Keywords

Introduction

The increasing movement of people and goods across the globe has allowed numerous organisms to jump natural dispersal barriers and become introduced to new sites (Work et al. 2005). In some cases, they become established, rapidly expand their populations, and become extremely noxious, causing significant ecological impacts and economic harm (Mack et al. 2000; Pimentel et al. 2000). Ecological impacts from introduced species can include significant changes in ecosystems services (Hobbs et al. 2013), and these and other impacts are extensively reviewed in other chapters of this book.

This group of ecologically and economically harmful organisms—“invasive species” (sensu Richardson et al. 2000)—represents approximately 10% of all new non-native plant introductions (Williamson and Fitter 1996). For certain invasive species, for example, those expected to cause large damages and/or those that have not yet extended their range significantly, eradication may be optimal (Simberloff 2008). Though rarely, in highly unique cases, eradication has been achieved (Gardener et al. 2010, 2013), including Rubus species in Santiago Island, Galapagos (Renteria et al. 2012), and zebra mussels in a small pond in the continental USA (Adams and Lee 2011). Efforts to eliminate invasive species have helped us understand factors that affect eradication success, which can include intrinsic ecological characteristics of the target species, such as fast growth and high offspring, insufficient budget, related logistic constraints, and social attachment by settlers (i.e., seen as beneficial or harmful; e.g., Cruz et al. 2009; Simberloff 2003).

In addition to the fairly well-described ecological impacts caused by invasive species (Daehler 2003), recent studies have focused particularly on analyzing the social impacts and related costs these introduced organisms can generate (Liu et al. 2011). For instance, there are reductions in boating and fishing caused by colonization of Eurasian watermilfoil (Myriophyllum spicatum) and decreased recreation (i.e., park use) due to the tree Melaleuca quinquenervia in the USA (Charles and Dukes 2008). These examples illustrate how invasive species can negatively impact socioeconomic values. Understanding the critical role that the broader social system plays in invasive species management may improve management effectiveness and perceived success (García-Llorente et al. 2008; Gardener et al. 2010; Kholi et al. 2008; Epanchin-Niell et al. 2010; Larson et al. 2011; Kalnicky et al. 2014; Rai and Scarborough 2014).

Despite the many examples of negative ecological, social, and economic impacts from invasive species, their management may not be beneficial for all affected stakeholders. Some invasive species clearly cause great harm and are not generally viewed as beneficial (e.g., fire ants—Solenopsis invicta), mainly because they were unintentionally introduced and cause significant negative damage to livestock and humans (Pimentel et al. 2001). However, a subset of invasive species was intentionally introduced for perceived social and economic benefits , and these were only later identified as invasive once their ecological effects became apparent (Kennedy and Hobbie 2004). Three notable examples include salt cedar (Tamarix spp.), introduced to control erosion, M. quinquenervia to dry up the Everglades, and kudzu (Pueraria lobata) for erosion control and livestock forage (Di Tomaso 1998; Webster et al. 2006). For these, and other species, there can be much less motivation to eradicate or actively manage invasions given positive public perceptions (Moyle 2001; Colautti and MacIsaac 2004; Webster et al. 2006; Pejchar and Mooney 2009; Adams et al. 2011; Davis et al. 2011).

Perceived benefits can complicate invasive species’ control and management and frustrate policy interventions if diverse stakeholders have opposing views about their positive or negative impacts (Schlaepfer et al. 2011). For example, the negative effects that Pinus species can cause to the native ecosystems they invade are well known (Richardson and van Wilgen 2004), but in some regions (e.g., South Africa), they are highly valued for timber and non-timber forest products that support local residents (de Wit et al. 2001). While removing these trees may positively affect stream flow (Richardson and van Wilgen 2004) and diminish their ecological impact, it might result in significant economic losses to those using the trees (Turpie et al. 2003), who might oppose the control and reduction of this species.

