1. Process‐based forest models (PBMs) are important tools for quantifying forest growth and vulnerability, particularly under climate change. The 3‐PG model (Physiological Processes Predicting Growth) is one of the most widely used forest growth simulators for this purpose worldwide.
2. Here, we present r3PG, a new Fortran implementation of 3‐PG, wrapped into an r package. r3PG can simulate monospecific as well as mixtures of evergreen and deciduous tree species in even‐aged or uneven‐aged stands.
3. The combination of Fortran functions with an r interface makes the model extremely fast. This facilitates the use of r3PG for extensive computer experiments and sensitivity analysis. We demonstrate this in a case study including (a) single model runs; (b) a sensitivity analysis and a full Bayesian calibration of the model and (c) spatial simulations of forest growth across Switzerland.
4. r3PG is faster and easier to use than previous implementations of 3‐PG in visual basic. We believe that this will make 3‐PG even more useful and popular for ecologists and climate change scientists.

中文翻译：

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r3PG –使用基于3-PG过程的模型模拟森林生长的r包

1. 基于过程的森林模型（PBM）是量化森林生长和脆弱性（尤其是在气候变化下）的重要工具。3-PG模型（预测生长的生理过程）是全球范围内为此目的使用最广泛的森林生长模拟器之一。
2. 在这里，我们介绍r3PG，它是3-PG的新Fortran实现，包装到r包中。r3PG可以模拟均匀年龄或不均匀年龄林分中的单物种以及常绿和落叶树种的混合物。
3. Fortran函数与r接口的组合使模型非常快速。这有助于将r3PG用于广泛的计算机实验和灵敏度分析。我们在一个案例研究中证明了这一点，该案例研究包括：（a）单个模型运行；（b）对该模型进行敏感性分析和完整的贝叶斯校准，以及（c）瑞士各地森林生长的空间模拟。
4. 与Visual Basic中以前的3‐PG实现相比，r3PG更快，更易于使用。我们相信，这将使3-PG对于生态学家和气候变化科学家而言更加有用和受欢迎。