Physiognomic and physiologic changes in mountain grasslands in response to environmental and anthropogenic factors

Mountain grasslands provide valuable ecosystem services for sustainable development and human wellbeing. These habitats have suffered important changes related with their physiognomic (biomass) and physiologic (greenness) properties. Some of these changes received significant attention i.e. woody encroachment, while others, like the changes in biomass and greenness of those grasslands that have not experienced woody encroachment are almost unknown. We calculated physiognomic and physiologic properties for dense grasslands not affected by woody encroachment through the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Infrared Index (NDII) from Landsat-5 Thematic Mapper. Imagery taken in the late-1980s and late-2000s in the Spanish Pyrenees were analyzed with multi-temporal vectors to detect increases or decreases of biomass and greenness. To understand the source of these changes, we modeled them with anthropogenic (land use, i.e. grazing, ski resorts, and related infrastructures) and environmental factors (topographic, lithologic and climatic). Anthropogenic factors were most strongly correlated with decrease in the biomass and greenness, showing degradation patterns of the grasslands at localized patches. Nonetheless, environmental factors were most strongly correlated with positive changes in both indices, detecting a continuous pattern in the increase in biomass and greenness. In areas that had high livestock stocking rates, grasslands biomass and greenness decrease, while in areas that had low stocking rates, biomass and greenness increases. Grasslands at low elevation showing decrease in biomass and greenness were either on gentle slopes and largely affected by human activities, or on steep slopes locally affected by ski resorts. In areas that have been disturbed by anthropogenic factors, the increase of rain in early summer trigger erosion processes, enhancing the negative effect of anthropic pressure on grassland greenness and biomass. In contrast, grasslands at high elevations, on steep slopes, and those that had north or west aspects and that had an acidic lithology, with less continentality, and that received more rain, had the most increase in biomass and greenness. Those results suggest that changes in mountain grasslands, apart from woody encroachment, are deeply altering their physiology and physiognomy, pointing out direct relationships with current management practices and climate trends.This research was funded by the following research projects; Ref.:125/2010 MMAMRM (Spanish Ministry of Agriculture and Environment), CGL2011-27259 (Spanish Ministry of Economy and Competitiveness and Innovation) co-financed by the FEDER, and FW7 ENV.2009.2.1.3.2-LEDDRA (European Community). CGB was supported by the AXA Research Fund (PDOC_2011_W2) and Killam Postdoctoral Fellowship (University of Alberta (2012-2013)). F. Fillat and R. García provided interesting comments and supporting climatic information.Peer reviewe

Increased Soil Frost Versus Summer Drought as Drivers of Plant Biomass Responses To Reduced Precipitation: Results from A Globally-Coordinated Field Experiment

Reduced precipitation treatments often are used in field experiments to explore the effects of drought on plant productivity and species composition. However, in seasonally snow-covered regions reduced precipitation also reduces snow cover, which can increase soil frost depth, decrease minimum soil temperatures and increase soil freeze-thaw cycles. Therefore, in addition to the effects of reduced precipitation on plants via drought, freezing damage to overwintering plant tissues at or below the soil surface could further affect plant productivity and relative species abundances during the growing season. We examined the effects of both reduced rainfall (via rain-out shelters) and reduced snow cover (via snow removal) at 13 sites globally (primarily grasslands) within the framework of the International Drought Experiment, a coordinated distributed experiment. Plant cover was estimated at the species level and aboveground biomass was quantified at the functional group level. Among sites, we observed a negative correlation between the snow removal effect on minimum soil temperature and plant biomass production the next growing season. Three sites exhibited significant rain-out shelter effects on plant productivity, but there was no correlation among sites between the rain-out shelter effect on minimum soil moisture and plant biomass. There was no interaction between snow removal and rain-out shelters for plant biomass, although these two factors only exhibited significant effects simultaneously for a single site. Overall, our results reveal that reduced snowfall, when it decreases minimum soil temperatures, can be an important component of the total effect of reduced precipitation on plant productivity

Integrando escalas y métodos LTER para comprender la dinámica global de un espacio protegido de montaña: el Parque Nacional de Ordesa y Monte Perdido

