1,721,038 research outputs found
Climate Warming Persistence Triggered Tree Ingression After Shrub Encroachment in a High Alpine Tundra
No full textClimate warming can induce the encroachment of shrubs and may trigger treeline dynamics. However, the responses of shrubs and trees to climate change may be modulated by other environmental drivers such as land-use change and biological interactions. The European Alps are one of the three areas experiencing the most intense warming globally in the twentieth century. We analyse, through a multidisciplinary approach, the shrub and tree encroachment at the Stelvio Pass (Italian Alps) focusing on three target species (Rhododendron ferrugineum, Larix decidua, Pinus mugo) to reconstruct their dynamics and assess which drivers (climate change, land-use change, biological interactions provided by shrub facilitation) promoted their ingression. Shrub colonization started in 1867, in coincidence with the end of the Little Ice Age. Tree recruitment started since 1960 for P. mugo and 1972 for L. decidua and correlated strongly with air warming and shortening of the snow cover duration. Climate (air temperature, snow cover) exhibited the highest correlation with shrub and tree dynamics both during the period of recruitment and in the following and preceding 5-year period. Air warming appeared to be crucial for tree ingression and persistence. Land-use change was not related to shrub encroachment, and only weakly to tree recruitment. Both the correlation analysis as well as the patterns of recruitment highlighted that shrubs were characterized by different ecological requirements from trees. There was not a “nurse effect” of shrubs on trees, and this biotic interaction changed with the developmental stage of the involved species, being lowest for seedlings and highest for adults, requiring further investigations. Future scenarios of climate change indicate a further and intense warming, and our data show that it is likely that shrub and tree encroachment will proceed, with relevant consequences on the extremely vulnerable high-elevation alpine ecosystems
Vegetation as an ecological indicator of surface instability in rock glaciers
No full textWe studied relationships between vegetation, substrate texture, and surface movement
velocity in two active rock glaciers in the Central Alps (northern Italy). We also compared
the vegetation on the two active rock glaciers with that of adjacent stable areas and with
that of an inactive rock glacier. The vegetation patterns on the two active rock glaciers
differed sharply from those on the stable areas nearby and on the inactive rock glacier with
respect to both total plant cover and floristic composition. Surface movement on the two
active rock glaciers ranged from 0-5 to 35-40 cm yr.1 and was largely independent
of slope inclination. The most unstable sites were almost free of mosses and lichens and
were characterized by vascular species tolerating surface instability in virtue of varying
morphological adaptations. However, the distributional pattern of vascular species could
not be directly related to surface instability but depended on a combination of substrate
texture and movement intensity
Climate change triggered synchronous woody plants recruitment in the last two centuries in the treeline ecotone of the Northern Hemisphere
Full text linkClimate change triggers several ecosystem responses, including woody plant encroachment. We analyse woody plant recruitment across the treeline ecotone (the forest -tundra ecotone) of the Northern Hemisphere (NH) over an extended period (1801-2010) and its relation with atmospheric CO2 and air temperature. We detected a synchronous trend of woody plant recruitment across the NH, indicating a major climatic and environmental change, triggered by a combination of CO2 fertilization and air temperature changes. The drivers of woody plant recruitment changed with time: CO2 fertilization was the main driver in the period 1801-1950, while air temperature was the main driver after 1950, despite the drastic acceleration of CO2 increase in the last decades. These data support the hypothesis that we are shifting from a fertilization -dominated to a warming -dominated period. The temporal patterns of woody plant recruitment are consistent with the occurrence of the 1980 regime shift, a major change occurred in the Earth's biophysical systems. Indeed, the recruitment drop promoted by the 1960s-1980s air cooling, was followed by an intensive recruitment increase triggered by the restart of air warming in the last decades. The largest sensitivity and fastest resilience of evergreen and Pinaceae to the restart of air warming allows to hypothesize that, among the woody plant functional and taxonomic groups, they could perform the largest expansion also in future decades
Divergent Responses of Alpine Rock Glaciers to Climate Change: A Review of Ecological and Abiotic Dynamics
