Compositional shifts of alpine plant communities across the high Andes.

Aim: Climate change is transforming mountain summit plant communities worldwide, but we know little about such changes in the High Andes. Understanding large-scale patterns of vegetation changes across the Andes, and the factors driving these changes, is fundamental to predicting the effects of global warming. We assessed trends in vegetation cover, species richness (SR) and community-level thermal niches (CTN) and tested whether they are explained by summits' climatic conditions and soil temperature trends. Location: High Andes. Time period: Between 2011/2012 and 2017/2019. Major taxa studied: Vascular plants. Methods: Using permanent vegetation plots placed on 45 mountain summits and soil temperature loggers situated along a ~6800 km N-S gradient, we measured species and their relative percentage cover and estimated CTN in two surveys (intervals between 5 and 8 years). We then estimated the annual rate of changes for the three variables and used generalized linear models to assess their relationship with annual precipitation, the minimum air temperatures of each summit and rates of change in the locally recorded soil temperatures. Results: Over time, there was an average loss of vegetation cover (mean = −0.26%/ yr), and a gain in SR across summits (mean = 0.38 species m2/yr), but most summits had significant increases in SR and vegetation cover. Changes in SR were positively related to minimum air temperature and soil temperature rate of change. Most plant communities experienced shifts in their composition by including greater abundances of species with broader thermal niches and higher optima. However, the measured changes in soil temperature did not explain the observed changes in CTN. Main conclusions: High Andean vegetation is changing in cover and SR and is shifting towards species with wider thermal niche breadths. The weak relationship with soil temperature trends could have resulted from the short study period that only marginally captures changes in vegetation through time.EEA Santa CruzFil: Cuesta, F. Universidad de las Américas. Grupo de Investigación en Biodiversidad Medio Ambiente y Salud – BIOMAS; Ecuador.Fil: Carilla, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Carilla, Julieta. Universidad Nacional de Tucumán. Instituto de Ecología Regional; Argentina.Fil: Llambí, L.D. Universidad de Los Andes. Instituto de Ciencias Ambientales y Ecológicas; Venezuela.Fil: Llambí, L.D. Consorcio para el Desarrollo Sostenible de la Ecorregión Andina (CONDESAN); Perú.Fil: Muriel, P. Pontificia Universidad Católica del Ecuador. Escuela de Ciencias Biológicas Laboratorio de Ecofisiología; Ecuador.Fil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC); Argentina.Fil: Meneses, R. I. Universidad Católica del Norte. Instituto de Investigaciones Arqueológicas y Museo; Chile.Fil: Feeley, K. J. University of Miami. Biology Department. Coral Gables; Estados UnidosFil: Pauli, H. Austrian Academy of Sciences. Institute for Interdisciplinary Mountain Research; Austria.Fil: Pauli, H. University of Natural Resources and Life Sciences. Department of Integrative Biology and Biodiversity Research; Austria.Fil: Aguirre, N. Universidad Nacional de Loja. Carrera de Ingeniería Forestal. Centro de Investigaciones Tropicales del Ambiente y Biodiversidad (CITAB); Ecuador.Fil: Beck, S. Museo Nacional de Historia Natural - Instituto de Ecología (UMSA). Herbario Nacional de Bolivia; Bolivia.Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Tovar, C. Royal Botanical Gardens Kew. Jodrell Laboratory; Reino Unid

New land in the Neotropics: a review of biotic community, ecosystem, and landscape transformations in the face of climate and glacier change

The high tropical Andes are rapidly changing due to climate change, leading to strong biotic community, ecosystem, and landscape transformations. While a wealth of glacier, water resource, and ecosystem-related research exists, an integrated perspective on the drivers and processes of glacier, landscape, and biota dynamics is currently missing. Here, we address this gap by presenting an interdisciplinary review that analyzes past, current, and potential future evidence on climate and glacier driven changes in landscape, ecosystem and biota at different spatial scales. We first review documented glacier changes and landscape evolution over past decades to millennia and analyze projected future glacier shrinkage until 2100 for two case studies in the tropical Andes. The effects of climate and glacier change on high Andean biota are then examined from paleoecological research and comparative gradient analyses to chronosequence and diachronic studies of vegetation dynamics. Our analysis indicates major twenty-first century landscape transformations with important socioecological implications which can be grouped into (i) formation of new lakes and drying of existing lakes as glaciers recede, (ii) alteration of hydrological dynamics in glacier-fed streams and high Andean wetlands, resulting in community composition changes, (iii) upward shifts of species and formation of new communities in deglaciated forefronts,(iv) potential loss of wetland ecosystems, and (v) eventual loss of alpine biota. We advocate strengthening an interdisciplinary research agenda with a strong policy formulation link that enables enhanced cross-sectorial cooperation and knowledge sharing, capacity building of relevant stakeholders, and a more active participation of both government agencies and social organizations

