Systematic Botany and Functional Biodiversity, Leipzig University, Johannisallee 21, 04103 Leipzig, Germany.
Systematic Botany and Functional Biodiversity, Leipzig University, Johannisallee 21, 04103 Leipzig, Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstraße 4, 04103 Leipzig, Germany.
Sci Total Environ. 2024 Sep 1;941:173572. doi: 10.1016/j.scitotenv.2024.173572. Epub 2024 May 31.
Forest canopy gaps can influence understorey microclimate and ecosystem functions such as decomposition. Gaps can arise from silviculture or tree mortality, increasingly influenced by climate change. However, to what degree canopy gaps affect the buffered microclimate in the understorey under macroclimatic changes is unclear. We, therefore, investigated the effect of forest gaps differing in structure and size (25 gaps: single tree gaps up to 0.67 ha cuttings) on microclimate and soil biological activity compared to closed forest in a European mixed floodplain forest. During the investigation period in the drought year 2022 between May and October, mean soil moisture and temperature as well as soil and air temperature fluctuations increased with increasing openness. In summer, the highest difference of monthly means between cuttings and closed forest in the topsoil was 3.98 ± 9.43 % volumetric moisture and 2.05 ± 0.89 °C temperature, and in the air at 30 cm height 0.61 ± 0.35 °C temperature. For buffering, both the over- and understorey tree layers appeared as relevant with a particularly strong influence of understorey density on soil temperature. Three experiments, investigating soil biological activity by quantifying decomposition rates of tea and wooden spatulas as well as mesofauna feeding activity with bait-lamina stripes, revealed no significant differences between gaps and closed forest. However, we found a positive significant effect of mean soil temperature on feeding activity throughout the season. Although soil moisture decreased during this period, it showed no counteracting effect on feeding activity. Generally, very few significant relationships were observed between microclimate and soil biological activity in single experiments. Despite the dry growing season, decomposition rates remained high, suggesting temperature had a stronger influence than soil moisture. We conclude that the microclimatic differences within the gap gradient of our experiment were not strong enough to affect soil biological activity considerably.
林冠空隙会影响林下微气候和生态系统功能，如分解。空隙可以由抚育或树木死亡形成，越来越受到气候变化的影响。然而，林冠空隙在多大程度上影响宏观气候变化下林下缓冲微气候尚不清楚。因此，我们研究了结构和大小不同的森林空隙（25 个空隙：单个树木空隙最大可达 0.67 公顷的采伐）对微气候和土壤生物活性的影响，与欧洲混合洪泛森林中的封闭森林进行了比较。在 2022 年干旱年的调查期间（5 月至 10 月），与封闭林分相比，土壤水分和温度以及土壤和空气温度波动随着开放性的增加而增加。在夏季，在表层土壤中，采伐与封闭林分之间的月均差异最大为 3.98±9.43%体积水分和 2.05±0.89°C温度，在 30cm 高度的空气中为 0.61±0.35°C温度。为了缓冲，上层和下层树木层都表现出相关的作用，特别是下层密度对土壤温度的影响特别强烈。通过量化茶叶和木制刮刀的分解率以及用诱饵薄片条调查土壤中型动物的取食活动，进行了三项实验来研究土壤生物活性，结果表明，空隙与封闭林分之间没有显著差异。然而，我们发现整个季节土壤温度对取食活动有显著的正效应。尽管在此期间土壤水分减少，但它对取食活动没有抵消作用。一般来说，在单个实验中，微气候和土壤生物活性之间很少观察到显著的关系。尽管生长季节干燥，但分解速率仍然很高，这表明温度的影响大于土壤水分。我们的结论是，我们实验中林冠空隙梯度内的微气候差异不足以对土壤生物活性产生显著影响。
