Kathleen A. Farley

Trading Water for Carbon with Biological Carbon Sequestration

Carbon sequestration strategies highlight tree plantations without considering their full environmental consequences. We combined field research, synthesis of more than 600 observations, and climate and economic modeling to document substantial losses in stream flow, and increased soil salinization and acidification, with afforestation. Plantations decreased stream flow by 227 millimeters per year globally (52%), with 13% of streams drying completely for at least 1 year. Regional modeling of U.S. plantation scenarios suggests that climate feedbacks are unlikely to offset such water losses and could exacerbate them. Plantations can help control groundwater recharge and upwelling but reduce stream flow and salinize and acidify some soils.

Does plantation forestry restore biodiversity or create green deserts? A synthesis of the effects of land-use transitions on plant species richness

Plantations are established for a variety of reasons including wood production, soil and water conservation, and more recently, carbon sequestration. The effect of this growing land-use change on biodiversity, however, is poorly understood and considerable debate exists as to whether plantations are ‘green deserts’ or valuable habitat for indigenous flora and fauna. This paper synthesizes peer-reviewed articles that provide quantitative data on plant species richness in plantations and paired land uses, most often representative of pre-plantation land cover. The results of this synthesis suggest that the value of plantations for biodiversity varies considerably depending on whether the original land cover is grassland, shrubland, primary forest, secondary forest, or degraded or exotic pasture, and whether native or exotic tree species are planted. The results of this study suggest that plantations are most likely to contribute to biodiversity when established on degraded lands rather than replacing natural ecosystems, such as forests, grasslands, and shrublands, and when indigenous tree species are used rather than exotic species. These findings can help guide afforestation and reforestation programs, including those aimed at increasing terrestrial carbon sequestration.

Grasslands to Tree Plantations: Forest Transition in the Andes of Ecuador

Abstract Over the past four decades the establishment of pine plantations in high altitude páramo grasslands has been a growing land use change in Ecuador. As a result, plantation forestry has transformed some highland landscapes from grasslands to ones dominated by exotic trees. This transformation is analyzed in the context of forest transition theory, which provides a framework for explaining scenarios of increasing forest cover. Forest transition theory predicts that reforestation and afforestation, encompassing the establishment of secondary forests and plantations, respectively, occur when economic development leads to the abandonment of agricultural land or when forest scarcity prompts increases in plantation establishment. This research demonstrates that projected forest scarcity has played an important role in páramo to pine transitions. However, it also indicates that, in Ecuador, afforestation has been seen as a potential means to economic development rather than a consequence of it. Furthermore, this case brings into question some of the assumptions of forest transition theory with respect to the environmental benefits of transition. The evidence presented indicates that, in the case of páramo to pine transitions, the biophysical response includes a loss of soil carbon, nitrogen, and water retention capacity, implying important trade-offs between the ecosystem services provided by páramos and those provided by pine plantations. These results suggest that both the existing land cover prior to forest transition and the type of forest cover established during transition merit more attention in forest transition theory.

Compensation for ecosystem services: an evaluation of efforts to achieve conservation and development in Ecuadorian páramo grasslands

Ecosystem services programmes have been advocated for their potential to join conservation and poverty alleviation efforts, integrate working landscapes, and provide a flow of ecosystem services upon which populations rely. Ecuadorian paramo grasslands have rapidly become the focus of compensation for ecosystem services (CES) programmes intended to conserve hydrologic services, carbon sequestration and biodiversity. This paper reviews CES programmes in Ecuadorian paramos using a combination of semi-structured interviews with project personnel, policy makers and community leaders involved in CES programme development, document analysis, and archival research. Findings indicate that, in some cases, CES schemes can support local development, with potential to contribute to poverty alleviation; however, measures of programme effects on poverty were lacking. The programmes fell across the spectrum of activity-reducing to activity-enhancing, with some functioning as protected areas and others integrating working landscapes; however, designation of land as protected did not necessarily imply more restrictive use. Finally, these cases all reflect scenarios in which limited information is available linking land use with ecosystem services production and underscore the idea that adequate understanding of ecosystem production functions continues to be a barrier to development of effective programmes, particularly where the provision of multiple ecosystem services is anticipated.