These examples highlight the importance of understanding the social landscape in which invasive species exist, including identifying stakeholders and defining their roles and perhaps, critically, identifying which groups would view invasive species removal as beneficial or detrimental. Recent literature on social conflicts and invasive species management recognizes the need to explicitly include both ecological and socioeconomic aspects of invasive species assessments, identify impacts on diverse stakeholders, and consider policy mechanisms (e.g., incentive payments) that address their concerns (Estévez et al. 2015).

Despite a recognized need for management programs that incorporate mechanisms to reduce the negative ecological, economic, and social impacts of invasive species (e.g., Adams and Lee 2012), we often lack sufficient information to guide policy and management decisions about new invasions (e.g., Leung et al. 2002) or to understand impacts that such management projects may have on different stakeholders. However, researchers have used a variety of methods to inform these decisions despite the inherent uncertainty associated with new and potential invasions, i.e., bioeconomic modeling (e.g., Adams and Lee 2012). Such investigations are useful for gauging socioeconomic impacts and simulating the effects of potential invasive species management approaches (e.g., Lee et al. 2009; Adams et al. 2011; Adams and Lee 2012). What is most clear from these, and related studies, is that identifying the appropriate management approach requires a strong understanding of the target species’ effects and impacts—ecological and otherwise. The identified negative and positive impacts can be later included in managerial decision-making that may help to reduce the risk of failure of restoration projects (Rai and Scarborough 2014).

Conceptually, this can be done using a coupled human-natural systems approach that incorporates observations on both the ecological and social systems and their interactions (Liu et al. 2007). However, in practice, this is rarely done (Pejchar and Mooney 2009; Estévez et al. 2015). Notable exceptions include analyses of the social dynamics surrounding an invasive species introduction by conceptually “mapping” local stakeholders being impacted (positively or negatively), describing the relationship among stakeholders, and analyzing the expected impacts of management alternatives on stakeholders groups (e.g., Leung et al. 2002; Richardson et al. 2009). This is a critical area of inquiry that has received insufficient attention in the scientific literature.

Here, we use descriptive analysis and survey and interview methods to understand the case of the invasive and economically important tree Cedrela odorata in the Galapagos Islands, Ecuador, where the tree is viewed as both beneficial and harmful to stakeholders; explore the complex social, economic, and ecological aspects of invasive species management; and identify the stakeholders that could be impacted by potential managerial actions targeting this invasive tree.

Despite the significant ecological impacts of Cedrela in Galapagos (see chapter by Rivas-Torres and Rivas) and its economic importance for the local timber market (Methods section), no studies have assessed the socio-environmental dynamics of Cedrela or the impacts of alternative Cedrela management approaches (e.g., Cedrela eradication and site restoration) on stakeholders. In the following sections, we summarize the ecological impacts of Cedrela to assess its biotic effects and describe the stakeholder groups engaged on this issue, including governmental agencies, local residents, and timber workers. Next, we explore the costs and benefits to stakeholder groups associated with Cedrela management and forest restoration and the loss of the tree as a key commodity. Finally, we present a conceptual model of the socioecological landscape that could inform Cedrela management by the GNP . Using this model, we compare two competing policy alternatives that are being considered for adoption: (1) continued use of Cedrela for the local wood products market and (2) complete extraction and eradication of Cedrela within the GNP (GNP Directorate 2014). Besides adding to the small but important literature on the socioecological impacts of invasive species management, this chapter also fills critical knowledge gaps about Cedrela impacts and alternative management approaches. Results of this study also have practical importance for the management of invasive species in the Galapagos Islands.

