The juvenile life stage is a crucial determinant of forest dynamics and a first indicator of changes to species' ranges under climate change. However, paucity of detailed re‐measurement data of seedlings, saplings and small trees means that their demography is not well understood at large scales, and rarely represented in forest models in detail. In this study we quantify the effects of climate and density dependence on recruitment and juvenile growth and mortality rates of thirteen species measured in the Spanish Forest Inventory. Single‐census sapling count data is used to constrain demographic parameters of a simple forest juvenile dynamics model based on the perfect plasticity approximation model (PPA) within a likelihood‐free parameterisation method, Approximate Bayesian Computation. Our results highlight marked differences between species, and the important role of climate and stand structure, in controlling juvenile dynamics. Recruitment had a hump‐shaped relationship with conspecific density, and for most species conspecific competition had a stronger negative effect than heterospecific competition. Mediterranean species showed on average higher mortality and lower growth rates than temperate species, and in low density stands recruitment and mortality rates were positively correlated. Under climate change our model predicted declines in recruitment rates for almost all species. Reliable predictive models of forest dynamics should include realistic representation of critical early life‐stage processes and our approach demonstrates that existing coarse count data can be used to parameterise such models. Approximate Bayesian Computation may have wide application in many fields of ecology to unlock information about past processes from single survey observations.

中文翻译：

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使用近似贝叶斯计算从计数数据中捕获幼树动态

幼年期是决定森林动态的关键因素，也是气候变化下物种范围变化的第一个指标。然而，由于缺乏对幼苗，幼树和小树的详细重新测量数据，这意味着对它们的人口统计资料还没有大规模地了解，并且很少在森林模型中得到详细描述。在这项研究中，我们量化了气候和密度依赖性对西班牙森林清单中所测量的13种物种的招募和幼年生长及死亡率的影响。单人口调查树苗计数数据用于在无可能参数化方法（近似贝叶斯计算）内基于理想可塑性近似模型（PPA）来约束简单森林少年动力学模型的人口统计参数。我们的结果强调了物种之间的显着差异，以及气候和林分结构在控制幼虫动态中的重要作用。招聘与种特异性密度呈驼峰形关系，对于大多数物种，种特异性竞争比异种竞争具有更强的负面影响。与温带物种相比，地中海物种平均具有更高的死亡率和更低的增长率，而在低密度林分中，招募与死亡率呈正相关。在气候变化下，我们的模型预测几乎所有物种的招募率都会下降。可靠的森林动力学预测模型应包括关键的早期生命阶段过程的真实表示，而我们的方法证明了现有的粗略计数数据可用于对此类模型进行参数化。