UK Overseas Territories team blog

About the project

In May and June 2011, I was lucky enough to spend eight weeks in the Turks and Caicos Islands, one of the UK Overseas Territories (UKOTs) in the Caribbean. I worked with the Kew UKOTs team and the TCI Department of Environment and Coastal Resources (DECR) carrying out fieldwork for my Masters thesis in Conservation Science. I was studying the invasive tree Casuarina equisetifolia, known in the Caribbean as Australian pine. C. equisetifolia is commonly known as she-oak in its original range in South-East Asia and Australia. In 2009, a previous MSc student, Chloe Hardman, predicted suitable habitat for this species in TCI using the Maxent software which models species distribution based on environmental variables. She found that native species richness was reduced in plots invaded by this tree. Building on this research, I set out to map the current distribution of the species and prioritise areas for its control.

Casuarina equisetifolia on Bambarra beach, Middle Caicos, stretching as far as the eye can see (Image: Alexandra Davey)

Determining the spread of Casuarina during the last ten years

Using aerial photographs of the islands from 2001 and 2007, in which patches of the invasive tree were clearly visible, I manually digitised the distribution of C. equisetifolia in each of these years using ArcMap GIS (Geographic Information Science) software, developed by ESRI. This allowed me to examine not only the current locations of C. equisetifolia but how its distribution has changed over a six year period.  This invasive tree grows mostly along the northern and eastern coasts, which have the longest expanses of sandy beach, and along roadsides and in settlements. In the six years covered by the photographs the area of land occupied by the species had increased on both North and Middle Caicos.

Using the digitised distributions, I generated presence points in ArcMap. These points were then overlaid on environmental variables, such as distance to roads and elevation, in Maxent to produce a predictive model of suitable habitat for the species. Using digitised presence points avoided the bias often introduced by the difficulty of accessing some areas on the ground. The new model showed a greater area to be suitable for C.equisetifolia than the previous one had. The most important environmental predictor of suitable habitat was distance to the northern coast. On North and Middle Caicos areas close to the north coast are the most disturbed by human activity.

Fieldwork in Important Plant Areas

TCI endemic orchid Encyclia caicensis growing on Wild Cow Run, an Important Plant Area on Middle Caicos threatened by Casuarina equisetifolia (Image: Sara Green)

I selected two Important Plant Areas (as determined by another MSc student, Sophie Williams, in 2009) for further study and mapped the presence of C. equisetifolia in 2011. I then compared the trees’ distribution with that in 2007 and 2001. This showed the importance of disturbance caused by human activity in determining the spread of the species - land that had been cleared for development was very quickly colonised. On the island of North Caicos the majority of trees established themselves in the last 10 years. This area may be a good site to trial methods of controlling the tree.

These maps show the spread of the species on Horsestable Beach, Important Plant Area on North Caicos. Red squares show location of Casuarina equisetifolia in 2001, 2007 and 2011. (Image: Alexandra Davey)

Investigating control methods

In the final part of my study I looked at how the level of C. equisetifolia establishment affects native species. I found that native species richness decreased significantly with increasing height of the invasive Casuarina trees. I also performed a small baseline study into the current use of C. equisetifolia in making charcoal. This research contributes to the larger question of whether charcoal production could provide a future control strategy for this invasive species. One possible scheme would entail the funds raised from sale of licences to coppice C. equisetifolia in very heavily infested areas being used to pay for eradication schemes in newly invaded areas. Everyone involved in the study confirmed that Casuarina wood makes very good charcoal.

Recommendations

The principal recommendations arising from my work were to restrict development in the southern parts of North and Middle Caicos which as yet remain undisturbed and more or less free from Casuarina. Tight control of unnecessary or premature land clearance prior to development would also help to restrict the spread of the species.

The six months I spent on this project have been an excellent learning experience for me. I am very grateful to all those at Kew who have helped me and feel privileged to have first-hand experience of the work the UKOTs team carries out in the field. I could not have done the project without the support of the TCI DECR and in particular without the help of Bryan Naqqi Manco, Judnel Blaise and Sara Green in the field. Thank you!

