ReviewConsidering landscape-level processes in ecosystem service assessments
Graphical abstract
Introduction
Understanding the processes that determine the benefits people obtain from nature, so-called ecosystem services, is crucial for the planning of sustainable, resilient and multifunctional landscapes (Fisher et al., 2009). Despite the existence of ecosystem services that are generated and consumed in-situ, such as non-timber forest products that benefit local communities, many ecosystem services are delivered at landscape scales. Consequently, these services are affected not only by local processes, but also by landscape-level processes that occur in heterogeneous spaces (Villard and Metzger, 2014; Herrero-Jáuregui et al., 2018; Qiu, 2019). Yet, accounting for landscape-level processes to quantify ecosystem services is challenging, as this requires assessing processes occurring simultaneously at multiple scales and in landscapes with different structures (Mitchell et al., 2015a, Mitchell et al., 2015b). However, understanding landscape-level processes is key to develop clear spatial and temporal strategies for managing ecosystem services (Boesing et al., 2020; Metzger et al., 2021).
Landscape-level processes are those that take place in heterogeneous areas, composed of various land use and cover classes. These areas are commonly defined as “landscapes” (Turner, 1989; but see Englund et al., 2017, for a discussion of different concepts of “landscape” in ecosystem services literature). Landscape-level processes include processes that occur at the interface between landscape classes (e.g. edge effects, cross-habitat spillover processes), or that are affected by the diversity and spatial distribution of resources (e.g. complementation and supplementation processes, fragmentation effects). They also comprise dispersion or movement processes across landscape classes with different resistance to ecosystem service flows, such as landscape connectivity and permeability (see Box 1 for illustration and Table 1 for definitions). The importance of landscape-level processes for ecosystem service provision is particularly evident when there is a disconnection or mismatch in the spatial occurrence of areas with the capacity to provide services (supply areas) from those demanding these services (demand areas; Brauman et al., 2007). The provision of services then requires flows of species, humans, or matter to connect supply and demand areas (Fisher et al., 2009). This connection can be, for example, water flows linking reservoirs to cities, bees moving from native habitat to crops for pollination, humans moving from cities to protected areas to enjoy cultural services, or transport of raw materials and food from production areas (e.g. forest, rivers, sea) to consumption areas (e.g. cities). In some cases, the service is provided by interrupting or reducing the flow, as in the case of flood regulation (Vollmer et al., 2016) or disease control (Wood and Lafferty, 2013).
Ecosystem service provision can thus be understood as the result of the interactions of a chain of components (supply and demand areas connected through biotic or abiotic flows), herein referred as the “service provision chain” (Fisher et al., 2009; Serna-Chavez et al., 2014; Syrbe and Walz, 2012; Villamagna et al., 2013). Interactions between these components occur through the landscape and thus are affected by landscape processes (Mitchell et al., 2015a, Mitchell et al., 2015b; Metzger et al., 2021). While supply and flows are particularly affected by the structure of the landscape (Box 1), the demand for services acts as a driver affecting landscape structure. Given these spatial properties in the provision of ecosystem services, there has recently been increasing research activity at the interface of landscape ecology and ecosystem services, exploring the causal relationships linking landscape-level processes to the supply, demand and flows of different types of services (Babí Almenar et al., 2018; Duarte et al., 2018; Haan et al., 2020; Ridding et al., 2018). Concomitant with the expansion of this research field, several open-access tools (such as InVEST, Integrated Valuation of Ecosystem Services and Tradeoffs; Sharp et al., 2018) have been developed to quantify and map ecosystem services, most of them providing spatially explicit models (Bagstad et al., 2013; Nelson et al., 2009).
Despite the development of those open-access tools and increasing research at the interface of landscape ecology and ecosystem services (Duarte et al., 2018), it is unclear how far current assessments of ecosystem services have considered landscape processes, and what the implications of disregarding these processes for planning and conservation are. It is thus important to evaluate how far this research field and tool development has matured, and particularly explore how far ecosystem service assessments integrate supply, demand and flow in a spatially explicit way, and to what extent assessments incorporate the influence that landscape-level processes have on each component of the service provision chain.
