Hurricanes are also responsible for transport of seeds over long distances (Czarnecka, 2005). Grasslands were found to consist of a mosaic pattern where dense clusters of a single plant form. This suggests that seed rain around the plant is the primary seed dispersal process at work in these areas (Czarnecka, 2005). Wind may help to spread species to new patches, but the primary seed dispersal mechanism would be likely to be seeds falling to the ground. Compared to brush lands, the dominant species were within the Carex family. The dominant species in the brush lands was Origanum vulgare. Seed dispersal by anemochore dominated in the grasslands, with nearly 43% of the plants using this methods exclusively. Among brush land plants, dispersal by plants that depended on animals for dispersal, either by eating the fruit or hitchhiking on coats and wings (Czarnecka, 2005).

In communities, such as the monocrop plantation discussed earlier, there were few animals to transport seeds for even short distances with in the community. This severely limited the ability of biodiversity to establish in these areas. Perhaps one of the more surprising results in the study by Au, Corlett, & Hau, (2006) is that there were higher numbers of seeds and a higher number of species in the shrub land. One would expect a forest to have higher numbers. However, this finding supports the importance of birds living in the shrub land as a major contributing source of seeds.

A study of the composition and seed dispersal of various plant communities reveals that the presence of animals is important to maintaining diversity in the community. Seedbanks may be high in areas with few animals to aid dispersal, but birds and other animals play an important part in increasing the number of taxa found with in a community. In a monocrop plantation with few animal species, the seed bank suffered as did the diversity of the area.

Plant...

These plants depend on the animals to increase their numbers. As the number of plants increase, the community can support a larger number of animals. Birds were found to be one of the most important animals, in terms of seed dispersal in all of the communities studied. It is not surprising that brush lands tended to have the highest diversity and plant density. Shrubs often make excellent hiding places and nesting places for large numbers of birds.
This study focused on the effects such as hurricanes, and manmade disasters, such as severe deforestation in terms of their effects on plant diversity and density. Manmade disasters often have devastating effects that leave lasting footprints on the natural environment. In the studies examined, natural communities had higher numbers of species than those, which had been damaged by human beings. Hurricanes were responsible for the introduction of new species. However, lacking a hurricane, mono-crop plantations suffered permanent damage in the number of species of flora and fauna that they could support.

References

Au, N., Corlett, R., & Hau, B. (2006). Seed rain into upland plant communities in Hong Kong, China. Plant Ecology. 186 (1), 13-22.

Czarnecka, J. (2005). Seed dispersal effectiveness in three adjacent plant communities xerothermic grassland, brushwood, and woodland. Ann. Bot Fennici. 42: 161-171.

Elsa, W., Lee, B. Hau, C., & Corlett, R. (2005). Natural regeneration in exotic tree plantations in Hong Kong, China.

Forest Ecology and Management. 212 (1-3), 358-366.

Wescott, D.(2007) Birds are important for plant seed dispersal in tropical rainforests. CSIRO Sustainable Ecosystems. Retrieved November 14, 2007 at http://www.csiro.au/science/weed.seed.dispersal.html.