- Alexandra -
 

Related links

Science Directory project page: Invasive Species in the UK Overseas Territories

Science Directory project page: Turks and Caicos Islands Pine Recovery Programme

Find out more about Geographic Information Science (GIS): Kew's GIS Unit

Imperial College MSc Conservation Science theses

Williams, S. (2009) The Identification and Conservation of Important Plant Areas: A case study from the Turks and Caicos Islands (pdf)

Hardman, C. (2009) Invasive plants in the Turks and Caicos Islands (pdf)

Davey, A. (2011) Mapping the distribution and prioritising the control of Casuarina equisetifolia in the Turks and Caicos Islands (pdf)

Introducing Joseph Hooker

Joseph Hooker was born in 1817 into a botanical family. His father, William Hooker, was the Professor of Botany at Glasgow University and later became the first official director of the Royal Gardens at Kew. Although Joseph Hooker trained in medicine, he was far more enthusiastic about botany. In 1839, at the age of just 22, he joined the HMS Erebus under the captaincy of James Clark Ross, as it set off to map the Antarctic regions. His official role was that of Assistant Surgeon, but he was able to spend a considerable amount of time collecting plant specimens whilst ashore and making detailed records of them during the long voyages between ports. Among the ship's ports of call were the islands of St Helena, Ascension and the Falkland Islands, now three of the UK Overseas Territories (UKOTs), as well as the South Shetland Islands (part of the British Antarctic Territory).  The plant specimens Joseph Hooker collected during this voyage are held in Kew's Herbarium and those from the UKOTs can be viewed through the UK Overseas Territories Online Herbarium.

Joseph Hooker (1817-1911)

St Helena

In June 1840, HMS Erebus anchored off St Helena for the first time and Joseph Hooker was able to travel up to the central mountain ridge of Diana’s Peak, where he was excited to see a tree fern, Dicksonia antarctica, for the first time. He observed that much of the island’s original vegetation had disappeared, either eaten by goats or overwhelmed by plants introduced as crops or ornamentals by settlers and passing ships. Based on his own findings and those of preceding botanists, he calculated that the island was originally home to about 45 unique plant species.

On St Helena, Joseph Hooker collected a specimen of the fern Dryopteris napoleonis which was named after Napoleon Bonaparte who was imprisoned on the island by the British

Falkland Islands

Nearly two years later, after crossing the Antarctic Circle several times, HMS Erebus sought shelter from the Antarctic winter in the Falkland Islands. At first, Joseph Hooker agreed with Charles Darwin that the islands had ‘a desolate and wretched aspect’. Over the six months that he spent on the islands, Hooker revised his opinion of their botanical interest although plant collecting was not easy due to the short days. At the Governor’s request, he listed the potential uses of island plants, ranging from the value of tussac grass (Poa flabellata) in providing grazing for cattle to diddle-dee (Empetrum rubrum) as a potential source of food if grouse were to be introduced. He also recommended further investigation into the healing properties of the balsam bog plant (Bolax gummifera) and that two plants, little cress (Cardamine glacialis) and the local scurvy grass, Oxalis enneaphylla, would provide a remedy for scurvy, an illness resulting from a shortage of fresh fruit and vegetables.

Joseph Hooker collected this specimen of silvery buttercup from the Falkland Islands and named it Hamadryas argentea

South Shetland Islands and Ascension

From the Falkland Islands, HMS Erebus sailed south, calling at the South Shetland Islands and Cockburn Island, where Hooker listed just 19 species of plant, all of them mosses, algae and lichens, and including two previously unknown moss species. After visiting St Helena again during its return from the Antarctic, the ship stopped at Ascension. In his journal, Joseph Hooker recorded that ‘St Helena has been well designated a barren rock, but it is a paradise compared with Ascension, which ... presented a black conical mass of volcanic matter’.