To explore how landscape-level processes are incorporated in the assessment of service provision chain, we first carried out a literature review to answer the following questions: i) What components of service chain (supply, demand and flows) are considered in ecosystem service assessments at the landscape scale?; ii) Which landscape-level processes are being considered to estimate supply, demand and flows?; iii) Is there a relationship between the landscape processes considered and different types of services (provisioning, regulating, and cultural; Maes et al., 2013)? For all ecosystem service types, we expect that the higher the disconnection or mismatch in the spatial distribution of supply and demand areas, the greater the influence of processes that act at the landscape level (but this also depends on the functional connections, e.g. the type of supply/demand flow, particular of each ecosystem service).
We then propose a novel framework for ecosystem service assessment that allows incorporating landscape-level effects across the whole service provision chain. We also discuss the main challenges for applying a landscape perspective in ecosystem service assessments. We hope the development of such perspective can boost the incorporation of landscape-level processes in spatially explicit assessments of ecosystem services, and improve ecosystem service management.
Section snippets
Landscape processes and ecosystem services – a review
We used the Scopus database to search for peer-reviewed publications using the search terms “ecosystem service*” AND (spatial* OR map*) AND land* AND model* AND (supply OR demand OR flux* OR flow). We only included papers that mentioned at least one of the three components of the ecosystem service provision chain (i.e., supply, demand and flow; Fisher et al., 2009) comprising the period from January 2009 to November 2020. We thus considered articles that analyzed ecosystem services at the
Risks of ignoring landscape processes and the entire provision chain in ecosystem service assessments
Although space was considered for most ecosystem service assessments, those assessments are still limited to a partial consideration of the service provision chain, with poor incorporation of landscape-level processes. Such partial evaluation of services may impair assessments for a number of reasons. First, by focusing only on part of the service chain and estimating provision through supply or demand, there is a great risk of overestimating provision. As the provision of a service depends on
Moving forward - promoting models that incorporate landscape-level processes
Our proposed framework is based on existing conceptual models that assume provision as a combination of supply, demand and flows (Fisher et al., 2009; Mitchell et al., 2015a, Mitchell et al., 2015b; Villamagna et al., 2013) and on previous cell-based models (e.g. Mitchell et al., 2015a, Mitchell et al., 2015b). Our framework provides an advance by placing these interactions into a new model where multiple landscape processes (affecting supply, demand and flow) can be easily accounted
Future challenges
There is a pressing need to better quantify, spatialize and value the benefits that nature brings to society. The development of such an approach, at the interface between landscape ecology and ecosystem services, requires overcoming several challenges, three of which we highlight below. All these challenges are even more complex when we consider that several services occur simultaneously in the landscape and may interact in multiple ways across their supply, demand and flow components,
Conclusion
After more than 10 years of the emergence of frameworks and tools to evaluate ecosystem services through an integrated analysis of supply, demand and flows, the incorporation of landscape-level processes into ecosystem assessments is still limited. Most of these assessments consider only landscape composition, ignoring the influence of context or surrounding landscapes, and associate supply with provision in a simplistic way, ignoring demand and flows.
The still limited inclusion of landscape
CRediT authorship contribution statement
Conceptualization: all authors contributed to discussions and brainstorming meetings which defined the general outline; Literature review: JPM, JVR, AFSC and SLC; Framework development and modeling approach: JPM, RKR, AFSC; Funding acquisition: JPM, JRR; Writing, review & editing: JPM wrote the manuscript and all authors edited and approved the manuscript.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
JPM and JRR were supported by a joint collaboration funding (FAPESP/SPRINT project n. 2017/50015-5) involving the University of São Paulo (USP) and the University of Queensland (UQ). JPM was funded by the National Council for Scientific and Technological Development (CNPQ, 307934/2011-0), and all Brazilian members were also supported by another FAPESP grant (Interface Project, N. 2013/23457-6). JVR was supported by a University of Queensland Research Training Scholarship, University of
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