A Multi-Perspective Assessment Method with a Dynamic Benchmark for Human Activity Impacts on Alpine Ecosystem under Climate Change

Intense human activities and rapid climate changes both have obvious impacts on alpine ecosystems. However, the magnitudes and directions of the impacts by these two drivers remain uncertain due to a lack of a reasonable assessment method to distinguish between them. The impact of natural resilience is also generally included in the dynamics of a disturbed ecosystem and is liable to be mixed into the impact of human activity. It is urgent that we quantitatively discriminate human activity impacts on the ecosystem under climate change, especially for fast-developing alpine regions. Here, we propose an assessment method to determine human activity impacts under a dynamic climate, taking the potential net primary production (NPP) of an ecosystem as a benchmark. The potential NPP (NPPP) series under the changing climate was retrieved by an improved integrated biosphere simulator based on the initial disturbed ecosystem status of the assessment period. The actual NPP (NPPA) series monitored by remote sensing was considered as the results derived from the joint impacts of climate change, natural resilience and human activity. Then, the impact of human activity was quantified as the difference between the NPPP and NPPA. The contributions of human activity and natural forces to ecosystem NPP dynamics were then calculated separately and employed to explore the dominant driver(s). This assessment method was demonstrated in a typical alpine ecosystem in Northwest China. The results indicate that this method capably revealed the positive impacts of local afforestation and land-use optimization and the negative impacts caused by grazing during the assessment period of 2001–2017. This assessment method provides a quantitative reference for assessing the performances of ecological protections or human damage to alpine ecosystems at the regional scale.

Dendrometer measurements of arctic-alpine dwarf shrubs and micro-environmental drivers of plant growth - Dataset from long-term alpine ecosystem research in central Norway

Here, we present fine-scale measurements of stem diameter variation from three common arctic-alpine dwarf-shrub species monitored in two mountain regions of Central Norway. All three species (Betula nana, Empetrum nigrum ssp. hermaphroditum, and Phyllodoce caerulea) are abundant within the studied regions and highly important contributors to potential future arctic-alpine vegetation shifts. A profound understanding of their radial growth patterns therefore has the potential to yield crucial information regarding climate-growth relations within these ecosystems. We used high-resolution dendrometers (type DRO) to monitor 120 specimens, taking measurements near the shoot base of one major horizontal stem. Along with the shrub growth measurements, we measured on-site micro-environmental data at each studied site, including shoot zone and root zone temperatures as well as soil moisture. All data were recorded at an hourly scale and are presented as daily mean values. The monitoring period spanned five full years (2015 - 2019), with additional data from 2014 and 2020. Data were collected within one of the most continental climate regions of Europe, the Vågå/Innlandet region, and in the oceanic climate region Geiranger/Møre og Romsdal, spanning a steep climate gradient over just ~100 km horizontal distance. Both study regions are characterized by steep elevational gradients and highly heterogeneous micro-topography. The studied sites were chosen to represent these natural conditions using the transect principle. The collection of our original data is subject of our long-term alpine ecosystem monitoring program since 1991, from which numerous publications function as the basis for a recent project on the use of dendrometer data in alpine ecosystem studies.