The mixed-conifer forests in California’s Sierra Nevada include species from several genera (Pinus, Abies, Pseudotsuga, Calocedrus and Sequoiadendron). These forests have complex disturbance regimes dominated by low to moderate severity fire that often resulted in patchy spatial patterns and multiaged stands. Leaf area index (LAI) describes the total leaf surface area per unit area in a forest community and is related to wood and biomass production and ecosystem values such as water usage, water yields and carbon sequestration. LAI can also serve as a representation of growing space occupancy and the basis for stocking control, including in multiaged stands. Nine study sites were sampled with 22–37 0.05 ha plots per study site to estimate LAI and other metrics. LAI was highest in study sites with greater proportions of shade tolerant Abies and Calocedrus species and on higher productivity sites. Recent drought-related mortality has reduced stocking and LAI. The combination of fire suppression and timber harvest over the past century has resulted in stands with higher densities, and greater proportions of shade tolerant species. Managing these structures to restore their presettlement character will involve reducing overall stocking, increasing proportions of intolerant species and increasing fine-scale heterogeneity. LAI allocation—allocating leaf area to age classes, species or canopy strata—can be used to design new structures that resemble presettlement structures and are resilient to disturbances.

中文翻译：

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加利福尼亚内华达山脉复杂针叶林的叶面积指数变化：对种群控制的影响

加利福尼亚内华达山脉的针叶林混交林包括几个属的物种（松属，冷杉，假tsu，Cal蒲和红杉）。这些森林具有复杂的扰动机制，其中以中低度火势为主，常常造成斑驳的空间格局和多龄林。叶面积指数（LAI）描述了森林群落中每单位面积的总叶表面积，并与木材和生物量的生产以及生态系统价值（如用水量，水产量和碳固存）相关。LAI还可以代表空间占用率的增长，以及包括多年龄展位在内的库存控制基础。对9个研究地点进行了采样，每个研究地点的土地面积为22-37个0.05公顷，以估计LAI和其他指标。LAI在耐荫冷杉和Calocedrus比例更高的研究地点最高物种和较高生产力的地点。最近与干旱有关的死亡率降低了种群和LAI。在过去的一个世纪中，灭火和木材采伐相结合，导致了林分密度更高，耐荫树种比例更高。管理这些结构以恢复其预设特征将涉及减少总种群，增加不耐性物种的比例并增加精细尺度的异质性。LAI分配（将叶子面积分配给年龄类别，物种或树冠层）可用于设计类似于预设结构并能抵抗干扰的新结构。