With growing recognition of the ecological importance of grasslands, efforts to prevent their degradation, enhance the soil quality, and maintain ecological balance have become central to temperate grassland management. However, many temperate grasslands experience varying intensities and modes of grazing. Effective grazing management is crucial to avoid damage and promote the sustainable development of temperate grasslands. This study adopts a variety of research methods. Firstly, through the collection and sorting of data, it is clear that the research content mainly focuses on more than 70 response variables. Secondly, the comprehensive effects of different grazing intensity, grazing mode, and grazing history on these response variables were studied, and then detailed studies were conducted to analyze the effects of different grazing intensity and grazing mode under different temperate grassland types on these response variables. According to the analysis of the comprehensive effects and effects of different temperate grassland types, significant heterogeneity was found in 13 response variables (H, R, E, Height, Coverage, Density, TB, PB-PF, SWC, TK, OK, and N(20-60 cm)). Finally, in order to study the source of heterogeneity of these 13 response variables, subgroup analysis was carried out to analyze whether it was caused by environmental factors (MAP, MAT, MAP xMAT), and then publication bias test and Egger's test were carried out to prove the reliability of the research results. The results showed that the heterogeneity of 12 response variables (R, H, E, height, coverage, density, TB, PB, PF, SWC, OK and N (20-60 cm)) was attributed to environmental factors. However, due to insufficient data after subgroup analysis, the heterogeneity of TK cannot be determined.

Fire can influence plant diversity directly by damaging or killing individuals or indirectly by changing soil properties. However, the impacts of prescribed burning on biodiversity and the relationship between soil and biodiversity in northeast China remain poorly understood. In this study, we explored the impact of low-intensity prescribed burning on temperate forest ecosystems in northeast China by investigating changes in post-fire plant biodiversity and soil properties and characterising the relationship between these variables. Contrary to previous studies, the results showed that prescribed burning in Pinus koraiensis plantations did not increase understory biodiversity. In contrast, it resulted in a significant decrease in biodiversity over the three-year period. Legumes (especially Lespedeza bicolor) were the understory species that benefitted the most from the fire. Burning changed the connection between soil and plant diversity. After burning, soil organic C overtook nitrate as the main driver of plant biodiversity. Our findings showed that prescribed burning alters soil chemical properties, particularly soil organic C, thus affecting the understory plant composition and biodiversity.

The phyllosphere is an important but underestimated habitat for a variety of microorganisms, with limited knowledge about leaf endophytes as a crucial component of the phyllosphere microbiome. In this study, we investigated the mechanisms of communities and co-occurrence networks of leaf endophytes in response to forest thinning in a temperate forest. As we expected, contrasting responses of fungal and bacterial endophytes were observed. Specifically, the diversity of leaf endophytic fungi and the complexity of their co-occurrence networks increased significantly with thinning intensity, whereas the complexity of endophytic bacterial co-occurrence networks decreased. In particular, microbiota inhabiting damaged leaves seem to be more intensively interacting, showing an evident fungi-bacteria trade-off under forest thinning. In damaged leaves, besides the direct effects of thinning, thinning-induced changes in neighbor tree diversity indirectly altered the diversity of leaf fungal and bacterial endophytes via modifying leaf functional traits such as leaf dry matter content and specific leaf area. These findings provide new experimental evidence for the trade-offs between leaf endophytic fungi and bacteria under the different magnitudes of deforestation, highlighting their dependence on the presence or absence of leaf damage.

AimIncreased tree mortality linked to droughts and fires is occurring across temperate regions globally. Vegetation recovery has been widely reported; however, less is known about how disturbance may alter forests structurally and functionally across environmental gradients. We examined whether dry forests growing on low-fertility soils were more resilient to coupled extreme drought and severe fire owing to lower tree mortality rates, higher resprouting success and persistence of juveniles relative to wetter forests on more fertile soils.LocationFire-tolerant eucalypt forests of temperate southeastern Australia.Time period2020-2023.Major taxa studiedEucalyptus, Corymbia, Angophora.MethodsDemographic surveys of tree mortality and regeneration in all combinations of dry/wet forest, fertile/less fertile substrates exposed to extreme drought and fire were conducted. We used Bayesian regression modelling to compare tree mortality, diameter, response traits, population structure and occurrence of fire scars between substrates/forest types.ResultsOverall mortality (20%-33%) and topkill (34%-41%) were within historically reported ranges for various forests and soil types. However, we observed an atypical trend of increased mortality and topkill in the largest trees, particularly when they had structural damage from past fires. Trees in wet forests on more fertile soils had the highest levels of mortality. Numbers of persistent resprouting juveniles were highest in dry forests on low-fertility soils. Dry forests growing on low-fertility soils appear more resilient to compound disturbances due to lower rates of mortality and higher rates of juvenile persistence. Wet forests on more fertile soils may experience greater demographic change due to higher mortality of small and large trees.Main conclusionsMesic forests on relatively fertile soils were found to be at relatively high risk of demographic change from compound disturbances. Combined, fire and drought are likely to reduce the number of large trees in affected areas, with consequences for forest carbon cycling and storage.