Cambio en el uso del suelo/cobertura y los patrones de configuración espacial de la jalca peruana entre 1987 y 2007

Resumen La Jalca, considerada como un área de transición entre los páramos y la puna, es también un ecosistema de pastizales altoandinos naturalmente fragmentado con una creciente actividad humana que no ha sido cuantificada aun en detalle. Este estudio tiene por objetivo analizar el cambio del uso del suelo y los cambios en la configuración espacial de los parches (fragmentación) de la jalca del sur de Cajamarca. Usando imágenes satelitales de 1987 y 2007 (LANDSAT 5TM) se reconstruyeron mapas de cobertura y se identificaron los parches de jalca para cada año. Nuestros resultados muestran que la jalca se redujo en un 25% (75.000 ha) durante el periodo analizado. La actividad agrícola es la principal responsable de esta pérdida en extensión de Jalca, especialmente en las zonas más altas donde los cultivos han ocurrido a mayores alturas en el 2007 que en 1987. Sin embargo, en términos relativos el incremento de plantaciones (1000%) y minería (500%) es más dramático que el de la agricultura (26%). Adicionalmente se observa un proceso de fragmentación creciente donde los parches de jalca se están volviendo más pequeños y perdiendo los límites naturales de jalca-bosques o jalca-arbustales para estar rodeados de actividades humanas. Abstract The Jalca, a transitional area between the paramos and the puna, is also a naturally fragmented grassland ecosystem with an increasing human activity not detailed quantified yet. This study analyzes: 1) the land use and land cover changes and 2) changes in the spatial configuration (fragmentation) of the Jalca of South Cajamarca. Land cover maps were constructed by classifying satellite images (LANDSAT 5M) taken on 1987 and 2007 to analyze land cover and land use change and Jalca patches were identified from those maps for the fragmentation analysis. Our results show a reduction of Jalca areas by 25% (75.000 ha) between 1987 and 2007. Agriculture is the main driver of this reduction in extent especially in the upper zones of the Andes showing an upward expansion of crops. However, in relative terms, the increase in plantations (1000%) and mining areas (500%) is more dramatic than that of agriculture (26%). Additionally the Jalca has suffered a fragmentation process where Jalca patches have become smaller and have lost the natural borders jalca-forest and jalca-shrublands to be surrounded by human activities

Dinámica del carbono en los ecosistemas de páramo de los Andes neotropicales: revisión de literatura sobre modelos y parámetros relevantes

Resumen Los suelos del páramo almacenan cantidades excepcionales de carbono debido a las condiciones edáficas y climáticas sobre las cuales se desarrollan. Este gran reservorio de carbono está amenazado debido a los efectos del cambio climático y las dinámicas de uso de la tierra. No obstante, el desarrollo de mecanismos de mitigación como los promovidos por REDD+ son una alternativa que puede ayudar a reducir los impactos de estas amenazas y promover su conservación. Sin embargo, para la aplicación de estos tipos de mecanismos es fundamental que los procesos asociados al mantenimiento y dinámica del ciclo del carbono sean comprendidos y los posibles impactos puedan ser proyectados. En este trabajo, a partir de una extensa revisión de artículos indexados, se presenta una síntesis del estado actual del conocimiento y se discute las ventajas y limitaciones de la aplicación de modelos de carbono orgánico del suelo y sus parámetros asociados. Como resultado de esta revisión, concluimos que los modelos disponibles actualmente contienen limitaciones importantes asociados a los procesos y flujos de la descomposición de la materia orgánica que impiden su aplicación en los páramos andinos. Adicionalmente, información sobre las variables de ingreso es limitada y lo mismo aplica para información independiente que permita validar los resultados modelados. El artículo concluye con recomendaciones sobre prioridades futuras de investigación, enfatizando la urgencia del desarrollo de estudios comparativos sobre los efectos del uso de la tierra en la dinámica del carbono, en lugar del desarrollo de estudios experimentales en condiciones controladas. Abstract Paramo soils store exceptionally large amounts of carbon because of the specific edaphic and climatic conditions in tropical high-altitude ecosystems. This soil C-stock is threatened by changes in climate and land use, but potentials for its conservation on the basis of REDD+ type mechanisms are high. However, for application of such mechanisms it is crucial that properties and processes involved are adequately understood and impacts can be predicted. In this paper, an overview is given of the current knowledge and applicability of soil carbon models and parameters involved, based on a full search of publications in international refereed journals. The conclusion is that existing models are not readily applicable to paramo soils because of the specific decomposition processes and pathways. Moreover, information on relevant input parameters is scant and the same holds for data that can be used to validate model outputs. Recommendations are given for future research, emphasizing the urgency of comparative studies of land use impacts, rather than of experimental studies

Thermal niche traits of high alpine plant species and communities across the tropical Andes and their vulnerability to global warming

