The combined effects of conservation policy and co-management alter the understory vegetation of urban woodlands: A case study in the Tama Hills area, Japan

Abstract

We examined the relative impacts of socioeconomic and biophysical variables on understory vegetation in urban woodlands using the example of satoyama woodland in peri-urban areas of Tokyo, Japan to determine an appropriate institutional framework for enhancing biodiversity and ecosystem services in urban woodlands. Satoyama woodland was historically managed, however, the recent abandonment endangers its biodiversity and ecosystem services. We addressed two main working questions: (1) Which variables (among conservation measures, management actors, and other environmental variables) are the main constraints on the current understory vegetation of urban woodland? (2) How does each management actor behave in the context of different conservation measures and how does this behavior affect the understory vegetation? We employed dwarf bamboo (Pleioblastus chino) as an indicator of the intensity of satoyama woodland management and combined ecological analysis with interviews of municipal officials. We found that the conditions of understory vegetation were mainly affected by differences in the behavior of management actors, as the height of dwarf bamboo was shortest at the woodland managed by community group, followed by municipality and private landowner. This suggests that it will be necessary to consider both biophysical variables and socioeconomic variables in urban ecosystem management. We also found that different management actors had different reasons to conduct or not conduct woodland management. To improve management by these multiple actors, we recommend: developing management plans for conserved areas, providing economic and non-economic support, and developing clear indicators for monitoring the effects of management, with their different behaviors in mind.

Introduction

Woodlands in urban areas serve as a base for biodiversity and provide multiple ecosystem services in cities around the world (Barthel et al., 2005, Bolund and Hunhammar, 1999, Miller, 2005). As the global population continues to concentrate in and around cities (UN, 2009), the conservation values of urban ecosystems and their biodiversity and ecosystem services are expected to increase (Grimm et al., 2008). Thus, local governmental authorities and other interested organizations around the world have begun to form conservation policies for enhancing the biodiversity and ecosystem services of woodlands in and around their cities (Hill et al., 2010, Van Gossum et al., 2009). It is necessary to consider human activities when conserving urban woodlands, since woodlands and other types of green spaces in urban areas have been massively affected by many kinds of human activities (Luck et al., 2009, Pickett et al., 2010). Among other impacts, habitats for certain species and recreational values have been significantly affected by woodland management (Heyman et al., 2011, Konijnendijk, 2003). Clearance of the woody understory may increase the diversity of vascular plants (Götmark, Paltto, Norden, & Gotmark, 2005), but at the same time may make the forest less attractive to passerine birds and reduce their abundance and diversity (Heyman, 2010) and may have significant impacts on other taxa in various ways (Alvey, 2006). The clearing of understory to enhance the recreational value of the forest is common in urban woodlands (Tyrväinen, Silvennoinen, & Kolehmainen, 2003), and unmanaged urban woodland may create safety and security concerns among nearby urban residents (Jorgensen et al., 2007, Nielsen and Møller, 2008). On the other hand, unmanaged remnant natural vegetation in Stockholm serves as an important place for recreation by local people (Florgard & Forsberg, 2006). The effects of woodland management can be diverse, so local authorities and other organizations must clearly consider the outcomes.

Woodlands in cities are rarely managed by single actors; most often, they are managed by multiple interacting actors, such as local governmental authorities, local community groups, and private landowners (Colding, Lundberg, & Folke, 2006). Many of the local governmental authorities in urban areas conduct woodland management activities in protected areas and other types of conserved areas. However, the urban ecosystem management by local governments is often spatially limited, since management in protected areas is costly and most governments have limited budgets (Colding et al., 2006). Furthermore, managers employed to manage public parks sometimes do not have sufficient ecological knowledge and do not understand how to maintain a park's ecological characteristics (Andersson, Barthel, & Ahrné, 2007). Local community groups, who are the users of the land and who can manage the land individually or in a cooperative manner, have recently been recognized as playing an important role in the co-management of urban ecosystems (Andersson et al., 2007, Barthel et al., 2005, Colding et al., 2006). The management activities of these groups are often volunteer-based and organized similarly to non-governmental organizations (NGOs), non-profit organizations (NPOs), and other type of groups with shared interests such as biological conservation (Ernstson, Sorlin, & Elmqvist, 2008). Some activities of local community groups maintain biodiversity and provide ecosystem services based on their local ecological knowledge (Andersson et al., 2007), but these activities often cover relatively small areas (Tsunekawa, 2003) and may be spatially limited within a larger region (Yokohari & Bolthouse, 2011). In a city dominated by private land, as is the case in most cities in the United States and Japan, private landowners may also play a crucial role in the management of urban woodlands (Gillespie et al., 2012, Tsunekawa, 2003). Since the abundance of private woodlands and their management are often driven by economic factors (e.g., the prices of woodland products), there is a risk that a focus on purely economic values may result in an undesirable ecological state (e.g., unsustainable or excessive harvesting of trees) if private landowners pursue their own profits and ignore the land's ecological benefits for the public. As these descriptions show, every actor has certain advantages and disadvantages in their ability and desire to manage the land in a publicly desirable way. To develop more effective woodland management, policy-makers and landscape planners should recognize the roles of these multiple actors and make great efforts to develop an institutional framework or government systems that create a mix of policies and measures targeted at each management-related actor (Andersson and Ostrom, 2008, Bengston et al., 2004, Van Gossum et al., 2009).

