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The development of seedling production technology and methods of establishing high yielding plantations of Picea obovata Ledeb. on a scientific basis is one of the urgent problems of forestry in Mongolia. In this study, we aimed to solve the following problems: to conduct a comparative analysis of the seedling growth parameters and biomass accumulation grown on different nutrient substrates; to assess the relationship between seedling growth, biomass accumulation and soil properties; to determine the most optimal nutrient substrates for seedling production of Siberian spruce in greenhouse conditions in Northern Mongolia. Six formulations of nutrient substrates (T1, Т2, Т3, Т4, Т5, Т6) were used for the seedling production of Picea obovata Ledeb. in greenhouses equipped with a sprinkler system. Nutrient substrates were prepared using black soil, manure, compost, peat, sawdust, sand in different composition ratios. During the 4-year-observation period height, root collar diameter, root length and aboveground and belowground biomass of seedlings were measured at the end of each growing season. We divided the biomass of seedlings into several structural elements. We found that all tested nutrient substrates, except the control substrate, had a positive effect on seedling growth in height and diameter. Comparative analyses showed that different ratio and composition of black soil, compost, manure, sawdust, and sand in the nutrient substrate had different effects on seedling growth (p > 0.001) and biomass accumulation (p > 0.001). Among the proposed nutrient substrates, the treatments T2 (50 % black soil + 20 % sand + 20 % peat + 10 % compost) and T6 (60 % black soil + 20 % sand + 10 % peat + 10 % compost) were selected as the most effective soil substrate that are suitable for further seedling production of Siberian spruce under greenhouse conditions in Mongolia. Therefore, it was observed that good root system development was a determinant of seedling growth in height, diameter, and aboveground biomass accumulation especially from 3–4 years of age. Spruce seedling growth was positively correlated not only with humus content (r = 0.46), but also with soil acidity (r = 0.43) and available phosphorus (r = 0.48). The results of this investigation made an important contribution to the development of production technology for growing standard and large-sized seedlings of Picea obovata in greenhouse complexes in Northern Mongolia.
Хуш модны физиологийн судлах нь энэ модны төрөл зүйл уур амьсгалын өөрчлөлтөд хэрхэн хариу үйлдэл үзүүлэхийг ойлгоход модны жилийн цагирагийн өсөлт болон физиологийн судалгаа хийсэн зарим үр дүнгээс танилцуулж байна.
Climate change is increasing the intensity and frequency of extreme heat events. Ecological responses to extreme heat will depend on vegetation physiology and thermal tolerance. Here we report that Larix sibirica, a foundation species across boreal Eurasia, is vulnerable to extreme heat at its southern range margin due to its low thermal tolerance (Tcrit of photosynthesis: ~ 37–48 °C). Projections from CMIP6 Earth System Models (ESMs) suggest that leaf temperatures might exceed the 25th percentile of Larix sibirica’s Tcrit by two to three days per year within the next two to three decades (by 2050) under high emission scenarios (SSP3-7.0 and SSP5-8.5). This degree of warming will threaten the biome’s continued ability to assimilate and sequester carbon. This work highlights that under high emission trajectories we may approach an abrupt ecological tipping point in southern boreal Eurasian forests substantially sooner than ESM estimates that do not consider plant thermal tolerance traits.
Extreme heat is becoming increasingly common across the boreal biome. Better quantification of vegetation physiology and thermal tolerance is needed to predict ecological responses to these extreme heat events. Here we report that Larix sibirica, a foundation species across boreal Eurasia, has a low thermal tolerance of photosynthesis (Tcrit: ~37-48°C) at its southern range margin. Projections from Earth System Models (ESMs) participating in CMIP6 suggest that leaf temperatures might exceed the 25th percentile of Larix sibirica’s Tcrit by 2 to 3 days per year under high emission scenarios (SSP5-8.5 and SSP3-7.0) by 2050. Such exceedances would cause sustained damage to Larix sibirica’s photosynthetic apparatus and its ability to assimilate carbon. This work highlights that we may be rapidly approaching an ecological tipping point in boreal Eurasia within the next two to three decades. It also demonstrates the need to consider thermal tolerance information to forecast the terrestrial carbon cycle and presents a framework to do so.
