Island ecosystems - priorities for conservation?

Perspectives in Plant Ecology Evolution and Systematics, 2010

Current threats to the planet's biodiversity are unprecedented, and they particularly imperil insular floras. In this investigation, we use the threat factors identified by the Millennium Ecosystem Assessment as the main drivers of biodiversity loss on islands to define and rank 13 current, continuing threats to the plant diversity of nine focal archipelagos where volcanic origin (or in the Seychelles a prolonged isolation after a continental origin) has produced a high degree of endemicity and fragility in the face of habitat alteration. We also conduct a global endangerment assessment based on the numbers of insular endemic plants in the endangered (EN) and critically endangered (CR) IUCN categories for 53 island groups with an estimated 9951 endemic plant species, providing a representative sample of the world's insular systems and their floristic richness. Our analyses indicate that isolation does not significantly influence endangerment, but plant endemics from very small islands are more often critically endangered. We estimate that between 3500 and 6800 of the estimated 70,000 insular endemic plant species worldwide might be highly threatened (CR +EN) and between ca. 2000 and 2800 of them in critical danger of extinction (CR). Based on these analyses, and on a worldwide literature review of the biological threat factors considered, we identify challenging questions for conservation research, asking (i) what are the most urgent priorities for the conservation of insular species and floras, and (ii) with the knowledge and assets available, how can we improve the impact of conservation science and practice on the preservation of island biodiversity? Our analysis indicates that the synergistic action of many threat factors can induce major ecological disturbances, leading to multiple extinctions. We review weaknesses and strengths in conservation research and management in the nine focal archipelagos, and highlight the urgent need for conservation scientists to share knowledge and expertise, identify and discuss common challenges, and formulate multidisciplinary conservation objectives for insular plant endemics worldwide. To our knowledge, this is the most up-to-date and comprehensive survey yet to review the threat factors to native plants on oceanic islands and define priority research questions.

Global Ecology and Conservation, 2021

'Island Biodiversity’ in E. Morgera and J. Razzaque (eds.) Biodiversity and Nature Protection Law (Edward Elgar, 2017) 175-188, 2017

Islands are home to important and often unique biological resources. Paradoxically, the small size and isolation of many islands that contributes to this biodiversity also mean that islands are particularly vulnerable to threats to biodiversity. They also present particular and difficult challenges for island States when responding to biodiversity threats. Although the importance of biodiversity is generally accepted, and addressed through a number of legal instruments, it is only in the last decade or so that the particular challenges for island nations have been recognised. There is virtually no dedicated literature the regulation of island biodiversity. Regulation is typically through general instruments, or soft-law measures. The chapter considers the state of knowledge on island biodiversity, identifying key threats and challenges, and indicates how existing and new regulatory approaches can be developed to face these challenges.

Protected Area Management - Recent Advances [Working Title]

Oceanic islands are known for their high levels of plant diversity, due to disjunct geographical distribution that leads to speciation. The main factors contributing to genetic speciation includes the creation of a barrier within a previously widely distributed taxon and the limited dispersal of seeds, which favours genetic differentiation and, thus, fosters rapid speciation. Plant survival and population fitness vary according to environmental factors and to human interference. This chapter depicts the importance of oceanic islands as biodiversity hotspots, discusses the threats to which endemic plants on islands are exposed, namely climate change, invasive alien species, urbanisation, touristic activities, fire, changes in agriculture practices and collecting pressure. The best practices worldwide to protect endemic plant species in protected areas are also addressed, namely the implementation of prevention and mitigation actions, the programs executed to protect endemic species, ...

Proceedings. Biological sciences / The Royal Society, 2016

MacArthur and Wilson's theory of island biogeography predicts that island species richness should increase with island area. This prediction generally holds among large islands, but among small islands species richness often varies independently of island area, producing the so-called 'small-island effect' and an overall biphasic species-area relationship (SAR). Here, we develop a unified theory that explains the biphasic island SAR. Our theory's key postulate is that as island area increases, the total number of immigrants increases faster than niche diversity. A parsimonious mechanistic model approximating these processes reproduces a biphasic SAR and provides excellent fits to 100 archipelago datasets. In the light of our theory, the biphasic island SAR can be interpreted as arising from a transition from a niche-structured regime on small islands to a colonization-extinction balance regime on large islands. The first regime is characteristic of classic determinis...

1996

BioScience, 2015

Islands make up 5.3% of Earth's land area yet maintain an estimated 19% of bird species, 17% of rodents, 17% of flowering plants, and 27% of human languages. Species diversity is disproportionately threatened on islands in relation to the islands' proportion of both global land area and species, with 61% of all extinct species and 37% of all critically endangered species confined to islands. Languages are disproportionately threatened on islands in relation to land area with 11% of extinct languages and 25% of critically endangered languages on islands. Islands are a priority area for integrated conservation efforts because they have 14 times greater density of critically endangered terrestrial species and 6 times greater density of critically endangered languages than continental areas. Invasive species and habitat loss are the largest threats to island terrestrial species diversity. Proven management actions can reduce these threats, benefiting both local peoples and species diversity on islands.

Biodiversity and Conservation, 2010

Oceanic islands have been the grand stage of documented extinctions. In view of limited resources, efficient prioritization is crucial to avoid the extinction of taxa. This work lists the top 100 management priority species for the European archipelagos of the Macaronesian region (Azores, Madeira and the Canary Islands), taking into account both their protection priority and their management feasibility. Bryophytes, vascular plants, molluscs, arthropods and vertebrates were scored by species experts following two sets of criteria: (i) protection priority, including ecological value, singularity, public institutions’ management responsibilities and social value; (ii) management feasibility, including threats knowledge and control feasibility, external socio-economical support for management and biological recovery potential. Environmental managers weighted the same criteria according to their management importance. Final species scores were determined by the combination of both species valuation and criteria weighting. Vascular plants dominate the Top 100 list, followed by arthropods and vertebrates. The majority of listed taxa are endemic to one archipelago or even to a single island. The management feasibility criteria did not dictate that all taxa must be eminently endangered, as for most of the species it should be relatively easy to control threats. The main advantages of this process are the independent participation of scientists and conservation managers, the inclusion of criteria on both protection priority and management feasibility and the taxonomically unbiased nature of the process. This study provides a potentially useful biodiversity conservation tool for the Macaronesian archipelagos that could be readily implemented by the respective regional governments in future legislation.