Aim The climate variability hypothesis (CVH) predicts that locations with reduced seasonal temperature variation select for species with narrower thermal ranges. Here we (a) test the CVH by assessing the effect of latitude and elevation on the thermal ranges of Andean vascular plant species and communities, and (b) assess tropical alpine plants vulnerability to warming based on their thermal traits. Location High tropical Andes. Taxon Vascular plants. Methods Temperature data for 505 vascular plant species from alpine communities on 49 summits, were extracted from 29,627 georeferenced occurrences. Species thermal niche traits (TNTs) were estimated using bootstrapping for: minimum temperature, optimum (mean) temperature and breadth (maximum‐minimum). Plant community‐weighted scores were estimated using the TNTs of their constituent species. CVH was tested for species, biogeographical species groups and communities. Vulnerability to global warming was assessed for species, biogeographical species groups and communities. Results Species restricted to the equator showed narrower thermal niche breadth than species whose ranges stretch far from the equator, however, no difference in niche breadth was found across summits’ elevation. Biogeographical species groups distributed close to the equator and restricted to alpine regions showed narrower niche breadth than those with broader ranges. Community‐weighted scores of thermal niche breadth were positively related to distance from equator but not to elevation. Based on their TNTs, species restricted to equatorial latitudes and plant communities dominated by these species were identified as the most vulnerable to the projected 1.5°C warming, due to a potentially higher risk of losing thermal niche space. Main conclusions Our study confirms that the CVH applies to high tropical Andean plant species and communities, where latitude has a strong effect on the thermal niche breadth. TNTs are identified as suitable indicators of species’ vulnerability to warming and are suggested to be included in long‐term biodiversity monitoring in the Andes

Calidad del agua en relación con las propiedades del geoecosistema: un estudio de caso de una zona de jalca cerca de Cajamarca, Perú

Resumen Este estudio presenta una primera aproximación a la relación entre hidrología,calidad del agua, geología y suelos para un ecosistema de jalca cerca de Cajamarca en el norte de Perú. Debido a que las áreas de jalca son propensas a la degradación de sus suelos húmicos, como resultado del uso del suelo y del cambio climático, se requiere mayor información sobre su hidrología y geoecología. Durante dos campañas de campo se evaluó la geología, geomorfología, suelos y vegetación del área. Además, se realizaron mediciones de conductividad eléctrica hidrológica y se tomaron muestras a lo largo de varias quebradas (arroyos). Aunque en la región hay importantes proyectos mineros, no existe actividad minera en las cuencas estudiadas. Los suelos mostraron una clara relación con su sustrato y en muchos casos tuvieron un alto contenido de materia orgánica, que se demuestra por el predominio de horizontes A mólicos y úmbricos. La hidrología es impulsada por un excedente de agua de alrededor de 300 mm por año y el caudal de los ríos está íntimamente relacionado con la estacionalidad de las lluvias. Hemos encontrado que existe una clara relación entre el sustrato subyacente y la química del agua de los arroyos y pantanos. Se pueden distinguir dos tipos de agua: uno originado de rocas extrusivas dacíticas (ignimbritas), con niveles extremadamente bajos de sólidos disueltos totales, un predominio de Ca2+ y HCO3 -, niveles de sodio relativamente altos y una baja RAS (relación de adsorción de sodio). El otro tipo de agua se origina en zonas de roca madre dominadas por calizas, mostrando niveles mucho más altos de sólidos disueltos totales. La contaminación química del agua, expresada en nitratos y amonio, estuvo relacionada especialmente con zonas pobladas. Abstract This study gives a first approximation of the relationship between hydrology and water quality, geology, and soils for a jalca ecosystem near Cajamarca in Northern Peru. As the jalca areas are prone to degradation of their humic soils as a result of land use and climate change, more information is needed on their hydrology and geoecology. During two field campaigns the area was surveyed with regard to geology, geomorphology, soils, and vegetation. Furthermore, hydrological routings were executed, measuring electrical conductivity (EC25) of stream waters and selectively sampling these waters. Soils showed a clear relationship with their substrate and were in many cases high in organic material as shown by the dominance of mollic and umbric A horizons, respectively. The hydrology is driven by a water surplus of around 300mm per year, and stream discharge is closely related to the seasonality of the rainfall. We found that there is a clear relationship between the underlying substrate and the water chemistry of the streams and fens. Two set of water types can be distinguished: one originating from dacitic extrusive rocks (ignimbrites), with extremely low total dissolved solid levels, a dominance of Ca2+ and HCO3 -, and relatively high sodium levels and with low SAR (sodium adsorption ratio) values. The other type of water originates from limestone dominated bedrock areas, showing much higher total dissolved solid levels. Chemical water pollution, as expressed by nitrates and ammonium, was especially related to settlements