Biodiversity and Ecosystem Functioning（生物多样性和生态系统功能）

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（一）作者简介

G. David Tilman，美国著名生态学家，任教于美国明尼苏达大学，主要研究方向为资源竞争和生态系统多样性。代表性文章为“Tilman, David; Downing, John A. (1994). “Biodiversity and stability in grasslands”. Nature. 367 (6461): 363–365”和“Tilman, David (1994). “Competition and Biodiversity in Spatially Structured Habitats” . Ecology. 75 (1): 2–16.”

（二）摘要

本文为综述论文，主要讨论了生物多样性对生态系统功能的影响。

标题中的生物多样性值物种的多样性，生态系统功能主要指生产力，稳定性，入侵性和营养动态。
总体而言，生物多样性的增加会促进生态系统功能，而且这种影响会随着时间的推移越发显著。

全文作者主要想回答如下四个问题：

Q1: Are diversity effects real—that is, can they be documented in well-designed experiments? （生物多样性对生态系统功能的影响是真的吗？可以通过设计实验证明影响的存在吗？）
Q2: What underlying processes and mechanisms could cause changes in diversity to impact ecosystem functioning? （生物多样性对生态系统功能的影响背后涉及的机理和过程是什么？)
Q3: How general are diversity effects?(这种影响是广泛存在于自然界中的吗？）
Q4: How important are diversity effects—that is, how large are they relative to effects of other factors? （生物多样性相对于其他因子，如干旱，CO2浓度，氮浓度，其对生态系统功能的影响会更大吗？）

Q1: Are diversity effects real—that is, can they be documented in well-designed experiments? （生物多样性对生态系统功能的影响是真的吗？可以通过设计实验证明影响的存在吗？）

20实际90年代以来，人们开展了一些实验来检验物种多样性-生态功能关系，并试图揭示多样性的作用机制。这些实验得到了一定结论，但也存在很多争议（张全国等，2002）
“生态箱”实验、“Cedar Creek”草地多样性实验、微宇宙实验、欧洲草地实验

Q2: What underlying processes and mechanisms could cause changes in diversity to impact ecosystem functioning? （生物多样性对生态系统功能的影响背后涉及的机理和过程是什么？)

Timan在文章中总结了diversity-productivity theory、diversity-invasion theory以及diversity-stability，这里主要介绍前两个。

1. Diversity-productivity theory 物种多样性与生产力的关系及作用机理

生态系统生产力是生态系统功能的重要表现形式，而植物群落的生产力则是生态系统生产力的基础。物种多样性对系统生产力有重要影响，其相关格局主要有三种形式(江小雷,2010)：

A.群落生产力随物种多样性的增加而增加;
B.群落生产力随物种多样性的增加而增加；
C.群落生产力随物种多样性的增加而增加，在物种多样性水平中等时达到最大，之后随着物种多样性的继续增加而下降。

目前，对于促成这种关系的潜在生态学机理缺乏足够的了解，有关物种多样性-生产力关系模型和作用机理存在很多争议。对于多样性和生产力的正相关作用机理(即A)主要有两种假设：抽样效应(sampling/selecting effects)，生态位互补效应（niche complementarity）(江小雷,2010).

抽样效应: 指物种丰富的群落有更大的可能性包含高产物种，而这些高产物种往往成为生态系统功能的主要贡献者(张全国,2003)
生态位互补: 不同物种在资源利用上存在差异,或者物种之间存在正的相互关系，这预示着物种多样性会导致生态系统功能的优化。(张全国,2003)
超产（transgressive overyielding）: 混合群落生产力高于其所含任何物种的单产，超产现象的出现意味着互补机制必然在发挥作用(张全国,2003)

( ps: 关于这三者更详细的定义也可参考(张全国,2002)，是2002噢！)

物种多样性的长期作用机制：“ 抽样”向“ 互补”转型？

Tilman的文章中显示，在短期观测实验中不存在超产现象，但是随着时间的推移，超产现象开始出现（下面两张图来自Tilman的文章）
下面为（张全国，2003）文中给出的解释

下面给出另外两篇英文文章，及维基百科中关于抽样效应和生态位互补的解释和示意图作为补充

（1）Barot, Sébastien, et al. 2017

Links between species diversity and ecosystem functioning

The impact of biodiversity on ecosystem functioning has extensively been studied through manipulations of species richness. This has led to a wealth of experimental studies and a comprehensive general framework, most of which can also be transposed to within-species genetic diversity, which is our focus here. Positive effects of species richness on ecosystem functioning (especially biomass production, we hereafter use the term production for biomass production in natural ecosystems and for the yield in agro-ecosystems) have been shown to arise due to two types of mechanisms (Loreau and Hector 2001) that can be disentangled through a variance partitioning approach (Loreau 1998): sampling effects and complementarity between species.