The accurate estimation of tree above-ground (AGB) and below-ground (BGB) biomass components and their root/shoot ratio play key roles in stand and country-level forest biomass and carbon stock estimation. Nevertheless, site-specific and appropriate biomass equations and root/shoot ratio are hardly available for natural larch (Larix sibirica Ledeb.) forests in Mongolia. The present study aimed (1) to develop allometric equations to estimate the above- and below-ground biomass of L. sibirica trees, and (2) to estimate the root/shoot ratio applicable for estimating the root biomass based on above-ground biomass of natural larch forests in northern Mongolia. A total of 40 trees with DBH ranging from 6.8 to 40.8 cm were sampled for tree biomass analyses. For each biomass component, we calculated the proportion of biomass allocated to different components, and also tested four allometric equations based on diameter at breast height (DBH) and height (H) as independent variables. Our results, based on measurements of oven-dried biomass, revealed that stem biomass on average accounted for 44.5% and followed by branch (28.6%) and root (19.9%) biomass, respectively. Stem and branch biomass proportions were gradually increased with increasing DBH, while a contrary trend was observed for needles. The root/shoot ratio averaged 0.25. A comparison of the allocation of root biomass by diameter fractions showed an ever-growing trend of coarse roots with an increase in stem diameter, which often exceeded more than 50% of the total root biomass. However, biomass equations, which include both DBH and H were more precise than equations that are solely based only on DBH. Consequently, among the proposed allometric regression models for estimating the AGB and BGB, the equation y ¼ aDb Hc was selected as the best-fitted equation for estimating each biomass component in Siberian larch forests. These allometric equations are available to be used for the estimation of natural larch forest biomass and carbon stocks in the Khentii Mountains of Mongolia, where extreme continental climate conditions dominate
Development of seedling production technology and method for establishment of high productive plantations of Picea obovata Ledeb. on a scientific basis is one of the urgent problems of forestry in Mongolia. In this study, we aimed at solving the following objectives: to conduct comparative analyses of the seedling growth performance and the biomass accumulation in relation to different soil substrates; to assess the relationships between seedling growth, biomass accumulation and soil properties; and to select the most optimal soil substrates for seedling production of Siberian spruce in greenhouse conditions of Northern Mongolia. Six types of soil substrates (treatments) were used for the seedling production of Picea obovata Ledeb. in greenhouses equipped with a sprinkling irrigation system. Soil substrates were prepared using black soil, manure, compost, peat, sawdust and sand in various ratios. During the 4-year-observation period the height, root collar diameter and root length were measured, and the above- and below-ground biomass of seedlings were determined at the end of each growing season. The seedling biomass was separated into biomass structural components. In comparison, all tested soil substrates except for control treatment showed a positive effect on the seedling growth in height and diameter. Our comparative analyses revealed that different ratios and compositions of black soil, compost, manure, sawdust and sand in the soil substrate had different effects on seedling growth (p > 0,001) and biomass accumulation (p > 0.001). Among the proposed soil substrates, the treatments T2 (50 % black soil + 20 % sand + 20 % peat + 10 % compost) and T6 (60 % black soil + 20 % sand + 10 % peat + 10 % compost) were selected as the most effective soil substrate that are suitable for further seedling production of Siberian spruce in greenhouse conditions of Mongolia. However, we found that the biomass of root system is the determining factor for seedling growth in height and diameter, especially from 3–4 years of age. The growth of Spruce seedlings was positively correlated not only with humus content (r = 0.46), but also with soil acidity (r = 0.43) and available phosphorus (r = 0.48). The findings of this assessments have made an important contribution to the development of technology for largescale seedling production of Picea obovata seedlings in greenhouse complexes in Northern Mongolia.
