Can short-term payments for ecosystem services deliver long-term tree cover change?

Highlights

• The long-term impact of short-term Payments for Ecosystem Services (PES) projects is rarely evaluated.

• I compared changes in tree cover on PES farms and the surrounding landscape over a 13-year period.

• Relative to the landscape, PES farms had higher reductions in treeless pastures and higher increases in tree cover.

• These differences are still visible on the landscape eight years after payments ended.

• Short-term PES can trigger lasting improvements in tree cover change on silvopastoral farms.

Abstract

Payments for ecosystem services (PES) have been heralded as an effective strategy to increase tree cover in agricultural landscapes, but their efficacy beyond the payment period has rarely been evaluated. I compared land covers before and 13 years after implementation of a short-term PES project that promoted the adoption of silvopastoral systems (SPS) in a cattle ranching landscape in Colombia. I used satellite images to quantify on-farm changes and farm-to-landscape differences in land cover change. On average, treeless pasture area decreased by 7% more and areas with tree cover increased 8% more on silvopastoral farms relative to the surrounding landscape. Short-term payments facilitated the adoption of SPS leading to a significantly greater increase in tree cover, which is still visible on participant farms a decade later. The results highlight the potential of short-term PES as a tool to facilitate the permanent adoption of SPS and to support restoration efforts in pasture-dominated landscapes.

Introduction

The need to regain agricultural productivity, mitigate climate change, and secure the provision of goods and ecosystem services has led many countries to make substantial commitments to global, regional and national forest landscape restoration (FLR) initiatives. Under the FLR approach, different interventions including riparian buffer and remnant habitat protection, passive and assisted forest regeneration, and sustainable agricultural and forestry management, are combined to create multifunctional landscapes that support rural livelihoods, ensure water supply, conserve biodiversity, and increase carbon stocks. However, finding effective strategies to set in motion permanent transformations in land management practices at the landscape scale remains a challenge (IUCN and WRI, 2014).

Across tropical Latin America, more than 70% of all agricultural lands are used for pasture and by some estimates more than 60% of this land has been degraded by unsustainable practices that undermine productivity (Montagnini, 2008, Murgueitio et al., 2011). Silvopastoral systems (SPS), which combine pastures with different tree arrangements and certain animal management practices, can help restore pasture productivity while reducing the environmental impacts of cattle grazing. Given the scale of extensive cattle production across Latin America, the adoption of SPS as part of an intensification strategy that integrates crop diversification, forest protection, and the release of marginal lands for conservation can contribute to regional restoration efforts (Murgueitio et al., 2011). Nevertheless, adoption of SPS in the region is still limited mainly by access to technical knowledge and financial capital (Calle et al., 2009, Ding et al., 2017).

Payments for ecosystem services (PES) are a common mechanism used to ensure the steady supply of services provided by nature. PES are predicated on the idea that paying landowners to adopt and maintain specific land uses is a cost-effective way to ensure the flow of services (Engel et al., 2008). PES schemes have largely focused on improving water supply, biodiversity protection, and carbon sequestration through forest conservation, but are increasingly targeting sustainable agricultural systems that can provide some ecosystem services as well as additional livelihood co-benefits (Rapidel et al., 2012, Kay et al., 2019). PES projects are as diverse as their degree of success, and while questions about their effectiveness and economic efficiency remain unresolved, they continue to be widely popular in Latin America and elsewhere (Grima et al., 2016, Börner et al., 2017, Salzman et al., 2018).

Two aspects of PES are especially relevant to their efficiency: additionality and permanence. Additionality is the ability to deliver results above and beyond what could be expected in the absence of the incentive, whereas permanence is the ability of payment-induced changes to persist in the long-term (Wunder et al., 2008). Additionality can be compromised if payments fail to yield extra environmental benefits (e.g., participants get paid to protect forests they did not intend to cut) or if payments have unintended negative consequences (e.g., undesirable activities are displaced elsewhere). On the other hand, the permanence of PES outcomes is generally expected to depend on the provision of long-term payments. The exception are “asset building” PES in which short-term incentives are provided specifically to facilitate the implementation of environmentally-beneficial practices that are also profitable and therefore are thought to be sufficient to induce lasting change (Engel et al., 2008, Pagiola et al., 2016). This assumption has been questioned on the grounds that introducing payments can “crowd-out” or weaken people’s intrinsic motivations and therefore undermine their pro-environmental behaviors in the post-PES period (Ezzine-de-Blas et al., 2019). Ultimately, the sustainability of environmental outcomes following short-term PES programs needs to be tested rather than assumed.