Methods

Background and Target Species

In the 1940s, the invasive tree Cedrela odorata (Meliaceae; hereafter Cedrela) was introduced to the farms located in the highlands of Santa Cruz Island (at the center of the Galapagos archipelago; Lundh 2006) and today is also found on the other three inhabited Galapagos islands (see chapter 6 by Rivas-Torres and Rivas in this volume for study site and species details). Within the Galapagos, Cedrela is a highly valued timber species for the local, on-island market. The tree is native to tropical America, ranging from central Mexico to Brazil; but despite this wide distribution, its population densities (strongly diminished by illegal and legal logging) are considered low within this native range. Ironically, although it is invasive in the Galapagos, the tree is protected from extraction and even categorized as broadly threatened and vulnerable within its native distribution (IUCN Red List 2016).

Cedrela is well known around the world for its excellent wood quality , which is one of the reasons it was exported to sites outside of its original range and introduced to many Pacific archipelagos like Hawaii and Galapagos (Cintron 1990). Cedrela is now the main timber resource in the Galapagos, and its wood is mostly used locally for furniture for the ~30,000 inhabitants and handicrafts for the tourism industry, which includes ~170,000 visitors to the islands (Gardener and Grenier 2011). The annual market value of Cedrela timber in the Galapagos local market is estimated to be US$2,000,000 (http://www.cdfdevelopment.org/our-work/biodiversityconservation.html Charles Darwin Foundation 2012), although this rough estimate represents a rare data point on the potential impacts of Cedrela management.

Seven decades after its intentional introduction, Cedrela is dominating the canopy of several forested areas and invading some of the principal ecosystems of the archipelago (Renteria and Buddenhagen 2006; Trueman et al. 2014), causing negative ecological impacts (see chapter 6 on allelopathy by Rivas-Torres and Rivas in this volume). In 2007, due to its threatened status in the American continent, the extraction of Cedrela was prohibited everywhere in Ecuador including the Galapagos (Ministerio del Ambiente, Acuerdo 167, Articulo 1, 2007). However, in 2009, the extraction of Cedrela was allowed to restart in the islands but mostly in the agricultural areas of Santa Cruz, i.e., not intensively in the protected zone where Cedrela dominates. Since then, the GNP has been regulating the extraction of Cedrela, mainly outside of the protected area by providing permits to users that specify location and timing of Cedrela extraction. The GNP is in the planning stages of a new rule incorporating Cedrela extraction into their restoration efforts (Galapagos Management Plan, Galapagos National Park Directorate 2014: 199), which presents a unique opportunity to assess how a change in the Cedrela market in Santa Cruz affects stakeholders.

Study Area

In the Galapagos, the biggest naturalized population of Cedrela (i.e., established without human intervention) exists on Santa Cruz Island, where the tree is considered invasive and is even dominating extensive areas. An ongoing project using satellite images and drones and mapping (for the first time with a peer reviewed and open methodology) the actual coverage of most invasive plants in the Galapagos (Rivas-Torres et al. 2016; http://institutodegeografia.org/vega-2/), recorded that this invasive tree now dominates a block of ~1000 hectares of continuous forest [hereafter also called “Cedrela forest”] in that island alone. Cedrela forest covers a portion of the humid highlands in the southern side of Santa Cruz at ~200 masl, around 5 km from the main site where Cedrela was first introduced. This forest is in the protected area, on the border (“buffer zone”) that divides the developing agricultural zone with the National Park (see map on chapter 6 ). Given its location, the GNP has the authority to decide any actions—such as management and restoration plans —that must be taken in this invasive-dominated forest. In fact, the GNP spends on average US$132,000 per year on Cedrela-related restoration activities, including the operation of a greenhouse near the Cedrela forest that can produce 60,000 native seedlings to support restoration projects in this highly invaded zone. Outside this forest, Cedrela is found mainly on private lands within the “agricultural zone” in Santa Cruz and in small patches or as single individuals extending along steep hillsides. Although the GNP has a prohibition on planting or propagating Cedrela throughout the entire archipelago (Gardener et al. 2013), its many wind-dispersed seeds allow it to disperse naturally and colonize other ecosystems outside the block (Renteria and Buddenhagen 2006).