Los espacios protegidos, por el hecho de albergar una gran geo-biodiversidad y asegurar una baja intervención humana, constituyen lugares muy adecuados para el seguimiento de organismos y procesos a escala ecológica, así como para la obtención de series temporales largas a escala geológica. En el marco de la red LTER-España, el Parque Nacional de Ordesa y Monte Perdido (PNOMP) y el Instituto Pirenaico de Ecología-CSIC están impulsando estudios para la detección de cambios a distintas escalas mediante variados métodos y aproximaciones. Destacamos aquí los más consolidados, entre los que se encuentran los análisis de registros de sedimentos en lagos, espeleotemas en cuevas, la dinámica de uno de los pocos glaciares activos de la Península ibérica, el análisis físico-químico de aguas corrientes e ibones de alta montaña, el registro del cambio climático actual en árboles longevos, la afección que éste ejerce sobre masas actuales de pinos en el límite superior del bosque y de abetales en zonas húmedas, la matorralización de algunos pastos y los procesos mecanicistas que subyacen, la reorganización de la diversidad florística en pastos tras el abandono paulatino o drástico de la ganadería, la biodiversidad de las comunidades alpinas y la dinámica poblacional de especies amenazadas o indicadoras de hábitats o de motores de cambio global. Los seguimientos ecológicos actuales muestran que tanto el cambio climático como el de usos del suelo están teniendo una considerable trascendencia en la fisionomía y la estructura de algunos de los ambientes más icónicos y frecuentes del parque (deterioro del glaciar, termofilización de la flora en cumbres alpinas, densificación del bosque en su límite superior, pérdida de productividad en algunos pastos supraforestales, etc.). También sugieren una importante variabilidad espacial en los procesos (por ej. en el PNOMP conviven pastos matorralizados y pastos muy estables), y evidencian que los cambios observados no siempre siguen los paradigmas establecidos (por ej., las especies amenazadas mantienen dinámicas poblacionales estables). La integración de resultados parciales proporcionados por cada aproximación relativiza la importancia de las percepciones que cada estudio destaca por separado, y permite medir los cambios actuales en el marco de referencia de los cambios a escala geológica. Predecir la resistencia y resiliencia de los ecosistemas o las poblaciones de seres vivos para enfrentarse a los futuros cambios ambientales es complicado, no sólo por la falta de conocimientos disponibles sino también porque las respuestas que observamos no siempre son tan rápidas o lineales como se espera. La modelización constituye una herramienta cada vez más utilizada, pero requiere de evidencias reales para validar sus pronósticos, por lo que la observación de los procesos que actúan en el PNOMP ha de incluir un esfuerzo continuado de monitorización multiescalar y multidisciplinar de los distintos componentes de la geo, hidro-, crio- y biosfera, sin olvidar el componente humano. Entender la complejidad supone conectar las interacciones que existen entre todos los sistemas y ponderar sus efectos según las escalas de trabajo.Instituto Pirenaico de Ecología, Consejo Superior de Investigaciones Científicas, EspañaEmpresa pública SARGA, EspañaJOLUBE Consultor Botánico, Editor y Fotógrafo, EspañaDepartament d’Ecologia, Universitat de Barcelona, EspañaUnidad de Tres Cantos, Instituto Geológico y Minero de España, EspañaInstitut de Recerca de Biodiversitat, Universitat de Barcelona, EspañaParque Nacional de Ordesa y Monte Perdido, Españ

Artazako artadiko ektomikorriza-komunitatearen karakterizazioa

Es destacable la importancia de los ectomicorrizos en los bosques situados en territorios templados, ya que se trata de un tipo de simbiosis formada por la práctica totalidad de los árboles en dichos territorios. En una parcela limitada en el hayedo de Artaza se ha estudiado la diversidad de la comunidad de ectomicorrizos, su distribución espacio-temporal y su relación con los factores ambientales. En 45 muestras de tierra se han distinguido 30 morfotipos. No se ha observado ningún patrón espacio-temporal de los ectomicorrizos y dos de los morfotipos han mostrado una correlación positiva con los factores ambientales.Lurralde epeletako basoetan ektomikorrizek duten garrantzia azpimarratzekoa da, ia zuhaitz guztiak eratzen baitute sinbiosi mota hau. Artazako aradian mugatutako partzelan, ektomikorriza komunitatearen dibertsitatea, hauek espazioan eta denboran duten banaketa eta ingurugiro faktoreekin duten erlazioa aztertu da. 45 lur laginetan, 30 morfotipo desberdindu dira. Ez da espazioan eta denboran ektomikorrizen patroirik ikusi eta bi morfotipok erekutsi dute korrelazio positiboa ingurugiro faktoreekin.Il convient de souligner l'importance des ectomycorhizes pour les forêts sous climats tempérés, puisqu'il s'agit d'une symbiose formée par la quasi-totalité des arbres des territoires concernés. La diversité du peuplement d'ectomycorhizes a été étudiée sur une parcelle délimitée de la hêtraie d'Artaza, ainsi que la répartition spatio-temporelle et les rapports du peuplement avec les facteurs environnementaux. 30 morphotypes ont été isolés pour 45 échantillons de terre. Aucun modèle spatio-temporel d'ectomycorhizes n'a été observé, et deux des morphotypes ont révélé être en relation avec les facteurs environnementaux.Remarkable is the importance of the ectomycorrhizas in forests situated in temperate climes, as it concerns a type of symbiosis formed by practically all the trees in these territories. The diversity of the community of ectomycorrhizas, their spatiotemporal distribution and their relation with environmental factors have been studied in a defined plot in the beech wood of Artaza. In 45 samples of soil 30 morphotypes were distinguished. No spatio-temporal pattern of the ectomycorrhizas was observed and two of the morphotypes showed a positive correlation with environmental factors