The institutional analysis and development framework, which is commonly used for the analysis of natural resource management institutions (Andersson and Ostrom, 2008, Ostrom, 2011, Ostrom and Cox, 2010), recognizes that management actions by actors are affected by rules (so-called “rules-in-use”) and various other factors. Conservation measures, which are often implemented under governmental laws, are a typical example of such rules that affect actions by the government itself and by local community groups, private landowners, and others by creating regulations or incentives that encourage or constrain certain actions by these stakeholders. Appropriate evaluation of current management-related measures with multiple actors in mind is essential to learn how to develop a more effective and balanced institutional framework. However, such measures have seldom been assessed in previous research on the conservation of open space (Bengston et al., 2004). The few studies that have been done (e.g., Hill et al., 2010) mostly dealt with the protection of open spaces and did not pay much attention to land management. Moreover, they most often dealt with a single type of actor or a single conservation measure. Effective conservation measures can be developed by analyzing how combinations of multiple types of actors and multiple conservation measures affect the structure of woodland vegetation. In addition, the institutional analysis and development framework emphasizes that biophysical conditions (e.g., landforms) also affect the outcome of management actions (Ostrom, 2011, Ostrom and Cox, 2010). Woodland structures are crucially affected by landforms and other biophysical factors, especially under highly heterogeneous conditions such as those of hilly mountainous areas (Kobayashi & Koike, 2010), and the effect of conservation measures and management by different actors may vary accordingly. All these socioeconomic (e.g., incentives for conservation measures, profitability of woodland products) and biophysical aspects may affect woodland structure, but few researchers have investigated the relative importance of socioeconomic and biophysical parameters when they considered the structure of urban ecosystems (e.g., Luck et al., 2009).

In Japan, a typical type of woodland called satoyama has developed. This is woodland dominated by coppices that were managed as a source of raw material for charcoal for rural residents during Japan's pre-development era (Takeuchi, 2003). Woodlands were also managed by collecting fallen stems and leaves, and by clearing the understory, with the harvested products used as fuel and compost (Ichikawa, Okubo, Okubo, & Takeuchi, 2006). Satoyama woodlands are often located on slopes and they make up the typical Japanese agricultural landscape that also includes farmlands in the valley below the slopes. Long-term interactions between human society and the natural environment have contributed to culturally distinctive woodland composition and structures and to the preservation of species that have become adapted to the typical human disturbances that occur in such landscapes (Takeuchi, 2003).

During the late 20th century, large areas of woodland disappeared as a result of large-scale urban development (Ichikawa et al., 2006). The spatial pattern of urban development was highly heterogeneous because of the complex landforms (Ichikawa et al., 2006) and because of the inadequate land use zoning regulations of local authorities (Saizen, Mizuno, & Kobayashi, 2006). Under the current urban planning law, which was implemented in 1968, the Japanese urban planning system defined two major land use zoning types: Urbanization Promotion Areas and Urbanization Control Areas. Urbanization Promotion Areas are areas that have been prioritized for urban development, whereas urban development is generally prohibited in Urbanization Control Areas, which are chosen to preserve farmland and woodland in and around urban areas. Although not all woodlands are necessarily conserved as a result of formal urban planning, those that have survived provide biodiversity and ecosystem services (Yokohari, Brown, & Takeuchi, 1994). Thus, municipalities use conservation measures when they want to actively protect woodlands by selecting certain areas as conserved areas within both Urbanization Promotion Areas and Urbanization Control Areas. Researchers predict a new landscape change trend will develop as a result of aging society and shrinking population (Yokohari & Bolthouse, 2011). The number of residential developments has decreased and active management of the remnant coppice woodlands (i.e., creating and executing management plans to restore desired goal such as enhancing biodiversity), rather than the passive management of these lands (i.e., purchasing land to set it aside only), has become a crucial policy issue.

The biggest issue facing the management of satoyama woodlands is their abandonment by private landowners, and this problem is unique to these woodlands because of their history. Until the early 20th century, some parts of these woodlands were maintained as common resources by villagers; they were subsequently divided into privately owned land during the forestry modernization that occurred during the latter part of the 20th century (Yokohari & Kurita, 2003). Most of these woodlands were abandoned when they lost their economic value as a source of fertilizer or of charcoal and other fuels (Ichikawa et al., 2006). This abandonment resulted in changes in the woodland structure and subsequent losses of plant biodiversity (Iida & Nakashizuka, 1995), historical scenery (Takeuchi, 2003), and traditional ecological knowledge related to the practices that had sustained these woodlands (Cetinkaya, 2009). Such degradation of satoyama due to insufficient management was recently recognized in Japan's National Biodiversity Strategy as a critical issue for national biodiversity conservation (Ministry of Environment Japan, 2002). For both biodiversity conservation and the provision of ecosystem services in urban areas of Japan, it is necessary to maintain the traditional management systems of satoyama landscapes (Yokohari & Bolthouse, 2011). However, only limited areas of woodlands can be managed without additional support from the government or other sources (Tsunekawa, 2003).

