澜沧江中游水生昆虫生活史和生态学性状多样性的海拔格局: 气候和土地利用的影响
Elevational patterns of life history and ecological trait diversity of aquatic insects in the middle of the Lancang River: The effects of climate and land use variables
通讯作者: * E-mail:kai.chen@njau.edu.cn
编委: 陈圣宾
责任编辑: 闫文杰
收稿日期: 2021-08-21 接受日期: 2022-01-8
基金资助: |
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Corresponding authors: * E-mail:kai.chen@njau.edu.cn
Received: 2021-08-21 Accepted: 2022-01-8
物种通过功能性状响应环境变化, 探究群落功能性状多样性的海拔格局是揭示生物多样性空间分布格局和形成机制的重要研究内容。气候变化和土地利用是影响溪流生物多样性变化及其群落构建的重要因素, 然而气候和土地利用沿海拔梯度如何影响水生昆虫功能性状垂直分布格局的系统研究仍旧比较缺乏。本文基于2016年和2018年在云南澜沧江中游1,000-3,000 m海拔共56个溪流样点的水生昆虫群落调查数据, 利用线性和二次回归模型探索并比较了生活史性状(化性、生活史快慢、成虫寿命)和生态学性状(营养习性、生活习性、温度偏好)的群落加权平均性状多样性指数沿海拔梯度的分布特征, 并通过随机森林模型解析流域尺度气候和土地利用变量对生活史和生态学性状多样性垂直分布格局的影响。结果表明: 生活史性状中, 少于1世代、无季节性、慢季节性、成虫寿命长等性状多样性沿海拔梯度呈显著的“U”型分布格局, 而快季节性和成虫寿命极短多样性呈显著的单峰型海拔格局, 成虫寿命短多样性呈显著递增的海拔格局。生态学性状中, 温度偏好多样性与海拔梯度无关, 附着者和爬行者的多样性沿海拔梯度分别呈显著的递增和“U”型格局, 滤食者、植食者和捕食者的多样性分别呈显著递增、递减和“U”型海拔格局。随机森林模型分析结果表明, 气候和土地利用对生活史性状多样性的解释量高于对生态学性状多样性的解释量, 年平均温度和农业面积百分比是共同的关键因素。综上, 水生昆虫群落功能性状多样性海拔格局存在差异, 主要受不同自然环境梯度和人类干扰因素驱动。研究结果可为制定澜沧江流域生物多样性保护对策提供理论基础。
关键词:
Aims: Species respond to environmental changes through functional traits. Exploring the elevational pattern of community functional trait diversity is an important aspect in understanding the spatial distribution and formation mechanisms of biodiversity. Climate change and land use are important factors that affect stream ecosystems, their biodiversity, and community assembly. However, there is still a lack of systematic studies on the elevational distribution of functional trait diversity of aquatic insect assemblage under the effects of climate and land use variables.
Methods: We collected aquatic insect community data from 56 stream sites along elevational gradients ranging between 1,000-3,000 m in 2016 and 2018 in the middle of the Lancang River Basin, Yunnan Province, China. We then utilized a linear or quadratic regression model to explore and compare the elevational patterns of life history (voltinism, development, and adult life span) and ecological traits (trophic habit, habit, and thermal preference) diversity indices. Then, we used random forest model to analyze the effects of climatic and land use variables on the diversity of life history and ecological traits of aquatic insect assemblages.
Results: Of all life history traits, diversity of semivoltine, nonseasonal, slow seasonal, and long adult life span demonstrated significantly U-shaped elevational patterns. While diversity of fast seasonal, and very short adult life span exhibited significantly hump-shaped elevational patterns, and short adult life span diversity demonstrated a significantly increasing elevational pattern. Of all ecological traits, thermal preference diversity displayed no significant pattern along the elevation gradient. Diversity of clinger and sprawler exhibited a significantly increasing pattern and a U-shaped elevational pattern, while diversity of collector-filter, herbivore, and predator exhibited significantly increasing, decreasing, and U-shaped elevational patterns, respectively. Random forest models revealed that variation of life history trait diversity explained by climate and land use variables were higher than that in ecological trait diversity, with annual mean temperature and percentage of agriculture area as common key factors.