The more insects there are, the more food there is for insectivores and the higher the likelihood for insect-associated ecosystem services. Yet, we lack insights into the drivers of insect biomass over space and seasons, for both tropical and temperate zones. We used 245 Malaise traps, managed by 191 volunteers and park guards, to characterize year-round flying insect biomass in a temperate (Sweden) and a tropical (Madagascar) country. Surprisingly, we found that local insect biomass was similar across zones. In Sweden, local insect biomass increased with accumulated heat and varied across habitats, while biomass in Madagascar was unrelated to the environmental predictors measured. Drivers behind seasonality partly converged: In both countries, the seasonality of insect biomass differed between warmer and colder sites, and wetter and drier sites. In Sweden, short-term deviations from expected season-specific biomass were explained by week-to-week fluctuations in accumulated heat, rainfall and soil moisture, whereas in Madagascar, weeks with higher soil moisture had higher insect biomass. Overall, our study identifies key drivers of the seasonal distribution of flying insect biomass in a temperate and a tropical climate. This knowledge is key to understanding the spatial and seasonal availability of insects-as well as predicting future scenarios of insect biomass change.

In past decades, ash dieback has caused a rapid decline of European ash (Fraxinus excelsior) in temperate forests of Europe. Numerous studies focus on mitigating the negative impacts of ash dieback to forest ecosystems or identifying resistant genotypes. The role of natural selection toward genotypes withstanding ash dieback for ash regeneration has been less frequently studied with experimental means to date. This is, however, necessary in times of global change, because the preservation of ash in Europe's forests will depend, above all, on the adaptability of the future generations of ash trees. To quantify the extent and effects of ash dieback severity for ash regeneration we selected five forest stands moderately damaged and five forest stands highly damaged by ash dieback, in Schleswig-Holstein, Germany. We reciprocally transplanted naturally regenerated ash seedlings sampled in the field between these 10 sites. A shading treatment added to each half of the plots per site was meant to test for effects of altered light conditions in the herb layer due to canopy opening caused by ash dieback. With this approach, we tested seedling survival, performance and fungal infection for an interacting effect of origin and target site in regard to ash dieback severity and environmental factors over 2 years and recorded leaf traits (specific leaf area, leaf dry matter content) in the second year. Reduced light conditions under the shading nets had strong effects, influencing first year performance and infection probability as well as second year survival, growth and leaf trait characteristics. Soil conditions had only a marginal influence on transplanted seedlings. Transplantation direction between moderately and highly damaged sites affected infection marginally during the first year and survival as well as leaf traits significantly during the second year. Most notably, seedlings transplanted from moderately damaged to severely damaged sites exhibited the highest infection probability and lowest SLA, while seedlings transplanted vice versa were least likely to be infected and exhibited the highest SLA. Results hint at a first filtering effect by the ash dieback history of a forest stand and might indicate a transition from ecologically to evolutionary driven differentiation of ash seedling responses.

