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Post-doctoral Researcher Institut für Evolutionsbiologie und Umweltwissenschaften Universität Zürich Winterthurerstrasse 190 8057 Zürich Switzerland |
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| timothy.paine@ecofog.gf | |
| URL | http://manuplants.org/paine |
| office | ++41 (0)44 635 61 20 |
| fax | ++41 (0)44 635 57 11 |
| skype | cetimothypaine |
Community structure, diversity, functional traits, species coexistence, species range limits
Paine, CET, C Stahl, E Courtois, S Patiño, C Sarmiento and C Baraloto. In prep. Functional explanations for variation in bark thickness in tropical rain forest trees.
Paine, CET, C Baraloto, J Chave, B Hérault and F Jabot. In prep. Functional trait distributions reveal mechanisms of community assembly in tropical rain forests.
Sarmiento, C, S Patiño, CET Paine, J Beauchêne, A Thibaut and C Baraloto. In review. Within-individual variation in tropical tree wood density. American Journal of Botany.
Gagnon, PR, HA Passmore, WJ Platt, JA Myers, CET Paine, and KE Harms. In review. Does pyrogenicity protect burning plants? Ecology.
Gonzalez, M, A Roger E Courtois, F Jabot, N Norden, CET Paine, C Baraloto, C Thébaud and J Chave. 2010. Shifts in species and phylogenetic diversity between sapling and tree communities indicate negative density-dependence in a lowland rain forest. Journal of Ecology. 98: 137-146. abstract
1. As trees in a given cohort progress through ontogeny, many individuals die. This risk of mortalty is unevenly distributed across species because of many processes such as habitat filtering, inter-specific competition and negative density dependence. Here, we predict and test the patterns that such ecological processes should inscribe on both species and phylogenetic diversity as plants recruit from saplings to the canopy.
2. We compared species and phylogenetic diversity of sapling and tree communities at two sites in French Guiana. We surveyed 2084 adult trees in four 1-ha tree plots and 943 saplings in sixteen 16-m2 subplots nested within the tree plots. Species diversity was measured using Fisher’s alpha (species richness) and Simpson’s index (species evenness). Phylogenetic diversity was measured using Faith’s phylogenetic diversity (phylogenetic richness) and Rao’s quadratic entropy index (phylogenetic evenness). The phylogenetic diversity indices were inferred using four phylogenetic hypotheses: two based on rbcLa plastid DNA sequences obtained from the inventoried individuals with different branch lengths, a global phylogeny available from the Angiosperm Phylogeny Group, and a combination of both.
3. Taxonomic identification of the saplings was performed by combining morphological and DNA barcoding techniques using three plant DNA barcodes (psbA-trnH, rpoC1 and rbcLa). DNA barcoding enabled us to increase species assignment and to assign unidentified saplings to molecular operational taxonomic units.
4. Species richness was similar between saplings and trees, but in about half of our comparisons, species evenness was higher in trees than in saplings. This suggests that negative density dependence plays an important role during the sapling-to-tree transition.
5. Phylogenetic richness increased between saplings and trees in about half of the comparisons. Phylogenetic evenness increased significantly between saplings and trees in a few cases (4 out of 16) and only with the most resolved phylogeny. These results suggest that negative density dependence operates largely independently of the phylogenetic structure of communities.
6. Synthesis. By contrasting species richness and evenness across size classes, we suggest that nega- tive density dependence drives shifts in composition during the sapling-to-tree transition. In addition, we found little evidence for a change in phylogenetic diversity across age classes, suggesting that the observed patterns are not phylogenetically constrained.
Baraloto, C, CET Paine, S Patiño, D. Bonal, B. Hérault and J. Chave. 2010. Functional trait variation and sampling strategies in species-rich communities. Functional Ecology. 24: 208-216. abstract pdf
1. Despite considerable interest in the application of plant functional traits to questions of community assembly and ecosystem structure and function, there is no consensus on the appropriateness of sampling designs to obtain plot-level estimates in diverse plant communities.
2. We measured 10 plant functional traits describing leaf and stem morphology and ecophysiology for all trees in nine 1-ha plots in terra firme lowland tropical rain forests of French Guiana (N = 4709).
3. We calculated, by simulation, the mean and variance in trait values for each plot and each trait expected under seven sampling methods and a range of sampling intensities. Simulated sampling methods included a variety of spatial designs, as well as the application of existing data base val- ues to all individuals of a given species.
