Species-based or process-based conservation? Dealing with neophytes in the core areas of German national parks
Introduction
In the cultural landscapes of Europe, only a few wilderness areas remain where natural ecosystems exist largely without direct human intervention (Sabatini et al., 2018). These wilderness areas include the National Parks (NPs), which have been created to protect large-scale ecological processes and conserve semi-natural or natural areas with their typical ecosystems and species communities (Dudley, 2008; Sabatini et al., 2018). The guiding principle of the core areas (process protection zones) of German NPs is that “nature can be nature” (Europarc Germany, 2008). By following the concept of process-based conservation, NPs particularly emphasise the inherent value of nature (Dudley, 2008; IUCN, 2019).
A primary objective of NPs is to protect natural biodiversity (IUCN, 2019). Alongside land use and climate change, eutrophication and increased CO2 concentrations, biological invasions pose a major threat to biodiversity on a global scale (Sala et al., 2000; Millenium Ecosystem Assessment, 2005; Pyšek et al., 2020). Protected areas are generally considered less vulnerable to biological invasions than their surroundings (Pauchard, Fuentes, Jiménez, Bustamante, & Marticorena, 2013). Their low degree of invasibility results, among other things, from the absence of anthropogenic land use and the lower degree of disturbance, at least in the core areas of strictly protected areas such as NPs (Foxcroft, Jarošík, Pyšek, Richardson, & Rouget, 2011; Pauchard et al., 2009, 2013). Nevertheless, protected areas experience biological invasions (Braun, Schindler, & Essl, 2016; De Poorter, 2007; Foxcroft, Pyšek, Richardson, Genovesi, & MacFadyen, 2017; Vardarman, Berchová-Bímová, & Pěknicová, 2018), and neobiota can threaten local populations of native species (Florens et al., 2016; Foxcroft, Pyšek, Richardson, Pergl, & Hulme, 2013; Hulme et al., 2014; Pyšek et al., 2013).
NPs aim at process-based AND species-based conservation. Process-based conservation is primarily concerned with providing undisturbed conditions for uncontrolled nature development. In the context of species-based conservation, however, the NP administrations also promote individual species or groups of species that are particularly valuable through targeted measures such as reintroductions or support measures. To protect certain species, NPs also often manage neobiota (Braun et al., 2016; Dayer et al., 2020; Pyšek et al., 2013; Simberloff, 2017). The aim is to reduce or eliminate the environmental impact of certain neobiota on endangered native species or habitats. The control and eradication measures also take place in the core areas of NP and, in most cases, result in some changes in ecosystems and their natural dynamics. This approach is controversially discussed in Germany, as the "Wildnis in Deutschland" (wilderness in Germany) initiative, for example, is fundamentally opposed to targeted interventions against neobiota in core areas of German wilderness areas (Zoologische Gesellschaft Frankfurt, 2017). Wattendorf, Konold, Hertz-Kleptow, Schumacher, and Bihlmaier (2017) recommended for forested core areas of German biosphere reserves that direct measures to control neobiota are only worthwhile if they can be successfully completed within a planned time frame of usually 10 years. These measures aim at creating more natural starting conditions in monocultures for further forest development in the core areas. For a number of neophytes established in forested core areas, it is considered that they are practically impossible to eradicate locally and that measures against these species in the core areas are therefore contrary to conservation goals (Wattendorf et al., 2017). The active control of neobiota thus fundamentally conflicts with the conservation goal of protecting natural processes in wilderness areas (Foxcroft et al., 2013; Schumacher, Finck, Riecken, & Klein, 2018; Brackhane, Schoof, Reif, & Schmitt, 2019).
This study focuses on precisely this conflict of objectives between the principle of process-based protection and targeted management of neobiota for native species conservation. We focus on the example of neophytes in the terrestrial NPs in Germany. In order to gain a comprehensive understanding of this conflict and its consequences, we first review and describe the measures carried out against neophytes in the core areas. This is the first time such a review of neophyte control in German terrestrial NPs has been published. There was also no harmonised methodological approach until now for the management of neophytes among the NPs.
To provide an approach to resolve the conflict of objectives, we developed a decision-making process, which we present in this study. Within this process, we propose important decision criteria for managing neophytes in core areas and link them together. The process provides a transparent and reproducible recommendation regarding the species-specific measures currently implemented in the individual NPs. In addition, it provides indications for future measures.
To reduce conflicts between the goals of process-based and species-based conservation in the NPs, preventive measures such as monitoring against the introduction of neobiota are of paramount importance (Genovesi & Monaco, 2013; Pyšek et al., 2013). They may reduce or avoid the intensity of subsequent control or eradication measures. Research and monitoring of invasive species are also required under the international Convention on Biological Diversity (CBD, 2000, 2002). Monitoring is key to the early detection of new invasive species (Guiding Principle COP 6). We therefore examined the implementation of precautionary measures in addition to control and eradication measures.
This study also follows the objectives of the Convention on Biological Diversity: (1) to ensure that scientific evidence contributes to the effectiveness of protected areas (Goal 4.4 COP 7), and (2) to research and evaluate the influence of neophytes on biodiversity. We investigate the following research questions:
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What preventive and management measures against neophytes are carried out in the core areas of German terrestrial NPs?
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What criteria should be considered when deciding how to manage neophytes in core areas of NPs?
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Which or how many of the measures implemented in the NPs should be continued, adapted or stopped?
In addition, we discuss under which conditions the need for active neophyte management outweighs the goal of process-based conservation.
Section snippets
Methods
Neophytes are plants that have entered an area outside their natural range with the direct or indirect involvement of humans after 1492 and live there in the wild (Essl & Rabitsch 2002; Klingenstein, Kornacker, Martens, & Schippmann, 2005; Kowarik, 2010; Essl et al., 2011). This study focusses on the territory of Germany for the purposes of defining native species and neophytes, using the "Standard list of ferns and flowering plants in Germany" (Wisskirchen & Haeupler, 1998). It is important to
Implemented measures and managed neophytes
In five of the 12 NPs investigated, no management of neophytes took place in the core areas in the last ten years. The remaining seven NPs reported 30 measures against 16 neophytes, including preventive measures. The managed neophytes are six herbaceous and ten woody plant species (Table 1). Most of the measures involve eradication measures (n = 16) followed by control measures (n = 10) (Table 2, see also Supplementary Materials). In four of the NPs preventive measures are being implemented or
The decision-making process in the context of process-based conservation without a predefined end state
NPs should ensure that natural processes are as undisturbed as possible (Dudley, 2008). They should thus provide space for natural development without a predefined end state. The extent to which natural succession is already allowed to continue undirected by management is very variable among the NPs and mostly dependent on their age. A few, mostly older NPs in Germany do not manage neophytes (anymore). Some of the younger NPs analysed here, however, carry out intensive management. The
Conclusions
The decision-making process described in this paper does not resolve the conflict between the implementation of process-based and of species-based conservation in core areas. However, it does make the decisions more transparent and thus more communicable. The process is designed to help NP administrations assess the need for and the meaningfulness of individual measures, to effectively protect the biodiversity of NPs, to make efficient use of existing resources, and to successfully implement
Declaration of Competing Interest
The authors report no declarations of interest.
Acknowledgements
Our sincere thanks go to Doreen Schmiedel and to the staff of the National Park Administrations who supported us in this study. We are grateful to Volker Scherfose, Ingo Kowarik, Moritz von der Lippe and Stefan Heiland for their valuable comments on earlier versions of the manuscript. This study was supported by the German Federal Agency for Nature Conservation (BfN, Germany) with funds of the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMUB, Germany).
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