Ecological Data

To summarize the ecological impacts Cedrela may have over native and invasive plants, we tabulated the results from relevant investigations measuring invasive tree impacts (i.e., Jaeger et al. 2007) and observations by G. Rivas-Torres (and Rivas-Torres et al. 2017). Some of its main and obvious ecological impacts are related to changes in plant composition and environmental conditions of the sites this tree invades, such as changes in solar radiation to the forest understory and allelopathic effects (Rivas-Torres and Rivas’ chapter 6 in this volume) that can limit growth of seedlings and juveniles.

Socioeconomic Data

Cedrela management approaches and associated costs were assessed based on in-field observations and surveys with key stakeholders. Next, we quantified the GNP’s management costs for reversing the negative ecological impacts by this invasive tree (Annex 1 [Online]: Table 11.1). This quantification was performed using the Annual Operating Plan (AOP) (Galapagos National Park Directorate 2014), which is part of the Galapagos Management Plan (Galapagos National Park Directorate 2014), and includes detailed information on the yearly budget used by the GNP to perform restoration-type activities. We used the GNP’s greenhouse and detailed expense database reported as part of the AOP (2015) to estimate management costs (see, e.g., Annex 1: Tables 11.1 and 11.2) and then projected the costs onto the entire ~1000 hectares which comprise the Cedrela forest. This invaded site was selected because it is the first likely target for restoration efforts due to GNP’s control over the area and high density of Cedrela.

For almost 2 years, G. Rivas-Torres accompanied GNP staff and other park workers (e.g., informal loggers hired to extract Cedrela as part of a treatment) and observed day-to-day restoration practices and identified the primary stakeholders involved in Cedrela management and its wood market. We identified four primary stakeholder groups (GNP staff, handcrafters, and chainsaw and sawmill workers), which were interviewed to confirm in-field observations about their roles, to understand their participation in the Cedrela market and help contextualize the socioeconomic importance of Cedrela. Based on a series of interviews with these stakeholders, we developed a survey instrument to (1) define the involved stakeholders, (2) describe the activities they perform in the actual extraction of Cedrela, and (3) identify other potential users and participants of this wood market (for answers and methods details, please refer to Annex 1, Tables 11.3 and 11.4; and Annex 2, Figs. 11.4 and 11.5). The data informed a conceptual map identifying the main stakeholders for this market (Fig. 11.1).

Fig. 11.1
figure 1

Conceptual map denoting the five primary stakeholder groups in the Cedrela wood market in Santa Cruz, Galapagos Islands. The first connection links the tree owner selling the Cedrela tree or hiring a chainsaw worker to do the extraction. This action is followed by the production of a timber product by the chainsaw workers who obtain the logs from the felled tree onsite. At this stage, either the chainsaw worker or the previous or new owner of this timber product has the extraction and transport permit approved from the GNP, which controls the extraction process. After getting this permit, Cedrela logs and planks are transported and sold to either sawmills or handcrafters. The handcrafters can also buy wood from the sawmills after it has been bought from the original owner

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To create the qualitative model for the Galapagos Cedrela market, we used three main sources: 2+ years of in-field interactions with the identified groups, the conceptual stakeholders’ map (Fig. 11.1), and the relevant answers from the surveys, such as costs related to Cedrela products and how they differ between stakeholders (i.e., Annex 1, Tables 11.3 and 11.4; and Annex 2, Figs. 11.4 and 11.5). Income data from the surveys informed our predicted impacts model (Fig. 11.2). This exercise also helped identify critical information gaps that should be filled to reduce uncertainty in the decision-making process.

