Portail documentaire

Climatic drivers of greening trends in the Alps / Gianluca Filippa in Remote sensing, 11 (2019) 

Public Citation [article]  inRemote sensing > 11 (2019) . - 1-15 Titre : Climatic drivers of greening trends in the Alps Type de document : Imprimé Auteurs : Gianluca Filippa ; Edoardo Cremonese ; Marta Galvagno ; Michel Isabellon ; Arthur Bayle ; Philippe Choler ; Bradley Z. Carlson ; Simone Gabellani ; Umberto Morra di Cella ; Mirco Migliavacca Année de publication : 2019 Article en page(s) : 1-15 Catégories : [CBNPMP-Géographique] Alpes [CBNPMP-Thématique] Relations climat-végétation [LOTERRE-Biodiversité] Changement climatique Résumé : Since the 1980s, vegetated lands have experienced widespread greening at the global scale. Numerous studies have focused on spatial patterns and mechanisms of this phenomenon, especially in the Arctic and sub-Arctic regions. Greening trends in the European Alps have received less attention, although this region has experienced strong climate and land-use changes during recent decades. We studied the rates and spatial patterns of greening in an inner-alpine region of the Western Alps. We used MODIS-derived normalized difference vegetation index (NDVI) at 8-day temporal and 250 m spatial resolution, for the period 2000–2018, and removed areas with disturbances in order to consider the trends of undisturbed vegetation. The objectives of this study were to (i) quantify trends of greening in a representative area of the Western Alps; and (ii) examine mechanisms and causes of spatial patterns of greening across different plant types. We show that 63% of vegetated areas experienced significant trends during the 2000–2018 period, of which only 8% were negative. We identify (i) a climatic control on spring and autumn phenology with contrasting effects depending on plant type and elevation, and (ii) land-use change dynamics, such as shrub encroachment on abandoned pastures and colonization of new surfaces at high elevation. Below 1500 m, warming temperatures promote incremental greening in the transition from spring to summer, but not in fall, suggesting either photoperiod or water limitation. In the alpine and sub-alpine belts (>1800 m asl), snow prevents vegetation development until late spring, despite favorable temperatures. Instead, at high elevation greening acts both in summer and autumn. However, photoperiod limitation likely prevents forested ecosystems from fully exploiting warmer autumn conditions. We furthermore illustrate two emblematic cases of prominent greening: recent colonization of previously glaciated/non vegetated areas, as well as shrub/tree encroachment due to the abandonment of agricultural practices. Our results demonstrate the interplay of climate and land-use change in controlling greening dynamics in the Western Alps. Lien pérenne : DOI : 10.3390/rs11212527 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=148069 Filippa, Gianluca, Cremonese, Edoardo, Galvagno, Marta, Isabellon, Michel, Bayle, Arthur, Choler, Philippe, Carlson, Bradley Z., Gabellani, Simone, Morra di Cella, Umberto, Migliavacca, Mirco 2019 Climatic drivers of greening trends in the Alps. Remote sensing, 11: 1-15.

Documents numériques

Consultable Article (2019) URL

Observed long-term greening of alpine vegetation-a case study in the French Alps / Bradley Z. Carlson in Environmental Research Letters, 12 (2017) 

Public Citation [article]  inEnvironmental Research Letters > 12 (2017) . - 1-12 Titre : Observed long-term greening of alpine vegetation-a case study in the French Alps Type de document : Imprimé Auteurs : Bradley Z. Carlson ; Monica C. Corona ; Cédric Dentant (1976-) ; Richard Bonet ; Wilfried Thuiller (1975-) ; Philippe Choler Année de publication : 2017 Article en page(s) : 1-12 Catégories : [CBNPMP-Géographique] Alpes françaises [CBNPMP-Géographique] Parc National des Ecrins [LOTERRE-Biodiversité] Changement climatique [CBNPMP-Thématique] Relations climat-végétation Résumé : We combined imagery from multiple sources (MODIS, Landsat-5, 7, 8) with land cover data to test for long-term (1984–2015) greening or browning trends of vegetation in a temperate alpine area, the Ecrins National Park, in the context of recent climate change and domestic grazing practices. We showed that over half (56%) of the Ecrins National Park displayed significant increases in peak normalized difference vegetation index (NDVImax) over the last 16 years (2000–2015). Importantly, the highest proportional increases in NDVImax occurred in rocky habitats at high elevations (> 2500 m a.s.l.). While spatial agreement in the direction of change in NDVImax as detected by MODIS and Landsat was high (76% overlap), correlations between log-response ratio values were of moderate strength (approx. 0.3). In the context of above treeline habitats, we found that proportional increases in NDVImax were higher between 1984 and 2000 than between 2000 and 2015, suggesting a slowing of greening dynamics during the recent decade. The timing of accelerated greening prior to 2000 coincided with a pronounced increase in the amount of snow-free growing degree-days that occurred during the 1980s and 1990s. In the case of grasslands and low-shrub habitats, we did not find evidence for a negative effect of grazing on greening trends, possibly due to the low grazing intensity typically found in the study area. We propose that the emergence of a longer and warmer growing season enabled high-elevation plant communities to produce more biomass, and also allowed for plant colonization of habitats previously characterized by long-lasting snow cover. Increasing plant productivity in an alpine context has potential implications for biodiversity trajectories and for ecosystem services in mountain landscapes. The presented evidence for long-term greening trends in a representative region of the European Alps provides the basis for further research on mechanisms of greening in alpine landscapes. Lien pérenne : DOI : 10.1088/1748-9326/aa84bd Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=148066 Carlson, Bradley Z., Corona, Monica C., Dentant, Cédric (1976-), Bonet, Richard, Thuiller, Wilfried (1975-), Choler, Philippe 2017 Observed long-term greening of alpine vegetation-a case study in the French Alps. Environmental Research Letters, 12: 1-12.

Documents numériques

Consultable Article (2017) URL