Tag Archives: diversity

Guest Lecture Series

‘Explaining the high diversity of rainforest trees.’ – Owen T. Lewis.

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13th February 2015.

Review

The session focussed on current ideas as to how rainforests can successfully sustain such a high diversity of trees in such a relatively close proximity to one another. One aim of the study is that gaining a greater understanding of plant diversity will therefore provide a greater insight and understanding in to animal and insect diversity.

The initial question as to why rainforest tree diversity is so high, is intriguing as all species of plant life within the population all compete for the same key resources, space, sunlight, water and soil nutrients, however a higher species diversity is maintained than would be expected.

The Janzen-Connell hypothesis suggests that the survival and growth of seedling is distant dependent, the hypothesis states that the closer the seedlings to the parent tree, the higher the density of host specific predators and pathogens, therefore the lower the chance of survival of seedlings. There is a ‘sweet spot’ an optimal distance from the parent tree for survival and growth of seedlings. This theory was in part proven by the research team in Belize using a variety of fungicides and insecticides to decrease the number of pathogens near to the parent tree.

Due to the increased chance of survival for those seedlings that are dispersed greater distances from the parent tree, it is therefore unlikely that when the parent tree dies it will be replaced by its own species, it is increasingly likely that another species will utilise the space instead. This phenomenon prevents any one species becoming too dominant within the population, which as a result helps to maintain a high species diversity.

Opinions

I found the session to be of use to me as it highlighted an idea that I had not offered much thought to, the driving factors and the science behind the mechanisms of the high species diversity were interesting to me and presented new ways of thinking.

Career

I could not see myself pursuing a career in ecology (and conservation) as I feel it does not link as closely to my degree and interests as other fields of biology do.