4. For each trait in each plot, we defined a performance index for each sampling design as the proportion of resampling events that resulted in observed means within 5% of the true plot mean, and observed variance within 20% of the true plot variance.
5. The relative performance of sampling designs was consistent for estimations of means and variances. Data base use had consistently poor performance for most traits across all plots, whereas sampling one individual per species per plot resulted in relatively high performance. We found few differences among different spatial sampling strategies; however, for a given strategy, increased intensity of sampling resulted in markedly improved accuracy in estimates of trait mean and variance.
6. We also calculated the financial cost of each sampling design based on data from our ‘every individual per plot’ strategy and estimated the sampling and botanical effort required. The rela- tive performance of designs was strongly positively correlated with relative financial cost, sug- gesting that sampling investment returns are relatively constant.
7. Our results suggest that trait sampling for many objectives in species-rich plant communities may require the considerable effort of sampling at least one individual of each species in each plot, and that investment in complete sampling, though great, may be worthwhile for at least some traits.
Courtois, E, CET Paine, P-A Blandinières, D. Stein, J-M Bessière, E Houël, C Baraloto, J Chave. 2009. Diversity of the volatile organic compounds emitted by 55 species of tropical trees: A survey in French Guiana. Journal of Chemical Ecology. 35: 1349-1362. abstract
Volatile organic compounds (VOCs) are pro- duced by a broad range of organisms, from bacteria to mammals, and they represent a vast chemical diversity. In plants, one of the preeminent roles of VOCs is their repellent or cytotoxic activity, which helps the plant deter its predators. Most studies on VOCs emitted by vegetative parts have been conducted in model plant species, and little is known about patterns of VOC emissions in diverse plant communities. We conducted a survey of the VOCs released immediately after mechanical damage of the bark and the leaves of 195 individual trees belonging to 55 tropical tree species in a lowland rainforest of French Guiana. We discovered a remarkably high chemical diversity, with 264 distinct VOCs and a mean of 37 compounds per species. Two monoterpenes (α-pinene and limonene) and two sesquiterpenes (β-caryophyllene and α-copaene), which are known to have cytotoxic and deterrent effects, were the most frequent compounds in the sampled species. As has been established for floral scents, the blend of VOCs is largely species-specific and could be used to discriminate among 43 of the 55 sampled species. The species with the most diverse blends were found in the Sapindales, Laurales, and Magnoliales, indicating that VOC diversity is not uniformly distributed among tropical species. Interspecific variation in chemical diversity was caused mostly by variation in sesquiterpenes. This study emphasizes three aspects of VOC emission by tropical tree species: the species-specificity of the mixtures, the importance of sesquiterpenes, and the wide-ranging complexity of the mixtures.
Paine, CET and KE Harms. 2009. What shapes tropical seedling community structure? Seed dispersal versus environmental conditions. Oecologia. 160: 19-150. abstract pdf
Though it is recognized that both stochastic and deterministic processes structure all communities, empirical assessments of their relative importance are rare, particularly within any single community. In this paper, we quantify the dynamic effects of dispersal assembly and niche assembly on the seedling layer in a diverse Neotropical rain forest. The two theories make divergent predictions regarding the roles of seed arrival and environmental heterogeneity in generating community structure. Put simply, dispersal assembly posits that the stochasticity inherent to seed arrival structures communities, whereas niche assembly suggests that heterogeneity in post-dispersal environmental conditions is more important. We experimentally sowed 15,132 seeds of eight tree species at varying levels of density and diversity. Every six months we censused the seedlings that germinated and assessed the abiotic and biotic conditions of each plot. We assessed the density, diversity, and species composition of three nested subsets of the seedling layer: seedlings germinated from sown seeds, all seedlings germinated between July 2003 and 2004, and all woody seedlings. We partitioned the variance in density and diversity of each subset of the seedling layer into components representing seed-addition treatments and environmental conditions at 6- to 12-month intervals. Seed additions initially explained more variance in the density and diversity than did environmental heterogeneity for seven of eight sown species, but explained little variance in the density or diversity of the entire seedling layer. Species composition was better explained by seed-addition treatments than by environmental heterogeneity for all three subsets and in all time periods. Nevertheless, the variance in community structure explained by seed-addition treatments declined over the twoyears following germination, presaging shifts in the relative importance of dispersal assembly and niche assembly. Our study quantifies how dispersal assembly and niche assembly may vary among the components of an ecological community and shift dynamically through time.