Fig. 11.2
figure 2

Hypothetical qualitative model for the present Cedrela (“status quo”) wood market in Santa Cruz Island, Galapagos. Stakeholders are presented in dark gray, while products are presented in white. Different steps or transitions are denoted by a number, and are presented in light gray. Prices for different steps are presented where information was available. For definition of *high quality wood and +lower quality wood please refer to notes in Annex 1 Table 11.3

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Status Quo and Alternative Models Assembly

According to section 2.1.2 of the Galapagos Management Plan (Galapagos National Park Directorate 2014), one of the main objectives of the GNP is to “Ensure the rational use of supply services generated by ecosystems.” This objective is reinforced in subsection 2.1.2.5: “Generate and implement a comprehensive management plan on introduced timber species in coordination with relevant entities.” To provide relevant information to help fulfill this objective, we assembled an alternative qualitative model that analyzed how the present model depicting the wood market status quo, and how stakeholders using Cedrela in Galapagos, are affected by an integrative GNP plan to manage this invasive tree. Since Cedrela is an invasive plant regulated by the GNP, by extension, this plan hypothetically (i.e., stated by this study but not yet implemented) also deals with controlling its extraction both inside and out of the boundaries of the protected area. We built the alternative model under the assumptions that the Park will establish a logging and management plan for the Cedrela forest and will also manage and control Cedrela planted on private lands (Fig. 11.3).

Fig. 11.3
figure 3

Alternative hypothetical qualitative model for the Cedrela wood market in Santa Cruz Island, Galapagos. Stakeholders are presented in dark gray. Different steps or transitions are denoted by a number and are presented in black captions. This model suggests that the steps 3 and 4, i.e. the restoration of Cedrela novel forest, the creation of a plan to manage wood extraction and the control of the expansion of invasive plants in this and other extraction sites, should be performed by the GNP if this agency assumes the integral control of the Cedrela market. A box is showing the path GNP will have to take if buying a tree from the Cedrela owner, which will then follow a similar path as in model of Fig. 11.2

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Results

We identified two main impacts related to the presence and extraction of this invasive tree. First, when Cedrela is present, it can significantly reduce the establishment and growth of other native canopy species (i.e., by using allelopathic mechanisms , i.e., Chapter 6 by Rivas-Torres and Rivas of this volume), and, second, when this tree is extracted, other invasive species can take over the restored sites (Jaeger and Kowarik 2010; Annex 1: Table 11.1, “Impact”). For managing the impact to native plants caused by the presence (shade) of Cedrela, we first determined (using available literature and restoration plans) that clear-cuts of Cedrela (e.g., Jaeger and Kowarik 2010), followed by reforestation with native seedlings (e.g., Gardener et al. 2009) to increase native propagules pressure (Wilkinson et al. 2005), are preferred. From an ecological perspective and considering GNP objectives, we determined that mechanical (and to a lesser extent, chemical) control is the most appropriate activity (see, e.g., Renteria et al. 2006) to reduce the establishment and expansion of other invasive species after Cedrela extraction.

Using the GNP Annual Operative Plan (Galapagos National Park Directorate 2014), specifically the expense section detailed per item and the greenhouse detailed expenses from the Ecosystems Unit of the GNP, we matched each item related to clear-cut of invaded areas, seedling production, reforestation with native seedlings, and mechanical and chemical control of restored areas that the GNP usually performs in other restoration projects. The values calculated for all the items of these four different activities were used to monetize and project the costs for the restoration of the ~1000 hectares that form the Cedrela forest. In total, we calculated that a gross amount of US$7,440,000 is necessary to clear-cut, produce the necessary seedlings to restore the extracted sites, plant native seedlings, and maintain them in initial stages, if the entire 1000 ha block of Cedrela forest is to be restored (Annex 1: Table 11.1).

After more than 2 years of interaction with the identified groups, the relevant answers from the surveys (Annexes 1 and 2 and more results on Annex 4) and direct discussions with GNP staff allowed us to create a preliminary stakeholders’ diagram (or “systems thinking diagram,” Bosch et al. 2007) that was formed mainly by five well-defined groups: private tree owners, chainsaw workers, the Galapagos National Park , sawmill workers, and handcrafters. This preliminary diagram (Fig. 11.1) was shared with and validated by GNP staff. The resulting diagram with the five defined stakeholder groups consisted of six connections. These “connections,” or relations between stakeholders, are important to define because they can inform future managerial actions such as restoration or planned extraction of invasive trees and can ensure the success of such conservation initiatives (Ford-Thompson et al. 2012).