However, he still discovered plants of interest: ‘I found here and there a little purslane, a minute grass and a Euphorbia. The green peak yielded only one small indigenous shrub and 9 ferns’. He also noted that the garrison of soldiers on the island subsisted on a ‘scanty supply of tepid water, preserved in tanks, and salt meats and ship’s biscuits, varied with turtle’. His recommendations for introductions of fruit trees and other crop plants were implemented by the Admiralty, to provide fresh food and improve water supplies. Hooker did, however, express his concern that the plant introductions would prove harmful to the island’s native vegetation ‘especially to the rich carpet of ferns that clothed the top of the mountain when I visited it’.

This euphorbia (Euphorbia origanoides) was one of the few plants Joseph Hooker saw growing on Ascension's barren volcanic surface

Unique island plants

His visits to these remote islands influenced Hooker’s thinking on global plant distribution, which he discussed at length with Charles Darwin in the course of their correspondence prior to the publication of Darwin’s On the Origin of Species. In a presentation to the British Association for the Advancement of Science in 1866, just after he had become Director of Kew, Hooker considered the links between island floras and those of their nearest continents. Of St Helena’s 45 unique species, he noted that many of them belonged to unique genera and had no obvious close relatives in Africa or South America. He stated: ‘The botany of St. Helena is thus most interesting; it resembles none other in the peculiarity of its indigenous vegetation, in the great rarity of the plants of other countries, or in the number of species that have actually disappeared within the memory of living men.’ 

In Joseph Hooker's footsteps

Hooker’s concerns about the threats to native island plants from invasive exotic species have proved well founded. Following on from a project looking at South Atlantic Invasive Species, Kew’s UKOTs team continues to work with conservationists in St Helena, the Falklands and Ascension to monitor their indigenous plants and evaluate the risks from introduced species. We are working with our UKOTs partners to ensure that UKOTs native plants are held in safe storage as seeds in Kew's Millennium Seed Bank or can be propagated in native species nurseries for possible return to their natural habitats when conditions permit. 

- Pat -
 

Related links

Find out more about Sir Joseph Hooker's expeditions and scientific activities at the exhibition 'Joseph Hooker: Naturalist, Traveller and More' in the Shirley Sherwood Gallery of Botanical Art.

• Invasive Species in the UK Overseas Territories
• Conservation of Ascension Island’s Endemic Plants
• Falkland Islands Plant Conservation
• Falkland Islands Native Plants Project
• Supporting Critical Species Recovery and Horticultural Needs on St Helena
• Increasing Local Capacity to Conserve St Helena's Threatened Native Biodiversity
• Seed Conservation in the UK Overseas Territories
• Developing Ex Situ Conservation Collections of UK Overseas Territories Plant Species In-Territory and at Kew
• UK Overseas Territories Online Herbarium
• South Atlantic Invasive Species Project  

Caicos pines in trouble

Dead pine trees dominate much of the pineyard landscape

A large part of my MSc Conservation Science course at Imperial College London, involved my being lucky enough to work with the UKOTs team at Kew on the research for my MSc thesis. My project was part of an on-going study of the effects of an invasive pine scale insect on the national tree of the Turks and Caicos Islands – the Caicos pine (Pinus caribaea var. bahamensis). This insect is making a huge impact on the populations of Caicos pine in the pineyards on this UK Overseas Territory (UKOT), and the resulting loss of tree cover is likely to affect other plants and animals found in this habitat.

Examining the effects of pine scale insect on an immature pine tree

What we did

My main research objectives were to:

1. Undertake the first year of monitoring the effectiveness of various management practices on the numbers of invasive scale insects
2. Estimate the size of the pine population and levels of decline
3. Investigate the influence of the Caicos pine on the surrounding plant community

Harry Earle-Mundil (another Imperial College MSc student who carried out his dissertation project on TCI last year) set up a series of monitoring plots and began trials of different treatments to investigate their effects on the levels of scale insect infestation:

• Treatment 1: broadleaf clearance (clearing plants that are competing with the pines and which prevent new pine seedlings establishing themselves)
• Treatment 2: broadleaf clearance accompanied by spraying the pines with insecticidal soap
• These treatments were compared with control plots without any form of treatment.