Conclusion: In summary, the elevational patterns of functional trait diversity in aquatic insect assemblage differed between life history and ecological trait diversity, in which differences are driven by different natural and human disturbance gradients. These results can provide theoretical supports for aquatic biodiversity maintenance and conservation in the Lancang River Basin.
Keywords:
本文引用格式
付飞, 魏慧玉, 常育腾, 王备新, 陈凯 (2022)
Fei Fu, Huiyu Wei, Yuteng Chang, Beixin Wang, Kai Chen (2022)
气候和土地利用沿海拔梯度的变化是影响生物多样性海拔格局的重要因素(Parmesan & Yohe, 2003; Finn & Poff, 2005; Sharma et al, 2020)。气候因子如降水和气温随海拔呈一定分布规律, 通常中海拔地区温湿度最适宜, 物种丰富度最高(Rahbek, 2005)。土地利用改变沿海拔梯度也存在特定规律, 通常低海拔地区土地利用改变的干扰程度更强, 如农业用地和城镇化等土地利用变化现象在低海拔地区更为密集和频繁(Allan, 2004; Nogués-Bravo et al, 2008; Murdoch et al, 2020), 土地利用改变引起溪流环境从上游到下游栖境同质化, 是影响生物群落垂直分布特征的重要人为因素(Teresa & Casatti, 2012; Harvey & Altermatt, 2019; Perkin & Wilson, 2021)。
溪流沿海拔梯度形成树枝状网络生态系统, 是响应全球变化最为敏感的生态系统之一(Wang et al, 2017)。水生昆虫是溪流生态系统中具有重要生态功能的组成部分(Covich et al, 1999; Mermillod- Blondin, 2011), 对环境变化和人类干扰敏感(DeWalt et al, 2005; Dohet et al, 2015)。水生昆虫的生活史性状(如生活史快慢等)是物种长期适应环境变化形成的特定生活史策略(Verberk et al, 2008); 生态学性状(如温度偏好、营养习性等)影响物种对栖息环境的适应度, 与物种的扩散和定居能力相关(Gladstone-Gallagher et al, 2019)。因此, 生活史和生态学性状是水生昆虫沿海拔梯度响应环境扰动的重要功能性状(Verberk et al, 2008; Stuart-Smith et al, 2013)。如襀翅目Anacroneuria paleta稚虫前翅长度和头囊宽度、A. tachira的头囊宽度均与海拔梯度呈显著相关(Cressa et al, 2008); 蜉蝣目Baetis alpinus稚虫在低海拔(640-760 m)、中海拔(1,355 m)和高海拔(> 2,190 m)溪流分别呈现多于1世代(bi- & multi- voltine)、1世代(univoltine)和少于1世代(semivoltine)的化性分布特征(Humpesch, 1979); 底栖动物集食者、撕食者和刮食者等取食功能类群的相对丰度沿海拔梯度分别呈“U”型、递减和单峰格局(Tomanova et al, 2007)。有研究表明气候因子和土地利用是影响溪流水生昆虫多样性随海拔变化的重要因素, 其中温度是控制水生昆虫生活史性状最重要的环境因素之一(Ward & Stanford, 1982; Hamilton et al, 2020), 土地利用变化直接或间接地改变水生昆虫群落生态学性状组成(Lytle & Poff, 2004)。当前对水生昆虫群落生活史和生态学性状多样性的海拔格局及其受气候和土地利用共同作用的形成机制的差异性研究仍然比较缺乏。
澜沧江流域海拔高程显著, 水系发达, 干流和支流纵贯云南西部, 具有丰富的水生昆虫多样性(王川等, 2013), 是开展气候和土地利用影响水生昆虫群落功能性状海拔格局研究的理想区域。本研究通过采集和分析澜沧江流域云南段中游水生昆虫的生活史和生态学性状数据, 探索水生昆虫群落生活史和生态学性状多样性沿海拔梯度的分布特征, 揭示沿海拔梯度气候和土地利用变化对水生昆虫功能性状多样性的影响, 以期为澜沧江水生生物多样性研究提供数据积累, 为生物多样性的海拔格局及其构建机制研究提供理论支撑。
