This a relatively well known relationship, coming to sight in the comparison of tropical (usually nutrient poor) soil environments with temporate environments. A relatively old ecological theory explains that poor conditions (limited resources) lead to high competition and thus disable dominance of one or few species and also to the evolution of manifold strategies to cope with the nutrient limitation. In rich environments the best competitor may occupy most of the (niche) space. Productivity theory somehow argues contrarily. However poor soils are known to house a great diversity of soil animals of the decomposer net, due to the accumulation of leaf litter with high C/N ratio on the floor with a very species rich mesofauna (oribatid mites, collembola), in contrast to leaves rich in N are often rapidly decomposed by (few species of) earthworms, resulting in bar soil surface.

Generally, tropical forests are characterized by high biomass and plant diversity althoughsoils are generally nutrient poor (leached) due to the chemical weathering under high temperature and rainfalls. There, a species rich decomposer web of bacteria, fungi (mycorrhiza) and soil mesofauna acts as a very effective filter retaining the nutrients being leached by rainwater and thus avoiding nutrient loss. The plant also are retaining and recycling nutrients, minimizing nutrient loss and so the leaf litter is usually poor in N and other nutrients.

This a relatively well known relationship, coming to sight in the comparison of tropical (usually nutrient poor) soil environments with temporate environments. A relatively old ecological theory explains that poor conditions (limited resources) lead to high competition and thus disable dominance of one or few species and also to the evolution of manifold strategies to cope with the nutrient limitation. In rich environments the best competitor may occupy most of the (niche) space. Productivity theory somehow argues contrarily. However poor soils are known to house a great diversity of soil animals of the decomposer net, due to the accumulation of leaf litter with high C/N ratio on the floor with a very species rich mesofauna (oribatid mites, collembola), in contrast to leaves rich in N are often rapidly decomposed by (few species of) earthworms, resulting in bar soil surface.

Generally, tropical forests are characterized by high biomass and plant diversity althoughsoils are generally nutrient poor (leached) due to the chemical weathering under high temperature and rainfalls. There, a species rich decomposer web of bacteria, fungi (mycorrhiza) and soil mesofauna acts as a very effective filter retaining the nutrients being leached by rainwater and thus avoiding nutrient loss. The plant also are retaining and recycling nutrients, minimizing nutrient loss and so the leaf litter is usually poor in N and other nutrients.

Hello Abbas,

Can you tell us what sort of diversity you refer to?alpha,beta or gamma?if so,is it related to above-ground relationships,below ground or mere plant community diversity?

In any case, Prof David Wardle would offer you much professional input,kindly reach-out to him https://www.researchgate.net/profile/David_Wardle3 or Prof Dr Matty Berg  https://www.researchgate.net/profile/Matty_Berg

Goodluck

There are many shapes of this relationship in nature: positive, negative, and hump-shaped. It is likely that each situation (region, data set) is has its own explanation for its particular relationship. See:

Adler, et al. 2011, Productivity Is a poor predictor of plant species richness, Science 23:1750-1753

Dear All, Thank you so much for your help.

 Especially, Dr. Hubert Höfer's description is very helpful for my understanding.  

Thanks Beckline Mukete and Truman P Young for your suggestions. 

Dear Dr. Hubert Höfer, 

Will be grateful , if you can give some reference texts / papers also.

Thanks,

Dear Sawaid Abbas,

I must confess, that my explanations on the relation between poor soils and high diversity in their generality stem back to long passed time of ecological theories discussed in tropical ecology. So, I have some difficulties (and not the time) to find good references from these times. As T. Young expressed, we know today, that many factors influence diversity on different scales. When looking for recent literature, however, there are some really good treatments and reviews, where you will find many of my arguments described and discussed:

book: Amazonia 1984. Pergamon Press

Cadisch & Giller (eds) 1997: Driven by Nature. Plant litter quality and decomposition. CAB International, 407 pp.

Bardgett, Usher & Hopkins (eds) 2005. Biological diversity and function in soils. Cambridge University Press.

There is certainly a multitude of papers addressing productivity and diversity. For soil fauna Patrick Lavelle has published a lot on soil biodiversity.

I hope this helps.

Hubert

Dear Dr. Hubert Höfer,

Many Thanks.

Regards , 

Sawaid 

An excellent response Hubert , impressed with your arguments. Same theory applies about the increase in plant  species diversity with increase in C:N ratio. 

Hi Saiwad,

You can find a Syllabus on the following address:

https://www.researchgate.net/publication/305805991_Syllabus_-_The_Tropical_Rain_Forest

It answers the question you posed, among others.

Cheers,

Frank

Working Paper Syllabus - The Tropical Rain Forest

Dear Dr. Frank, 

Many thanks sharing the syllabus, it is very clear and helping. 

Regards, 

Sawaid ABBAS

Interesting discussion . It is really interesting to observe much greater biodiversity on low fertility soils than high fertility soils , for example , on soils of tropical amazon, prairie etc...

Dear Hubert Höfer, 

If  C:N ratio is higher in secondary forest recovery and species diversity is associated with  the C:N, So does this mean that the poor soil is not a limiting factor in forest recovery – we don’t need to artificially add nutrients   ?

Thanks,