Mirando pastos desde el espacio

5 páginas. Presentación elaborada para las II Jornadas IPErinas, celebradas el 12 de diciembre de 2013.Peer reviewe

Assessment of the effects of biophysical and anthropogenic factors on woody plant encroachment in dense and sparse mountain grasslands based on remote sensing data

Land abandonment exacerbated by climate change has led to increased woody plant encroachment of mountain grasslands in many regions of the world. The present study assessed woody plant encroachment below potential tree line in the Central Pyrenees of Spain and the association of this encroachment with changes in land use. Remote sensing data from Landsat-5 Thematic Mapper (TM) from the mid-1980s and mid-2000s were analyzed by supervised classification for identification of land cover types. The transition matrix indicated that shrublands were the most dynamic plant communities. Consequently, 21% of cultivated areas, 19% of dense grasslands, and 24% of sparse grasslands became shrublands during the period analyzed, and 35% of shrublands became forest. Generalized additive mixed models (GAMMs) were used to identify biophysical and anthropogenic factors that were significantly correlated with woody plant encroachment of dense and sparse grasslands. Distance to the nearest woody plant habitat (shrub or forest) was the most strongly correlated factor with woody plant encroachment of both types of grassland. This factor explained 69% and 71% of the variance in models of dense and sparse grasslands, respectively. Besides this factor, anthropogenic factors had larger effects on woody plant encroachment of dense grasslands, regions that were more productive and accessible. However, biophysical and especially topographic factors had slightly greater effects on woody plant encroachment of sparse grasslands, regions that were less productive and accessible. The changes in land cover that we observed indicated that land cover has become more homogeneous. There have been reductions in the variety, functions, and services of grasslands, particularly in areas below the potential tree line that are vulnerable to the development of woody plant habitats. © The Author(s) 2014.This research was funded within the framework of the research project CGL2011-27259 (Spanish Ministry of Economy and Competitiveness and Innovation), co-financed by the FEDER, project DIPA 125/2010 MMAMRM (Spanish National Park organization), and project FW7 ENV.2009.2.1.3.2 - LEDDRA (European Community).Peer Reviewe

Influence of Agropastoral System Components on Mountain Grassland Vulnerability Estimated by Connectivity Loss

21 páginas.- Ilustraciones.- © 2016 Gartzia et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Over the last decades, global changes have altered the structure and properties of natural and semi-natural mountain grasslands. Those changes have contributed to grassland loss mainly through colonization by woody species at low elevations, and increases in biomass and greenness at high elevations. Nevertheless, the interactions between agropastoral components; i.e., ecological (grassland, environmental, and geolocation properties), social, and economic components, and their effects on the grasslands are still poorly understood. We estimated the vulnerability of dense grasslands in the Central Pyrenees, Spain, based on the connectivity loss (CL) among grassland patches that has occurred between the 1980s and the 2000s, as a result of i) an increase in biomass and greenness (CL-IBG), ii) woody encroachment (CL-WE), or iii) a decrease in biomass and greenness (CL-DBG). The environmental and grassland components of the agropastoral system were associated with the three processes, especially CL-IBG and CL-WE, in relation with the succession of vegetation toward climax communities, fostered by land abandonment and exacerbated by climate warming. CL-IBG occurred in pasture units that had a high proportion of dense grasslands and low current livestock pressure. CL-WE was most strongly associated with pasture units that had a high proportion of woody habitat and a large reduction in sheep and goat pressure between the 1930s and the 2000s. The economic component was correlated with the CL-WE and the CL-DBG; specifically, expensive pastures were the most productive and could maintain the highest rates of livestock grazing, which slowed down woody encroachment, but caused grassland degradation and DBG. In addition, CL-DBG was associated with geolocation of grasslands, mainly because livestock tend to graze closer to passable roads and buildings, where they cause grassland degradation. To properly manage the grasslands, an integrated management plan must be developed that includes an understanding of all components of the agropastoral system and takes into account all changes that have occurred in dense mountain grasslands. Addressing the problems individually risks the improvement of some grasslands and the deterioration of others.The Spanish National Park organization (project Dinamica de la interaccion pasto-arbusto y su efecto en la conservacion de las comunidades vegetales subalpinas del Parque Nacional de Ordesa y Monte Perdido a lo largo de un gradiente climatico. Ref.: 125/2010 MMAMRM) and the European Community (project Land and Ecosystem Degradation and Desertification: Assessing the Fit of Responses, FW7 ENV.2009.2.1.3.2) provided financial support.Peer reviewe

