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.

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.

Stable isotopes are useful for obtaining hydroclimatic and past environmental information. The record of stable isotopes in snow not only reflects the deposition condition but also provides information on post-depositional processes, which benefits ice core studies. In this study, delta O-18 and delta D in new snow, surface snow and snowpack were measured to analyze deposited and post-depositional processes on a temperate glacier at the southeast margin of the Tibetan plateau. The results indicated that new snow and surface snow were relatively depleted in heavy isotopes during the post-monsoon period and enriched in heavy isotopes during the westerly and pre-monsoon period. Surface snow was enriched in O-18 and D relative to new snow sampled during the same period. Isotopic homogenization was observed in May and June snowpack, illustrating the effect of melting on isotopes. The relatively low slope ( 8) during the westerly and pre-monsoon periods corresponded to temperature change. Although the vertical isotopic composition of snowpack sampled in April recorded the deposited information of winter precipitation, the post-depositional processes could have altered the isotopic composition of snow. During the accumulation period, wind drift was an crucial factor leading to abrupt isotopic modification in snow, which was verified using the energy-balance model and wind regime. During the ablation period, the decreasing trend of the slope and the gradual enrichment of O-18 and D in the leaving snow mainly resulted from the isotopic exchange between liquid and solid water. The study enhanced our understanding of the controlling post-depositional processes on temperate glaciers.

Using ground-penetrating radar (GPR), we measured and estimated the ice thickness of the Baishui River Glacier No. 1 of Yulong Snow Mountain. According to the position of the reflected media from the GPR image, combined with the radar waveform amplitude and polarity change information, the ice thickness and the changing medium position at the bottom of this temperate glacier were identified. Water paths were found in the measured ice, including ice caves and crevasses. A debris-rich ice layer was found at the bottom of the glacier, which produces strong abrasion and ploughing action at the bedrock surface. This results in the formation of different detrital layers stagnated at the ice-bedrock interface and numerous crevasses on the bedrock surface. Based on the obtained ice thickness and differential GPS data, combined with Landsat images, the kriging interpolation method was used to obtain grid data. The average ice thickness was 52.48 m and between 4740 and 4890 m above sea level, with a maximum depth of 92.83 m. The bedrock topography map of this area was drawn using digital elevation model from the Shuttle Radar Topography Mission. The central part of the glacier was characterized by small ice basins with distributed ice steps and ice ridges at the upper and lower parts.

Snow cover, which is undergoing significant change along with global climate change, has considerable impacts on the functioning of terrestrial ecosystems. However, how snow cover change affects the vegetation gross primary production (GPP) in temperate regions still requires in-depth exploration. In this study, we investigated how changes in the winter snow depth (WSD) and snowmelt date (SMD) affect spring GPP and summer GPP through their influences on the start date of the growing season (SGS) and the maximum daily GPP (GPP(max)), respectively. across temperate China from 2001 to 2015, based on both in situ measurements and satellite products (i.e., GLASS GPP, WestDC snow depth and GLEAM soil moisture). Soil moisture is identified as an important factor in the snow-GPP relationship in temperate China. Since most of temperate China is water-limited, thicker snow cover along with later snowmelt generally resulted in earlier SGS via a significant increase in soil moisture (47% of the area), which lengthened the growth period and enhanced spring carbon uptake in these areas. However, in wetter regions (7% of the area), thicker snow cover with later snowmelt would be more likely to delay the SGS, thus reducing spring GPP. Moreover, although the direct impact mechanisms of snow cover dynamics on summer GPP have not been identified, the snow-induced SGS change was found to have delayed effects on summer photosynthesis capacity, as earlier SGS increased the GPP(max) and thus summer GPP. However, the photosynthesis enhanced by earlier SGS meanwhile increased the plant water consumption, which would bring water stress and reduce summer GPP if the subsequent precipitation is unable to compensate for the water consumption. Our findings on the effects of snow cover change on carbon uptake would provide the basic mechanisms for assessing how future climate change will affect ecosystem productivity. (C) 2019 Elsevier B.V. All rights reserved.

Based on the historical documents and measured data from the active-layer temperature (ALT) at A, B and C locations (4 670, 4 720 and 4 770 m a.s.l.) on Baishui Glacier No. 1, southeastern Tibetan Plateau, this paper analyzed spatial-temporal characteristics of ALT and its relationship with air temperature, and revealed the response of the active layer ice temperature towards climate change in the monitoring period. The results showed that the influence of air temperature on the active-layer ice temperature had a hysteresis characteristic on the upper of ablation zone and the lag period increased gradually with the altitude elevating. The decrease amplitude of ALT in the accumulation period was far below its increase magnitude in the ablation period. At the same time, the mean glacier ice temperatures at 10 m depth (T-10) in A, B and C profile were obviously higher than most of glaciers previously studied. Measured data also showed that the mean ALT increased by 0.24 degrees C in 0.5-8.5 m depth of the C profile during 28 years from July 11, 1982 to July 10, 2009.

Current climate models are effective at projecting trends in mean winter temperature; however, other ecologically relevant parameters-such as snow cover and soil frost dynamics-are less well investigated. Changes in these parameters are expected to have strong ecological implications, especially in the temperate zone, where it is uncertain whether snow and soil frost will occur with regularity in the future. We explored trends in days with snow on the ground (snowdays), minimum soil temperature (MST), and number of soil freeze/thaw cycles (FTCs, i.e. changes in sign from negative to positive in any pair of consecutive soil temperature records at 5 cm depth) at 177 German weather stations for 1950-2000. Future trends were explored by statistical modelling based on climatic and topographic predictors. Snowdays decreased uniformly at a rate of 0.5 d yr(-1) in the recent past. This trend is projected to continue to a point where significant parts of Germany will no longer regularly experience snow cover. MST has increased, and is projected to do so in the future, mainly in southern Germany. FTCs have been decreasing uniformly in the recent past. No evidence for increased FTCs or decreased MST with decreasing insulation due to missing snow cover was found. FTCs are projected to decrease disproportionately in northeastern Germany, where past frequencies were higher. Ecological implications of the significant decrease in the occurrence and magnitude of the climate parameters studied include changes in nutrient cycling, productivity and survival of organisms over wintering at the soil surface. Ecological research is needed, as the effects of diminished winters on ecosystems are not well understood.