Using the baseline data Harry collected, combined with data I collected this year, the effects of the treatments on the numbers of scale insects and health of the pines treated remain inconclusive, which is not surprising after only one year of monitoring. Continued monitoring is important for true trends to be determined.

Recording measurements of tagged pine seedlings in one of the monitoring plots

What we are finding

The total population of Caicos pine on the TCI is estimated at less than 735,000 with almost 99% of the live pines being immature (i.e. not yet producing cones and seeds). The three islands where the pine occurs show a variance in pine densities and population structures, and show a variety of different stages of succession towards the mature pineyard vegetation. The overall decline in pine numbers is estimated at almost 60%; however the decline of mature trees stands at almost 98%. Although mature pines can often survive fire, the majority of immature pines are likely to die if a fire spreads throughout the pineyards, after agricultural burning or a lightning strike, for example. With the huge decline of mature trees of reproductive age, a fire is likely to result in catastrophic effects on the population of Caicos pine.

On Middle Caicos, an increase in the number of dead pine trees was found to cause a significant reduction in the surrounding plant species richness, showing that the invasive scale insect also has a wider impact on the whole plant community within the pineyard. High densities of dead pine trees were also found to reduce the diversity of the surrounding plant community. In addition, areas with live mature pines showed different plant species compostion compared to those which had no surviving trees. This invasive scale insect therefore has the potential to affect the whole ecosystem, not just the Caicos pine.

Working together

I am extremely grateful for the opportunity to contribute to the conservation work undertaken by the UKOTs team in the Turks and Caicos Islands and for the wealth of support received from the staff at both Kew and the Department of Environment and Coastal Resources in TCI. Although continued monitoring and further research is clearly needed, I am hopeful that the UKOTs team will be able to use these preliminary findings and that they will provide a solid foundation for the conservation of the Caicos pine.

- Sara -

Find out more

Turks and Caicos Islands Pine Recovery Programme

Insects and invasives: investigating threats to Turks and Caicos Islands plants

Turks and Caicos Islands Online Herbarium

Earle-Mundil, H. (2010) Permanent monitoring plots for the national tree Pinus caribaea var. bahamensis and assessment of the distribution and conservation status of an associated endemic species Stenandrium carolinae in the Turks and Caicos Islands (pdf). (MSc dissertation)

Green, Sara (2011). The Caribbean Pine (Pinus caribaea var. bahamensis): monitoring and ecology, in the Turks and Caicos Island (pdf). (MSc dissertation)

Marcelo Sellaro, a bromeliad specialist from Kew's Horticulture Department, and Anna Haigh, a botanist with a special interest in aroids, recently returned from a field trip to Montserrat, one of the UK Overseas Territories (UKOTs).  Although Kew's UKOT's team have been involved in botanical assessments of parts of the island during the last decade, there is always more to learn about Monserrat's plants, both native and introduced.  During this visit, Marcello and Anna were able to add several plants to the list of species found on the island.
 

Marcelo collecting seed

Montserrat's plant diversity

The Caribbean region has been identified as one of 34 global biodiversity hotspots due to its plant-species richness as well as high levels of endemism (plants unique to the area). A recent inventory of plant species on Montserrat, carried out by Kew's UKOTs team, listed as many as 800 native species, including many species of limited global distribution and several which are globally threatened. Its botanical riches are paralleled in the diversity of its fauna.

Approximately 5000 people currently live on Montserrat, and although the island has a total area of 102 km², the distribution of both people and wildlife is severely limited by volcanic activity in the south of the island. In 1995 there was an eruption of the previously dormant Soufriere Hills volcano, and it is still active today but on a much reduced scale. A great deal of vegetation in the south of Montserrat has been destroyed by volcanic activity, resulting in the loss of 60% of the island’s forest cover. Montserrat has very interesting areas where secondary forests show how nature can create new environments after devastation caused by human activity and natural events, such as volcanoes and hurricanes. There are trails in the Centre Hills which provide access through the forest, enabling residents and visitors to explore the area. The Centre Hills are recognised as one the most valuable sources of income for the island, primarily through tourism, but also as a source of ash for the concrete industry.

