Pacific Northwest conifer forest stand carrying capacity under future climate scenarios
Pacific Northwest conifer forest stand carrying capacity under future climate scenarios
复制标题
DOI：
10.1111/nrm.12381
复制
发表时间：
2023-07
影响因子：
1.6
通讯作者：
R. Heiderman;Mark J. Kimsey
中科院分区：
文献类型：
--
作者：
R. Heiderman;Mark J. Kimsey
最大林分密度指数（SDIMAX）根据树木数量与其大小之间的关系表示林分的承载能力。利用联邦、州和私人森林管理团体协作网络提供的地块级清单数据，为美国华盛顿州西部和俄勒冈州重要的太平洋西北地区针叶树开发 SDIMAX 模型。在集成学习模型中探讨了特定地点气候和环境变量的影响。基于不同代表性二氧化碳浓度路径（RCP 4.5 和 RCP 8.5）和时间范围（2050 年代和 2080 年代）下的全球环流模型的未来气候预测被用于时空替代，以了解建模 SDIMAX 的潜在变化。在未来的气候条件下，该地区大部分地区的承载能力都会下降。在 2050 年代和 2050 年代 RCP 4.5 下，以花旗松 (Pseudotsuga menziesii (Mirb.) Franco) 为主的森林的模拟平均 SDIMAX 下降了 5.4% 和 11.4%，而以西部铁杉 (Tsugaheterophylla (Raf.) Sarg.) 和太平洋银杉 (Abies amabilis) 为主的森林则下降了 6.6% 和 8.9%。 2080 年代分别为 RCP 8.5。预计的未来条件通常超出任何当代气候概况的范围，从而导致所谓的外部条件。在研究区域内，在 2080 年代 RCP 8.5 下，最终模型中包含的气候变量分别有 45% 和 46% 是花旗松和铁杉模型的外部气候变量。尽管超出输入数据范围进行推断是不合适的，而且未来气候预测仍然存在许多未知因素，但这些结果可以对森林承载力潜在变化的方向和幅度进行一般解释。
Maximum stand density index (SDIMAX) represents the carrying capacity of a forest stand based on the relationship between the number of trees and their size. Plot‐level inventory data provided through a collaborative network of federal, state, and private forest management groups were utilized to develop SDIMAX models for important Pacific Northwest conifers of western Washington and Oregon, USA. The influence of site‐specific climatic and environmental variables was explored within an ensemble learning model. Future climate projections based on global circulation models under different representative CO2 concentration pathways (RCP 4.5 and RCP 8.5) and timeframes (2050s and 2080s) were utilized in a space‐for‐time substitution to understand potential shifts in modeled SDIMAX. A majority of the region showed decreases in carrying capacity under future climate conditions. Modeled mean SDIMAX decreased 5.4% and 11.4% for Douglas‐fir (Pseudotsuga menziesii (Mirb.) Franco) dominated forests and decreased 6.6% and 8.9% for western hemlock (Tsuga heterophylla (Raf.) Sarg.) and Pacific silver fir (Abies amabilis), dominated forests under the RCP 4.5 in the 2050s and RCP 8.5 in the 2080s, respectively. Projected future conditions often fall outside the range of any contemporary climate profile, resulting in what may be referred to as extramural conditions. Within the study region, 45% and 46% of climate variables included in the final model were extramural for the Douglas‐fir and hemlock models, respectively, under RCP 8.5 in the 2080s. Although extrapolating beyond the range of input data is not appropriate and many unknowns remain regarding future climate projections, these results allow for general interpretations of the direction and magnitude of potential shifts in forest carrying capacity.