1 材料与方法
1.1 研究区域概况
图1
1.2 数据采集
1.2.1 水生昆虫
1.2.2 环境数据
从中国科学院资源环境科学与数据中心(
表1 研究区域溪流采样点位环境因子概况
Table 1
环境变量 Environmental variables | 平均值 Mean | 标准差 SD | 最小值 Min | 最大值 Max |
---|---|---|---|---|
海拔 Elevation (m) | 2,030 | 480 | 1,274 | 2,899 |
森林面积百分比 % forest area | 75.5 | 16.0 | 21.6 | 98.4 |
农业面积百分比 % agriculture area | 1.3 | 4.7 | 0.0 | 32.0 |
不透水面积百分比 % impervious area | 0.08 | 0.4 | 0.0 | 3.0 |
年平均气温 Annual mean temperature (℃) (BIO 1) | 10.3 | 3.0 | 2.4 | 16.4 |
季节性气温变异(标准差 × 100) Temperature seasonality (standard deviation × 100) (BIO 4) | 494.5 | 42.9 | 430.1 | 594.7 |
气温年较差 Temperature annual range (℃) (BIO 7) | 23.5 | 0.9 | 21.7 | 26.3 |
年平均降水量 Annual precipitation (mm) (BIO 12) | 920.6 | 101.4 | 649.4 | 1,232.5 |
季节性降水变异(变异系数) Precipitation seasonality (Coefficient of variation) (BIO 15) | 62.0 | 2.2 | 58.0 | 70.9 |
1.3 水生昆虫性状
水生昆虫的生活史性状和生态学性状对温度(Briers et al, 2004; Epele et al, 2011)和物理栖境特征(Morais et al, 2004; Statzner & Bêche, 2010)的变化响应敏感。本文选择的生活史性状包括: 生活史快慢(即昆虫生长发育速率)、成虫寿命(即水生昆虫从羽化为成虫到死亡的时间)和化性(即昆虫1年能够发生的世代数); 生态学性状包括: 营养习性(即获取食物的行为模式)、生活习性(即水生昆虫在溪流中的运动模式)和温度偏好性(即水生昆虫生长发育偏好的适宜温度)。将以上6个生物学性状划分为22个性状类别(表2), 所有生物学性状及其类别数据主要从已发表的文献资料中获取(Poff et al, 2006; Twardochleb et al, 2021)。
表2 水生昆虫生活史和生态学性状及其类别
Table 2
性状 Trait | 性状类别 Trait modality |
---|---|
生活史性状 Life history | |
化性 Voltinism | 少于1世代 Semivoltine |
1世代 Univoltine | |
多于1世代 Bi- & multi-voltine | |
生活史快慢 Development | 快季节性 Fast seasonal |
慢季节性 Slow seasonal | |
无季节性 Nonseasonal | |
成虫寿命 Adult life span | 极短 Very short |
短 Short | |
长 Long | |
生态学性状 Ecological traits | |
营养习性 Trophic habit | 集食者 Collector-gatherer |
滤食者 Collector-filterer | |
植食者 Herbivore | |
捕食者 Predator | |
撕食者 Shredder | |
生活习性 Habit | 掘穴者 Burrower |
攀附者 Climber | |
爬行者 Sprawler | |
附着者 Clinger | |
游泳者 Swimmer | |
温度偏好 Thermal preference | 喜凉 Cold-cool |
广温 Cool-warm | |
喜温 Warm |
1.4 数据分析
1.4.1 性状多样性计算
本文采用群落加权平均性状多样性指数(community-level weighted means, CWM)表征水生昆虫群落生活史和生态学性状多样性, CWM指数基于性状组成和分类单元的相对多度定量测定群落组成性状多样性, 对于评价群落的动态及生态系统特性具有重要意义(Lavorel et al, 2008), 计算公式如下:
