European Grasslands Challenge Rainforests as the Most Species-Rich Spaces On Earth

[Staff]

European Grasslands Challenge Rainforests as the Most Species-Rich Spaces On Earth
ScienceDaily
Mar. 15, 2012

http://www.sciencedaily.com/releases/2012/03/120315225743.htm?utm_source=feedburner&utm_medium= email&utm_campaign=Feed%3A+invasivenews+%28Invasiv e+Species+News%29
excerpt from above:

"The coexistence of large numbers of species in one space and the questions it raises have long fascinated ecologists," said Professor Bastow Wilson, from the University of Otago, New Zealand. "For example it's a core ecological principle that two species occupying the same niche cannot co-exist long-term, so how can 942 plant species co-exist in one hectare of tropical rainforest?"

While tropical rainforests of South America and Central Africa are often believed to be the most species rich areas on Earth, Professor Wilson's team sought to establish if this is true, especially if smaller spatial scales are analysed…

[Gloria]

Hmmm...
So is this saying the most species rich place on earth may be caused by human activity?
The number of species in any given area over time (maybe much time) changes dramatically. After disturbance pioneer species move in then slowly the area returns to what climate and geology can sustain, until more disturbance. When disturbance is continuous what happens and how long can this go on? Is it in fact a sustainable situation? Many questions...

The city of Manila holds the human world record for the most densely populated space and now an international team of ecologists are seeking the natural equivalent, the most species rich area on earth.

"We surveyed the global literature to find records of plant species richness at scales from 1 mm² up to 1 hectare. Above 50 m², all the maximum values were from tropical rainforests in Costa Rica, Columbia or Ecuador," said Wilson. "However, looking at smaller scales we have found that long-grazed or mown grasslands are the most species rich places on Earth."

[Equilibrium]

I dunno.... I guess those unanswered questions are supposed to draw our attention away from what's going on in South America right now.

[Cirsium]

Originally Posted by Gloria

Hmmm...
So is this saying the most species rich place on earth may be caused by human activity?
The number of species in any given area over time (maybe much time) changes dramatically. After disturbance pioneer species move in then slowly the area returns to what climate and geology can sustain, until more disturbance. When disturbance is continuous what happens and how long can this go on? Is it in fact a sustainable situation? Many questions...

Since species richness is only a numerical value for the species present, a lot of different factors probably influence it. Disturbance is one, but I think it would be hard to come up with a consistent disturbance/richness relationship that would hold true over a large number of different kinds of areas.

These two links discuss some general considerations about species richness:
Species richness
Intermediate Disturbance Hypothesis - Wikipedia, the free encyclopedia
.

[Gloria]

Interesting reading. Wikipedia can always be counted on as a place to find sources for futher information.
I suppose one reason for the comparison to most populated human space was to help us understand that "most" is a varible measure.As in comparing large areas like countries as opposed to cities where humans tend to congregate in mass. Also it makes it very clear that more is not always better(depending on perspective) but does make for a lot of interaction to work with.

Intermediate Disturbance Hypothesis - Wikipedia, the free encyclopedia

The Intermediate Disturbance Hypothesis (IDH) states that local species diversity is maximized when ecological disturbance is neither too rare nor too frequent. At low levels of disturbance, more competitive organisms will push subordinate species to extinction and dominate the ecosystem.[1] At high levels of disturbance, due to frequent forest fires or human impacts like deforestation, all species are at risk of going extinct. According to IDH theory, at intermediate levels of disturbance, diversity is thus maximized because both competitive K-selected and opportunistic r-selected species can coexist.

Debate over the validity of the IDH is ongoing as the theory is tested in various ecological communities. Other evidence exists for[8][9] and against[10][11] the hypothesis.
However, the IDH theory has gained traction in the field of ecology and remains a useful framework for understanding the influence of disturbance on biodiversity within communities. Due to the complicated interactions of ecosystems, the IDH, like all theories, represents a simplification of competition interactions. Thus, some have come to understand the theory as a series of similar phenomena dictated by the unique aspects of each community.[13