Bibliography - S. A. Bohlman

1. Bohlman, S. A., and Stephen W. Pacala, 2012: A forest structure model that determines crown layers and partitions growth and mortality rates for landscape-scale applications of tropical forests. Journal of Ecology, British Ecological Society, 100, doi:10.1111/j.1365-2745.2011.01935.x 508-518
   [ Abstract ]

   1. We present a model to quantify tropical forest structure and explain variance in dynamic rates (growth and mortality) that is computationally simple and can be applied to landscape-scale forest inventory and, potentially, remote sensing-derived data. 2. The model is a modification of the perfect plasticity approximation (PPA) based on tree allometry, tree locations and sizes. The model quantifies crown area index (CAI) (number of crowns per unit ground area) and assigns trees to crown layers, which determines the expected number of crowns above each tree and thus its light environment. 3. The structural model, parameterized and tested for the Barro Colorado Island, Panama 50-ha forest dynamics plot using data from forest inventories and stereo aerial photographs, reproduces most canopy and understorey structural and dynamic properties. The PPA model worked as well or better than a computationally intensive, spatially explicit model. A single allometry for all trees worked equally well as functional group or species allometries. Models of growth and mortality were always improved by adding crown layers as defined by the PPA model. 4. The mean CAI of the 50-ha plot was 3.1 with low variance. The observed variance was lower than when tree locations were randomized, which drastically lowered the variance in tree density per plot, indicating that there are regulating forces towards a small range of crown area indices. 5. Synthesis. A number of simplifying characteristics in structure were uncovered with the PPA structural model applied to a tropical forest: species allometries were not needed despite the high species diversity in the forest; the model worked on a range of plot sizes; and the variance in CAI was surprisingly low, suggesting regulatory mechanisms. The PPA structural model can be used to develop a fully dynamic simulation model for tropical forests. The ability of the simulation model to predict temporal changes in landscape patterns of biomass, dynamic rates, and species and/or functional group composition will provide validation for the partitioning of dynamic rates by crown layers in the PPA structural model.

2. Bohlman, S. A., and S. T. O'Brien, 2006: Allometry, adult stature and regeneration requirement of 65 species on Barro Colorado Island, Panama. Journal of Tropical Ecology, 22(02), doi:10.1017/S0266467405003019 123-136
   [ Abstract ]

   This study provides a community-level analysis of how regeneration requirement and adult stature are related to tree allometry (diameter, height and crown size) throughout post-seedling ontogeny on Barro Colorado Island, Panama. Comparing 65 species, gap species are taller, have higher diameter growth rates and occupy more low-canopy sites (≤10m canopy height) than shade species at small diameters (≤10 cm dbh). For trees >10 cm dbh, diameter-height relationships and growth rates no longer differ between gap and shade species, but shade species have larger, particularly deeper, crowns than gap species. Species with tall adult stature have more slender stems with larger crowns compared with treelet and mid-canopy species starting at 5 cmdbh. From 10 to 40 cm dbh, diameter growth rate is also significantly greater for tall species. The consistent allometric differences between functional groups on a community level will, in part, determine vertical and horizontal stand structure.

3. Muller-Landau, H. C., R. C. Condit, J. Chave, S. C. Thomas, S. A. Bohlman, S. Bunyavejchewin, S. Davies, R. Foster, S. Gunatilleke, N. Gunatilleke, K. E. Harms, and T. Hart, et al., 2006: Testing metabolic ecology theory for allometric scaling of tree size, growth, and mortality in tropical forests. Ecology Letters, 9(5), doi:10.1111/j.1461-0248.2006.00904.x 575-588
   [ Abstract ]

   The theory of metabolic ecology predicts specific relationships among tree stem diameter, biomass, height, growth and mortality. As demographic rates are important to estimates of carbon fluxes in forests, this theory might offer important insights into the global carbon budget, and deserves careful assessment. We assembled data from 10 oldgrowth tropical forests encompassing censuses of 367 ha and > 1.7 million trees to test the theory’s predictions. We also developed a set of alternative predictions that retained some assumptions of metabolic ecology while also considering how availability of a key limiting resource, light, changes with tree size. Our results show that there are no universal scaling relationships of growth or mortality with size among trees in tropical forests. Observed patterns were consistent with our alternative model in the one site where we had the data necessary to evaluate it, and were inconsistent with the predictions of metabolic ecology in all forests.

4. Bohlman, S. A., and D. Lashlee, 2005: High spatial and spectral resolution remote sensing of Panama Canal Zone watershed forests: An applied example mapping tropical tree species. The Rio Chagres: A Multidisciplinary Profile of a Tropical Watershed, 52, doi:10.1007/1-4020-3297-8_16 245-258
   [ Abstract ]

   High spatial resolution airborne and satellite sensors have been used with varying degrees of success to measure deciduousness, canopy structure, and light interception, and to identify tree species in the Panama Canal Watershed. Results reported to date indicate that remotely sensed data have a high degree of accuracy in measuring deciduousness and leaf density in the upper canopy, but less accuracy than in temperate systems in measuring canopy light interception for semi-deciduous lowland tropical forests in the canal watershed. Of particular relevance to evergreen forests like the upper Río Chagres basin, this work examines whether high spectral resolution data, like that collected by the HYDICE system, can separate canopy species based on hyperspectral signatures in the 0.4 to 2.5-μm wavelength region. If a few well-selected spectral bands could accurately differentiate species, tropical canopies in remote and rugged terrain could be mapped using relatively simple, but optimized sensor systems.

Direct link to page: http://cmi.princeton.edu/bibliography/results.php?author=3954