1990-2020年阿根廷门多萨流域冰川变化研究

冰川是南美洲阿根廷门多萨流域(33°S)重要的淡水资源,冰川作为气候变化的敏感指示器,对于理解和评估全球和区域气候变化具有重要意义。为了解门多萨流域冰川分布及变化趋势,探讨其对区域水资源和生态系统的影响,为应对气候变化提供科学依据,研究基于1990-2020年Landsat遥感影像,参考RGI冰川编目数据和阿根廷国家冰川清单,通过比值阈值法和人工解译法得到7期冰川边界,研究了门多萨流域冰川面积分布与变化特征。并结合TerraClimate气候数据,揭示了该区域在研究期间的气候变化趋势,探讨了区域气候变化对冰川变化的影响。结果表明:①2020年门多萨流域冰川面积为134.09±11.86 km^(2),1990-2020年冰川总体呈极显著波动下降趋势(p<0.01),面积共减少了86.87±21.30 km^(2)(39.31±10.14%),其中,2010-2020年冰川面积退缩速率最高。②门多萨流域冰川规模>10 km^(2)占比最大,<0.1 km^(2)占比最小,>10 km^(2)规模冰川退缩速度最大;冰川主要分布在南坡,西北坡冰川最少,东南、东北坡冰川退缩速度最大;冰川主要分布在坡度5°~40°之间,50°~55°的冰川退缩速度最大;冰川主要分布在海拔4200~5400 m之间,<4000 m冰川退缩速率最大。③20世纪50年代末以来门多萨地区气温整体呈现极显著的上升趋势(p<0.001),研究区年均最高、最低气温每十年上升0.53、0.29℃。气温持续上升是门多萨流域冰川退缩的长期原因,降水变化是该区域冰川变化的短期原因。本研究为门多萨流域预防冰川变化导致的水资源可用性变化和地质灾害预防提供参考。

Proximity to corridors benefits bird communities in vegetated interrow vineyards in Mendoza, Argentina

Management under ecological schemes and increasing habitat heterogeneity,are essential for enhancing biodiversity in vineyards.Birds provide several contributions to agriculture,for example pest control,recreation and enhancing human mental health,and have intrinsic value.Birds are also ideal model organisms because they are easy to survey,and species respond differently to agricultural land use at different scales.Vegetated borders of crops are key for many species of birds,and distance to the border have been found to be an important factor in vineyard-dominated agroecosystems.We evaluate if there are differences in the bird assemblage,between the interior compared to borders within vineyards,using a hierarchical community occupancy model.We hypoth-esized that occupancy of birds is greater in environments with greater heterogeneity,which in this study was considered to be contributed by the proximity to vegetated corridors.We expected that vineyard borders close to corridors will have higher bird occupancy than the center of the vineyard.The research was conducted in three vineyards with biodiversity-friendly management practices,in Gualtallary,Mendoza,Argentina.Bird surveys were conducted over three breeding seasons from 2018 to 2020.Occupancy and richness of the bird community was more closely associated with the borders adjacent to the corridors than with the interior of the vineyards,as we initially predicted,although the assemblage of birds did not differ much.More than 75%of the registered species consume exclusively or partially invertebrates.Biodiversity-friendly management and ecological schemes,together with vegetated corridors provide multiple benefits for biodiversity conservation.These ap-proaches not only minimize the use of agrochemicals but also prioritize soil cover with spontaneous vegetation,which supports a diverse community of insectivorous bird species,potentially contributing to pest control.

Annual variation of adult survival of a south-temperate House Wren population in Argentina

Identifying factors affecting the survival of individuals is essential for understanding the evolution of life-history traits and population dynamics.Despite numerous studies on this subject in north-temperate environments,there is a lack of equivalent studies at similar latitudes in the south.Here,we used a 14-year dataset of capture,banding,and resighting to estimate the annual variation in the apparent adult survival probability of a south-temperate population of House Wrens(Troglodytes aedon bonariae).We evaluated temporal variation in sur-vival and the effect of environmental(climatic)and demographic variables(adult abundance,total number of fledglings produced during each breeding season)on survival estimators.We found that the probability of adult survival decreased as the abundance of breeding adults increased.This density-dependent effect could be related to the resident lifestyle of southern House Wrens,which could determine an intense competition for territories and resources that ultimately would affect their survival.

Phytogenic Mounds (Nebkhas): Effect of Tricomaria usillo on Sand Entrapment in Central-West of Argentina

Nebkhas, developed by the trapping of sand within the body of a plant, were studied in the Médanos Grandes system, arid central Argentina, during the springs of 2009-2010. The dynamics of nebkhas was studied in three draas (megadunes), and considering both orientations: leeward and windward. The Drift Potential (DP) for the study area was 42, evidencing the inactivity of the sand dunes or the scarce activity only in crests. Dominant sand movement is in south-southeast direction, with deflation processes at the southern side of the nebkhas. All nebkhas showed uniformity in the morphometry. Tricomaria usillo is the dominant plant species in the nebkha formation process;and results showed a significant positive relationship between nebkha and canopy volumes.

