Fragmentation and thresholds in hydrological flow‐based ecosystem services

Abstract

Loss and fragmentation of natural land cover due to expansion of agricultural areas is a global issue. These changes alter the configuration and composition of the landscape, particularly affecting those ecosystem services (benefits people receive from ecosystems) that depend on interactions between landscape components. Hydrological mitigation describes the bundle of ecosystem services provided by landscape features such as woodland that interrupt the flow of runoff to rivers. These services include sediment retention, nutrient retention and mitigation of overland water flow. The position of woodland in the landscape and the landscape topography are both important for hydrological mitigation. Therefore, it is crucial to consider landscape configuration and flow pathways in a spatially explicit manner when examining the impacts of fragmentation. Here we test the effects of landscape configuration using a large number (>7,000) of virtual landscape configurations. We created virtual landscapes of woodland patches within grassland, superimposed onto real topography and stream networks. Woodland patches were generated with user‐defined combinations of patch number and total woodland area, placed randomly in the landscape. The Ecosystem Service model used hydrological routing to map the “mitigated area” upslope of each woodland patch. We found that more fragmented woodland mitigated a greater proportion of the catchment. Larger woodland area also increased mitigation, however, this increase was nonlinear, with a threshold at 50% coverage, above which there was a decline in service provision. This nonlinearity suggests that the benefit of any additional woodland depends on two factors: the level of fragmentation and the existing area of woodland. Edge density (total edge of patches divided by area of catchment) was the best single metric in predicting mitigated area. Distance from woodland to stream was not a significant predictor of mitigation, suggesting that agri‐environment schemes planting riparian woodland should consider additional controls such as the amount of fragmentation in the landscape. These findings highlight the potential benefits of fragmentation to hydrological mitigation services. However, benefits for hydrological services must be balanced against any negative effects of fragmentation or habitat loss on biodiversity and other services.

Analyzing Land-Use Change Scenarios for Ecosystem Services and their Trade-Offs in the Ecological Conservation Area in Beijing, China

“…In the past two decades, the population growth, the rapid development of technology, and the real estate industry, and the government’s overall planning policies have aggravated land-use changes in Beijing. It has been demonstrated that land-use change has been identified as one of the most important driving factors of ecological change [ 2 , 56 , 57 ], and, ultimately, is the factor that determines the relative supply and strength of ES, and their interdependent processes [ 4 , 12 , 58 ]. In this study, the expansion of human-built landscapes resulted in the reduction of forest land, water bodies, and cultivated land, which, in turn, reduced the provision of multiple ES and changed the relationships between them as projected under three different scenarios.…”

Templates for Climate-smart Landscape Design

“…Neutral landscape models have been applied for understanding effects of landscape pattern on movements of single and interacting biota (Etherington 2016;With 1997) ). Our systematic generation of combined topography and land cover patterns also adds to simulations of changed patch sizes on actual topographies (Thomas et al 2020). By capturing some of the main constraints to land use distribution and ecosystem service supply they allow a structured approach to understand and predict ES interactions and multifunctionality.…”

“…level of fragmentation) on multifunctionality and their interactions with welldocumented effects of composition, that is the representation of different land uses, and especially functionally critical uses like intensive agriculture and native forest. Thomas et al 2020) show that all ecosystem services (ES) respond to some degree to landscape pattern (composition and con guration) given its in uence on ecological and social processes (Duarte et al 2020). How landscape pattern affects ES pairwise interactions and ES multifunctionality is more complex to understand.…”

“…Studies have explored the effects of landscape scenarios for ES by either manipulating current pattern (Cordingley et al 2015;Richards et al 2018) or simulating multiple fragmentation levels (Thomas et al 2020). Virtual landscape simulations which manipulate composition and con guration in controlled designs take this further as a powerful method for understanding how their combination effects ecosystem services (Langhammer et al 2019).…”

LUCI-EntEx v1.0: A GIS-based algorithm to determine stream entry and exit points at boundaries of any given shape

“…LUCI has a proven record of providing reliable output for exploring the impact of land use or management changes on ecosystem service provision in multiple countries, enabling better spatial planning of land management interventions (Emmett et al 2017;Thomas et al, 2019;Tomscha et al, 2019;Pedersen Zari et al, 2020). Uniquely, LUCI is able to model at a range of spatial scalesfrom field or plot level up to catchment/watershed or even national level (Sharps et al, 2017;Emmett et al, 2017, Thomas et al, 2019. It is also capable of comparing different ecosystem services at once, identifying where co-benefits or trade-offs may exist in the landscape.…”