Thermochemical pretreatment, including carbonization, has been suggested as a method to reduce particulate matter (PM) emissions during the combustion of biomass. However, the carbonization efciency might not be equal for all types of biomass because of composition heterogeneity and diferences in combustion conditions. Therefore, an assessment of PM emission reduction by carbonization of various types of biomass at diferent combustion temperatures is required. In this study, seven diferent types of biomass (larch, poplar, miscanthus, bamboo grass, rice straw, rice husk, and dairy manure) and their biochars (prepared at 400 °C) were combusted at 650, 750, and 850 °C. The results showed that PM emission was reduced as much as 95.45% after carbonization as a result of volatile matter removal. The efciency of PM reduction was greatest at low combustion temperatures for all feedstocks. Although the combustion temperatures did not strongly afect PM emissions from low-ash (≤6.7%) biomass, higher heating temperatures (≥750 °C) stimulated PM emissions from ash-rich rice straw and dairy manure biochar. The transformation of minerals in rice straw, rice husk, and dairy manure was also investigated at diferent combustion temperatures (650, 750, and 850 °C). Mineral analysis revealed that enhanced PM emission from ashrich biochar samples was attributable to a greater concentration of Na and K, which likely resulted from melting at higher combustion temperatures. We found that carbonization can substantially reduce PM emissions for low-alkali-containing biomass and that a lower combustion temperature of biochar is preferable to suppress PM emissions for high-alkali-containing biomass. Our fndings reveal a possible approach to waste-to-energy production with reduced health risks
We aimed to test the hypothesis that large-scale forest fre followed by illegal logging inhibits the regeneration of boreal forests in Mongolia. For this purpose, we compared regeneration of the forest between fve stands in a large-scale post-fre site, i.e., (1) undisturbed stand in the unburnt and remaining forest, (2) stand disturbed by illegal logging in the unburnt and remaining forest, (3) stand disturbed by forest fre, (4) stand disturbed by forest fre followed by illegal logging and located in proximity to the remaining forest, which acts as a seed source, and (5) stand disturbed by forest fre followed by illegal logging and located far from the remaining forest, which acts as a seed source. The stand disturbed by logging showed similar species composition of regenerated individuals as the undisturbed stand. In the stand disturbed by logging, Picea obovata and Pinus sibirica were abundant because of advance regeneration on the intact forest foor. In the stand disturbed by forest fre and that disturbed by forest fre followed by illegal logging, Larix sibirica and Betula platyphylla were abundant, and the regenerated individuals of these two species were new individuals after the disturbances. L. sibirica was abundant in the stand disturbed by forest fre because the mother trees survived the forest fre because of their thick bark. B. platyphylla was abundant in the stand disturbed by forest fre followed by illegal logging because the mother trees of L. sibirica were logged and the seeds of B. platyphylla are able to disperse further than that of L. sibirica. However, in the stand disturbed by forest fre followed by illegal logging that was located far from the remaining forest, the regeneration was much reduced because only few seeds, including that of B. platyphylla, were dispersed into this stand and sprouts of B. platyphylla were damaged by the logging operation. In addition, the regeneration of L. sibirica and B. platyphylla was likely to have been reduced for several years after the forest fre because of the loss of safe sites for their invasion by the changes of the forest foor condi- tions. Therefore, it is likely that large-scale forest fres that are followed by illegal logging inhibit the regeneration in many parts of the post-fre site and those parts will change into open forests of B. platyphylla or grassland.
The success of reforestation largely depends on the quality of the seedling. This study focuses on comparative assessments of the experimental planting of Picea obovata seedlings under various growing conditions, including in a greenhouse and open field. The objectives were to carry out a comparative study of the effect of different care regimes on the growth of seedling, and to choose the most optimal treatment that accelerates the growth of seedlings on the basis of the results taken from the comparative analysis. The study was carried out in the Experimental Forest Nursery of the Institute of Geography and Geoecology, MAS in the period between 2018 and 2020. The experimental planting design included four treatments with varying irrigation norms, air temperatures, air relative humidity, shading rates. Two of these experiments were put in greenhouses, and the remaining two treatments were in the open field. Repeated measurements and sampling were performed at the end of each growing season. The results showed high variation in seedling height (p < 0.0001; F = 38.6) and diameter (p < 0.0001; F = 43.2) growth and biomass accumulation (p < 0.0001). These variables therefore, positively corresponded to the air temperature, air relative humidity and moisture sufficiency in the soils. We found that the seedlings had faster growth in height (52.4%) and diameter (62.3%), and there was more biomass accumulation (128.1%) under greenhouse conditions than outdoors. With regard to the biomass allocation, a three-year observation showed a greater proportion of stem biomass in the total biomass, and, conversely, the predominant proportion of needle biomass accounted for open field treatments. However, the creation of stable condition in the greenhouse with a high relative humidity (more than 75%; daily watering norm of 20 liters per day) and an internal temperature of 25°C (40% shading) had the most positive effect on the growth and accumulation of biomass of seedlings. Consequently, we conclude that to meet the existing needs for seedlings for the restoration of natural Picea obovata forests, seedling production in greenhouses should be recommended.