After creating the socioeconomic model for the ongoing (i.e., “status quo”) Cedrela market (Fig. 11.2), we described the preliminary impacts of adopting a new management policy (i.e., manage and control Cedrela extraction inside and outside the protected GNP) and how some activities might help to ameliorate these effects. Thus, using the “status quo” conceptual model to describe these expected impacts, we identified that:

  • First, the GNP would have to establish some mechanisms if taking total control of Cedrela management, such as buying adult trees and subsidizing private owners (Dehnen-Schmutz et al. 2004), in order to stop Cedrela’s extraction and plantation in private lands (Fig. 11.3, step 1). If the private owners decide to sell the standing Cedrela trees to GNP, then this agency would have to supervise the extraction of these trees (Fig. 11.3, step 2, box A) and follow similar steps as presented in the “status quo” model (Fig. 11.3, from step 1: “hire”—onwards).

  • Second, to meet the actual demand for wood in the archipelago, on one hand, the GNP would have to create and implement a management plan for sustainable extraction (Richardson 1998) of Cedrela wood from the Cedrela forest (which concentrates the higher density of Cedrela trees) and, on the other hand, assume the costs related to the ecological restoration with the desired native species for sites where Cedrela would be extracted (Fig. 11.3, step 3).

  • Third, parallel to a restoration plan, GNP should contemplate the expansion control of other invasive species that could establish and colonize in extracted sites within the Cedrela forest. Experimental plots are currently established in this site to understand forest dynamics in this “novel” ecosystem.

  • Fourth, for those trees to be extracted from the Cedrela forest, GNP could arrange concession areas identified for removal to sawmills and handcrafters (Fig. 11.3, step 5), who would be in charge of obtaining the resources and hiring the personnel to extract the wood from those areas and produce the derived goods (Fig. 11.3, steps 6–10), following (more or less) the steps detailed in the first “status quo” model (Fig. 11.3). Concessions by the GNP to extract Cedrela within the ~1000 ha are suggested as an alternative based on the understanding that the actual Cedrela extraction (i.e., clear-cut to prepare the sites for restoration) represents the most expensive cost among the different activities that are necessary to restore this invaded forest (Annex 1: Table 11.1) and might be a good option to reduce the National Park’s expenses.

Discussion

This analysis allowed us to identify the main stakeholders in the Cedrela market, assess the importance of Cedrela for these stakeholders and Galapagos’ society and economy, and, most importantly, analyze the impacts to stakeholders if a different management alternative is implemented in this timber market. Since Cedrela is the main source of wood for this tropical archipelago, it is essential to create a plan to manage this highly significant timber source; but, as expected, the importance of Cedrela in Galapagos’ society represents a potential barrier to future Cedrela management projects (Marshall et al. 2011). For instance, this study identified stakeholders in the Cedrela market, in particular the ones that depend entirely on the availability of its wood, such as handcrafters, who will be negatively affected if timber availability from this invasive species is reduced or eliminated.

After recognizing target groups that could be affected by potential management action involving Cedrela extraction and control (to reduce its ecological impacts), decision-makers (in this case the GNP) may want to include these stakeholders in the management process to reduce the probability of conservation project failure (Glen et al. 2013). Additionally, information and education campaigns that include impacted actors could be robust tools to inform them about the indirect and direct benefits of controlling Cedrela for the Galapagos community and help to engage them in an intended management project. These campaigns could also include follow-up surveys to evaluate stakeholders’ perceptions about the management action of controlling Cedrela, information that could be included to reduce social impacts of this action and thus increase project effectiveness (García-Llorente et al. 2008). Other investigations have shown that active participation and information transfer among stakeholders are helpful to obtain sustainable logging and restoration initiatives (Larson et al. 2011) and if well-implemented might also reduce the impacts on affected social groups (García-Llorente et al. 2008).

