Instituto de Física, Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo, CP 11400, Uruguay.
Departamentos de Sistemas Ambientales y Producción Animal y Pasturas, Facultad de Agronomía, Universidad de la República, Garzón 780, Montevideo, CP 12900, Uruguay.
Ecol Appl. 2017 Dec;27(8):2277-2289. doi: 10.1002/eap.1605. Epub 2017 Oct 19.
The contribution of plant species richness to productivity and ecosystem functioning is a longstanding issue in ecology, with relevant implications for both conservation and agriculture. Both experiments and quantitative modeling are fundamental to the design of sustainable agroecosystems and the optimization of crop production. We modeled communities of perennial crop mixtures by using a generalized Lotka-Volterra model, i.e., a model such that the interspecific interactions are more general than purely competitive. We estimated model parameters -carrying capacities and interaction coefficients- from, respectively, the observed biomass of monocultures and bicultures measured in a large diversity experiment of seven perennial forage species in Iowa, United States. The sign and absolute value of the interaction coefficients showed that the biological interactions between species pairs included amensalism, competition, and parasitism (asymmetric positive-negative interaction), with various degrees of intensity. We tested the model fit by simulating the combinations of more than two species and comparing them with the polycultures experimental data. Overall, theoretical predictions are in good agreement with the experiments. Using this model, we also simulated species combinations that were not sown. From all possible mixtures (sown and not sown) we identified which are the most productive species combinations. Our results demonstrate that a combination of experiments and modeling can contribute to the design of sustainable agricultural systems in general and to the optimization of crop production in particular.
植物物种丰富度对生产力和生态系统功能的贡献是生态学中的一个长期存在的问题，对保护和农业都有相关的影响。实验和定量建模都是设计可持续农业生态系统和优化作物生产的基础。我们使用广义的Lotka-Volterra 模型来模拟多年生作物混合物的群落，即一种种间相互作用比纯粹竞争更普遍的模型。我们从美国爱荷华州的一个大型多年生草料物种多样性实验中分别观察到的单种和双种生物量来估计模型参数 - 承载能力和相互作用系数。相互作用系数的符号和绝对值表明，物种对之间的生物相互作用包括非共生、竞争和寄生（不对称的正负相互作用），其强度各不相同。我们通过模拟两种以上物种的组合并将其与多物种实验数据进行比较来检验模型拟合度。总体而言，理论预测与实验结果吻合较好。使用该模型，我们还模拟了未播种的物种组合。从所有可能的混合物（播种和未播种）中，我们确定了哪些是最具生产力的物种组合。我们的结果表明，实验和建模的结合可以为一般可持续农业系统的设计和作物生产的优化做出贡献。