The success of reforestation largely depends on the quality of the seedling. This study focuses on comparative assessments of the experimental planting of Picea obovata seedlings under various growing conditions, including in a greenhouse and open field. The objectives were to carry out a comparative study of the effect of different care regimes on the growth of seedling, and to choose the most optimal treatment that accelerates the growth of seedlings on the basis of the results taken from the comparative analysis. The study was carried out in the Experimental Forest Nursery of the Institute of Geography and Geoecology, MAS in the period between 2018 and 2020. The experimental planting design included four treatments with varying irrigation norms, air temperatures, air relative humidity, shading rates. Two of these experiments were put in greenhouses, and the remaining two treatments were in the open field. Repeated measurements and sampling were performed at the end of each growing season. The results showed high variation in seedling height (p < 0.0001; F = 38.6) and diameter (p < 0.0001; F = 43.2) growth and biomass accumulation (p < 0.0001). These variables therefore, positively corresponded to the air temperature, air relative humidity and moisture sufficiency in the soils. We found that the seedlings had faster growth in height (52.4%) and diameter (62.3%), and there was more biomass accumulation (128.1%) under greenhouse conditions than outdoors. With regard to the biomass allocation, a three-year observation showed a greater proportion of stem biomass in the total biomass, and, conversely, the predominant proportion of needle biomass accounted for open field treatments. However, the creation of stable condition in the greenhouse with a high relative humidity (more than 75%; daily watering norm of 20 liters per day) and an internal temperature of 25°C (40% shading) had the most positive effect on the growth and accumulation of biomass of seedlings. Consequently, we conclude that to meet the existing needs for seedlings for the restoration of natural Picea obovata forests, seedling production in greenhouses should be recommended.
The amount of carbon stored in deadwood is equivalent to about 8 per cent of the global forest carbon stocks1. The decomposition of deadwood is largely governed by climate2,3,4,5 with decomposer groups—such as microorganisms and insects—contributing to variations in the decomposition rates2,6,7. At the global scale, the contribution of insects to the decomposition of deadwood and carbon release remains poorly understood7. Here we present a field experiment of wood decomposition across 55 forest sites and 6 continents. We find that the deadwood decomposition rates increase with temperature, and the strongest temperature effect is found at high precipitation levels. Precipitation affects the decomposition rates negatively at low temperatures and positively at high temperatures. As a net effect—including the direct consumption by insects and indirect effects through interactions with microorganisms—insects accelerate the decomposition in tropical forests (3.9% median mass loss per year). In temperate and boreal forests, we find weak positive and negative effects with a median mass loss of 0.9 per cent and −0.1 per cent per year, respectively. Furthermore, we apply the experimentally derived decomposition function to a global map of deadwood carbon synthesized from empirical and remote-sensing data, obtaining an estimate of 10.9 ± 3.2 petagram of carbon per year released from deadwood globally, with 93 per cent originating from tropical forests. Globally, the net effect of insects may account for 29 per cent of the carbon flux from deadwood, which suggests a functional importance of insects in the decomposition of deadwood and the carbon cycle.
Warming in Central Asia has been accelerating over the past three decades and is expected to intensify through the end of this century. Here, we develop a summer temperature reconstruction for western Mongolia spanning eight centuries (1269–2004 C.E.) using delta blue intensity measurements from annual rings of Siberian larch. A significant cooling response is observed in the year following major volcanic events and up to five years post-eruption. Observed summer temperatures since the 1990s are the warmest over the past eight centuries, an observation that is also well captured in Coupled Model Intercomparison Project (CMIP5) climate model simulations. Projections for summer temperature relative to observations suggest further warming of between ∼3°C and 6°C by the end of the century (2075–2099 cf. 1950–2004) under the representative concentration pathways 4.5 and 8.5 (RCP4.5 and RCP8.5) emission scenarios. We conclude that projected future warming lies beyond the range of natural climate variability for the past millennium as estimated by our reconstruction. (1) (PDF) Accelerated Recent Warming and Temperature Variability Over the Past Eight Centuries in the Central Asian Altai From Blue Intensity in Tree Rings. Available from: https://www.researchgate.net/publication/353486939_Accelerated_Recent_Warming_and_Temperature_Variability_Over_the_Past_Eight_Centuries_in_the_Central_Asian_Altai_From_Blue_Intensity_in_Tree_Rings [accessed Aug 27 2021].
