Using simulated temperature regimes to test growth and development of an invasive forest insect under climate change

Temperature and its impact on fitness are fundamental for understanding range shifts and population dynamics under climate change. Geographic climate heterogeneity, behavioural and physiological plasticity, and thermal adaptation to local climates makes predicting the responses of species to climate change complex. Using larvae from seven geographically distinct wild populations in the eastern United States of the non-native forest pest Lymantria dispar dispar (L.), we conducted a simulated reciprocal transplant experiment in environmental chambers using six custom temperature regimes representing contemporary conditions near the southern and northern extremes of the US invasion front and projections under two climate change scenarios for the year 2050. Larval growth rates increased with climate warming compared to current thermal regimes and responses differed by population. A significant population-by-treatment interaction indicated that growth rates increased more when a source population experienced the warming scenarios for their region, especially for southern populations. Our study demonstrates the utility of simulating thermal regimes under climate change in environmental chambers and emphasizes how the impacts from future increases in temperature can be heterogeneous due to geographic differences in climate-related performance among populations.

Moho carbonation at an ocean-continent transition

Carbonation of mantle rocks during mantle exhumation is reported in present-day oceanic settings, both at mid-ocean ridges and ocean-continent transitions (OCTs). However, the hydrothermal conditions of carbonation (i.e., fluid sources, thermal regimes) during mantle exhumation remain poorly constrained. We focus on an exceptionally well-preserved fossil OCT where mantle rocks have been exhumed and carbonated along a detachment fault from underneath the continent to the seafloor along a tectonic Moho. Stable isotope (oxygen and carbon) analyses on calcite indicate that carbonation resulted from the mixing between serpentinization-derived fluids at ~175 °C and seawater. Strontium isotope compositions suggest interactions between seawater and the continental crust prior to carbonation. This shows that carbonation along the tectonic Moho occurs below the continental crust and prior to mantle exhumation at the seafloor during continental breakup.

Classifying California’s stream thermal regimes for cold-water conservation

Stream temperature science and management is rapidly shifting from single-metric driven approaches to multi-metric, thermal regime characterizations of streamscapes. Given considerable investments in recovery of cold-water fisheries (e.g., Pacific salmon and other declining native species), understanding where cold water is likely to persist, and how cold-water thermal regimes vary, is critical for conservation. California’s unique position at the southern end of cold-water ecosystems in the northern hemisphere, variable geography and hydrology, and extensive flow regulation requires a systematic approach to thermal regime classification. We used publicly available, long-term (> 8 years) stream temperature data from 77 sites across California to model their thermal regimes, calculate three temperature metrics, and use the metrics to classify each regime with an agglomerative nesting algorithm. Then, we assessed the variation in each class and considered underlying physical or anthropogenic factors that could explain differences between classes. Finally, we considered how different classes might fit existing criteria for cool- or cold-water thermal regimes, and how those differences complicate efforts to manage stream temperature through regulation. Our results demonstrate that cool- and cold-water thermal regimes vary spatially across California. Several salient findings emerge from this study. Groundwater-dominated streams are a ubiquitous, but as yet, poorly explored class of thermal regimes. Further, flow regulation below dams imposes serial discontinuities, including artificial thermal regimes on downstream ecosystems. Finally, and contrary to what is often assumed, California reservoirs do not contain sufficient cold-water storage to replicate desirable, reach-scale thermal regimes. While barriers to cold-water conservation are considerable and the trajectory of cold-water species towards extinction is dire, protecting reaches that demonstrate resilience to climate warming remains worthwhile.

Climatic controls on mountain glacier basal thermal regimes dictate spatial patterns of glacial erosion

Climate has been viewed as a primary control on the rates and patterns of glacial erosion, yet our understanding of the mechanisms by which climate influences glacial erosion is limited. We hypothesize that climate controls the patterns of glacial erosion by altering the basal thermal regime of glaciers. The basal thermal regime is a first-order control on the spatial patterns of glacial erosion. Polythermal glaciers contain both cold-based portions that protect bedrock from erosion and warm-based portions that actively erode bedrock. In this study, we model the impact of various climatic conditions on glacier basal thermal regimes and patterns of glacial erosion in mountainous regions. We couple a sliding-dependent glacial erosion model with the Parallel Ice Sheet Model (PISM) to simulate the evolution of the glacier basal thermal regime and glacial erosion in a synthetic landscape. We find that both basal thermal regimes and glacial erosion patterns are sensitive to climatic conditions, and glacial erosion patterns follow the patterns of the basal thermal regime. Cold temperature leads to limited glacial erosion at high elevations due to cold-based conditions. Increasing precipitation can overcome the impact of cold temperature on the basal thermal regime by accumulating thick ice and lowering the melting point of ice at the base of glaciers. High precipitation rates, therefore, tend to cause warm-based conditions at high elevations, resulting in intensive erosion near the peak of the mountain range. Previous studies often assessed the impact of climate on the spatial patterns of glacial erosion by integrating climatic conditions into the equilibrium line altitudes (ELAs) of glaciers, and glacial erosion is suggested to be maximal around the ELA. However, our results show that different climatic conditions produce glaciers with similar ELAs but different patterns of basal thermal regime and glacial erosion, suggesting that there might not be any direct correlation between ELAs and glacial erosion patterns.

Impact of deforestation on radiative and thermal regimes of the territory of Ukraine on the base of global climate models data

This paper is dedicated to the influence of partial deforestation with using global retrospective modelling data from The Land Use Model Intercomparison Project (LUMIP) for the territory of Ukraine. This experiment aims to global gradual deforestation and has two phases. The first phase, defined as the pre-industrial period (1850—1899) with constant unchangeable anthropogenic impact. For this period deforestation modelled with further replacement with grass cover with a linear trend 400000 km2/yr or 20 million km2 per 50 years in general. The second phase is next 30 years with no significant changes in forest cover (1900—1929). For conducting this research the data of several global climate models were applied. The results of analysis have demonstrated that a partial deforestation with grass substitution influences the surface reflectivity or albedo and redistribution of shortwave radiative fluxes. In turn, it provokes changes in thermal regime. It was found that the most significant changes in surface reflectivity and the strongest correlation coefficients between albedo and deforestation are in the winter season due to the presence of snow cover. As a result, statistical significant increase of albedo is with maximum values up to 24 %/50 years in some grids in winter. Then in the summer season maximal changes are up to 2.7 %/50 years due to small differences between forest and grass albedos. As a consequence, changes in albedo cause changes in surface and air temperature regimes. Strong dependencies were found in winter between changes in albedo and temperatures with maximum temperature decrease 2.5…2.0 %/50 years. In warm season correlations are weaker in comparison to cold season, but nevertheless, temperatures decrease also take place with maximum values 2.0…1.5 %/50 years. The analysis between deforestation and daily air temperature range has shown that particularly in winter season there is an increase of 0.5...1.5 %/50 years, whereas such tendency is not observed in warm season. Calculations of year air temperature range demonstrated controversial results among climate models, as follows it is hard to make a conclusion about the contribution of forest cover reduction to changes in this index. It was revealed, that global climate models with higher resolution are more sensitive to changes in albedo and, as a consequence to other characteristics than models with coarse ones. It should be noticed that obtained results concern pre-industrial period with minimal anthropogenic impact, when observed a stable snow cover in winter in Ukraine. In the current climate change with significant warming and reduction of snow season duration deforestation can have opposite effects on radiative and thermal regimes that require further studying.