How Threatened are Bromeliads?
Environmental Problems in the Neotropics
With the exception of one species originating from West-Africa, (Pitcairnia feliciana) the bromeliads are endemic to the Americas, and most of them occur in the Neotropics which is a floristic realm covering Central and South America. Some bromeliads also exist in the very South of North America. The Neotropics contain diverse ecosystems from humid, cloud and dry forests to open, dry, and hot desert-like habitats. Also characteristic to this region are a complex set of conflicts regarding the nature. Countries in Central and South America are regarded as emerging or third world nations, more or less characterised by poverty, a growing demographic pressure on all natural resources, export of natural goods along with a weak national conservation policy and law.
In the home countries of many bromeliad species natural resources are of special importance to the people since major parts of the population still depend directly on them in terms of living space, livelihood, food, medicine as well as regarding religion and traditions. Often conservation issues are regarded less important as mayor focus often is poverty reduction and/or political stability. Emerging problems are: exploitation of the natural resources, conversion and overuse of the land area, bio-piracy, and social conflicts. There are drastic consequences to these problems, such as deforestation, ecosystem degradation, fragmentation, habitat loss, extinction of species, spread of pests and invasive species, erosion, desertification, and local poverty. For more information on the conservation and development problems in the Neotropics, for example, see UNEP, the UNEP links of interest One Planet Many People with free download articles or PowerPoint presentations and the Global Environmental Outlook.
How Threatened are Bromeliads?
The World Conservation Union (IUCN has included 151 bromeliad species (IUCN, www.iucnredlist.org, access 10/17/2006) at varying levels of conservation status in their international Red List of Threatened Species. Unfortunately all of the bromeliad species listed are endemic to Ecuador and all other bromeliad species are neglected. Some of the species were listed only because they have a small geographical range, which can indeed be a threat for extinction (compare Pitman & Jørgensen 2002). But sensitivity of species to anthropogenic extinction is not explicitly defined by their range-size, rather also by their ability to react to environmental changes.
For example, in endemism-rich dry forests, most plants need to be stress-tolerant in order to survive the dry season, during which drought even affects the forest floor species. In the Neotropics many dry-forest endemics are also recorded in deforested areas or even have a higher potential to survive in fragmented forests. They may in fact increase their range size and abundance when forest-free sites are created by human land use (Ibisch 1998, Ibisch et al. 2001). In moderately disturbed, tropical, Andean forests the percentage of endemic plant species is higher than in intact ones (Kessler 2001). Most endemics seem to be less competitive and need the creation of disturbed sites in order to prosper. Sometimes bromeliad species’ distribution are related to azonal sites like rock outcrops that are seldom affected by land-use and have, therefore, good chances of persisting in natural habitat islands within a converted forest.
Indeed especially humid forest bromeliads are threatened by land-use changes and current deforestation rates in the Neotropics. In humid forests, the effects of ecosystem degradation are more severe, as for example shade-dependant bromeliad species disappear when deforestation leads to microclimatic changes.
Another problem to bromeliads in the countries of origin is that they sometimes are regarded as weeds and are even burnt down as agricultural practice by the local people as only few of the bromeliads are edible or of medicinal value.
The assessment of species’ threat must consider their specific sensitivity and the conservation status of the habitats so still there is the quest for conservation targeted research. Regarding the conservation status of the world’s bromeliads we have to state that so far we do not dispose of adequate information.
Vera Porwollik & Pierre L. Ibisch (BSI Conservation Chair)
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