Despite the large number of existing PES programs, the use of rigorous impact evaluation methods comparing the actual outcomes to the counterfactual scenario without PES is relatively recent (Börner et al., 2017). Earlier claims about program effectiveness were frequently based on anecdotal evidence and descriptive indicators or simple before/after comparisons (Pattanayak et al., 2010). As empirical studies based on experimental and quasi experimental designs such as matching (Alix-García et al., 2012, Arriagada et al., 2012), randomized control trials (Jayachandran et al., 2017, Wiik et al., 2019), difference-in-difference (Pagiola and Ríos, 2013, Scullion et al., 2011), and framed field experiments (Andersson et al., 2018) become increasingly common, a more nuanced understanding of the contextual and design factors that determine the success of long-term PES programs is emerging (Börner et al., 2017).

By contrast, short-term PES programs have received far less attention and evaluations of their additionality, and especially the permanence of their outcomes beyond the payment period are still rare (Zapata, 2012, Pagiola et al., 2016). This is partly due to the fact that collecting the data needed for such analyses—baseline, change during, and change post-intervention inside and outside the target area—is typically beyond the scope and resources of short-term PES programs. This gap in research is unfortunate given the potential for asset-building programs to deliver both environmental improvements and social co-benefits without the need for perpetual payments (Pagiola et al., 2016). Thus, long-term observational studies directly comparing PES to control areas are needed to understand how effective short-term payments really are at achieving permanent landscape transformation (Börner et al., 2017). Likewise, comparisons to the landscape as a whole are also necessary to elucidate the impact of specific PES interventions relative to broader long-term regional trends in land use.

In recent years, several PES programs have been implemented in Latin America to harness the restoration benefits of SPS. The Regional Integrated Silvopastoral Ecosystem Management (RISEM) project was a 5-year effort to promote SPS adoption in a Colombian cattle ranching landscape by providing technical assistance and short-term PES to 75 farmers (2947 ha) from 2002 to 2007. Individual farmers received an initial baseline sum and thereafter were paid annually for land use changes expected to favor biodiversity conservation and carbon sequestration. Payments were capped at $6,600 USD total per farmer (World Bank, 2008). During the 5-year period, farmers replaced 78% of their treeless pastures with different silvopastoral arrangements using multipurpose trees; established 354 km of live fences and 23 ha of riparian corridors; and protected 210 ha of existing forests. Stocking rates increased by 44%, milk production increased in the dry season, and herbicide use decreased by 43%; these changes resulted in a 132% increase in net income per hectare. As more tree cover was added into degraded pastures, carbon sequestration increased and soil erosion decreased by 45% (World Bank, 2008). Significant increases in biodiversity were observed in several of the project-supported land uses, especially complex silvopastoral systems where abundance and diversity of birds, ants, and dung beetles often resembled that of secondary forests (Sáenz et al., 2006, Giraldo et al., 2011, Rivera et al., 2013). In addition, where riparian corridors were protected from livestock, water quality improved rapidly as reflected in an 80% decline in turbidity and biological oxygen demand, and the diversification of aquatic macroinvertebrate communities (Chará et al., 2007).

The RISEM project was the first PES project to include a control group; it also collected detailed land use and household information at baseline, and annual land use monitoring data for both groups. By the time of the last payment in 2008, PES recipients had made significantly more environmentally beneficial land use changes than control farmers demonstrating the additionality of the intervention (Pagiola and Ríos, 2013). Household re-surveys conducted four years later in 2011 found that most of these changes had been maintained in place, suggesting the potential for permanent results (Zapata, 2012, Pagiola et al., 2016).

Here, I evaluate the effectiveness of the RISEM in generating long-term additional and permanent outcomes on SPS farms by examining total tree cover change in the 13-year period since project implementation started. Specifically, I: (1) test for before/after changes on SPS farms; and (2) compare differences in change between SPS farms and the landscape in which they are immersed.