Environmental factors play vital roles in successful plantation and cultivation of tree seedlings. This study focuses on problems associated with reforestation under extreme continental climatic conditions. The objectives were to assess relative seedling performance (survival and growth) with respect to plantation age, and to analyze the influence of specific climatic factors during the early stages of Scots pine (Pinus sylvestris L.) plantations. The study was carried out in reforested areas of the Tujyin Nars region of northern Mongolia on six Scots pine plantations ranging from 5 to 10 years. In each of the six plantations, five 900 m2 permanent sample plots were established and survival rates and growth performance measured annually over 7 years. Results show high variation in survival among the plantations (p\0.001, F = 29.7). Seedling survival in the first year corresponded directly to the number of dry days in May. However, survival rate appeared to stabilize after the second year. The insignificant variation of height categories throughout the observation period indicated low competition among individuals. Two linear mixed-effect models show that height and radial growth were best explained by relative air humidity, which we consider to be a reliable indicator of site-specific water availability. Insufficient amounts and uneven distribution of rainfall pose a major threat during the first year of plantation establishment. Humidity and water availability are decisive factors for a successful seedling plantation. This highlights the impact of drought on forest plantations in northern Mongolia and the importance of developing climate resilient reforestation strategies.
Scots pine (Pinus sylvestris L.) forests are one of the main vegetation types in the Asian forest-steppe zone. However, over-harvesting currently threatens the natural regeneration and sustainability of these forests. In this study, we examine the long-term effects of different logging intensities on soil properties and natural regeneration in a natural Scots pine forest in the West Khentii Mountains (Mongolia), 19 years after selective logging. Our experimental design included five treatments: clear cut (CC), treatments with high (HI), medium (MI), low (LI) intensities, and a reference parcel with no logging impact at all (RE). We described and quantified the harvest events and applied ANOVA and LMM modeling to analyze and explain the long-term impacts of the logging intensities on soil properties and natural regeneration. We found that logging has a significant negative influence on the physical and chemical properties of the soil because it increases soil compaction and reduces soil nutrients. The most critical impacts of logging were on soil bulk density, total porosity, organic matter, and total nitrogen and phosphorus. The LMM modeling showed that organic matter (OgM), total nitrogen (TN), available K (AK) and pH values are especially impacted by logging. Our study revealed that the values for all of these variables show a linear decrease with increasing selective logging intensity and have a level of significance of p < 0.05. Another finding of this study is that selective logging with low and medium intensities can promote natural regeneration of Scots pine to numbers above those of the reference site (RE). High intensity logging and clear-cuts, however, limit the regeneration of Scots pine, reduce overall seedling numbers (p < 0.05), and create conditions that are suitable only for the regeneration of deciduous tree species. This underlines the risk of Scots pine forest degradation, either by replacement by broad-leaf trees or by conversion into non-forest ecosystems.
Scots pine (Pinus sylvestris L.) forests are one of the main vegetation types in the Asian forest-steppe zone. However, over-harvesting currently threatens the natural regeneration and sustainability of these forests. In this study, we examine the long-term effects of different logging intensities on soil properties and natural regeneration in a natural Scots pine forest in the West Khentii Mountains (Mongolia), 19 years after selective logging. Our experimental design included five treatments: clear cut (CC), treatments with high (HI), medium (MI), low (LI) intensities, and a reference parcel with no logging impact at all (RE). We described and quantified the harvest events and applied ANOVA and LMM modeling to analyze and explain the long-term impacts of the logging intensities on soil properties and natural regeneration. We found that logging has a significant negative influence on the physical and chemical properties of the soil because it increases soil compaction and reduces soil nutrients. The most critical impacts of logging were on soil bulk density, total porosity, organic matter, and total nitrogen and phosphorus. The LMM modeling showed that organic matter (OgM), total nitrogen (TN), available K (AK) and pH values are especially impacted by logging. Our study revealed that the values for all of these variables show a linear decrease with increasing selective logging intensity and have a level of significance of p < 0.05. Another finding of this study is that selective logging with low and medium intensities can promote natural regeneration of Scots pine to numbers above those of the reference site (RE). High intensity logging and clear-cuts, however, limit the regeneration of Scots pine, reduce overall seedling numbers (p < 0.05), and create conditions that are suitable only for the regeneration of deciduous tree species. This underlines the risk of Scots pine forest degradation, either by replacement by broad-leaf trees or by conversion into non-forest ecosystems.