Upon abandonment in the late 20th century, management of these urban woodlands has been conducted by municipalities, local community groups, and private landowners (Kobori & Primack, 2003). These efforts have been assisted by national laws and some local municipal ordinances that have been used to conserve and enhance this woodland management (Sampei & Takeuchi, 2006). In our study system municipalities play a central role among the actors in improving management conditions because they have responsibility for the management in publicly purchased areas and also facilitate collaboration between multiple actors (Barthel et al., 2005). They offer an opportunity for community groups to participate, and provide incentives and regulations that motivate private landowners to manage the land within conserved areas. However, an effective institutional framework is required to balance the needs and activities of multiple management actors and the measures they are capable of taking and thereby achieve effective local-level management under the constraints of a limited public budget.

For example, the establishment of public parks, a major type of conservation measure, requires a huge initial cost to purchase the land and large ongoing costs for management of the land. A municipality can guarantee long-term management by providing ongoing budget support. In contrast, other conservation measures that do not require purchase of the land can decrease costs by eliminating the initial purchase cost, but provide weaker control over how the land is managed because the government does not own the land. Municipalities usually conserve satoyama woodlands by combining both types of strategy, and it is necessary to account for both approaches and the associated management measures when one tries to evaluate the institutional framework (Tsuchiya & Takeuchi, 2010). Although there is considerable public support for management of satoyama woodlands, inappropriate management (e.g., removing too much of the understory) may result in a publicly undesirable state (e.g., loss of endangered species; Kuramoto & Asou, 2003). It may also result in conflicts among stakeholders (e.g., some groups may wish to retain some of the understory to preserve certain bird species; Heyman, 2010), while these sorts of severe conflicts are uncommon in our study system.

There have been many studies on the technical methods for managing satoyama woodlands, such as a study on the content and effects of individual management activities (e.g., Kameyama, 1996). The context in which private landowners abandon their land and community groups launch activities to manage this land is also a popular field of research (e.g., Aoyagi and Yamane, 1992, Kuramoto and Asou, 2003). However, there have been few holistic evaluations of the overall institutional framework, including the effect of conservation measures on management by local governments, community groups, and private landowners. In addition, previous research that evaluated the impact of conservation measures on understory management in satoyama woodland did not develop adequate indicators that were sufficiently generalizable and objective because it focused on qualitative evaluations based on the researchers’ observations (Aoshima, Tsuchiya, Okubo, & Takeuchi, 2010), or employed detailed vegetation survey methods that were time-consuming and only effective on a limited spatial scale (Yokoyama, Kumagai, & Ito, 2006).

In this study, we employed the height of dwarf bamboo, Pleioblastus chino, as an indicator of the intensity of understory management, since this species is widespread in the understory of satoyama woodland in eastern Japan after the abandonment of understory management, and since the species sometimes reaches 4 m in height (Fig. 1). The relationships between the abundance of dwarf bamboo and the biological conservation and recreational uses of woodlands are an important research topic for Japanese satoyama woodlands, since dwarf bamboo can both significantly reduce the species richness of understory vegetation (Iida & Nakashizuka, 1995) and provide habitat for certain bird species (Yoshida, Hayama, & Yoshida, 2009). Some local user groups prefer open woodland without dense dwarf bamboo in the understory (Shigematsu, 1983), whereas other groups favor more natural dark woodlands with a dwarf bamboo understory (Yokoyama et al., 2006). Using the height of dwarf bamboo as an indicator had several benefits: it enabled us to quantify the results of understory management and to reduce the labor required to conduct field surveys over large areas, and was thus more practical than time-consuming formal vegetation survey methods. Because the growth of dwarf bamboo is significantly affected by biophysical variables such as the slope steepness, aspect, and slope position (Fujimura, 1994, Suzaki et al., 2005, Yamamoto et al., 2000), it was necessary to include these biophysical variables in our analysis to evaluate the impact of conservation measures, management actors, and other environmental variables.

In the present study, we examined the relative influence of various combinations of conservation measures, management actors, and environmental variables on the understory vegetation in urban woodlands using satoyama woodland in the peri-urban areas of Tokyo, Japan, as an example. We define “conservation measures” as national laws, local ordinances, and other forms of governmental policy such as incentive programs. Specifically, we addressed the following working question: Which variables (among conservation measures, management actors, and other environmental variables) are the main constraints on the current understory vegetation of urban satoyama woodland? By answering this question, we hoped to determine whether differences in the combinations of conservation measures and management actors really affected understory management and how the current institutional framework for urban understory management can be improved. We use the term “understory management” to refer to direct impacts such as cutting and removing understory vegetation. “Woodland management” is used when the management also includes direct impacts on other parts of vegetation (e.g., cutting down trees).