Burg, W.J. van der

Seed germination methods for native Caribbean trees and shrubs - With emphasis on species relevant for Bonaire

Summary:

This paper is intended as a basis for nature restoration activities using seeds of trees and (larger) shrubs native to Bonaire with the aim of reforestation. It describes the main seed biology issues relevant for species from this region, to facilitate decisions on time and stage of harvesting, safe storage, breaking dormancy and germinating seeds and planting the young trees in the field.

The paper also emphasises that natural process of seedling establishment and succession must be observed in order to be successful. The choice of species and method of protection once planted in nature will prove essential.

The paper ends with stressing that such a reforestation activity needs to be planned far ahead: seeds must be collected from tree species taking care of genetic diversity and their storage potential. Recalcitrant seeds (see paper) must be treated carefully and in a different way.

In Appendix I all knowledge from literature about collection, storage, germination and planting has been collected. Appendix II gives the growth characteristics of a selection of trees.

This report is part of the Wageningen University BO research program (BO-11-011.05-039) and was financed by the Ministry of Economic Affairs (EZ) under project number 4308701034. 

Date
2014
Data type
Research report
Theme
Education and outreach
Research and monitoring
Report number
PRI Repot 551
Geographic location
Bonaire

Key Elements Towards a Joint Invasive Alien Species Strategy for the Dutch Caribbean

Summary:

Recent inventories have documented no less than 211 exotic alien species in the wild for the Dutch Caribbean. These amount to no less than 27 introduced marine species, 65 introduced terrestrial plants, 72 introduced terrestrial and freshwater animals and 47 introduced agricultural pests and diseases. A list of these species, pests and diseases are found in resp. Debrot et al. (2011), Van der Burg et al. 2012, and Van Buurt and Debrot (2012, 2011). The rate of introductions and establishment of invasive alien species (IAS) worldwide has grown rapidly as a result of increasing globalisation. Invasive species cause major ecological effects (decimating native flora or fauna populations) as well as economic losses to these islands, across sectors such as agriculture (diseases, weeds and vectors), fisheries (fish diseases and the lionfish), industry (rodents and termites), tourism (roadside weedy species) and public health (mosquitos). Recently in Curaçao the kissing bug Triatoma infestans was found; this is a vector for Chagas disease. It almost certainly came in with palm leaves imported from South America to be used as roof covering for recreational beach “palapa’s”.

Several countries in the Caribbean have developed a strategy to address the invasive species problem already, such as Jamaica (Townsend 2009), the Bahamas (BEST Commission 2003) and St. Lucia (Andrew and John 2010, Chase 2011). Islands are particularly at risk because of a number of factors: their small size, resulting in small vulnerable plant and animal populations, a relatively large border which is difficult to control, a small human population lacking the necessary expertise and resources to take adequate measures. For islands, the sea acts as a strong natural barrier for natural transport of terrestrial flora and fauna, however human activities helped in overcoming this barrier. The issue of feral animals, especially roaming cattle, donkeys, goats create similar problems everywhere: they have a devastating effect on tree and shrub regeneration, which greatly degrades the natural vegetation, with severe soil degradation as a result. This shifts the competitive advantage to hardy exotics and creates runoff of nutrients and silt into the sea, where algal growth and silt deposition are damaging the coral. The new nature policy plan for the Caribbean Netherlands assigns a high priority to the invasive species problem (MinEZ 2013), which worldwide is considered second only to habitat destruction as a long-term threat to biodiversity (Kaiser 1999, Mooney 2001).

While acknowledging a focus on the Caribbean Netherlands in specific (Bonaire, Saba, St. Eustatius) this report sets the first key steps in developing a common frame of reference for the whole of the Dutch Caribbean (i.e. including the islands of Aruba, Curacao and St. Maarten). These islands share historical and cultural ties, partly similar climates, scarce expertise, and experience most IAS as a common problem. The magnitude and severity of the problem is evident and necessitates a joint strategy into which action at insular level can be embedded for maximum efficiency and synergy: a common Invasive Alien Species Strategy (IASS).

Management Recommendations:

The main action points for implementation are:

1. Develop and adopt guiding legal lists for action: Black lists, Alert lists and Watch lists, enumerating the species for which border control is essential or for which control and management actions would be required. A special task group should be made responsible for keeping these lists up to date.

