Progress 10/01/02 to 10/01/06
Outputs
The question whether natural variations in soil resources play a role in the maintenance of plant species diversity is an age-old question with much supporting, and refuting evidence. The goal of this project was to determine relationships among soil resources (nutrient fertility, soil water status, soil acidity, etc.,) and plant population processes within nine large tropical forest dynamics research plots in Panama, Ecuador, Colombia, Brazil, Malaysia, Sri Lanka, and Thailand. The Center for Tropical Forest Science (CTFS) of the Smithsonian Institution coordinated the periodic censuses of all trees within these plots (all 16-50 ha plots) using identical methods and provided plant productivity data. The large plant species diversity in tropical forests presented a unique opportunity to examine the question. During the project we completed soil chemical analyses for seven of the sites: Panama, Ecuador, Colombia, Brazil, Thailand (two plots), and India. Each set of
analyses encompassed 11 plant-essential nutrients, plus soil Aluminum, and soil pH. All of the chemical elements had highly variable concentrations in the plots, as expected, and all displayed heterogeneity. Heterogeneity indicates that the variability was not simply random but had a spatial component, i.e., bands of rich- and poor-soil, or patches. We expected to find soil spatial heterogeneity, but also expected similar levels of heterogeneity among sites. This was not true: in nearly all cases, each chemical element in each site displayed idiosyncratic patterns. This was a novel finding! We tested soil resource-based distribution of plant species in three of the sites in Colombia, Ecuador, and Panama. Using the spatial distribution maps of greater than 0.5 million individual trees of 1400 species and the 11 essential plant nutrients, we used robust statistical analyses to show that 36-51 percent of tree species showed strong associations to soil nutrient distributions. In a related
aspect I quantified soil resources in a large-scale forest fertilization experiment in Panama. This experiment involves fertilization with the nutrients that typically are need to large supply to sustain forest productivity: nitrogen, phosphorus, and potassium. I found only subtle effects of fertilization on forest productivity and soil fertility, which is perplexing. I completed an analysis of soil chemical heterogeneity in the study area, and I tracked the fate of the fertilizer during the first seven years of the experiment.
Impacts
The research showed that soil resources played a much more important role than expected in the organization of trees in three tropical forests. The research involved local stakeholders at each site, and we were able to train 19 local scientists to do further research in soil-plant relationships.
Publications
- John, R., Dalling, J.W., Harms, K.E., Yavitt, J.B., Stallard, R.F., Mirabello, M., Hubbell, S.P., Valencia, R., Navarrete, H., Vallejo, M. and Foster, R.B. 2007. Soil nutrients influence spatial distributions of tropical tree species. Proc. Natl. Acad. Sci. USA 104:864-869.
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Progress 01/01/05 to 12/31/05
Outputs
The question whether natural variations in soil resources play a role in the maintenance of plant species diversity is an age-old question with much supporting, and refuting evidence. The goal of this project is to determine relationships among soil resources (nutrient fertility, soil water status, soil acidity, etc.,) and plant population processes within nine large tropical forest dynamics research plots in Panama, Ecuador, Brazil, Malaysia, Sri Lanka, and Thailand. The Center for Tropical Forest Science (CTFS) of the Smithsonian Institution coordinates the periodic censuses of all trees within these plots (all 16-50 ha plots) using identical methods and provides plant productivity data. The large plant species diversity in tropical forests presents a unique opportunity to examine the question. During the past year we completed soil chemical analyses for seven of the sites: Panama, Ecuador, Columbia, Brazil, Thailand (two plots), and India. Each set of analyses
encompassed 11 plant-essential nutrients, plus soil Aluminum and soil pH. All of the chemical elements had highly variable concentrations in the plots, as expected, and all displayed soil heterogeneity. Heterogeneity indicates that the variability was not simply random but had a spatial component, i.e., bands of rich- and poor-soil, or patches. We expected to find soil heterogeneity, but also expected similar levels of heterogeneity among sites. This was not true: in nearly all cases, each chemical element in each site displayed idiosyncratic patterns. Remarkably we found for three sites that 65 to 72 percent of the plant species had very specific soil chemical requirements for establishment, growth, and reproduction. We expected a much smaller proportion of the forest (!), according to recent hypotheses about soil-plant relationships in tropical forests. The reasons for significant relationships between plant species and soil resources are under investigation. In a related aspect I
continue to study soil resources in a large-scale forest fertilization experiment in Panama. This experiment involves fertilization with the nutrients that typically are need to large supply to sustain forest productivity: nitrogen, phosphorus, and potassium. I continue to find only subtle effects of fertilization on forest productivity and soil fertility, which is perplexing. In this year we completed analyses of soil chemical heterogeneity in the study area to examine how heterogeneity contributes to the maintenance of plant diversity.
