|The invasion of Pittosporum undulatum in the Blue Mountains of Jamaica|
|The Australian tree Pittosporum undulatum was introduced to Cinchona Botanic Garden in the Blue Mountains of Jamaica in 1883. Sixty-six years later this bird-dispersed species was reported as "perhaps the commonest tree" in surrounding forest. Recent research carried out by the University of Wales Bangor, in association with the University of the West Indies and the University of Cambridge, has discovered that Pittosporum has a major suppressive effect on native plants: very few species can survive within its dense stands. It is expected that it also has profound impacts on native animals. It is also likely to have profound impacts on native animals. The frequency of Pittosporum seedlings in previously uninvaded forest greatly increased following the disturbance created by Hurricane Gilbert in 1988. The species has now spread throughout at least 1,300 hectares of primary and secondary montane forest. The potential range of species in the Blue Mountains could be as high as 44,000 hectares, severely threatening the survival of many of the 275 endemic flowering plant species.|
|Following cutting of Pittosporum, it has a high capacity to resprout; and even when its existing seedlings are uprooted, Pittosporum dominates the subsequent natural regeneration. We have found that the relatively benign herbicide glyphosate is effective at killing Pittosporum trees and seedlings, and we are continuing to search for effective non-chemical methods of control (including biological control). Experimental clearance has, however, shown that it would be very difficult and costly to remove Pittosporum from heavily invaded forest (disturbance of sufficient severity to prevent Pittosporum regeneration inevitably leads to domination by non-woody invasive weed species).|
|A key management requirement is to reduce the extent to which Pittosporum in the already heavily-invaded forest is acting as a seed source for continuing invasion of the remaining natural forests of the Blue Mountains. An innovative combination of local community participation and direct management by the national park authorities will be most effective. For the heavily invaded forest areas (which are those most accessible to local people), we advocate an approach of "conservation by utilisation": Pittosporum wood has good potential for use as timber and makes excellent firewood so local people could intensively harvest the species and gain resources and revenue through participation in this conservation activity. Control activities by National Park field staff should then concentrate on killing the satellite populations of Pittosporum that have become established within otherwise uninvaded forest and are acting as secondary foci for the invasion.|
This work is an output
from a research project partly funded by the United Kingdom Department
for International Development (DFID) for the benefit of developing countries.
The views expressed are not necessarily those of DFID. R4742 Forestry
Research Programme. The work was co-funded by the Darwin Initiative
of the United Kingdom Department of Environment, Transport and the Regions.
T.C.R. & J.R. Healey. (1996). The invasion of Jamaican montane
rainforests by the Australian tree Pittosporum undulatum. University
of Wales, Bangor. 54 pp. This report is a full account of the Pittosporum
invasion in Jamaica including its impact on all aspects of the forest environment.
It also contains a full description of the biology and world-wide distribution
of Pittosporum undulatum.
Goodland, T.C.R. & Healey, J.R. (1997). The effect of Pittosporum undulatum on the native vegetation of the Blue Mountains of Jamaica. University of Wales, Bangor. 39 pp. This report provides the fullest account of the effect that Pittosporum is having specifically on the plants in the forests of the Blue Mountains of Jamaica.
Goodland, T.C.R. & Healey, J.R. (1997). The control of the Australian tree Pittosporum undulatum in the Blue Mountains of Jamaica. University of Wales, Bangor. 25 pp. This report provides the most up to date recommendations for the control and management of Pittosporum in Jamaica.
|If you would like a copy of the full report go to the download page.|