兰州大学机构库 >生态学院
植物群落结构对叶片真菌病害影响的空间尺度依赖性研究
Alternative TitleSpatial scale-dependence of plant community structure effects on the foliar fungal diseases
王星星
Subtype硕士
Thesis Advisor刘向
2023-09-04
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name理学硕士
Degree Discipline生态学
Keyword高寒草甸 Alpine Meadows 稀释效应 Dilution Effect 密度效应 Density Effect 疾病生态学 Disease Ecology 整合分析 Meta-Analysis
Abstract

在生物多样性快速丧失的大背景下,理解生物多样性/宿主密度与传染性疾病之间的关系尤为重要。先前研究在探讨二者关系时,往往忽视了空间尺度可能带来的影响。通常而言,生物多样性与传染性疾病之间存在稀释效应(增加宿主多样性可以降低疾病风险);而宿主密度则通过密度效应影响传染性疾病(增加宿主密度可以增加疾病风险)。空间尺度可能直接影响稀释效应和密度效应的方向与强度。本研究以青藏高原高寒草甸为模式系统,基于野外控制性实验和数据整合分析两种研究方式,检验空间尺度对植物多样性与叶片真菌病害稀释效应和植物密度与叶片真菌病害密度效应的影响,具体如下:

一、基于青藏高原高寒草甸长期氮添加实验(氮添加梯度为 0、5、10 和 15g/m2),在实验样方内分别设置面积为 0.125 × 0.125 m,0.25 × 0.25 m 和 0.5 × 0.5m 的三种小样方,调查小样方内植物叶片真菌病害严重度,并结合宿主植物多度、非宿主植物相对多度和物种丰富度等指标,检验空间尺度对植物多样性与叶片真菌病害关系的影响。结果显示:在较小的空间尺度下稀释效应更强;同时多组结构方程模型结果显示,氮添加仅在 0.125 × 0.125 m 的空间尺度下通过降低物种丰富度增加叶片真菌病害,即表现出稀释效应。

二、通过整合 22 项研究中的 134 个案例发现植物群落中稀释效应受空间尺度的影响。从整体上看,在空间尺度相对较小的研究中更容易观察到稀释效应。同时本研究发现稀释效应的空间尺度依赖性在不同体系中有所差异:分实验设计来看,在观察性研究中,稀释效应在小的空间尺度下更强;而在实验性研究未观察到稀释效应的空间尺度依赖性。分生态系统类型来看,草地生态系统和森林生态系统中均未观察到稀释效应的空间尺度依赖性。

三、基于青藏高原高寒草甸长期放牧实验,在实验样方内分别设置面积为0.125 × 0.125 m,0.25 × 0.25 m 和 0.5 × 0.5 m 的三种小样方,调查小样方内植物叶片真菌病害严重度,并结合宿主植物多度、非宿主植物相对多度和物种丰富度等指标,检验空间尺度对植物密度与叶片真菌病害关系的影响。结果显示较小的空间尺度下宿主植物多度与物种水平病害严重度呈显著正相关,即密度效应在相对较小的空间尺度下更强。

四、通过整合 84 项研究中的 189 个案例发现在空间尺度相对较大的研究中更容易观察到密度效应,这与氮添加实验所得出的结果相反。这可能是与在该整合分析中农业生态系统案例居多有关,农业生态系统中植株个体通常较大,在较大的空间尺度下病原真菌才更容易在植株之间广泛传播,因此密度效应更容易在较大的空间尺度下被观察到。同时,本研究发现密度效应的空间尺度依赖性在不同体系中有所差异:分实验设计来看,在实验性研究中空间尺度和效应大小(Z)之间显著正相关,即密度效应在大的空间尺度下更强;而在观察性研究中未观察到密度效应的空间尺度依赖性。分植物种类来看,草本植物中密度效应在大的空间尺度下更强;而在木本植物中未观察到密度效应的空间尺度依赖性。分病原真菌生活史类型来看,死体营养型病原真菌中密度效应在大的空间尺度下更强;而在活体营养型病原真菌和半活体营养型病原真菌未观察到密度效应的空间尺度依赖性。分生态系统类型来看,农业生态系统中密度效应在大的空间尺度下更强;而在自然生态系统中未观察到密度效应的空间尺度依赖性。

本研究证实了空间尺度直接影响植物多样性/植物密度与叶片真菌病害之间的关系,阐明了空间尺度在调节植物多样性/植物密度与病害关系时所起的作用,也提醒生态学家在预测植物叶片真菌病害时需考虑空间尺度的影响。同时,由于生物多样性效益在局域尺度和区域尺度并不相同,因此在制定生物多样性保护政策时也需要将空间尺度的影响纳入考量。