2. Install effective border controls. To prevent is better than to cure: the costs of controlling or eliminating invasives once established can be very costly. For this reason and because of the earlier indicated special vulnerability of the island ecosystems, it is strongly recommended to prevent the entrance of (more) invasives.

3. Establish Invasive Species Management Teams. For the coordination of data collection, evaluation and the initiation of actions, a special team is required. This ISMT team shall have its own facilities and budget.

4. Define responsibilities and mandates. Ultimate responsibility for IAS control lies with the island governments. This means that policies regarding IAS will be determined by the government. However, to be effective and efficient the ISMT (see 9.) needs full mandate to act within the limits of their own budget.

5. Require quarantine documents. Phytosanitary certificates and animal health certificates will be required for all imports.

6. Enforcement. Staff must be trained and instructed how to perform border controls. They must obtain sufficient mandate and means to confiscate and dispose of prohibited goods.

7. Develop action plans. A plan of action needs to be ready, describing the successive steps and decisions that have to be made for key threat species at all stages of the invasion process.

8. Arrange access to properties. When an alien species is invasive and needs to be eliminated, it is important that regulations allow the exterminators access to all properties, private and public alike.

9. Assure public support. Large scale programs for extermination and control, especially of animals, needs extensive public support. Volunteers may prove essential to assure enough ‘eyes’ and manpower.

10. Make rapid surveys. In order to decide whether a complete eradication is needed or that monitoring and restricting the distribution (mitigation) is the best or only option, a survey of the extent of the problem must be assessed by experts.

11. Rapid response. Usually a rapid action can localise the problem to a restricted area or eliminate the first individuals effectively so that no further costs have to be made.

12. Make risk assessments before introducing natural enemies. In case species are already present in vast numbers, biological control is often a last resort. This usually means introducing a natural enemy from the area of origin of the species. This means introducing another alien species, which may become a pest in itself. Expert consultation and small-scale experimenting is usually needed before the potential natural enemies can be safely released.

13. Create an information system. A team of experts managing a computer database is needed. This ISMT team needs to develop a system for easy reporting of new discoveries of alien species, for maintaining and updating information on key threats. The information system supports policy, action and research at all levels of the invasion process.

14. Create a platform for cooperation. In order to develop the system further, a national as well as an island platform is needed for participation of all relevant stakeholders. These platforms will develop recommendations for the ISMT and the island governments, and may also act as support group for the ISMT. 

Date
2014
Data type
Research report
Theme
Governance
Education and outreach
Legislation
Research and monitoring
Report number
C020/14
Geographic location
Aruba
Bonaire
Curacao
Saba
Saba bank
St. Eustatius
St. Maarten

Naturalised and invasive alien plant species in the Caribbean Netherlands: status, distribution, threats, priorities and recommendations

Abstract:

The Netherlands are signatories of the international Convention on Biological Diversity (CBD). This implies that the nation will protect biodiversity on its territory. This includes the protection of natural fauna and vegetation from negative impact caused by invasive alien species (see 2.1. for a definition). By 10-10-2010 the BES islands (Bonaire, St Eustatius and Saba) became ‘special municipalities’ of the Netherlands. They together form “Caribisch Nederland” (Caribbean Netherlands, Hulanda Karibe). Due to this stronger link to the Netherlands many responsibilities have moved from the Antillean government to the Netherlands. This includes important responsibilities with respect to the protection of nature.

The present study was financed by the Dutch Ministry of Economic Affairs, Agriculture and Innovation and included a literature study, a field trip and writing of the present document with main observations, conclusions and recommendations. A major part of the report consists of an alphabetical list of (known) invasives with their current status (4.1.1.). Apart from the three islands belonging to Caribisch Nederland, for completeness, some attention is given to Aruba, Curacao and St. Maarten as well (esp. in 4.1.1. and Appendix II).

Stages of invasion
In order to define the problem of invasive alien (non-native) species of plants more accurately it is relevant to recognise the following categories:

Exotic: Species that are not part of the natural indigenous vegetation are called exotics. Examples are introductions as ornamental or agricultural species. If contained within the confines of gardens and farms, these species are not considered problematic.

Established: Species that occur ‘in the wild’, i.e. outside the control of cultivation or husbandry and are able to reproduce themselves resulting in new individuals, we call established (present). Species can stay in this phase, the ‘lag phase’ (see 2.1), for quite some time. It is the stage in which the species adapts to its new environment using its genetic flexibility. At this stage complete eradication is still an option, because the number of individuals and locations is limited. This means that the costs can be relatively low, compared to eradication at a later stage.