One key factor identified by this study that might help to implement such campaigns is that, in spite of the lack of interest to get subsidies from the governmental agencies, handcrafters are open to wood alternatives that could replace Cedrela timber (Annex 2: Fig. 11.4). This might be advantageous if a full eradication program is intended for this timber species. In the long run, GNP should consider the eradication of Cedrela as this is an invasive species causing impacts within a World Heritage Site. Nevertheless, all the alternative woody species defined by handcrafters are considered non-native species (Annex 2: Fig. 11.5), and so, the use of these trees as substitutes of Cedrela will need to be carefully analyzed.

The resulting “status quo” model presented in this study (Fig. 11.2) identified the stakeholders that are presently part of this timber market. It depicts how chainsaw workers, sawmill workers, and handcrafters directly interact with each other (and with other stakeholders such as tree owners) and the public in general, while the GNP mainly controls the extraction and transport of wood within the Galapagos boundaries. This model also shows how prices of the different products and services offered by stakeholders can drastically change throughout the market, like the sixfold additional price a high-quality wood piece can cost in the sawmills when compared to the prices quoted by chainsaw workers. These prices can serve as a reference if the GNP agency implements logging and management programs in the Cedrela forest and needs to consider costs of subsidies and other economic intervention strategies to reduce the impact of a market change.

In that regard, the alternative model (Fig. 11.3) diagrams how the different stakeholders and steps would likely be affected if the GNP agency establishes an integrative plan to manage the Cedrela extraction in Galapagos and if it implements a logging plan for the Cedrela forest. The important change in this alternative model (Fig. 11.3), when compared to the “status quo” model (Fig. 11.2), is the number of activities the GNP agency would have to cover in order to acquire the control of this market. The implementation of some activities recognized to help in the efficient management of timber species like Cedrela, such as subsidies, education campaigns (McDermott et al. 2013), active workshops with stakeholders and society (Rea and Storrs 1999), a logging plan, and the active control of colonizing invaders in extraction sites (Jaeger and Kowarik 2010), would definitely increase the operating costs that this governmental agency would need, to manage Cedrela forest and Cedrela in general. But, after step 4 of the alternative model (Fig. 11.3), i.e., control of the expanding invasive plants in extraction sites, the Park would not need to invest significant amounts of time and money since the next stages are already established for this market.

Similar to other systems where non-native trees have invaded, Cedrela has greatly altered native forests in the Galapagos, and a return to native forests requires extensive—but potentially feasible—restoration efforts (Meyer and Florence 1996; Jaeger et al. 2007; Rivas-Torres et al. 2017). Such efforts, as identified by the present empirical analysis, would directly impact the GNP (activities and budget). Indeed, some have suggested that restoration using native species is the only way to restore ecological function of historical forests after tree invasion (Jaeger and Kowarik 2010). If the GNP decides to restore the Cedrela forest to resemble native vegetation, it will have to extract Cedrela trees so that other native arboreal species, such as Scalesia pedunculata (which co-dominated this area in the past), can reestablish in the site as a first step. Restoration of Cedrela-dominated sites would also mean, among other things, eradicating adult trees that are inside the agricultural land (i.e., outside the protected area) and that can produce seeds that might colonize restored sites. Due to the capacity of adult Cedrela trees to produce winged seeds that can colonize distant sites, we proposed that GNP also should control the production of propagules outside of the protected area, which could impact other social groups (such as tree owners) and might need to involve strategies such as buying adult trees located in private lands and subsidizing this group of stakeholders (Fig. 11.3, step 1). Opening the canopy after Cedrela extraction might also mean other very pervasive invasive species could colonize and outcompete native plants (Renteria 2012). If the GNP does not invest sufficient effort in controlling the colonization of noxious invasive species (such as Rubus niveus and Cedrela) on newly opened extraction sites, these weeds might then dominate the landscape. Species like R. niveus grow very rapidly in open areas forming dense stands, inhibiting recruitment of other plants underneath (Renteria 2012). This is why (as outlined in Annex 1: Table 11.1) the GNP will need to plant native seedlings (previously nurtured in the greenhouse) and control mechanically—or when necessary, chemically—the recruitment of other invasive plants. Relevant studies highlight that a good restoration strategy has to include post-reforestation activities (in this case control of invasive plants colonization) that will help to ensure the sustainability of the restored forest (Jaeger and Kowarik 2010; Meyer 2014). Also, for Galapagos, the mechanical control of invasive plants has been recognized as highly effective, especially when performed in the initial stages of colonization (Gardener et al. 2010; Renteria et al. 2012).

