Spatial patterns and influencing factors of specific leaf area in typical temperate forests

比叶面积（SLA）能够反映植物自身生长对策、对光能的捕获能力、对外界环境变化的适应和对可利用资源的分配策略，对植物的生境适应状况和群落的自然演替程度也起到重要的指示作用。为了深入了解温带森林植物SLA随空间变化的变异特征及其影响因素，跨越1200 km选取中国东北部12个典型温带森林（寒温带兴安落叶松林、温带红松针阔混交林和暖温带落叶阔叶栎林），通过对样地内物种进行系统性的调查，分析了植物SLA在空间上的变化规律及环境因素的影响效应。结果显示：中国温带森林植物SLA范围为2.02-99.65 m2/kg（均值为34.18 m2/kg），其中乔木SLA范围为2.02-58.74 m2/kg（均值为21.32 m2/kg），灌木SLA范围为2.88-99.65 m2/kg（均值为31.60 m2/kg），草本SLA范围为4.66-98.53 m2/kg（均值为38.75 m2/kg）。SLA在不同森林类型之间差异显著，具体表现为：温带红松针阔混交林 > 暖温带落叶阔叶栎林 > 寒温带兴安落叶松林。SLA受到气候因素和土壤因素的影响，其中随着年均降水、土壤碳氮含量的增加显著增加；随着年均温度、紫外辐射、光合有效辐射，呈先增加后降低的趋势；随着土壤碳氮比的增加显著降低。以上结果揭示了温带森林SLA的空间变异规律，可以为将来区域乃至全球尺度下植物功能性状研究提供理论支撑。;Specific leaf area (SLA) can reflect plant growth strategies, the ability to capture light energy, adaptation to changing environments, and allocation strategies of available resources. SLA critically plays an important role in indicating plant adaptation to their habitat and the degree of community succession as well. SLA is a complex of plant leaf area and weight, and is defined as the ratio of single leaf area to its dry weight. The current research on SLA in temperate forests mostly focused on the spatial variation of dominant species or just a certain tree, and the vertical variation among forests. However, the systematic investigation of the entire community was rarely carried out. This research was conducted in the northeast of China in which covered three forest types. These types were respectively cold-temperate Larix gmelinii forests, temperate broad-leaved Korean pine mixed forests and warm-temperate deciduous broad-leaved Oak forests. This study selected 12 typical temperate forests spanning 1200 km, and performed a systematic survey to explore the spatial patterns and influencing factors of plant SLA. The results showed that the SLA of China's temperate forest plants ranged from 2.02 to 99.65 m2/kg (mean, 34.18 m2/kg). Specifically, the SLA range was 2.02-58.74 m2/kg for trees (mean, 21.32 m2/kg), 2.88-99.65 m2/kg for shrubs (mean, 31.60 m2/kg), and 4.66-98.53 m2/kg for herbs (mean, 38.75 m2/kg). Plant SLA significantly differed among different forest types, with the greatest SLA in temperate broad-leaved Korean pine mixed forest, followed by warm-temperate deciduous broad-leaved Oak forest and cold-temperate Larix gmelinii forest. Significant latitudinal pattern of plant SLA was observed. As latitude increased, SLA initially increased and then decreased. SLA was found to be affected by both climatic and soil factors. SLA increased significantly with the increasing mean annual precipitation, soil carbon content, and soil nitrogen content. However, with the increase of mean annual temperature, ultraviolet radiation, and photosynthetically active radiation, SLA first increased, followed by a decline. Moreover, it decreased significantly as the soil carbon to nitrogen ratio increased. In summary, this study reveals the spatial variation of SLA in temperate forests, and it can not only provide a new perspective for the study on the response of different forest ecosystems to global change, but also provide an important theoretical basis for the development of the adaptive management of natural forests in China. Moreover, it also provides a theoretical support for future studies on plant functional traits at the regional and global scales.