1.4.2 性状多样性的海拔格局分析
1.4.3 性状多样性对气候和土地利用的响应
构建随机森林(random forest, RF)模型解析流域气候因子和土地利用变化对生活史和生态学性状多样性的影响。RF模型利用bootstrap抽样法抽取响应变量(即性状多样性)和解释变量(即土地利用和气候因子)的训练样本, 采用向后筛选法剔除重要性较低的解释变量, 利用最终的解释变量组合构建最终模型, 利用袋外样本(out of bag)计算总解释量, 评估RF模型的精确度及最终解释变量的重要性。RF模型具有很高的模型准确率, 对异常值和噪声具有高容忍度, 不易出现过拟合, 同时响应变量的共线性不会对计算结果产生影响(Breiman, 2001; Cutler et al, 2007)。利用R软件的randomForest包(Liaw & Wiener, 2002)构建RF模型, 每个RF模型分别构建1,500棵回归树。
2 结果
2.1 水生昆虫物种组成
共采集和鉴定水生昆虫7目58科174个分类单元(附录1); 其中, 双翅目(18科47分类单元)、毛翅目(13科34分类单元)、鞘翅目(8科32分类单元)、蜉蝣目(6科25分类单元)、襀翅目(7科23分类单元)为丰富度较高的优势类群。
2.2 性状多样性指数的海拔分布格局
生活史性状多样性海拔格局中, 除多于1世代和1世代性状多样性, 其他生活史性状的多样性指数均与海拔梯度存在显著的二次或者线性相关关系(图2)。快季节性水生昆虫在各海拔段广泛分布, 其多样性呈现显著的单峰型海拔格局, 在2,000 m左右达到最高值; 无季节性和慢季节性水生昆虫的生活史性状多样性呈现显著的“U”型海拔格局, 在2,000 m左右最低。成虫寿命长、寿命短及寿命极短的水生昆虫, 其生活史性状多样性分别呈现显著的“U”型、递增、单峰型的海拔格局。少于1世代水生昆虫的生活史性状多样性呈现显著的“U”型海拔格局, 在2,000 m左右最低。
图2
图2
水生昆虫生活史性状多样性的海拔格局。黑色实线表示群落加权平均性状多样性指数(CWM)海拔分布格局的线性或二次相关关系显著(P < 0.05)或极显著(P < 0.01), 黑色虚线表示不显著(P > 0.05)。灰色区域为95%置信区间。
Fig. 2
The relationship between community-level weighted means (CWM) of aquatic insect life history traits and elevation. Black solid line indicates significant (P < 0.05) or highly significant (P <0.01) linear or quadratic relationships, black dotted line indicates non-significant (P > 0.05) relationships. The grey area indicates 95% confidence interval for the selected linear or quadratic model.
生态学性状多样性海拔格局中, 附着者、爬行者、滤食者、植食者和捕食者的生态学性状多样性与海拔梯度存在显著的线性或者二次相关关系(图3)。沿海拔梯度, 附着者的多样性呈现显著递增的分布格局, 爬行者的多样性呈现显著的“U”型分布格局; 滤食者、植食者和捕食者的多样性分别呈现显著的递增、递减和“U”型的分布格局。
图3
图3
水生昆虫生态学性状多样性的海拔格局。黑色实线表示群落加权平均性状多样性指数(CWM)海拔分布格局的线性或二次相关关系显著(P < 0.05)或极显著(P < 0.01), 黑色虚线表示不显著(P > 0.05)。灰色区域为95%置信区间。
Fig. 3
The relationship between community-level weighted means (CWM) of aquatic insect ecological traits and elevation. Black solid line indicates significant (P < 0.05) or highly significant (P < 0.01) linear or quadratic relationships, black dotted line indicates non-significant (P > 0.05) relationships. The grey area indicates 95% confidence interval for the selected linear or quadratic model.