Impacts
These research efforts will result in the largest set of data for soil fertility in lowland tropical forests conducted with consistent methodology and coordinated with ecological studies of plant ecology. The data set will be used by researchers interested in untangling complexities at the interface between plant ecology and ecosystem structure and function.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
The question whether natural variations in soil resources play a role in the maintenance of plant species diversity is an age-old question with much supporting, and refuting evidence. The goal of this project is to determine relationships among soil resources (nutrient fertility, soil water status, soil acidity, etc.,) and plant population processes within nine large tropical forest dynamics research plots in Panama, Ecuador, Brazil, Malaysia, Sri Lanka, and Thailand. The Center for Tropical Forest Science (CTFS) of the Smithsonian Institution coordinates the periodic censuses of all trees within these plots (all 16-50 ha) using identical methods and provides plant productivity data. The large plant species diversity in tropical forests presents a unique opportunity to examine the question. During the past year we held a training workshop for collaborators from Malaysia, Sri Lanka, and Thailand, and each of the trained researchers carried out the fieldwork at their
home sites. The analysis of those samples is currently under way in my research laboratory at Cornell. Some of the preliminary results are intriguing. For example, we have found that 15 to 20% of the plant species appear to have very specific soil resource requirements for establishment, growth, and reproduction. While this may seem like a small proportion of the forest flora, it is a remarkable constant proportion in the pan tropical forest. This occurs despite some forests having very large range of soil resources conditions versus ones in which the resources are quite uniform across the landscape. The reason for relationships between certain plant species and soil resources is under investigation. In a related aspect I continue to study soil resources in a large-scale forest fertilization experiment in Panama. This experiment involves fertilization with the nutrients that typically are need to large supply to sustain forest productivity: nitrogen, phosphorus, and potassium. I have
found only subtle effects of fertilization on forest productivity and soil fertility, which is perplexing. A new study is looking at soil phosphorus in more detail to understand its fate in the fertilized plots.
Impacts
The research will result in the largest set of data for soil fertility in lowland tropical forests conducted with consistent methodology and coordinated with ecological studies of plant ecology. The data set will be used by researchers interested in untangling complexities at the interface between plant ecology and ecosystem structure and function.
Publications
- Mangan, S.A., Eom, A-H., Adler, G.H., Yavitt, J.B., Herre, E.A. 2004. Diversity of arbuscular mycorrhizal fungi across a fragmented forest in Panama: insular spore communities differ from mainland communities. Oecologia 141: 687-700.
- Yavitt, J.B., Wright, S.J., Wieder, R.K. 2004. Seasonal drought and dry-season irrigation influence leaf-litter nutrients and soil enzymes in a moist, lowland forest in Panama. Austral Ecology 29: 177-188.
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Progress 01/01/03 to 12/31/03
Outputs
Most tropical forest grow on nutrient-poor soil yet attain high plant productivity. This apparent paradox depends upon a combination of rapid nutrient-cycling rates in soil, nutrient storage predominantly in plant biomass rather than soil, and deep rooting. The paradox also challenges the notion that low soil nutrient concentrations limit plant productivity in nutrient-poor soil, albeit most of the soil fertility / plant productivity research has been done beyond the tropics. My research is designed to determine the relationships among soil fertility and plant population processes within nine large forest dynamics research plots in Panama, Ecuador, Brazil, Malaysia, Sri Lanka, and Thailand. The Center for Tropical Forest Science (CTFS) of the Smithsonian Institution coordinates the periodic censuses of all trees within these plots (all 16-50 ha) using identical methods and provides plant productivity data. During the past year we developed a uniform protocol for soil
fertility research in remote tropical forests using local cooperators rather than professionals soil scientists to carry out all of the fieldwork and preliminary laboratory studies using standard procedures. We had a training workshop for collaborators from Panama, Ecuador and Columbia and each of the trained researchers carried out the fieldwork and laboratory studies at their home sites. The analyses of the samples ate Cornell is proceeding. In addition I had a special training session for researchers from Malaysia and those field studies have been completed.
Impacts
The research will result in the largest set of data for soil fertility in lowland tropical forests conducted with consistent methodology and coordinated with ecological studies of plant ecology. The data set will be used by researchers interested in untangling complexities at the interface between plant ecology and ecosystem structure and function.
Publications
- No publications reported this period
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