Stream acidification and base cation losses with grassland afforestation

Received 14 November 2007; revised 14 May 2008; accepted 3 June 2007; published 9 September 2008. [1] Afforestation of natural grasslands with fast-growing pine and eucalyptus species is increasing globally, but little is known about its effect on ecosystems and watersheds and, ultimately, the quality of water resources. To investigate the biogeochemical and hydrological consequences of this land use change, we sampled stream water in paired watersheds in Uruguay and Argentina. In watersheds planted with pine, we found no change in stream pH following afforestation, while in watersheds planted with eucalyptus, pH was 0.7 units lower on average than in streams draining grasslands. To further investigate the mechanism behind the decrease in pH, we sampled soils and streams of eucalypt catchments in Uruguay and analyzed exchangeable base cation concentrations, alkalinity, and dissolved inorganic carbon (DIC). At these sites, Ca, Mg, and Na concentrations were >30% lower in afforested soils than in grassland soils, and pH was significantly lower below 10 cm depth. Stream measurements taken over three years illustrate that these soil changes were also manifested in stream water chemistry. In the eucalypt watersheds, base cation concentrations were >40% lower, and alkalinity and DIC were halved in stream water. A test with data from additional sites where both pines and eucalypts were planted nearby showed that eucalyptus has a stronger acidifying effect than pine. Overall, our data suggest that repeated harvesting cycles at some locations could negatively impact the soil store of base cations and reduce downstream water quality. Our results can be used to help minimize negative impacts of this land use and to inform policy in this and other regions targeted for plantation forestry.

Effects of Land-Use Change on Water in Andean Páramo Grassland Soils

Mountain environments, including the Andean páramo grasslands of Ecuador, are important water source areas. They are often sites of programs and policies intended to achieve multiple management objectives, such as carbon sequestration, biological conservation, and water resource protection; yet such environments are often data poor. This creates challenges for programs that compensate landowners for protecting ecosystem services and uncertainty regarding which land uses are compatible. For example, does afforestation for carbon sequestration complement or hinder efforts to protect water resources in Andean páramos? We compared characteristics of high-elevation soil profiles at sites in two Ecuadorian páramo study areas and measured soil–water properties to assess whether changes in land use affected the soil hydrology. Using a space-for-time substitution, we compared soils in plantations of pines and Polylepis racemosa in grasslands with different grazing and burning regimes. Methods included soil description in soil pits; soil moisture measurement in soil pits and across surface transects; tracer studies of soil–water movement; and laboratory determination of bulk density, particle size, and humic acid composition. Of the land uses examined, only afforestation significantly affected soil moisture, whereas soil properties did not differ among grassland burning and grazing regimes. The results suggest that afforestation of páramos hinders the production of water and they underscore the need for further investigation to inform the trade-offs needed in managing páramo landscapes to support multiple ecosystem services.

Pathways to forest transition: Local case studies from the Ecuadorian Andes

Forest transition theory provides a framework for understanding scenarios where countries shift from a period of decreasing to increasing forest cover, through forest regrowth or plantation establishment. National-level research has helped elucidate some of the common pathways among countries that have undergone forest transition. However, the conditions that promote plantation establishment among rural landowners are not well understood. An evaluation of three plantations in the Ecuadorian Andes indicated that rural landowners responded to different priorities, opportunities, and constraints, which translated into different levels of importance for each of the proposed pathways to forest transition. In these cases, the most important pathways were associated with globalization and decisions by smallholders to use tree-based strategies to try to restore land or provide economic diversification. This study suggests that these pathways deserve further attention, particularly in developing country contexts or cases where forest transition is dominated by plantations.