2.3 气候和土地利用对性状多样性的影响
气候和土地利用对生活史性状多样性的解释量高于对生态学性状多样性的解释量(表3)。气候和土地利用对生活史性状多样性的解释量为10.4%-31.0%, 关键环境因子为年平均气温(BIO 1)、森林面积百分比和农业面积百分比。气候和土地利用对生态学性状多样性的解释量为0-18.5%, 关键环境因子为年平均气温(BIO 1)、农业面积百分比和不透水面积百分比, 其中攀附者和游泳者多样性的随机森林模型无任何解释量。
表3 水生昆虫群落加权平均性状多样性指数(CWM)对气候和土地利用响应的随机森林模型。解释变量重要性排序从左到右按降序排列。
Table 3
性状 Trait | 性状类别 Trait modality | 解释量 RF % variation | 解释变量 Explanatory variables |
---|---|---|---|
生活史性状 | |||
生活史快慢 Development | 快季节性 Fast seasonal | 25.7 | 森林面积百分比 + 年平均气温+ 年平均降水量 % forest area + BIO 1 + BIO 12 |
无季节性 Nonseasonal | 19.3 | 森林面积百分比 % forest area | |
慢季节性 Slow seasonal | 28.8 | 年平均气温 + 年平均降水量 + 农业面积百分比 BIO 1 + BIO 12 + % agriculture area | |
成虫寿命 Adult life span | 长 Long | 20.6 | 森林面积百分比 % forest area |
短 Short | 31.0 | 农业面积百分比 + 年平均气温 + 年平均降水量 + 季节性降水变异(变异系数) % agriculture area + BIO 1 + BIO 12 + BIO 15 | |
极短 Very short | 25.8 | 森林面积百分比 + 年平均气温 + 年平均降水量 % forest area + BIO 1 + BIO12 | |
化性 Voltinism | 多于1世代 Bi- & multi-voltine | 16.8 | 不透水面积百分比 + 年平均气温 + 农业面积百分比 + 季节性降水变异(变异系数) % impervious area + BIO 1 + % agriculture area + BIO 15 |
少于1世代 Semivoltine | 10.4 | 森林面积百分比 + 季节性降水变异(变异系数) + 农业面积百分比 % forest area + BIO 15 + % agriculture area | |
1世代 Univoltine | 16.9 | 年平均气温 + 不透水面积百分比 + 农业面积百分比 + 年平均降水量 BIO 1 + % impervious area + % agriculture area + BIO 12 | |
生态学性状 | |||
生活习性 Habit | 掘穴者 Burrower | 3.9 | 不透水面积百分比 + 年平均降水量 % impervious area + BIO 12 |
攀附者 Climber | 0 | NA | |
附着者 Clinger | 1.0 | 年平均气温 BIO 1 | |
爬行者 Sprawler | 11.5 | 农业面积百分比 + 年平均气温 + 气温年较差 % agriculture area + BIO 1 + BIO 7 | |
游泳者 Swimmer | 0 | NA | |
温度偏好 Thermal preference | 喜凉 Cold-cool | 6.3 | 年平均气温 + 不透水面积百分比 + 农业面积百分比 + 季节性降水变异(变异系数) BIO 1 + % impervious area + % agriculture area + BIO 15 |
广温 Cool-warm | 5.0 | 年平均气温 + 季节性降水变异(变异系数) + 年平均降水量 + 森林面积百分比 BIO 1 + BIO 15 + BIO 12 + % forest area | |
喜温 Warm | 0.9 | 不透水面积百分比 % impervious area | |
营养习性 Trophic habit | 滤食者 Collector-filterer | 15.6 | 农业面积百分比 + 年平均降水量 + 季节性降水变异(变异系数) % agriculture area + BIO 12 + BIO 15 |
集食者 Collector-gatherer | 7.5 | 农业面积百分比 + 不透水面积百分比 % agriculture area + % impervious area | |
