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As climate change drives increased drought in many forested regions, mechanistic understanding of the factors conferring drought tolerance in trees is increasingly important. The dendrochronological record provides a window through which we can understand how tree size and traits shape growth responses to droughts. We analyzed tree-ring records for 12 species in a broadleaf deciduous forest in Virginia (USA) to test hypotheses for how tree height, microenvironment characteristics, and species’ traits shaped drought responses across the three strongest regional droughts over a 60-yr period. Drought tolerance (resistance, recovery, and resilience) decreased with tree height, which was strongly correlated with exposure to higher solar radiation and evaporative demand. The potentially greater rooting volume of larger trees did not confer a resistance advantage, but marginally increased recovery and resilience, in sites with low topographic wetness index. Drought tolerance was greater among species whose leaves lost turgor (wilted) at more negative water potentials and experienced less shrinkage upon desiccation. The tree-ring record reveals that tree height and leaf drought tolerance traits influenced growth responses during and after significant droughts in the meteorological record. As climate change-induced droughts intensify, tall trees with drought-sensitive leaves will be most vulnerable to immediate and longer-term growth reductions.

Although rainfall is a major determinant of soil moisture content (SMC), various factors affect SMC. The effects of these environmental factors contribute to spatial heterogeneity in SMC, which influences diverse ecological processes. To better understand the dynamics in SMC, litter and slope gradient should be considered. To this end, we analyzed the impacts of litter and slope gradient on SMC from 2020 to 2021 on Mt. Jeombong, located in a temperate deciduous broadleaf forest. We classified the study period into foliage (with a developed canopy) and non-foliage (after leaf fall) seasons. Our results indicated that SMC was affected by slope gradient and litter layer. Rainfall absorption occurred more at gentle slope, leading to higher SMC. Additionally, rainfall absorption was interpreted as being intercepted by the litter layer. Consequently, the correlation coefficient between SMC increment and rainfall was lower in the non-foliage season (R2 = 0.37–0.56) than in the foliage season (R2 = 0.72–0.84). With temporal progression, however, SMC response to rainfall increased where the litter was thickly accumulated, suggesting that litter interception was gradually diminished by decomposition. In this study, spatial heterogeneity in the litter layer and slope gradient substantially influenced the supply of soil moisture from rainfall.

The past five decades have witnessed satellite remote sensing become one of the most efficient tools for fire detection and estimating total burned areas. Not all algorithms are appropriate for detecting high-temperature events on a global scale. It is difficult for traditional fire detection algorithms to capture small and low-intensity fires with significant accuracy. For this, we propose an improved fire detection algorithm by considering channel 4 and 11 µm of MODIS data with two different thresholds for hot and cold seasons. Moreover, false alarm rejections caused by the edges of clouds are designed for this algorithm. The validation against 231 reference fires showed good performance of our algorithm over the northern forests of Iran. This algorithm detected 72 fires, while the MODIS fire product, a widely used source for fire detection, detected only 26 fires. The results indicate an outperformance of 19.91%. The results show that our algorithm for the fire detection method overperforms the traditional methods and can be particularly useful for fire detection in the northern forests of Iran and can be applied in similar forests worldwide.

Tree mortality is one of the most influential drivers of forest dynamics, and characterizing patterns of tree mortality is critical to understanding forest dynamics and ecosystem function in the present era of global change. Here, we use a unique data set of mortality in a temperate deciduous forest to characterize rates and drivers of mortality. At the 25.6‐ha Center for Tropical Forest Science—Forest Global Earth Observatory forest dynamics plot at the Smithsonian Conservation Biology Institute (Virginia, USA ), we conducted two full tree censuses in 2008 and 2013 and then tracked mortality over the next 2 years (2014 and 2015). Overall, the mortality rate, m , of stems ≥10 cm diameter was 1.3–2.1%/yr. Biomass mortality, M , was 1.9–3.4 Mg·ha −1 ·yr −1 at the stand level (0.6–1.1%/yr of biomass), less than biomass gains from growth and recruitment, resulting in net live biomass accumulation. Small stems died at the highest rate; however, contributions to M increased toward larger size classes. Most species had m  < 2%/yr and M  < 0.25 Mg·ha −1 ·yr −1 (<3%/yr of biomass), whereas two to four species had anomalously high mortality rates during each census period, accounting for 15–24% of m ( n  = 2, Cercis canadensis , Ulmus species) and 39–75% of M ( n  = 4 Quercus species). Stems that died, whether or not in association with mechanical damage, tended to grow more slowly in preceding years than surviving stems and, for certain shade‐intolerant species, tended to be in neighborhoods with higher basal area. These findings show how relatively fine‐scale mortality processes contribute to stand‐level compositional change and carbon cycling. The mortality patterns reported here will provide a valuable basis for understanding future disturbance events within eastern deciduous forests and for comparing across forest types.