Other Abstract

It is essential to understand the relationship between biodiversity diversity/host density and infectious diseases on the background of rapid biodiversity loss. Many previous studies often ignored the impact of spatial scale on the relationship. In fact, there is a dilution effect between biodiversity and infectious diseases (increasing host diversity reduces disease risk). Host density may influence infectious diseases through density effect (increasing host density increases disease risk). Spatial scale can affect the direction and strength of dilution and density effects. In this study, we combined both field manipulative experiments and meta-analyses to explore the impacts of spatial scale on the relationships between plant diversity/density and foliar fungal diseases in Qinghai-Tibet alpine meadows, and the details are as follows:

1. We conducted a long-term nitrogen addition experiment in Qinghai-Tibet alpine meadows with 0, 5, 10 and 15 g/m2 nitrogen addition treatments. Within the treatment plots, we arranged three types of small quadrats with areas of 0.125 × 0.125 m, 0.25 × 0.25 m and 0.5 × 0.5 m to test how spatial scale affects the relationships between plant species richness, focal host abundance, the relative abundance of non-host and foliar fungal disease severity. We found that the dilution effect can be more easily observed at smaller spatial scales. Based on multigroup structural equation models, we found that nitrogen addition strengthened the dilution effect by reducing species richness only at 0.125 × 0.125 m spatial scale.

2. We gathered data from 134 cases presented in 22 studies to test the universality of scale-dependent dilution effects in plant communities. We found a marginally significant positive association between plot area and biodiversity-disease relationships in plant communities. The dilution effects were more easily observed in relatively smaller spatial-scale studies. Meanwhile, comparing different study systems, we found that the spatial scale dependence of the dilution effects varied among systems: Comparing the experimental designs, we found that dilution effects were more easily observed at smaller spatial scales in observational studies, but there was no significant IV relationship in manipulative studies. Comparing different ecosystems, we found that dilution effects were no significant relationships in grassland ecosystems and forest ecosystems.

3. We conducted a long-term grazing experiment in Qinghai-Tibet alpine meadows. Within the treatment plots, we arranged three types of small quadrats with areas of 0.125 × 0.125 m, 0.25 × 0.25 m and 0.5 × 0.5 m to test how spatial scale affects the relationships between plant species richness, focal host abundance, the relative abundance of non-host and foliar fungal disease severity. We found a significant positive association between host abundance and foliar fungal disease severity at 0.125 × 0.125 m spatial scale. The density effect is stronger at relatively small spatial scales

4. We gathered data from 189 cases presented in 84 studies to test the universality of scale-dependent density effects in plant communities. We found that density effects were more easily observed in studies with relatively large spatial scales. The grazing experiment results are the opposite of the nitrogen addition experiment. Because agricultural systems account for the majority in this meta-analysis: Plants are larger in agricultural systems than in natural systems, and fungal pathogens are more likely to spread on plants at larger spatial scales, so density effects are easier observed at larger spatial scales. We also found that the spatial scale dependence of the dilution effects varied among systems. Comparing experimental designs, we found that density effects were more easily observed at small spatial scales in manipulative studies. But there was no significant relationship in observational studies. Comparing the plant types, we found that density effects were more easily observed at small spatial scales in herbaceous plants, but there was no significant relationship in woody plants. Comparing the life histories, we found that density effects were more easily observed at small spatial scales in necrotroph pathogens, but there were no significant relationships in biotroph pathogens and hemibiotroph pathogens. Comparing the ecosystem types, we found that density effects were more easily observed at small spatial scales in agricultural systems, but there was no significant relationship in natural ecosystems.

We confirmed that the spatial scale directly affected the relationship between plant diversity/density and foliar fungal diseases, clarified the roles of spatial scale in regulating the relationship between plant diversity and disease risk, and reminded ecologists to consider the impact of spatial scale when predicting the foliar fungal diseases. Since biodiversity benefits differ at the local and regional scales, spatial impacts should also be considered when formulating biodiversity conservation policies.

MOST Discipline Catalogue理学 - 生态学
URL查看原文
Language中文
Other Code262010_220200930040
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/538058
Collection生态学院
Affiliation
兰州大学生态学院
Recommended Citation
GB/T 7714
王星星. 植物群落结构对叶片真菌病害影响的空间尺度依赖性研究[D]. 兰州. 兰州大学,2023.
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