植食者 Herbivore | 10.2 | 年平均气温 + 季节性气温变异(标准差 × 100) + 年平均降水量 + 农业面积百分比 BIO 1 + BIO 4 + BIO 12 + % agriculture area | |
捕食者 Predator | 18.5 | 季节性降水变异(变异系数) + 农业面积百分比 BIO 15 + % agriculture area | |
撕食者 Shredder | 17.8 | 农业面积百分比 + 季节性降水变异(变异系数) + 年平均气温 % agriculture area + BIO 15 + BIO 1 |
解释变量的描述和详细信息见
Description and details of explanatory variables are shown in
3 讨论
了解水生昆虫生活史和生态学性状多样性响应气候和土地利用变化的垂直空间分布格局, 有助于我们更清晰地认识群落构建的生态学过程及其形成机制, 可以为探究全球变化影响下生物群落功能性状组成和分布的动态变化提供重要基础。本研究结果表明, 水生昆虫生活史和生态学性状多样性沿海拔梯度的分布格局存在差异; 生活史和生态学性状多样性对气候和土地利用的响应程度也不一致, 但年平均温度和农业面积百分比是共同的关键因素, 而生活史性状多样性响应温度和土地利用的变化比生态学性状更加显著。在不同海拔梯度下, 共同作用的气候和土地利用变量及其他的溪流内环境因素(如流速、底质组成等), 是可能影响不同性状多样性海拔格局差异性的重要原因。
水生昆虫生活史性状多样性沿海拔梯度呈现显著的线性或二次关系, 其空间格局显著响应气候和土地利用变化。快季节性、成虫寿命极短和多于1世代的水生昆虫, 其生活史性状多样性均呈显著的单峰型海拔格局, 表明其群落组成拥有较高的多化性、较快的发育速度和较短的寿命等性状多样性, 是群落适应不利环境的一种生活史策略(Usseglio- Polatera et al, 2000; Pilière et al, 2016)。反之, 慢季节性、成虫寿命较长、少于1世代(或1世代)的水生昆虫, 其生活史性状多样性呈“U”型海拔格局。生活史性状多样性单峰和“U”型海拔格局在中低海拔处分别高于和低于高海拔处, 在海拔2,000 m左右达到峰值和最低值; 其原因可能是随着海拔高度降低, 气温降水梯度显著改变, 人类活动强度增加, 农业活动强度和用地面积增加, 森林覆盖度下降, 引起环境趋于同质化, 水温、水量变化幅度和频率降低等(Belmar et al, 2019)。水生昆虫适应频繁变化或不可预测环境干扰的功能性状包括快速生长发育、具滞育或休眠阶段、个体较小、成虫寿命较短以及扩散能力较强等(Vinson & Hawkins, 2003), 但影响不同生活史性状的因素存在差异性; 如生活史快慢和成虫寿命性状多样性主要受森林用地、气温和降水的影响, 但化性多样性同时受到不透水面积、农业用地面积以及气温和降水的影响(Barnum et al, 2017)。
水生昆虫生态学性状对流域尺度气候和土地利用的响应程度较低, 可能主要受到溪流内栖境(流速、底质组成、有机物等)的影响(韩洁等, 2019; Piano et al, 2020)。气候和土地利用的综合作用能够影响和改变溪流内生物栖境和水流流态(Lytle & Poff, 2004), 年平均气温、森林面积、农业用地面积、不透水面积等共同改变溪流河道的自然水文过程, 影响不同季节的溪流流速、流量等, 同时引起溪流内水温、溶解氧、pH值、总氮、总磷等理化因素的改变(Colzani et al, 2013; 韩洁等, 2019)。虽然温度偏好性状多样性对海拔梯度无响应, 但广温性水生昆虫在各个海拔段占据优势地位, 其生态学性状多样性随海拔梯度呈现单峰型变化, 这可能是在中海拔流域, 受水温和降水的季节差异性的影响(Larned et al, 2010), 溪流水温变化频繁, 水生昆虫群落适应性提高(Bogan et al, 2017; Piano et al, 2020), 因此具广温性水生昆虫在中海拔会占据主要生态位。喜凉物种的海拔分布特征同时受到气温和土地利用变化的影响, 但喜温物种仅受到不透水面积的影响, 可能原因是不透水面积增加导致沿岸带隐蔽度降低, 暴露程度更高的溪流具有更高的水温(Paul & Meyer, 2001)。