With the launch of the Sentinel-2 satellites, a European capacity has been created to ensure continuity of Landsat and SPOT observations. In contrast to previous sensors, Sentinel-2′s multispectral imager (MSI) incorporates three additional spectral bands in the red-edge (RE) region, which are expected to improve the mapping of vegetation traits. The objective of this study was to compare Sentinel-2 MSI and Landsat-8 OLI data for the estimation of leaf area index (LAI) in temperate, deciduous broadleaf forests. We used hemispherical photography to estimate effective LAI at 36 field plots. We then built and compared simple and multiple linear regression models between field-based LAI and spectral bands and vegetation indices derived from Landsat-8 and Sentinel-2, respectively. Our main findings are that Sentinel-2 predicts LAI with comparable accuracy to Landsat-8. The best Landsat-8 models predicted LAI with a root-mean-square error (RMSE) of 0.877, and the best Sentinel-2 model achieved an RMSE of 0.879. In addition, Sentinel-2′s RE bands and RE-based indices did not improve LAI prediction. Thirdly, LAI models showed a high sensitivity to understory vegetation when tree cover was sparse. According to our findings, Sentinel-2 is capable of delivering data continuity at high temporal resolution.

Aims: Leaf mass per area (LMA) is an important functional trait that can be measured in order to position a species along the resource acquisition–conservation continuum. However, the function of LMA in terms of shade tolerance in deciduous species remains controversial; therefore, how the community-level LMA composition changes during forest succession is not clear in forests dominated by deciduous trees. Herein, we examined how the community-level LMA changes during succession in winter-deciduous broad-leaf forests using long-term data of stem dynamics along a secondary successional chronosequence. Location: Cool temperate forests, central Japan. Methods: We used tree census data from 15 permanent plots with a stand age range of 17–81 years at the initial census, in which measurements were taken for 25 or 30 years at 5- or 10-year intervals. Species-specific LMAs were measured in the same geographic region. Results: Species-specific LMAs were negatively correlated with the estimated year in which the species was most abundant during the secondary succession, suggesting that species with low LMAs have high shade tolerance. Consistent with this, the CWM of LMA gradually decreased during secondary succession. We found that the recruitment of late successional species with low LMA, especially at mid-successional stages, drove changes in the CWM of LMA, while mortality occurred irrespective of LMA. Conclusion: Our results illustrate the detailed dynamic processes of the community-level composition of LMA across succession and demonstrate that tree recruitment contributes to increase in the CWM of LMA during the secondary succession of winter-deciduous broad-leaf forests.

Although drought in temperate deciduous forests decreases transpiration rates of many species, stand-level transpiration and total evapotranspiration is often reported to exhibit only minor interannual variability with precipitation. This apparent contradiction was investigated using four years of transpiration estimates from sap flux, interception-evaporation estimates from precipitation and throughfall gauges, modeled soil evaporation and drainage estimates, and eddy covariance data in a mature oak-hickory forest in North Carolina, USA. The study period included one severe drought year and one year of well above-average precipitation. Normalized for atmospheric conditions, transpiration rates of some species were lower in drought than in wet periods whereas others did not respond to drought. However, atmospheric conditions during drought periods are unlike conditions during typical growing season periods. The rainy days that are required to maintain drought-free periods are characterized by low atmospheric vapor pressure deficit, leading to very low transpiration. In contrast, days with low air vapor pressure deficit were practically absent during drought and moderate levels of transpiration were maintained throughout despite the drying soil. Thus, integrated over the growing season, canopy transpiration was not reduced by drought. In addition, high vapor pressure deficit during drought periods sustained appreciable soil evaporation rates. As a result, despite the large interannual variation in precipitation (ranging from 934 to 1346 mm), annual evapotranspiration varied little (610-668 mm), increasing only slightly with precipitation, due to increased canopy rainfall interception. Because forest evapotranspiration shows only modest changes with annual precipitation, lower precipitation translates to decreased replenishment of groundwater and outflow, and thus the supply of water to downstream ecosystems and water bodies.