No full textPeriglacial processes and permafrost-related landforms, such as rock glaciers, are particularly vulnerable to climate change because of their reliance on sustained low temperatures to maintain permafrost integrity. Rising temperatures lead to permafrost thawing, increased active layer thickness, and ground instability, which disrupt the structural and ecological stability of these environments. Rock glaciers, which are ubiquitous in high mountain systems, are especially sensitive to these changes and serve as key geo-indicators of current or past alpine permafrost conditions, reflecting the multifaceted impacts of warming on both ecological and abiotic components. In this review, we synthesize current scientific knowledge on the complex and divergent responses of alpine rock glaciers to climate change, highlighting a wide range of methodologies employed to study the complex interactions between climatic drivers and rock glacier dynamics. We first explore ecological impacts, focusing on how climatic changes influence vegetation patterns, species composition, and overall biodiversity associated with rock glaciers. Subsequently, we examine the dynamic behavior of rock glaciers, including their structural integrity, movement patterns, and hydrological roles within high mountain ecosystems. By integrating findings from various disciplines, this review underscores the importance of multidisciplinary approaches and long-term monitoring to advance our understanding of rock glacier ecosystem dynamics and their role in periglacial processes under climate change. Our synthesis identifies critical knowledge gaps, such as the uncertain drivers of divergent rock glacier responses and the limited integration of ecological and abiotic data in existing studies. We highlight research priorities, including the establishment of regional monitoring networks and the development of predictive models that incorporate vegetation and permafrost interactions. These insights provide actionable guidance for adaptive management strategies to mitigate the ecological and geological impacts of climate change on these unique and sensitive environments
Changes of rock glacier vegetation in 25 years of climate warming in the Italian Alps
No full textRock glaciers are periglacial landforms sensitive to climate change, and a harsh environment for vegetation colonization due to the potential occurrence of surface instability. Changes of rock glacier vegetation would provide evidence of the importance of climate change impacts, as the limitation provided by physical disturbance could be overcome by plant responses to warming. We assess, through the resurvey of ten rock glaciers (six active, four inactive) in the Italian Central Alps, the vegetation changes in response to 25 years of climate warming. Vegetation was analyzed through the phytosociological method in 1995 and 2020 adopting the same field protocol for both surveys with 1208 relevés. The relation with climate was assessed by multivariate analysis. Air warming occurred in the study area and vegetation changed both in active and inactive rock glaciers, with increases of species richness, cover, changes in floristic composition. After 25 years the differences between active and inactive rock glaciers persisted but with an appreciable decrease mainly due to the larger vegetation changes showed by active rock glaciers. The multivariate analysis confirmed the relation between vegetation changes and air warming. The observed vegetation changes were compatible also with the impact of the decrease of the physical disturbance limitation likely due rock glacier stabilization, in particular for the active rock glaciers located at lower elevations, while the opposite trend could be hypothesized for those at higher elevations. The changes of floristic composition allowed assess that a gap-filling process, instead of species upward migration, produced the vegetation changes, with species persistence coupled to the recruitment of new species from the neighbor communities. Persistence of climate warming in future could lead to vegetation homogenization and biodiversity loss due to the extinction debt of several alpine species
Monitoring long-term vegetation changes (1953-2018) in an alpine tundra ecosystem of the Italian Central Alps
No full textAlpine grassland and snowbed species after five years of manipulation experiments: phenology and growth
No full textPhytosociology of the vegetation communities of the Stelvio Pass area
Full text linkHigh elevation areas are sensitive and vulnerable to climate change and exhibited relatively rapid changes in response to warming involving changes of floristic composition, species upward migration, shrub and tree encroachment and surface area changes. For this reason, it is important to provide quantitative studies as tools allowing a long-term monitoring of vegetation in response to climate change. The Stelvio Pass area is a high elevation site located in the European Alps, and a unique case study on the alpine range providing historical detailed information on vegetation with the availability of phytosociological maps of vegetation elaborated in 1953 and 2003. Here we show and describe an updated and detailed phytosociological vegetation mapping which will constitute a robust base for the monitoring and quantitative assessment of any impacts of future climate and/or environmental change as well as a tool to plan suitable vegetation and biodiversity conservation actions in the alpine environment
Shrubs and trees encroachment in response to climate warming in an high elevation alpine environment (Italian Central Alps)
No full textPlant community distribution and biodiversity assessment for environmental change detection at Rothera Point, Adelaide Island, Antarctic Peninsula
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