Managing water services in tropical regions: From land cover proxies to hydrologic fluxes

Watershed investment programs frequently use land cover as a proxy for water-based ecosystem services, an approach based on assumed relationships between land cover and hydrologic outcomes. Water flows are rarely quantified, and unanticipated results are common, suggesting land cover alone is not a reliable proxy for water services. We argue that managing key hydrologic fluxes at the site of intervention is more effective than promoting particular land-cover types. Moving beyond land cover proxies to a focus on hydrologic fluxes requires that programs (1) identify the specific water service of interest and associated hydrologic flux; (2) account for structural and ecological characteristics of the relevant land cover; and, (3) determine key mediators of the target hydrologic flux. Using examples from the tropics, we illustrate how this conceptual framework can clarify interventions with a higher probability of delivering desired water services than with land cover as a proxy.

Carbon and Water Tradeoffs in Conversions to Forests and Shrublands

Carbon sequestration programs on land and in the oceans are gaining attention globally as a means to offset increasing fossil fuel emissions and atmospheric carbon dioxide concentrations (e.g., DeLucia et al. 1999; Caldeira and Duffy 2000; Schimel et al. 2000; Pacala et al. 2001; Hoffert et al. 2002; Jackson et al. 2002; Hungate et al. 2003; McNeil et al. 2003). Many industrialized nations now have national plans to foster land-based sequestration; Australias Plantations 2020 program is one example of such a national effort (Polglase et al. 2000). Ocean based sequestration, particularly deep ocean pumping of CO2 and iron fertilization, is also receiving considerable attention, although it remains even more controversial than land-based programs (e.g., Chisholm et al. 2001; Lawrence 2002; Buesseler and Boyd 2003; Tsuda et al. 2003). Despite uncertainties about the size and sustainability of sinks and markets, programs for emissions trading and carbon credits are underway, including the Chicago Climate Exchange and the European Union Greenhouse Gas Emission Trading Scheme. On land, many biological sequestration programs emphasize storing carbon in soil organic matter in agricultural fields, in woody encroached sites, and in the soils and wood of plantations. Land-based sequestration in agricultural soils restores all or part of the soil organic carbon (SOC) lost with plowing and intensive agriculture (Gebhart et al. 1994; Lal et al. 1999). No-till and low-till management are additional approaches proposed for increasing soil organic carbon in croplands. For plantations, the most controversial factors for carbon sequestration and management include the feasibility and permanence of the carbon sequestered, the scale of management needed to offset anthropogenic emissions, and the accompanying biogeochemical changes that would occur. As an example, a carbon sequestration rate of 3000 kg C/ha annually in plantations would require an area the size of Texas or Pakistan to offset 0.2Pg C per year of emissions; such a rough calculation ignores economic and biophysical limitations to storage and downstream losses of carbon as the wood is processed. A more complete evaluation of the feasibility of carbon storage by vegetation management, both scientifically and economically, is needed, including a more complete biogeochemical accounting of the consequences. The biogeochemical interaction that we examine in this chapter is water availability; other key interactions, such as with nitrogen, are beyond the scope of this chapter (e.g., Vejre et al. 2001, Dalal et al. 2003). Here we will examine some of the potential benefits of biological sequestration programs on land, some of the uncertainties surrounding them, and some unintentional consequences if they are initiated broadly. We will also address a related land cover change, woody plant encroachment, which has important consequences for carbon and water cycling. Woody plant encroachment differs from afforestation and abrupt land cover changes because it occurs over many decades. However, its global extent, potential for carbon sequestration, and similarities to afforestation make it important to address. For these land cover and land use changes we will estimate potential carbon sequestration rates, explore key biophysical interactions, and discuss examples of other biogeochemical and hydrological changes that may occur. For example, plantations may be the most beneficial environmentally when they are used to ameliorate groundwater upwelling, but they may also decrease water yield (defined as the amount of water from a unit area of watershed) (Herron et al. 2002, Farley et al. 2005). Our long-term goal is to identify these biogeochemical and hydrological costs and benefits that accompany sequestration scenarios.