Naturalised: If given enough time, species may start to adapt genetically to the new environment, by optimising its physiology and/or growth habit. As a result the species will start spreading more rapidly and effectively and becoming part of the natural flora. In most cases this is not considered a major problem; the plants will get their own function within the ecology of the island and will not replace indigenous species entirely. Moreover, the costs of complete eradication have become prohibitive at this stage, so only containment is an option.

Invasive: It is generally believed that about one in one thousand exotics becomes really problematic, e.g. with respect to environmental, ecological or economical impact (Williamson 1995). They start to grow out of control, massively invade natural habitats and reduce or eliminate native species. They have broken down the dispersal barrier and have become invasive. At this stage one can only try to achieve a stage of equilibrium, of mitigation, by intensive control measures. These are usually limited by financial resources, and can normally only be successful with commitment of the local society, e.g. shown by the enthusiastic support and hand labour of many volunteers.

Invasives of the Caribbean Netherlands
In this report 65 species of invasives are enumerated (4.1.1.) with their history and properties, based on a literature survey and completed with experience and findings of the authors. Four of the main problematic species are treated more extensively in 4.1.2. These are the Coral vine (Antigonon leptopus) which poses a great threat to nature, especially in St. Eustatius; the Rubber vine (Cryptostegia grandiflora) which is able to overgrow and smother shrubs and trees and is especially spreading on the Leeward Islands; the neem tree (Azadirachta indica) which is planted for shade and medicinal purposes, but is escaping on Bonaire; and ‘Donna grass’ (Bothriochloa pertusa) which is a very problematic species replacing the more palatable local grasses on the Windward Islands, most notably on St. Eustatius.

In a complementary list a further 80 species that need more investigation are mentioned (4.1.3.). This list is not complete but it enumerates species that are present on at least one of the islands. They need special attention because it is best to prevent them from entering at all or to eliminate the few plants or populations that have established themselves. Some species in this list are already present at some scale, like some of the arable weeds, but need careful monitoring to prevent them from entering nature.

A general problem are the free-roaming animals, cows, donkeys and especially goats (all non- native species) that are destroying nature in an uncontrolled way. Their presence has a detrimental effect on biodiversity, eating young seedlings and trees, and thereby preventing the natural regeneration and succession. Moreover, the bare soils that result are susceptible to water and wind erosion; material that is deposited in the surrounding seas.

Management recommendations:

Before an exotic has been introduced prevention is the most important action, i.e. keep the chance that exotic species may be introduced as low as possible. As soon as a first introduction has been realised and the exotic still occurs at low densities at few sites, eradication after first observation will be the most important action. Finally, if an exotic has already spread over different sites or even different habitats and has increased in densities, eradication might not be an achievable option anymore. Then containment and population management will be the most relevant actions to minimise the negative impact (mitigation). In general, prevention will generate the most cost-effective options to avoid problems due to invasive exotic plants (Davis 2009). The main observations are:

Prevention: Prevention plans need to be developed with regulations restricting the import of exotic species. This includes the development of ‘Black lists’ for the Leeward and Windward Islands respectively. Public awareness (customs and other officials, general public, landscapers, new inhabitants) must be raised and alternatives for imported exotics must be offered. Agricultural departments and customs offices on all islands are understaffed and not able to control the many routes through which exotics enter.

Eradication after first observation: Rapid first observation of an exotic plant after introduction into the wild is essential for the success of an eradication action. Therefore a ‘Watch list’ or ‘Grey List’ needs to be developed. Since the difference in climates, these watch lists will partly differ between islands and differ even more between the Leeward and Windward islands. Also knowledge about the natural flora and invasives must be increased through education, at schools as well as for professionals (rangers, customs personnel, agricultural department, etc.). Floras for the Windward Islands are outdated and not accessible.

Containment/population management: Management plans need to be developed for the control Antigonon, Cryptostegia and neem to be able to stop further spreading and to mitigate the impact on nature. Research on the life cycle of invasives and experiments for their control have to be carried out. The problem of roaming animals must be tackled. Small island communities are not able to do this without outside assistance. If chemical control is considered, special Dutch Caribbean regulations apply based on restricted import permissions for crop protection agents.  

Date
2012
Data type
Research report
Theme
Research and monitoring
Report number
C185/11
Geographic location
Bonaire
Saba
St. Eustatius