Seasonal influence and local factors affecting macroinvertebrate structure in a high-altitude Andean stream

Small water bodies are critical for maintaining freshwater biodiversity,but are among the least investigated aquatic environments.We examined physical and chemical variables at two reaches in Arroyo Tambillos,a small,high-elevation Andean stream,in NW Mendoza province,Argentina,across four seasons to examine how local factors and seasonality affected the structure of the macroinvertebrate community.The Arroyo Tambillos community was numerically dominated by ephemeropterans(mainly Massartellopsis irarrazavali)while the dipteran Chironomidae were the most species rich.Total macroinvertebrate abundance was highest in summer,driven mainly by taxa that were secondary in dominance(Austrelmis sp.and Andesiops peruvianus),while richness did not differ between seasons.However,benthic composition was different in Fall 2013(March)compared to other seasons,largely because of the increased abundance of Chironomidae.Canonical correspondence analysis discriminated Chironomidae species distributions in Fall 2013 by substrate type(i.e.,big and small boulder substrate).By contrast,discharge,velocity,and depth were the variables which most affected the macroinvertebrate abundance and distributions.Contrary to our expectations,most community changes observed occurred in fall instead of summer.Nivo-kryal stream communities like the one described here have become increasingly important for conserving mountain stream biodiversity as anthropogentic impacts and climate change increasingly impact lower stream reaches.Therefore,monitoring high-altitude streams like the Arroyo Tambillos may be critical for preventing the future loss of unique and sensitive stream biota.

Environmental and biological factors affecting the abundance of Prosopis flexuosa saplings in the central-west Monte of Argentina

Background:Trees and forests in drylands help mitigate the challenges through provision of economic products and vital environmental services such as habitat for biodiversity,prevention of erosion and desertification,regulation of water,microclimate,and soil fertility.The condition and changes in dry forests can be assessed by using ecological indicators able to quantify spatial and temporal changes in vegetation.One of the ways to determine the condition of the forest is to study the dominant tree species and its regeneration.Our study aimed to assess whether the abundance of Prosopis flexuosa saplings is affected by environmental and biological factors.Results:To evaluate the first variables we used data from remote sensing such as satellite images and Aster Global Digital Model(GDEM).The second set of variables was about exotic and native ungulates and we used feces of these animals and camera traps to take data.We found that sapling abundance related positively to sandy substrates and negatively to Wetness Index.On the other hand,in relation to biological variables,the abundance of saplings was positively affected by density of adult trees and by number of seeds dispersed by equines,but space use by Lama guanicoe had a negative relationship with saplings.This research shows that P.flexuosa saplings are benefited from sandy substrates and the conditions around adult trees.In addition to this,we found that exotic ungulates in low densities have neutral(i.e.cattle)or positive(i.e.equines)effects on sapling abundance.Conclusions:Based on these findings,we conclude that regeneration of the population of P.flexuosa in our study area has no major problems.In addition,we corroborated that the presence of exotic and domestic ungulates in low densities does not have deleterious consequences for saplings of the dominant tree,P.flexuosa.

Habitat and food preferences of European rabbits in core and edge populations along the invasion front PatagoniaMonte,Argentina

The European rabbit Oryctolagus cuniculus is an exotic herbivorous mammal undergoing an active phase of geographical expansion in the arid ecosystems of Argentina.The Adaptive Flexibility Hypothesis states that populations at the range edge(new populations)will exhibit greater fexibility in the use of resources compared with populations located in the range core(older populations).The objective of this work was to compare the rabbit’s use of spatial and trophic resources in relation to the establishment time of their populations.The sampling was carried out for 2 years(2017 and 2018)in sites with different establishment times for rabbit populations.Random sampling stratifed by type of habitat was applied using 115 fxed strip transects of 1,000 m2 laid out across the study areas.Fresh rabbit signs were recorded in each transect,and environmental and anthropic variables were measured.Our results show that the individuals from the range edge are more selective in the use of habitat than those from the range core.At the microhabitat level,we observed a pattern in the particular components of habitat use by rabbits mainly linked to food availability and proximity to water.From a trophic perspective,rabbits could show fexible adjustment to novel conditions and environments in the range edge.The variability in resource use by the European rabbit confrms its ecological fexibility,pivotal for their advance toward new environments in Argentina.

Use of wild trout for PBDE assessment in freshwater environments: Review and summary of critical factors

Certain wild animals represent sentinels to address issues related to environmental pollution,since they can provide integrative data on both pollutant exposure and biological effects.Despite their technological benefits,PBDEs are considered a threat to environmental health due to their persistence,toxicity,and capacity to be accumulated.These pollutants have been found geographically widespread in fish,particularly in predator species such as trout.The aim of this work is to critically review the applicability and usefulness of wild trout for assessing PBDEs in freshwater environments.Reviewed reports include data from highly industrialized areas as well as areas from remote regions with relatively low human activity,including European and North American great lakes and freshwater environments in Europe,Greenland,subarctic areas and Patagonia,respectively.A summary of relevant factors were grouped into organism-specific factors(food habits,age,size,lipid content,sex and reproduction,tissue type,mechanism of contaminant uptake and metabolism),and PBDE levels in the surrounding environment(sediment).Five wild trout species[rainbow trout(Oncorhynchus mykiss),brown trout(Salmo trutta),lake trout(Salvelinus namaycush),arctic char(Salvelinus alpinus),and brook trout(Salvelinus fontinalis)],collected worldwide within the 1994 to present time frame,were considered.Multivariate techniques(principal component analysis-PCA)and mapping approach,showed clear differences in geographic distribution patterns of PBDE levels in trout depending on the region studied:wild trout from European and North American great lakes have the highest PBDE loads.This pattern could be due to high industrial activity at these locations.A correlational approach used to explore intraspecific relationships between PBDE levels and morphometry,showed positive relationships only for brown trout.Further,brown trout showed the highest trout-to-sediment ratios,which is suggestive of a relatively greater capacity of this species to accumulate PBDEs in relation to sediment levels.Overall,results suggest that adult wild trout could be useful as a PBDE bioindicator.