This study was carried out in Scots pine (Pinus sylvestris L.) plantations that were previously established in West Khentii Mountains of Northern Mongolia. In this study, species composition, richness, diversity and plant cover changes among planted forests with different plantation ages were analyzed. We found an obvious difference of species composition between natural stands and plantations. Our findings revealed continuous changes in vascular plant composition among plantations by increasing light demanding species. A number of species from forest and forest-meadow mesophytes were replaced with xerophytes from forest-steppe and steppe. Current profound changes in species composition and a stable existence of invasive plant species from different ecological groups have a tendency to be stored during the initial stage of forest plantation establishment. The strong effect of planted trees on the growing environment appeared rather late, and has intensified since 15 years after the plantation establishment
Ground thermal conditions in marginal permafrost in Mongolia were assessed using ground temperatures measured year ‐round at 69 borehole sites. Permafrost is continuous in northern Mongolia and exists as sporadic/isolated patches in the south. Ground temperatures are strongly controlled by local environmental factors, such as topographic depressions that concentrate cold air during winter, ice‐rich strata that prevent penetration of sensible heat, and tree cover that reduces incident solar radiation. Permafrost temperatures are typically between −1 and 0°C; colder permafrost (< −2°C) occurs in the northern extent of continuous permafrost and at high elevations in the sporadic/isolated permafrost zones. Relict permafrost, which is thermally disconnected from seasonal air temperature fluctuations, is present near the latitudinal and elevational limits of perennially frozen ground. Cold and thermally responsive permafrost is dominant in the continuous and discontinuous zones, while warm and thermally unresponsive permafrost is dominant in the sporadic and isolated zones. Overall, the climate‐driven permafrost in the colder regions is stable, while the ecosystem‐driven permafrost in the warmer regions is degrading.
In this study, we assessed the effects of different harvesting intensities on the natural regeneration capacity and soil moisture and temperature regime of natural Scots pine (Pinus sylvestris L.) forests. This study was carried out as a follow-up study, in July 2017 on experimental plots previously established in 1998 (after 19 years). We inventoried tree seedlings, measured the moisture and temperature of the soils, and also collected soil samples from different depths of the soil at each treatment. Treatment were consisted of low, medium, high intensity thinning and clear-cutting except for reference stand. Data was collected from 15 subplots (with 3 replications). Natural regeneration was varied (F=3.29, p=0.05) among treatments, and relatively better natural regeneration was observed on treatments, harvested with low, medium harvesting intensities. The poorest regeneration density and intensified forest succession were found in clear-cuts. However, decreased critical low water content and increased soil temperature involved not only topsoil, but also subsoil. These findings suggested that logging intensity is a main driving factor of forest soil compaction, drainage and water availability in forest-steppe ecosystems in Mongolia.
The severity of recent droughts in semiarid regions is increasingly attributed to anthropogenic climate change, but it is unclear whether these moisture anomalies exceed those of the past and how past variability compares to future projections. On the Mongolian Plateau, a recent decade-long drought that exceeded the variability in the instrumental record was associated with economic, social, and environmental change. We evaluate this drought using an annual reconstruction of the Palmer Drought Severity Index (PDSI) spanning the last 2060 years in concert with simulations of past and future drought through the year 2100 CE. We show that although the most recent drought and pluvial were highly unusual in the last 2000 years, exceeding the 900-year return interval in both cases, these events were not unprecedented in the 2060-year reconstruction, and events of similar duration and severity occur in paleoclimate, historical, and future climate simulations. The Community Earth System Model (CESM) ensemble suggests a drying trend until at least the middle of the 21st century, when this trend reverses as a consequence of elevated precipitation. Although the potential direct effects of elevated CO2 on plant water use efficiency exacerbate uncertainties about future hydroclimate trends, these results suggest that future drought projections for Mongolia are unlikely to exceed those of the last two millennia, despite projected warming.