Recent research has mapped potential afforestation land to support China’s goal of achieving “carbon neutrality” and has proposed tree species selection to maximize carbon uptake. However, it overlooked biophysical climatic effects, which have a more significant impact on local temperature than CO2 reduction. This study aims to present a comprehensive understanding of how afforestation in China affects local and regional climates through biophysical processes. It focuses on the latitudinal patterns of land surface temperature differences (ΔLST) between five locally adapted forest types and adjacent grasslands using satellite-based observations. Our key findings are as follows: Firstly, broadleaf forests and mixed forests exhibit a stronger cooling effect than coniferous forests due to differences in canopy structure and distribution. Specifically, the net cooling effects of evergreen broadleaf forests (EBFs), deciduous broadleaf forests (DBFs), and mixed forests (MFs) compared to grasslands are −0.50 ± 0.10 °C (mean ± 95% confidence interval), −0.33 ± 0.05 °C, and −0.36 ± 0.06 °C, respectively, while evergreen needleleaf forests (ENFs) compared to grasslands are −0.22 ± 0.11 °C. Deciduous needleleaf forests (DNFs) exhibit warming effects, with a value of 0.69 ± 0.24 °C. In regions suitable for diverse forest types planting, the selection of broadleaf and mixed forests is advisable due to their enhanced local cooling impact. Secondly, temperate forests have a net cooling effect to the south of 43° N, but they have a net warming effect to the north of 48° N compared to grasslands. We recommend caution when planting DNFs, DBFs, and MFs in northeastern China, due to the potential for local warming. Thirdly, in the mountainous areas of southwestern China, especially when planting ENFs and MFs, tree planting may lead to local warming. Overall, our study provides valuable supplementary insights to China’s existing afforestation roadmap, offering policy support for the country’s climate adaptation and mitigation efforts.

Climatic changes have a significant impact on the composition and distribution of forests, especially on ecotone ones. In the Southern Ural, pine-broadleaf ecotone forests were widespread during the early Holocene time, but now have persisted as relic plant communities. This study aimed to analyze the current potential range and to model changes in habitat suitability of relic pine-broadleaf ecotone forests of the suballiance Tilio-Pinenion under scenarios of moderate (RCP4.5) and strong (RCP8.5) climate change. For modelling, we used MaxEnt software with the predictors being climate variables from CHELSA Bioclim, the global digital soil mapping system SoilGrids and the digital elevation model. In the Southern and Middle Urals, climate change is expected to increase the areas with suitable habitat conditions of these forests by the middle of the 21st century and decrease them in the second half of the century. By the middle of the 21st century, the eastern range boundary of these forests will shift eastward due to the penetration of broad-leaved tree species into coniferous forests of the Southern Ural. In the second half of the century, on the contrary, it is expected that climate aridization will again shift the potential range border of these forests to the west due to their gradual replacement by hemiboreal coniferous forests. The relationship between the floristic composition of pine-broadleaf forests and habitat suitability was identified. In low and medium habitat suitability, pine-broadleaf forests contain more nemoral species characteristic of deciduous forests of the temperate zone, and can be replaced by broadleaf forests after thinning and removal of pine. In the Volga Upland, suitable habitats are occupied by pine-broadleaf forests of the vicariant suballiance Querco robori-Tilienion cordatae. Projected climatic changes will have a significant impact on these ecotone forests, which remained completely unaltered for a long time.

To investigate the relative role of local versus landscape factors for local species diversity of snails and slugs in conservation forests. In landscapes with small, isolated patches of semi-natural habitats, many species that require large habitat areas have disappeared or are threatened. We asked whether small sedentary taxa that depend on local conditions, such as molluscs, are affected if total habitat area decreases in the landscape. Temperate broadleaved and oak-rich forest in southern Sweden. We sampled molluscs in 25 small conservation forests that are well-spaced out over a large region. In each forest, sampling was conducted in two plots, each of 1 ha, separated by about 25-100 m. Factors potentially influencing local diversity of molluscs were measured in the plots and in the surrounding landscape at different scales (in space and time) and were analysed by stepwise multiple regression and ordination (PCA and NMS). We recorded 53 species, and mean species richness per forest (plots pooled) was 22.6. The pH of the plant litter predicted both species richness and composition; other local (plot) factors of lower importance were canopy openness, stony ground and tree species. The area of conservation forest (woodland key habitat) within 10 km of plots was positively associated with species richness, and was also related to species composition. Openness of the landscape (agriculture) was a negative factor, but historical plot openness (1938-59) seemed to be unimportant. In addition, climate/topography (temperature and altitude) also predicted species composition of the sites. We rejected the hypothesis that microhabitat factors alone, or mainly, determine local species richness and composition of land molluscs. These representatives of small, sedentary organisms seem to be substantially influenced by the surrounding landscape, which should be considered in conservation work and in plans for the protection of forest biodiversity.