No abstract

1. Forest management influences a variety of ecosystem structures and processes relevant to meso-and microclimatic regulation, but little research has been done on how forest management can mitigate the negative effects of climate change on forest ecosystems.2. We studied the temperature regulation capacity during the two Central European extreme summers in 2018 and 2019 in Scots pine plantations and European beech forests with different management-related structural characteristics.3. We found that the maximum temperature was higher when more trees were cut and canopy was more open. Logging 100 trees per hectare increased maximum temperature by 0.21-0.34 K at ground level and by 0.09-0.17 K in 1.3 m above ground.Opening the forest canopy by 10% significantly increased T max, measured 1.3 m above ground by 0.46 K (including pine and beech stands) and 0.35 K (only pine stands). At ground level, T max increased by 0.53 K for the model including pine and beech stands and by 0.41 K in pure pine stands. Relative temperature cooling capacity decreased with increasing wood harvest activities, with below average values in 2018 (and 2019) when more than 656 (and 867) trees per hectare were felled. In the pine forests studied, the relative temperature buffering capacity 1.3 m above ground was lower than average values for all sample plots when canopy cover was below 82%. In both study years, mean maximum temperature measured at ground level and in 1.3 m was highest in a pine-dominated sample plots with relatively low stand volume (177 m 3 ha −1 ) and 9 K lower in a sample plot with relatively high stock volumes of Fagus sylvatica (>565 m 3 ha −1 ). During the hottest day in 2019, the difference in temperature peaks was more than 13 K for pine-dominated sample plots with relatively dense (72%) and low (46%) canopy cover. 4. Structural forest characteristics influenced by forest management significantly affect microclimatic conditions and therefore ecosystem vulnerability to climate change. We advocate keeping the canopy as dense as possible (at least 80%) byThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Background Over the last 25 years, the prominent forest certification system established by the Forest Stewardship Council (FSC) has used by many companies worldwide for claiming responsible forest management. The objectives of the Russian National FSC standard to decrease the size of clearcuts and the retention of forest elements such as residual seed trees need on-site validation to proof the effectiveness of FSC. To assess the ecological impacts of harvesting practices and benefits of FSC certification, we geospatially compared logging activities with and without FSC certification. Within a sample area covering approximately 3,000 km2 in the east of the Russian Arkhangelsk Region, we used available data on tree cover loss and satellite images to assess secondary impacts of clearcuttings on adjacent remnant forests and to quantify the logging intensity. Additionally, the size and structure as well as the density of skidding trails of ten specific clearcuttings located within the sample area were surveyed using satellite images and in the field observation to delineate the boundaries of clearcuts and forested remnants within the clearcuts. Results We found a significant increase of small-scale tree cover loss in the proximity of the clearcuts. Patchy dieback is possibly linked to the scale and intensity of logging in the surroundings. On the investigated clearcuts, FSC failed to reduce the size, to increase the retention of forest remnants including seed trees on logged areas, and to maintain larger tracts of undisturbed ground and soil compared to clearcuts that were logged before they received FSC-certification. Conclusions Trees and forest remnants remaining inside an increasingly stressed forest ecosystem matrix may not resist further harvesting-related and climate change-induced stresses and disturbances. Large-scale clearcuttings seem to have negative impacts even in adjacent forests and undermine the ecological effectiveness of FSC certification in the study area. The Russian FSC standard is not clearly setting effective guidelines that induce a change in clearcutting practices in order to reduce ecological risks.

Intact forests contribute to the ecosystem functionality of landscapes by storing and sequestering carbon, buffering and cooling the microclimate, and providing a range of related ecosystem functions. Forest fragmentation not only poses a threat to many organisms but also reduces the resistance and resilience of the ecosystem, which is especially relevant to the ongoing climate crisis. The effects of recent extreme heat years on forests in Germany have not been studied in detail for the influence of fragmentation. We investigate the relation of forest fragmentation with temperature and vitality in Germany per ecoregion at the canopy level using satellite imagery at 1-km and 30-m resolution. We compiled and correlated forest maps for connectivity based on Thiessen polygons, canopy temperatures on the hottest days based on land surface temperature, and forest vitality based on the maximum normalized difference vegetation index per growing season. We differentiated between ecoregions and main forest types. In 2022, larger intact tree-covered areas that are less fragmented have relatively low temperatures on hot days and higher overall vitality. Nearly 98% of the almost 1.95 million forest fragments at 30-m resolution in Germany are smaller than 1 km2, which cover nearly 30% of the total forest area. To counteract the forest crisis, forest and landscape management should aim to reduce fragmentation and maintain tree biomass and forest cover in the landscape. Increasing the size of continuous forest fragments contributes to ecosystem-based adaptation to climate change.

No abstract