And see Chris Emery's Dispatches piece in the February 2007 Frontiers in Ecology and the Environment (page 8), describing work by Koren et al. that finds that half the nutrient demand of Amazon forests comes from dust exported from the Sahara. The Koren piece is Environ. Res. Lett 2006; 1:14005.
-----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[EMAIL PROTECTED] On Behalf Of John White Sent: Tuesday, February 13, 2007 12:31 PM To: ECOLOG-L@LISTSERV.UMD.EDU Subject: Re: What would adding fertilizer do to a tropical forest? I forwarded the ECOLOG-L discussion about fertilizing tropical soils to William Woods, Director of the Environmental Studies Program at the University of Kansas <[EMAIL PROTECTED]>, who studies soils in the Amazon valley. Here is his response: Without major amendments tropical soils are generally considered to offer poor prospects for agricultural development. Amazonian soils represent a textbook case. Soil quality equals destiny in many readings of Amazonia's past, present, and future. Yet in the past few decades archaeologists have uncovered evidence of large and complex prehistoric societies in Amazonian environments despite earlier consensus that such development was untenable. More recently, geographers have discovered that these sites coincide with fertile, dark soils termed "terra preta" that occur in a variety of landscape contexts and extents, from patches of less than a hectare to many square kilometers. It is now clear that these soils are anthropic in origin and represent fonts of local environmental knowledge and know-how with ancient roots and contemporary pan-tropical applications. An intriguing property is their apparent persistence, even after cultivation cessation ranging from decades to centuries and possibly millennia. Local people continue to generate these soils with skilled practices, including carbon amendments and microbial management. Both the soils and these practices are important agricultural resources within contemporary Amazonia. They provide a global model for developing long- term future sustainability of food production in lowland tropical environments. They also constitute a significant reservoir for the short- and long-term sequestration of carbon. ----- Original Message ----- From: <[EMAIL PROTECTED]> Sent: Tuesday, February 06, 2007 2:29 PM Subject: Re: What would adding fertilizer do to a tropical forest? In most tropical soils adding mineral fertilizers to soil is not likely to have much impact. Since these soils have very low cation exchange capacity, cations, such as potassium, added to soils will be leached away very quickly. Phosporus is most likely to be fixed as iron and alluminium phosphates and will not be available to plants. Bob Mowbray Tropical Forest Ecologist ----- Original Message ----- From: "Jonathan Adams" <[EMAIL PROTECTED]> Sent: Thursday, February 01, 2007 5:36 PM Subject: What would adding fertilizer do to a tropical forest? For a long time I've heard people talk about the effects of adding mineral fertilizers to grasslands - how it causes a crash in species richness. Has anyone ever tried adding mineral fertilizer to tropical forest and studying (say) the species diversity of seedlings, or long term effects on regeneration? It may be interesting from the point of view of understanding maintainance of species richness. Examining effects on growth rate of tropical trees might also be relevant to the idea of setting up artificial forests for carbon sequestration. Jonathan Adams