Scientific innovation is overturning conventional paradigms of forest, water, and energy cycle interactions. This has implications for our understanding of the principal causal pathways by which tree, forest, and vegetation cover (TFVC) influence local and global warming/cooling. Many identify surface albedo and carbon sequestration as the principal causal pathways by which TFVC affects global warming/cooling. Moving toward the outer latitudes, in particular, where snow cover is more important, surface albedo effects are perceived to overpower carbon sequestration. By raising surface albedo, deforestation is thus predicted to lead to surface cooling, while increasing forest cover is assumed to result in warming. Observational data, however, generally support the opposite conclusion, suggesting surface albedo is poorly understood. Most accept that surface temperatures are influenced by the interplay of surface albedo, incoming shortwave (SW) radiation, and the partitioning of the remaining, post-albedo, SW radiation into latent and sensible heat. However, the extent to which the avoidance of sensible heat formation is first and foremost mediated by the presence (absence) of water and TFVC is not well understood. TFVC both mediates the availability of water on the land surface and drives the potential for latent heat production (evapotranspiration, ET). While latent heat is more directly linked to local than global cooling/warming, it is driven by photosynthesis and carbon sequestration and powers additional cloud formation and top-of-cloud reflectivity, both of which drive global cooling. TFVC loss reduces water storage, precipitation recycling, and downwind rainfall potential, thus driving the reduction of both ET (latent heat) and cloud formation. By reducing latent heat, cloud formation, and precipitation, deforestation thus powers warming (sensible heat formation), which further diminishes TFVC growth (carbon sequestration). Large-scale tree and forest restoration could, therefore, contribute significantly to both global and surface temperature cooling through the principal causal pathways of carbon sequestration and cloud formation. We assess the cooling power of forest cover at both the local and global scales. Our differentiated approach based on the use of multiple diagnostic metrics suggests that surface albedo effects are typically overemphasized at the expense of top-of-cloud reflectivity. Our analysis suggests that carbon sequestration and top-of-cloud reflectivity are the principal drivers of the global cooling power of forests, while evapotranspiration moves energy from the surface into the atmosphere, thereby keeping sensible heat from forming on the land surface. While deforestation brings surface warming, wetland restoration and reforestation bring significant cooling, both at the local and the global scale.image

Observing the isotopic evolution of snow meltwater helps in understanding the process of snow melting but remains a challenge to acquire in the field. In this study, we monitored the melting of two snowpacks near Baishui Glacier No. 1, a typical temperate glacier on the southeastern Tibetan Plateau. We employed a physically based isotope model (PBIM) to calculate the isotopic composition of meltwater draining from natural snowpacks. The initial condition of the PBIM was revised to account for natural conditions, i.e., the initial delta O-18 stratigraphy of snow layers before melting. Simulations revealed that the initial heterogeneity of delta O-18 in snow layers as well as ice-liquid isotopic exchange were responsible for most variations of delta O-18 in snow meltwater, whereas new snow and wind drift could result in sudden changes of the isotopic composition of the meltwater. The fraction of ice involved in the isotopic exchange (f) was the most sensitive parameter for the model output. The initial delta O-18 in the snowpack is mirrored in meltwater in case of smallfand is smoothed with a large exchange fractionf. The other unknown parameter of the PBIM is the dimensionless rate constant of isotopic exchange, which depends on water percolation and initial snow depth. The successful application of the PBIM in the field might not only be useful for understanding snow melting process but might also provide the possibility of predicting the isotopic composition of snow meltwater and improve the accuracy of hydrograph separation.

The Yulong Snow Mountain (YSM) is a region of temperate glaciers in the southeast Qinghai-Tibetan Plateau. The present study systematically assessed the glacier changes during the past several decades using ground-based and remotely sensed observations and referencing topographic maps. The images and maps revealed that the glaciers area in the YSM retreated by 64.02% from 1957 to 2017. The length of Baishui River Glacier No. 1 decreased by 12.5 m/year during this period, whereas the front elevation of this glacier increased by 10.83 m/year. The mean annual mass balance of this glacier was at - 0.42 metre water equivalent from 1957 to 2017, and its accumulative mass balance was - 27.45 metre water equivalent. The glacier retreats of glacier area, glacier front, and mass balance in the YSM primarily resulted from the increasing air temperature. These glacier retreats not only will have a negative impact on glacier tourism in the future, e.g., the retreat or disappearance of glaciers will reduce the attractiveness of mountainous scenic spots, but also will create new opportunities for the development of local tourism, e.g., last chance will simulate tourists' curiosity. Hence, the findings of our present study help to understand the mechanism between accelerated ablation of temperate glaciers and climate change in southeast regions of Qinghai-Tibetan Plateau and provide references for local tourism administrations.

In this study, snow samples collected from nine snowpacks from Mt. Yulong are measured to examine the monthly and annual isotopic variation. The results indicate that the late autumn and winter snow sampled in 2008/2009 show a similar high-low-high delta O-18 variation. In spring, the high-low-high curve still exists in the lower layers (1.5 m). Isotopic homogenization, smoothing the vertical variation of delta O-18 in snow, is observed in June and July when snow melting occurs. Samples collected in April of 2009, 2012 and 2017 show significant differences, suggesting annual changes of isotope contents in snow. This study suggests that the isotope contents in the snow profile can reflect meteorological information. At the monthly scale, we can distinguish the information on snow accumulation and melting by determining the monthly variation of vertical isotope contents in snow. At the annual scale, we can analyze the annual difference of corresponding meteorological factors. Collectively, observing the stable isotopes in snow could provide evidence for climate change, particularly when climatic data are lacking or are challenging to obtain in cold glacierized regions.