BEST 2.0 Regeneration Study
Habitat degradation and destruction, as well as the introduction of invasive species re-main amongst the key threats to the world’s biodiversity (Gurevitch & Padilla, 2004; Mor-rison & Mathewson, 2015; Secretariat of the Convention on Biological Diversity, 2014; Tilman, May, Lehman, & Nowak, 1994; World Resources Institute, 2005). Unfortunately, Bonaire’s ecosystems have not been spared from these anthropogenic influences; Freitas et al. (2005) describe that during the colonization by Europeans, Bonaire and Klein Bon-aire’s trees were (selectively) felt to such an extent that the islands were almost com-pletely cleared of their tree cover. Moreover, herbivores (i.e. goats (Capra hircus), sheep (Ovis aries), donkeys (Equus africanus africanus), pigs (Sus scrofa)) were introduced in order to build (and feed) the colony, and were left to roam the island (Freitas, Nijhof, Rojer, & Debrot, 2005; Hartog, 1978). Moreover, Bonaire’s history includes periods of ex-tensive charcoal burning, Caesalpinea coriaria seed collection – as these seedpots are a natural source of tannin, Aloe and salt production, as well as increasing tourism (Freitas et al., 2005; Stoffers, 1956; Westermann & Zonneveld, 1956). This has left a significant mark on Bonaire’s vegetation and, consequently, wildlife: currently, the vegetation is dominated by a small number of grazing resistant species, and palatable species – on which fruits many birds depend - have become scarce (Freitas et al., 2005; Williams, 2009).
Nowadays, the – be it illegal – roaming of introduced herbivores remains the greatest threat to Bonaire’s terrestrial biodiversity (Debrot, Graaf, Henkens, Meesters, & Slijker-man, 2011). In 2015, it was estimated that the goat population on Bonaire ranged between 19.800 and 52.600 (Lagerveld, Debrot, Bertuol, Davaasuren, & Neijenhuis, 2015). Many of these goats are owned by Bonairians since they are a cheap source of food and income if they graze on communal land. Buying food on Bonaire is expensive, making it more attractive to own goats in this way (Gogaardt, Jong, & Heide, 2015). Goat owners do seem to be willing to constrain goats, but buying feed and building fences is costly. Fortunately, there are some local initiatives to reduce the costs of holding goats sustainably (Gogaardt et al., 2015). Data on the exact number of donkeys and pigs on the entirety of Bonaire are lacking, but are deemed relatively small; a recent study estimates that there are about 200 donkeys and 60 pigs present in the area of Washington Slagbaai National Park and Labra-Brazil, compared to 11.000 goats (Geurts, 2015).
To counteract the negative effects of anthropogenically induced habitat degradation, ac-tive measures can be taken. Human involvement might also accelerate the restoration of vegetation composition, as the harsh climatic conditions of Bonaire might limit the speed of natural development. Reforestation is one of the most important tools for forest habitat restoration, and Echo has successfully applied for funding from the European Commission through BEST (Voluntary scheme for Biodiversity and Ecosystem Services in Territories of the European overseas), to execute a habitat restoration project in the Roi Sango valley (Image 1). Due to Roi Sango’s ecological importance – as exemplified by its designation as Important Bird Area (IBA-10) and Key Biodiversity Area (KBA-2 and KBA-3) – the project can especially benefit native and migrating birds by increasing the food availability year-round. Moreover, the project would aid the coral reef, through a reduced sediment influx (Borst & de Haas, 2005; Oleson et al., 2017). Besides the ecological impact of the refor-estation, the project aims to create public awareness for the importance, the degradation and vulnerability of Bonaire’s tropical dry forest.
The project has started in June 2017 and includes fencing off the 26 hectare valley area, removing exotic herbivores such as goats, donkeys and pigs, as well as planting 1.000 rare native tree species. To monitor the long-term successes of natural regeneration after ex-clusion of invasive herbivores, a comparison study is included in the project. The purpose of the current report is to propose the method of this study.
Firstly, a further elaboration on Echo and the Roi Sango area, including its vegetation, will be provided. Then, the report will turn to the evaluation plan, where the proposed study's objectives, and methods will be discussed. After this, the results of a baseline study investigating the quality of plot selection for the future study will be presented and ex-amined.