Nitrogen-fixing legumes are key species across ecosystems, as their ability to fix atmospheric nitrogen can facilitate neighboring plants. However, little is known about the fate of this legume effect in the face of extreme weather events, which are increasingly expected to occur in future.
Thanks for this interesting question.
In our South African Fynbos (a Mediterranean-type ecosystem) we have legumes that seem to be more drought resistant than their reseeding counterparts in the same genus. As we are experiencing severe drought in the winter rainfall region of South Africa, the endemic habitat of some of these legumes, we are concerned about their capacity to survive, because even with this adaptation to disturbance (in this case, fire), plants cannot survive the prolonged and severe drought cycles.
But further to your question about the effects of drought on legumes providing nutrients for other co-occuring species... When phosphorous acquisition is negated, this is a primary limiting factor for plant growth and development. In our poor soils, Aspalathus linearis is adapted both to low nitrogen and low phosphorous in the soil. Plants exude organic acids through cluster roots to facilitate P uptake, making the same available for other species in its rhizosphere. These mechanisms (nutrient acquisition, organic acid production, the metabolism and uptake of appropriate forms of P) all depend on water relations in the rhizosphere.
My educated guess is that drought not only severely limits the legume's intrinsic function, but also negates its capacity to "serve" co-occurring species.
I look forward to hearing your thoughts.
On the principle of resistance of legumes to drought: I agree with Rhoda Malgas, since a few years I work with a team of INRA of Toulouse in France. We will publish the results. We have vegetables that seem to be more resistant than their reseeding counterparts in the same genus. In addition to a significant drop in yield, we are also concerned about their ability to survive because even with this adaptation to disturbance (heritability), plants can not survive prolonged and severe drought cycles.
thanks ......Farid Benyahia, Rhoda Malgas and Issam Moussa for your help....
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