Improving the Accuracy of Vegetation Classifications in Mountainous Areas

12 páginas, 7 figuras, 2 tablas.[EN] In recent decades, mountainous areas that contain some of the best-preserved habitats worldwide are experiencing significant, rapid changes. Efficient monitoring of these areas is crucial for impact assessments, understanding the key processes underlying the changes, and development of measures that mitigate degradation. Remote sensing is an efficient, cost-effective means of monitoring landscapes. One of the main challenges in the development of remote sensing techniques is improving classification accuracy, which is complicated in mountainous areas because of the rugged topography. This study evaluated the 3 main steps in the supervised vegetation classification of a mountainous area in the Spanish Pyrenees using Landsat-5 Thematic Mapper imagery. The steps were (1) choosing the training data sampling type (expert supervised or random selection), (2) deciding whether to include ancillary data, and (3) selecting a classification algorithm. The combination (in order of importance) of randomly selected training data, ancillary data (topographic and vegetation index), and a random forest classifier improved classification accuracy significantly (4–11%) in the study area in the Spanish Pyrenees. The classification procedure includes important steps that improve classification accuracies; these are often ignored in standard vegetation classification protocols. Improved accuracy is vital to the study of landscape changes in highly sensitive mountain ecosystems.The Spanish government (Configuración Espacial de la Biodiversidad y Conservación del Ecosistemas project, I+D+I. CGL2008-00655/BOS, Ministry of Science and Innovation) and the European Community (Land and Ecosystem Degradation and Desertification: Assessing the Fit of Responses project, FW7 ENV.2009.2.1.3.2) funded this study. In addition, we thank the managers of Ordesa and Monte Perdido National Park for providing information and assistance. For assistance with the bibliographic search, we thank Cristina Pérez de Larraya. The suggestions of IC Barrio considerably improved earlier versions of the paper. We thank Bruce MacWhirter for his critical reading of the manuscript and for providing helpful suggestions. Finally, we thank the anonymous reviewers for their helpful comments.Peer reviewe

Sampling of the most frequented grazing zones of Sesa Grasslands (Ordesa and Monte Perdido National Park, Puertolas) and their influence on the pasture dynamics

7 págs, 1 figura, 2 tablas.-- Comunicación presentada a la XLV Reunión Científica de la Sociedad Española para el Estudio de los Pastos: "Producciones agroganaderas: gestión eficiente y conservación del medio natural" (Gijón, 28 de mayo al 3 de junio de 2005).[ES] Desde el nuevo paradigma de la ecología se considera al pastor y su ganado como un componente más de la dinámica natural del propio ecosistema y por ello la secuencia temporal y la intensidad del pastoreo condicionan los cambios entre las comunidades vegetales implicadas. Los aportes de fertilidad, el pisoteo y la propia herbivoría priorizan unas secuencias de cambio entre comunidades que resultan fáciles de detectar. En el piso subalpino del Parque Nacional de Ordesa y Monte Perdido, las comunidades vegetales más frecuentadas por el ganado son unas diez y, el majadeo, el ritmo diario de pastoreo o el abandono interrelacionan claramente a cinco de ellas. Se presenta un muestreo de la vegetación realizado durante el verano de 2004 y se estudia con detalle una zona cartografiada a escala 1:5000. Simultáneamente se inventarían los caminos y zonas más frecuentadas por el ganado y se correlacionan con las manchas de vegetación estudiadas con detalle en San Vicenda-Plana Canal-La Fueva. En base a los datos presentados se hipotetizan unas relaciones dinámicas entre las comunidades vegetales siguiendo las diferencias en aspectos topográficos y de uso ganadero.[EN] The new concept of ecosystem considers the shepherd and his flock as a component else of the ecosystem natural dynamics. Because that the temporal sequence and the grazing intensity determine the different changes of the plant communities involved. The fertility supplies, trampling and herb ivory facilitate some change sequences between communities that are easy to detect. About ten plant communities of the sub alpine belt of the Ordesa and Monte Perdido National Park are the most frequently used by the animals; five of them are clearly interrelated with the resting point, the daily rhythm of grazing or the abandonment. A vegetation sampling was made during the summer of 2004, simultaneously the animal ways and the most frequented zones were controlled on the map(scale 1:5000) making several correlations with the vegetation spots. Some hypothesis are exposed explaining dynamic relationship between plan communities, topography and animal behaviour.Peer reviewe