Short‐term plant–soil feedback experiment fails to predict outcome of competition observed in long‐term field experiment
Short‐term plant–soil feedback experiment fails to predict outcome of competition observed in long‐term field experiment
复制标题
短期植物-土壤反馈实验无法预测长期田间实验中观察到的竞争结果
DOI：
10.1002/ecy.3883
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发表时间：
2022
期刊：
影响因子：
4.8
通讯作者：
Tilman, David
中科院分区：
文献类型：
--
作者：
Beckman, Noelle G.;Dybzinski, Ray;Tilman, David
越来越多的证据表明，植物-土壤反馈(PSF)可能决定植物群落结构。然而，我们仍然对短期PSF实验的预测与涉及竞争植物的长期田间实验的结果进行了怎样的比较，我们仍然缺乏理解。我们进行了温室互作试验，以考察草原草物种的生长如何依赖于田间种植的同种或异种植物所培养的土壤群落。来源土壤来自长期竞争实验中的单一养殖(LTCE；美国明尼苏达州雪松溪生态系统科学保护区)。在LTCE内，在土壤氮素有效性低或高的条件下，6种多年生草原草在单一栽培或8个成对竞争小区中种植了12年。在六个案例中，一个物种明确排除了另一个物种；在两个案例中，这两个物种似乎共存。在第15年，我们收集了所有12种土壤类型的土壤(按两个氮素水平单一培养6种植物)，并在每种土壤类型中种植所有6种植物的幼苗7周。使用这次温室实验的生物量估计，我们使用Bever和他的同事推导的成对PSF预测了共存或竞争排除，并将模型预测与LTCE中的观测结果进行了比较。物种对之间的PSF从负值到正值不等，前者被预测为促进共存，后者被预测为促进竞争排斥。然而，这些短期PSF预测与在LTCE中观察到的竞争的实际结果没有系统的相似之处。其他力量可能对PSF预测背后的竞争互动或关键假设产生了更强烈的影响，这些假设可能没有得到满足。重要的是，由Bever等人得出的成对PSF评分。只有当两个物种表现出内部平衡时才有效，该平衡对应于稳定共存和创始人控制的Lotka-Volterra竞争结果。预测另外两种情况，无论初始条件如何，都会被任何一个物种竞争排除，这需要测量未培养土壤的生物量，这在方法上具有挑战性。根据我们讨论的几个警告，我们的结果提出了一个问题，即是否可以从短期PSF实验的结果预测该领域的长期竞争结果。
Mounting evidence suggests that plant–soil feedbacks (PSF) may determine plant community structure. However, we still have a poor understanding of how predictions from short‐term PSF experiments compare with outcomes of long‐term field experiments involving competing plants. We conducted a reciprocal greenhouse experiment to examine how the growth of prairie grass species depended on the soil communities cultured by conspecific or heterospecific plant species in the field. The source soil came from monocultures in a long‐term competition experiment (LTCE; Cedar Creek Ecosystem Science Reserve, MN, USA). Within the LTCE, six species of perennial prairie grasses were grown in monocultures or in eight pairwise competition plots for 12 years under conditions of low or high soil nitrogen availability. In six cases, one species clearly excluded the other; in two cases, the pair appeared to coexist. In year 15, we gathered soil from all 12 soil types (monocultures of six species by two nitrogen levels) and grew seedlings of all six species in each soil type for 7 weeks. Using biomass estimates from this greenhouse experiment, we predicted coexistence or competitive exclusion using pairwise PSFs, as derived by Bever and colleagues, and compared model predictions to observed outcomes within the LTCE. Pairwise PSFs among the species pairs ranged from negative, which is predicted to promote coexistence, to positive, which is predicted to promote competitive exclusion. However, these short‐term PSF predictions bore no systematic resemblance to the actual outcomes of competition observed in the LTCE. Other forces may have more strongly influenced the competitive interactions or critical assumptions that underlie the PSF predictions may not have been met. Importantly, the pairwise PSF score derived by Bever et al. is only valid when the two species exhibit an internal equilibrium, corresponding to the Lotka–Volterra competition outcomes of stable coexistence and founder control. Predicting the other two scenarios, competitive exclusion by either species irrespective of initial conditions, requires measuring biomass in uncultured soil, which is methodologically challenging. Subject to several caveats that we discuss, our results call into question whether long‐term competitive outcomes in the field can be predicted from the results of short‐term PSF experiments.