Changes in carbon storage with land management promoted by payment for ecosystem services

RESEARCH ARTICLE The effects of check dams and other erosion control structures on the restoration of Andean bofedal ecosystems Brett D. Hartman 1,2 , Bodo Bookhagen 1,3 , Oliver A. Chadwick 4 Restoring degraded lands in rural environments that are heavily managed to meet subsistence needs is a challenge due to high rates of disturbance and resource extraction. This study investigates the efficacy of erosion control structures (ECSs) as restoration tools in the context of a watershed rehabilitation and wet meadow (bofedal) restoration program in the Bolivian Andes. In an effort to enhance water security and increase grazing stability, Aymara indigenous communities built over 15,000 check dams, 9,100 terraces, 5,300 infiltration ditches, and 35 pasture improvement trials. Communities built ECSs at different rates, and we compared vegetation change in the highest restoration management intensity, lowest restoration management intensity, and nonproject control communities. We used line transects to measure changes in vegetation cover and standing water in gullies with check dams and without check dams, and related these ground measurements to a time series (1986–2009) of normalized difference vegetation index derived from Landsat TM5 images. Evidence suggests that check dams increase bofedal vegetation and standing water at a local scale, and lead to increased greenness at a basin scale when combined with other ECSs. Watershed rehabilitation enhances ecosystem services significant to local communities (grazing stability, water security), which creates important synergies when conducting land restoration in rural development settings. Key words: Aymara, human-environment system, indigenous people, land restoration, NDVI, wet meadow Implications for Practice • Check dams increase bofedal vegetation and standing water at a local scale but can also lead to landscape-level effects that extend beyond the surface area covered by check dams. • The effects of large-scale and long-term restoration efforts need to be evaluated in the context of environmental change resulting from regional shifts in climate and land use. • Check dams and other erosion control structures can increase grazing stability and water security for local com- munities. When land restoration is aligned with the provi- sion of ecosystem services, indigenous people are capable of achieving extensive areas of land restoration even under continued agriculture and grazing management. Introduction Significant portions of the world’s tropics have been degraded by human use, with land degradation concentrated in dryland montane areas managed by the rural poor (Bridges & Oldeman 1999; Lambin et al. 2003; Bai et al. 2008). Local and indigenous people can be effective at ecosystem restoration, provided there is sufficient social coordination and mobilization (e.g. Walters 2000; Long et al. 2003; Mingyi et al. 2003; Stringer et al. 2007; Blay et al. 2008). However, restoration efforts in rural environ- ments that are heavily managed to meet subsistence needs are November 2016 Restoration Ecology Vol. 24, No. 6, pp. 761–772 often complicated by high levels of disturbance from agricul- ture, grazing, fire, and biomass harvest (Brown & Lugo 1994; Lamb et al. 2005). To improve restoration success in rural devel- opment settings, there is a need to better understand restoration dynamics where land use pressure is high and management objectives include restoring ecosystem services important to local communities (e.g. grazing stability and water security). A geographic region where intensive management by rural poor populations has led to environmental degradation is the Central Andes of South America (Ellenberg 1979; Sarmiento & Frolich 2002). The Central Andes are dominated by dry, tropical montane Puna grasslands composed of bunchgrasses, rosette-forming herbs, and dwarf shrubs in upland positions, and bofedal vegetation composed of rosette-forming herbs and cushion-forming species in seeps, springs, wet meadows, and floodplains (Squeo et al. 2006). Large portions of the Central Author contributions: BDH, BB OAC designed research; BDH performed research; BDH, BB analyzed data; BDH, BB, OAC wrote the manuscript. 1 Department of Geography, University of California, Santa Barbara, CA 93106, U.S.A. 2 Address correspondence to B. D. Hartman, email hartman@geog.ucsb.edu 3 Institute of Earth and Environmental Science, University of Potsdam, Karl-Liebknecht-Street 24-25, 14476 Potsdam-Golm, Germany 4 Department of Geography and Environmental Studies, University of California, Santa Barbara, CA 93106, U.S.A.