Montserrat has a humid tropical climate with a wet season from July to December. Annual rainfall varies from 1100 mm at the coast to 2100 mm at higher elevations. In lowland areas that receive little rain, the vegetation is dominated by dry scrub, which may be replaced by littoral forest in coastal areas affected by sea spray. Mesic Forest is a forest type between Dry Forest and Wet Forest where water availability allows for the development of denser vegetation than at lower elevations. It contains a wide range of species and a well developed forest structure. It also supports a wide range of epiphytes (plants which rely on host trees for support) and climbing plants, such as bromeliads (members of the pineapple family - Bromeliaceae) and aroids (belonging to the Araceae family which includes the British plant lords-and-ladies - Arum maculatum). As altitude increases, the Wet Forest gives way to Elfin Woodland, a densely shrubby vegetation with a canopy 0.5–3 m in height. This habitat is restricted to the highest peaks of the Centre Hills.
 

Anna descending through wet forest in the Centre Hills

Finding out about Montserrat's plants

The Centre Hills Biodiversity Assessment was published in 2008. Kew's UKOTs team was responsible for the checklist of plants - they also made herbarium specimens - and this data helped us as a guide to find the bromeliads and aroids. This checklist contained eight species of Araceae, and Herbarium specimens collected prior to 2008 contained 11 species of Bromeliaceae from Montserrat. Most of the information available from Kew's Herbarium dates from 1907 and 1966 and is not very precise regarding localities and plant descriptions. It is interesting to note that many bromeliads and aroids were previously found on Chance’s Mountain. Today this area is completely covered by ash from the volcano in the Soufriere Hills. The most similar environment on the island, disturbed by agriculture in the past, is the Centre Hills, which are today protected by the government as a reserve.

There are several reasons why aroids are often overlooked during collecting. Some species flower only rarely and we were looking for these fertile specimens as these are usually required for accurate identifications. Aroids often have large leaves and are awkward to make good specimens from. They are very slow to dry, losing much information in the process, thus requiring very good field notes! And quite often aroids are found high up in trees out of reach.
 

Aroid leaves are big and bulky to collect and dry. In the distance the land surface is covered with volcanic ash.
 

What we found

During 12 days of field work with colleagues from the Montserrat National Trust (MNT) and the Environmental and Forestry Department, covering five different trails on the island, seven specimens of bromeliads plus nine aroids were found on this trip.  This enabled us to add to the national checklist, living collections at the MNT, and  to duplicate collections for ex situ conservation by seeds and cuttings at Kew.  We first saw Pitcairnia angustifolia at sea level, growing on rocks. Later on, grassy clumps of this species with huge inflorescences full of red hooded flowers were found everywhere on the island. The spines on the leaf margins, the type of inflorescence, number of flowers and colour are important characters for identification in Bromeliaceae and the variations we observed lead us to believe that this species has natural hybrids or varieties which have never before been described by botanists. Tillandsia utriculata, found from sea level to 1200 m altitude, is widely distributed and mostly grows as an epiphyte. Being a truly monocarpic species (which dies after flowering), it depends completely on seeds for survival and we were surprised to find a plant with a secondary inflorescence growing on the side. Epiphytic and sometimes terrestrial in dry habitats, we found Tillandsia recurvata in the Dry Forest where there is little or no rainfall. It also occurred close to the sea where plants need to tolerate winds and salt spray.
 

