响林下草本Simpson多样性的主导因子，郁闭度是影响林下草本Pielou均匀度指数的主导因子，海拔是影响林下草本Margalef丰富度指数的主导因子；结构方程显示海拔和林分结构(林分密度、郁闭度)对林下草本物种多样性整体水平起主导作用，通过影响土壤养分对林下草本物种多样性产生间接影响，但直接影响起主要作用；土壤对林下草本物种多样性整体水平起重要作用，仅存在直接影响。因此，维持合理的林分密度和郁闭度是提升林下草本植物多样性整体水平的有效途径。
Effects of stand density on understory plant diversity and biomass in a Pinus massoniana plantation in Wenfeng Mountain, Xinjin County
林分密度对新津文峰山马尾松人工林林下物种多样性和生物量的影响
Vegetation diversity of Luya Mountains
芦芽山植物群落的多样性研究
Patterns of species diversity in herbaceous communities at different altitude gradients and their relationships with environmental factors in Lüliang Mountains in Shanxi Province, China
山西吕梁山草本群落物种多样性的海拔梯度格局及与环境因子的关系
Response of forest growth to C : N : P stoichiometry in plants and soils during Robinia pseudoacacia afforestation on the Loess Plateau, China
DOI:10.1016/j.geoderma.2018.09.042
[本文引用: 1]
C:N:P stoichiometry in the plants and soils is an important indicator of biogeochemical cycles and functioning in ecosystems; however, the response of plant growth to ecological stoichiometry following afforestation remains unclear. To illustrate the C:N:P stoichiometry connections between the plants and soils and their effects on the growth of plants, soil and plant samples were collected from one farmland site and four Robinia pseudoacacia (RP) forests that were planted for 10, 15, 25, and 35 years. Plant community characteristics, growth of overstory trees and understory plants, physical and chemical properties of the soil, and C:N:P stoichiometry in plants and soil were measured. The results revealed that soil organic C, total N, total P, dissolved organic N, C:P and N:P ratios, and water content significantly increased, whereas soil bulk density, available P, and pH decreased with afforestation age. Leaf C:P and N:P ratios in RP were significantly higher than that in understory biomass because P concentrations gradually decreased in RP leaves and increased in understory biomass. The C, N, and P contents and stoichiometry in the soils and plants were significantly correlated, particularly for N:P ratio that can be used to reveal close coupling between plant and soil nutrients. The N:P ratio in RP leaf and understory biomass increased with afforestation age and varied from 14.44 to 20.81 and 7.59 to 10.96, respectively, suggesting that P limitation gradually increased in RP, and N limitation gradually declined in understory biomass. Furthermore, the responses of overstory trees and understory plant growth to N:P ratios were contradictory, because of their different nutrient acquisition patterns and nutrient-use efficiencies. Therefore, this finding provides evidence that the strong correlation between the plants and soils were tightly coupled to N and P concentrations and N:P ratios, and therefore, have the potential to influence the growth of forests on the Loess Plateau.
Changes in the understory diversity of secondary Pinus tabulaeformis forests are the result of stand density and soil properties
Advances in structural diversity of stand structure
林分结构多样性研究进展
Species diversity pattern and environmental explanation of evergreen deciduous broad-leaved mixed forest in Qizimei Mountains
七姊妹山常绿落叶阔叶混交林物种多样性格局及其环境解释
The influence of stand factors on species diversity of herb layer in Zhangbei poplar plantations
林分因子对张北杨树人工林林下草本层物种多样性的影响
研究人工林林分因子对林下草本层物种多样性的影响，对于人工林的抚育及合理经营有着重要意义。本研究调查了张北杨树人工林的林分死亡率、平均树高、平均枝下高、平均胸径、平均冠幅及林分密度等6个林分因子及林下草本层的群落特征，并计算出物种多样性指数，探究张北杨树人工林林分结构和林下物种多样性随林分因子的变化特征。结果表明：研究区林下草本层共发现维管植物44种，隶属于17科38属，其中以菊科（Compositae）、豆科（Leguminosae）、禾本科（Gramineae）植物最多；林下草本层物种水分生态类型主要以旱生类植物为主，合计25种，占总种数的56.82%，植物生活型谱中以地面芽植物为主，共27种，占总种数61.36%；物种丰富度指数、Shannon指数和Pielou均匀度指数在各样地内存在显著差异，且物种丰富度指数变异系数最大，Simpson指数在各样地之间不存在显著差异，变异系数最小；各样地之间的林分因子均存在显著差异，其中林分死亡率的变异程度最高，平均胸径的变异程度最低；影响林下草本层物种丰富度指数的主要林分因子有林分死亡率、平均枝下高、平均胸径和林分密度，影响Shannon指数的主要林分因子有林分死亡率、平均树高、平均胸径和林分密度，各林分因子对Simpson指数和Pielou均匀度指数的影响均无显著差异。适当调控林分密度，保持树种针阔混交，将有利于张北杨树人工林林下草本物种多样性的维持。
