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

Abstract

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.

Human activities have markedly altered the pattern and trend of net primary production in the Ili River basin of Northwest China under current climate change

“…This model included land surface processes, phenology, vegetation dynamics and soil biogeochemistry modules. Many ecosystem processes involving carbon sequestration, water yields and their interactions were integrated into the IBIS i , without including human interaction processes (Kucharik et al, 2000; Zhang et al, 2022). The IBIS i model was run for the years 1950–2017 using climate‐series data and adopted the actual status in 2000 as the initial conditions for the model start‐up.…”

“…Traditional statistical analysis and residual methods have been widely used to understand NPP in Central Asia and surrounding regions (Chen, Bao, et al, 2019; Chen, Park, et al, 2019; Li et al, 2018). However, traditional statistical methods cannot effectively exclude the impacts of climate change, which lead to uncertainty in our understanding of human impacts on NPP (Chen, Bao, et al, 2019; Chen, Park, et al, 2019; Zhang et al, 2022). Measurements of NPP using residual methods are established based on potential NPP changes driven solely by climate change (Chen, Bao, et al, 2019; Chen, Park, et al, 2019; Zhang et al, 2018).…”

Human impacts on vegetation carbon sequestration capacity in the Qilian Mountains, northeastern Tibetan Plateau since 2000

“…Mineral resources have been over-exploited and hydropower facilities have been illegally constructed (Ding et al, 2018; Li et al, 2019). Vegetation carbon sequestration in this region has changed markedly due to the dual impacts of natural forces (i.e., climate change and natural resilience) and human activities under the implementation of the WDS (Lan and Li, 2022; Lu et al, 2009; Teng et al, 2020; Zhang et al, 2022). In such a complex human-natural coupling ecosystem, an assessment of the human impacts on vegetation carbon sequestration capacity provides a demonstration for alpine regions of West China.…”

“…The potential GPP and NPP data were calculated from statistical relationships between the actual GPP and NPP data and climatic factors in areas that were free from human activities. These potential data reflect the maximum community GPP and NPP under changing climate conditions (Li et al, 2021; Zhang et al, 2022) and were used as a dynamic benchmark for the assessments (Chen et al, 2021; Li et al, 2018). Thus, the assessment results using the benchmark included the impacts of natural resilience and historic human activities before the assessment period, and so overestimate the human impacts during the assessment period (Zhang et al, 2022).…”

“…Process-based simulations of potential GPP and NPP that began with an actually-disturbed status by historic human activities provided a reliable benchmark for assessing the human impacts during the assessment period (Hegerl et al, 2010; Zhang et al, 2022). The simulated results reflected GPP and NPP changes that were driven by natural forces (Kucharik et al, 2006; Sitch et al, 2008).…”