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Browsing by Author "Kainer, Karen A."

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    Comparative models disentangle drivers of fruit production variability of an economically and ecologically important long-lived Amazonian tree
    (Nature Portfolio, 2021) Staudhammer, Christina L.; Wadt, Lucia Helena O.; Kainer, Karen A.; da Cunha, Thiago Augusto; University of Alabama Tuscaloosa; Empresa Brasileira de Pesquisa Agropecuaria (EMBRAPA); University of Florida; Universidade Federal do Acre (UFAC)
    Trees in the upper canopy contribute disproportionately to forest ecosystem productivity. The large, canopy-emergent Bertholletia excelsa also supports a multimillion-dollar commodity crop (Brazil nut), harvested almost exclusively from Amazonian forests. B. excelsa fruit production, however is extremely variable within populations and years, destabilizing local harvester livelihoods and the extractive economy. To understand this variability, data were collected in Acre, Brazil over 10 years at two sites with similar climate and forest types, but different fruit production levels, despite their proximity (similar to 30 km). One site consistently produced more fruit, showed less individual- and population-level variability, and had significantly higher soil P and K levels. The strongest predictor of fruit production was crown area. Elevation and sapwood area also significantly impacted fruit production, but effects differed by site. While number of wet days and dry season vapor pressure prior to flowering were significant production predictors, no climatic variables completely captured annual observed variation. Trees on the site with higher available P and K produced nearly three times more fruits, and appeared more resilient to prolonged drought and drier atmospheric conditions. Management activities, such as targeted fertilization, may shield income-dependent harvesters from expected climate changes and production swings, ultimately contributing to conservation of old growth forests where this species thrives.
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    Population Structure and Fruit Production of Carapa guianensis (Andiroba) in Amazonian Floodplain Forests: Implications for Community-Based Management
    (Sage, 2017) Londres, Marina; Schulze, Mark; Staudhammer, Christina L.; Kainer, Karen A.; State University System of Florida; University of Florida; Oregon State University; University of Alabama Tuscaloosa
    Andiroba (Carapa guianensis) is a multiple-use tree species that plays a crucial socioeconomic role across thousands of Amazonian traditional and indigenous communities. In the floodplain forests of the Amazon estuary, we partnered with local forest managers to investigate C. guianensis ecological parameters, addressing seed production rates, tree density, and size class structure across a range of environmental conditions and forest use history. C. guianensis population structure was measured in three forest types: baixio, restinga, and terra preta, differentiated by tidal influence, species dominance and composition, and edaphic conditions. We found significant differences across forest types, whereby seedling and sapling densities were higher in terra preta and adult densities were higher in baixio. Adult densities were 28.7, 23.0, and 19.5 trees/ha, and seedling densities were 22.9, 105, and 151 trees/ha in baixio, restinga, and terra preta forest types, respectively. Seed production rates varied significantly across forest types, year, size class, crown form, and crown illumination. There were higher numbers of viable seeds in terra preta versus baixio (5.5 kg and 2.6 seeds/tree/year, respectively) as well as more trees with better crown forms, more light, and larger diameter sizes. Long-term patterns of community timber management intensity by forest type significantly influenced both population structure and population-level seed production. Nonetheless, assessment of seed production for the total population suggests that the local community was collecting less than 1% of the viable C. guianensis seeds produced annually within community forest lands. This study illustrates the potential of management to impact the sustainability of an important multiple use species and shows the impact that community conservation planning and action can have on future natural resource availability.