Tillandsia recurvata growing on trees close to the seashore

Support for native plant conservation

Both aroids and bromeliads are attractive plants for horticulture. The Botanic Gardens on Montserrat is interested in promoting knowledge about native plants and also needs to provide an attractive garden. It contains an area that mimics the ghauts (steep-sided valleys) where water flows in the rainy season. In the arboretum, trees have created shady areas for recreation and could be used as support for native epiphytes and climbers. We gave a workshop at the Botanic Garden at the end of our trip, which was very successful. About 20 people from the MNT, Environmental and Forestry Department and the local community participated in the workshop, which was divided into three topics. We started by giving a talk about the botanical families, bromeliads and aroids, followed by activities involving identification and classification (taxonomy) and then practical cultivation, finishing with a discussion of cultivation practices.

- Anna and Marcelo -

Related links

Enabling the People of Montserrat to Conserve the Centre Hills

Establishment of Montserrat Botanic Garden

Strengthening capacity for Species Action Planning in Montserrat

A biodiversity assessment of the Centre Hills, Montserrat(Durrell Conservation Monograph, 2008)

Montserrat Online Herbarium   

At the end of August 2010, the British Virgin Islands (BVI) in the Caribbean faced the force of Hurricane Earl, with wind speeds of over 100 miles per hour. Among the many places in BVI suffering damage was the J.R.O’Neal Botanic Garden, located on the island of Tortola. To support the redevelopment of the Garden, Martin Hamilton from Kew's UK Overseas Territories Team (UKOTs) and Michele Sanchez from the Horticulture Department spent a fortnight working with colleagues from the BVI National Parks Trust (BVINPT), assisting in planning and in collecting new plants for display and conservation.

Kew’s UKOTs team has a long-standing working relationship with the BVINPT, having carried out botanical surveys for conservation projects on Virgin Gorda and Anegada. On a previous visit to BVI in 2005, Martin and Michele helped to establish some of the islands’ unique and threatened plant species in cultivation, and to develop suitable facilities for plant propagation. On this visit, they were saddened to find that the shade house, where plants can be grown with some protection from the fierce sun, had been one of the casualties of the hurricane.

Collecting cuttings for propagation

One of the priorities of this trip was to survey the garden and plant collections to find out which trees needed felling as a result of hurricane damage or disease, and to create a map showing the location of specimens. This map provided a basis for discussion with staff from BVINPT about future developments in the Garden, to maximise its potential for native species conservation and as a tourist attraction.

Another goal was to augment the Garden’s collection of native plants, by collecting wild plant material from various islands and propagating it. Together with Marcus Garvey, Head Gardener at the J.R.O’Neal Botanic Garden, and other members of BVINPT staff, Martin and Michele visited areas of natural vegetation on Tortola, Virgin Gorda and Anegada. In some places, where road-building was underway, they were able to rescue seedlings and epiphytes (plants that rely on host trees for support) which had been displaced. They also collected seeds and cuttings from several of the islands’ unique species. Some species, including Pisonia subcordata and Cordia rupicola, had been particularly fruitful in 2011, possibly due to the heavy rainfall associated with the 2010 hurricane or to the resulting vegetation disturbance which suited their growth patterns.

Sowing dust-like orchid seeds onto coconut fibre

Back at the Garden, Michele worked with Marcus and, amongst other members of the horticultural staff, the nursery supervisor Arona DeWindt, sowing seeds, preparing cuttings, planting seedlings and arranging epiphytes on bark. She demonstrated various techniques used in Kew’s nurseries to maximise the plants’ chances of germinating or rooting. For orchid seeds, which sometimes need specialised germination conditions, she initiated a trial using strips of coconut fibre and other readily available local materials. Seeds and some of the cuttings, which were carefully prepared for air-travel, were sent back to Kew, so do keep an eye on this blog for news of these plants!

Watch the video that Martin produced showing some of the areas they visited and their plant collecting and propagation activities.
 

- Martin -

Related links

Kew's UK Overseas Territories programme

Integrating National Parks, Education and Community Development for the British Virgin Islands

Darwin Initiative Assessment of the Coastal Biodiversity of Anegada, British Virgin Islands

UKOTs Online Herbarium