Sampling effects (Fig. 2, left) arise because communities with more species are more likely to host species that perform the best in a given environment. This requires that the more productive species dominate the community in terms of biomass or space occupancy, so that sampling effects are also called selection effects. Sampling effects lead to overyielding, i.e., on average diverse communities are more productive than the mean production of monocultures. In a constant environment, knowledge on the best performing species is enough to obtain a highly productive ecosystem. However, sampling effects occur both in space and time because environmental conditions vary among locations (e.g., due to soil properties) and years (e.g., due to climate) so that the best performing species is generally not the same across space and time.
Complementarity effects (Fig. 2, right) arise because of complementarity in the resource use or the ecological niches of different species (e.g., for soil mineral resources, Bessler et al. 2009; Scherer-Lorenzen et al. 2003) and/or because of facilitation between species (e.g., legumes providing nitrogen to non-legumes, Spehn et al. 2002). These effects may increase total ecosystem biomass production, sometimes leading to a production higher than that of the most productive monoculture. This is called transgressive overyielding.

（2）博士论文Salazar-Diaz, Ricardo… 2017 link

（3）Wiki：Effects on community productivity link

2. Diversity-Invasion theory 物种多样性与入侵性的关系及作用机理

(江小雷,2010)

3. Diversity-Stability theory

这里暂时不介绍，没读完

Q3: How general are diversity effects?(这种影响是广泛存在于自然界中的吗？

Tilman的观点： Hundreds of studies spanning terrestrial, aquatic, and marine ecosystems show that high-diversity mixtures are approximately twice as productive as monocultures of the same species and that this difference increases through time.
此外，Tilman还强调了考虑生态系统多功能性（下图），中文文献可以结合（王凯2022，link）
同时，Tilman还强调了考虑不同营养级的重要性（下图），中文文献可以结合（张全国，2003，英文文献可以结合（Brose, Ulrich，2016，link）

Q4: How important are diversity effects—that is, how large are they relative to effects of other factors? （生物多样性相对于其他因子，如干旱，CO2浓度，氮浓度，其对生态系统功能的影响会更大吗？）

Tilman的观点：Diversity loss has an effect as great as, or greater
than, the effects of herbivory, fire, drought, nitrogen addition, elevated CO2,
and other drivers of environmental change. The preservation, conservation,
and restoration of biodiversity should be a high global priority.
气候变化对生物多样性和生态系统功能的影响是个有趣的话题，《生物多样性公约》第十五次缔约方大会（COP15）重新确定于2021年5月17日至30日在云南省昆明市举办，有兴趣可以进一步了解，网址为 link

终于写完了，Tilman的这篇文章是课上选读的文章，因为没接触过，很多专业术语都不知道，趁着还有印象赶紧记一下。

（三）Reference

[1] 徐炜, et al. “生物多样性与生态系统多功能性: 进展与展望.” 生物多样性 24.1 (2016): 55.
[2] 张全国, and 张大勇. “生物多样性与生态系统功能: 进展与争论.” 生物多样性 10.1 (2002): 49-60.
[3] 张全国, and 张大勇. “生物多样性与生态系统功能: 最新的进展与动向.” 生物多样性 11.5 (2003): 351.
[4] 赵峰侠, and 徐明. “生产力与生物多样性关系的研究进展.” 自然资源学报 33.11 (2018): 2046-2056.
[5] 张景慧, and 黄永梅. “生物多样性与稳定性机制研究进展.” 生态学报 36.13 (2016).
[6] 王凯, 王聪, 冯晓明,等. 生物多样性与生态系统多功能性的关系研究进展[J]. 生态学报, 2022, 42(1):13.link
[7] 江小雷, 岳静, 张卫国,等. 生物多样性,生态系统功能与时空尺度[J]. 草业学报, 2010, 19(1):7. link
[8] 生态学中的选择效应和互补效应怎么理解？https://www.zhihu.com/question/433547288
[9] 维基百科：Ecological effects of biodiversity wiki: link
[10] 综述：Barot, Sébastien, et al. “Designing mixtures of varieties for multifunctional agriculture with the help of ecology. A review.” Agronomy for sustainable development 37.2 (2017): 1-20.
[11] 综述： Brose, Ulrich, and Helmut Hillebrand. “Biodiversity and ecosystem functioning in dynamic landscapes.” Philosophical Transactions of the Royal Society B: Biological Sciences 371.1694 (2016): 20150267. link
[11] 博士论文：Salazar-Diaz, Ricardo. Effect of plant diversity on the production of multi-species cropping systems, case of agroforestry systems in Talamanca, Costa Rica. Diss. Université de Montpellier, 2017. link