从高海拔到低海拔的溪流点位, 由于不透水面积的增加, 引起外源性有机碎屑输入中粗颗粒有机物减少, 细有机颗粒物增加, 溪流中沉积物逐渐增加, 不仅造成溪流内微生境的改变, 同时造成不同海拔段食物来源比例发生变化(Vannote et al, 1980; 王强等, 2017)。攀附者和游泳者性状多样性对气候和土地利用解释变量无响应, 可能原因是攀附者和游泳者受到点位尺度的溪流沉积物覆盖度(Rabení et al, 2005)和溪流底质粗糙度(Lamouroux et al, 2004)的显著影响。低海拔溪流沉积物和不透水面积的增加使穴居类群的栖息地可用性提高, 掘穴者多样性则随着海拔增加而降低(Fogaça et al, 2013; Barnum et al, 2017), 依赖于激流和大石块生境的附着者多样性则随着海拔增加而增加。爬行者多样性沿海拔梯度呈“U”型分布格局, 其多样性主要受到农业用地面积和气温的影响, 说明在低海拔地区农业用地和高海拔气温较低的区域, 水生昆虫群落主要以爬行者为主(Knysh et al, 2016)。植食者多样性随海拔增加而降低, 主要受到气温影响, 说明在温度较高的低海拔区域以藻类为食的植食者多样性较高(Tanaka & Mano, 2012)。滤食者多样性主要受到细颗粒有机物和流速的影响, 农业用地面积和降水是主要影响因子, 随海拔梯度降低, 溪流急流生境减少且细颗粒有机物含量增加, 因此滤食者多样性沿海拔梯度呈现显著递增的分布格局。捕食者类群主要为定殖类群, 原石蛾科和襀科作为捕食者中的优势类群, 其生活习性为爬行者; 同时, 由于高海拔的捕食者相互竞争作用强烈, 部分捕食者类群选择向低海拔地区扩散并定殖(Pilière et al, 2016), 因此捕食者多样性呈现出显著的“U”型海拔格局。集食者取食溪流底部的有机碎屑, 由于低海拔地区流速低, 有机碎屑较易沉积(王博涵等, 2017), 因此集食者沿海拔梯度降低而增加。撕食者主要取食枯枝落叶, 能够反映沿岸带植被覆盖密度的变化和河道底部堆积的情况(Haapala et al, 2003; 蒋万祥等, 2009), 相对于源头溪流沿岸带植被茂密覆盖度高, 低海拔溪流植被覆盖度普遍较低、农田较多, 撕食者多样性呈现中低海拔地区低于高海拔地区的变化趋势。
与其他平原和山区不同流域水生昆虫对气候和土地利用变化的响应相比, 本研究在澜沧江中游的研究也展示了相似的结果, Liu等(2021)研究发现随海拔梯度降低, 汉江上游流域的土地类型由森林用地为主逐渐转变为农田和城镇用地, 低海拔溪流因此存在更高的多化性、发育速度快、成虫寿命短、滤食者和集食者的水生昆虫性状多样性。Scotti等(2020)对欧洲阿尔卑斯山脉溪流的研究发现, 在低海拔、中海拔和高海拔的土地利用类型主要为牧场、森林以及草地和岩石, 低海拔溪流拥有较高的喜温底栖动物性状多样性, 中海拔溪流主要为1世代和撕食者性状的底栖动物类群, 高海拔溪流的多于1世代、成虫寿命短、滤食者的底栖动物性状多样性最高。
附录 Supplementary Material
附录1 澜沧江云南段中游水生昆虫分类单元名录
Appendix 1 Taxon list of the identified aquatic insect taxa in the middle of the Lancang River Basin, Yunnan Province, China
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DOI:10.17520/biods.2019359
[本文引用: 1]
群落分类多样性和功能多样性的海拔格局研究, 是了解生物多样性空间分布现状、揭示多样性维持和变化机制的重要途径。当前对水生昆虫分类多样性和功能多样性沿海拔梯度分布格局, 及其尺度依赖性依旧缺乏深入研究。本文基于2013-2018年在云南澜沧江流域500-3,900 m海拔梯度共149个溪流点位的水生昆虫群落调查数据, 利用线性或二次回归模型探索并比较了局部尺度(点位尺度)和不同区域尺度(100 m、150 m、200 m、250 m海拔段)的分类多样性指数(物种丰富度指数、Simpson多样性指数和物种均匀度指数)和功能多样性指数(树状图功能多样性指数(dbFD)、Rao二次熵指数(RaoQ)和功能均匀度指数(FEve))的海拔格局。结果表明, 在局部尺度, 物种丰富度指数和dbFD指数沿海拔梯度均无显著分布特征, Simpson多样性指数、RaoQ指数、物种均匀度指数和FEve指数沿海拔梯度呈现U型或者单调递减趋势。在区域尺度, 随着区域海拔带宽度的增加, 物种丰富度指数沿海拔呈不显著的单调递减格局, 但dbFD指数沿海拔分布由U型转变为单调递减趋势; Simpson多样性指数和RaoQ指数沿海拔梯度由显著U型趋势转变为无显著分布特征; 物种均匀度指数沿海拔梯度无显著分布特征, 但FEve指数呈显著增加的海拔格局。综上, 群落分类多样性指数和功能多样性指数沿海拔梯度分布存在局部和区域尺度的空间差异, 但区域尺度下二者海拔格局随海拔带宽度的增加存在一定程度的一致性。
Application of Akaike’s information criterion (AIC) in the evaluation of linear pharmacokinetic equations
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