Pastures represent the main land use type in Brazil and are used for livestock production and maintenance of land ownership. Most pasture areas exhibit signs of degradation related to inadequate management, which affects pasture biomass production. Terrestrial ecosystem models are effective tools for evaluating the economic and ecological returns associated with distinct management scenarios. In this paper, a new forage module implemented in the ECOSystem MOdel Simulator (ECOSMOS) is formulated, and ECOSMOS-Forage model calibration and evaluation results were obtained for estimating tropical forage growth under continuous and rotational stocking methods subject to grazing or cutting regimes. A set of equations to simulate the daily carbon allocation, growth, senescence, and morphological characteristics of cvs Marandu and Piatã were proposed. Biophysical and physiological parameters, including the solar radiation balance, soil water content, evapotranspiration and carbon assimilation, were calibrated and evaluated with one micrometeorological experiment. Additionally, two sets of parameters were calibrated for Marandu grass growth under continuous and rotational stocking. Based on the Marandu parameterization, a third set of parameters, thereby adjusting a few parameters, was derived for the Piatã grass under rotational stocking. The ECOSMOS-Forage model could successfully capture the energy, carbon and water fluxes and biomass dynamics during growth cycles. The net radiation, evapotranspiration and gross primary production were simulated with agreement index () values of 0.97, 0.89, and 0.95, respectively, during the calibration phase and 0.98, 0.90, and 0.93, respectively, during the evaluation phase. Regarding model application to simulate forage growth under rotational stocking, the model could estimate aboveground, leaf and stem dry matter accumulation levels with values ranging from 0.91 to 0.98. Although forage growth is relatively difficult to simulate, compared with annual crops, the results suggested that the model could provide high potential for simulating tropical perennial forage grasses.

中文翻译：

---

一种新的多年生饲料模块与 ECOSMOS 陆地生态系统模型相结合：Urochloa（同义词 Brachiaria）brizantha 的校准和评估


牧场是巴西的主要土地利用类型，用于畜牧生产和土地所有权的维护。大多数牧场表现出与管理不善有关的退化迹象，这影响了牧场生物量的生产。陆地生态系统模型是评估与不同管理方案相关的经济和生态回报的有效工具。本文制定了在 ECOSystem MOdel Simulator (ECOSMOS) 中实现的新饲料模块，并获得了 ECOSMOS-Forage 模型校准和评估结果，用于估计放牧或切割制度下连续和轮流放养方法下的热带饲料生长。提出了一组方程来模拟 cvs Marandu 和 Piatã 的日常碳分配、生长、衰老和形态特征。通过一项微气象实验对太阳辐射平衡、土壤含水量、蒸散量和碳同化等生物物理和生理参数进行了校准和评估。此外，还针对连续和轮换放养下马兰杜草的生长校准了两组参数。基于 Marandu 参数化，针对循环放养下的 Piatã 草导出了第三组参数，从而调整了一些参数。 ECOSMOS-Forage 模型可以成功捕获生长周期期间的能量、碳和水通量以及生物量动态。净辐射、蒸散量和总初级生产的模拟，校准阶段的一致性指数 ( ) 值分别为 0.97、0.89 和 0.95，评估阶段的一致性指数 ( ) 值分别为 0.98、0.90 和 0.93。 关于模型应用来模拟循环放养下的牧草生长，该模型可以估计地上、叶和茎干物质积累水平，其值范围为0.91至0.98。尽管与一年生作物相比，牧草生长相对难以模拟，但结果表明该模型可以为模拟热带多年生牧草提供很大的潜力。