The calculations of gross costs per each activity needed to reverse Cedrela impacts were obtained after projecting the present costs for the same managerial actions performed by the GNP in other areas subjected to restoration. Such costs are simply for reference and would have to be adjusted in the future depending on new economic and climatic circumstances. For example, the GNP would need to define contingency plans—and budgets—in case of natural phenomena like El Niño and La Niña or climate change-related events occurring, which may significantly affect the establishment of the planted native seedlings in restored areas because of drought or excessive rain (Trueman and d’Ozouville 2010). On the other hand, positive values on the presence of Cedrela forest—such as refuge for some native plants and large native herbivores like the giant Galapagos turtles, which are apparently finding food in invasive-dominated areas (Blake et al. 2012)—can be also included in the balance for the evaluation of costs and benefits of Cedrela-dominated site restoration. It is worth mentioning that the costs presented here are only for the entire 1000 hectares that form the Cedrela forest, meaning the GNP will not have to invest these amounts in full when beginning with this site’s management. Such costs could be covered gradually as the restoration efforts advance for the Cedrela forest.

It is still necessary to define if the GNP would be extracting timber from Cedrela forest—and/or other infested areas—until no more trees are available and invaded sites are restored and hopefully Cedrela is eradicated or if this agency will implement a logging plan that includes the actual crop and regeneration of Cedrela wood patches inside this forest that can help to supply and maintain the wood market in Galapagos. If the Park chose the latter, the costs presented in this study would increase substantially since some of the detailed activities, like the actual extraction and the post-extraction control of invaders, would have to be replicated several times per extraction patch/site and event. However, active wood production from the Cedrela forest could also be a significant income source for the Park, who could use the revenues from this activity for the control and management of this and other areas, and also—for instance—for subsidy payments to the private sector that might be affected by its exclusion from the Cedrela market. On the other hand, if the GNP chooses the former, desired Cedrela eradication might be achieved due to the exhaustion of this timber source, but in this case, the GNP would have to provide alternatives to the future absence of Cedrela timber in this closed market, which should be explored before beginning with the Cedrela extractions.

The two models presented here were empirically derived based on best available data and observations and on surveys that occurred over 2 years in the field, and they present the most detailed description to date of the wood market in Galapagos. The models were also verified with stakeholders. Still, these systems are not static, and future work is needed to revisit these models and revise them, perhaps including results from restoration techniques and feasibility to reconvert novel areas, different actors and users within the Cedrela wood market, and new socioeconomic impacts from changes in the management of the wood market for this invasive but economically valuable species. Nevertheless, we anticipate that the multidimensional analytical models here presented (i.e., that include the ecological impacts in addition to the socioeconomic aspects) will be useful for establishing conservation strategies and management priorities. These models identify which, and how, stakeholders might be impacted under alternative potential managerial scenarios, information that might be critical if new conservation programs intended to manage invasive timber species are established (Hulme 2006). They may also inform policy choices and decision-making processes for the management of other invasive timber species in the Galapagos archipelago and other highly invaded and inhabited areas where similar conservation conflicts might occur.