Paine, CET, KE Harms, and J Ramos. 2009. Water availability increases seedling performance and diversity in a tropical forest. Journal of Tropical Ecology. 25: 171-180. abstract pdf
Diversity is positively correlated with water availability at global, continental and regional scales. With the objective of better understanding the mechanisms that drive these relationships, we investigated the degree to which variation in water availability affects the performance (recruitment, growth and survival) of juvenile trees. Precipitation was supplemented throughout two dry seasons in a seasonal moist forest in south-eastern Peru. Supplementing precipitation by 160 mm mo-1 , we increased soil moisture by 17%. To generate seedling communities of known species composition, we sowed 3840 seeds of 12 species. We monitored the fates of the 554 seedlings recruited from the sown seeds, as well as 1856 older non-sown seedlings (10 cm < height < 50 cm), and 2353 saplings (> 1 m tall). Watering significantly enhanced young seedling growth and survival, increasing stem density and diversity. Watering diminished the recruitment of species associated with upland forests, but increased the survival of both upland- and lowland-associated species. Though supplemental watering increased the growth of older seedlings, their density and diversity were unaffected. Sapling performance was insensitive to watering. We infer that variation in dry-season water availability may affect seedling community structure by differentially affecting recruitment and increasing overall survival. These results suggest that differential seedling recruitment and survival may contribute to the observed relationships between water availability, habitat associations and patterns of tree species richness.
Paine, CET, KE Harms, SA Schnitzer, and WP Carson. 2008. Weak competition among tropical tree seedlings: implications for species coexistence. Biotropica. 40:432-440. This paper was selected for the 2009 Biotropica Award for Excellence in Tropical Biology and Conservation abstract pdf citation
The intensity of competition among forest tree seedlings is poorly understood, but has important ramifications for their recruitment and for the maintenance of species diversity. Intense competition among seedlings could allow competitively dominant species to exclude subordinate species. Alternatively, the low density and small stature of forest tree seedlings could preclude intense interseedling competition. In this case, other processes, such as size-asymmetric competition with adults, interactions with consumers, or neutral dynamics would prevail as those structuring the forest understory. We tested the intensity of, and potential for, intraspecific competition among tree seedlings of three species (Brosimum alicastrum, Matisia cordata, and Pouteria reticulata) in two Neotropical rain forests. We reduced stem densities by up to 90 percent and monitored individual growth and survival rates for up to 24 mo. Individual growth and survival rates were generally unrelated to stem density. Contrary to the predicted behavior of intensely competing plant populations, the distribution of individual heights did not become more left-skewed with time for any species, regardless of plot density; i.e., excesses of short, suppressed individuals did not accumulate in high-density plots. We further measured the overlap of zones of influence (ZOIs) to assess the potential for resource competition. Seedling ZOIs overlapped only slightly in extremely dense monodominant plots, and even less in ambient-density plots of mixed composition. Our results thus suggest that interseedling competition was weak. Given the low density of tree seedlings in Neotropical forests, we infer that resource competition among seedlings may be irrelevant to their recruitment.
Terborgh, J, G Nuñez, N. Pitman, F Cornejo, P Alvarez, V Swamy, B Pringle, and CET Paine. 2008. Tree recruitment in an "empty" forest. Ecology. 89:1757-1768. (Cover article) abstract pdf
To assess how the decimation of large vertebrates by hunting alters recruitment processes in a tropical forest, we compared the sapling cohorts of two structurally and compositionally similar forests in the Rio Manu floodplain in southeastern Peru. Large vertebrates were severely depleted at one site, Boca Manu (BM), whereas the other, Cocha Cashu Biological Station (CC), supported an intact fauna. At both sites we sampled small (>1 m tall, <1 cm dbh) and large (>1 cm and <10 cm dbh) saplings in the central portion of 4-ha plots within which all trees >10 cm dbh were mapped and identified. This design ensured that all conspecific adults within at least 50 m (BM) or 55 m (CC) of any sapling would have known locations.
We used the Janzen-Connell model to make five predictions about the sapling cohorts at BM with respect to CC: (1) reduced overall sapling recruitment, (2) increased recruitment of species dispersed by abiotic means, (3) altered relative abundances of species, (4) prominence of large-seeded species among those showing depressed recruitment, and (5) little or no tendency for saplings to cluster closer to adults at BM. Our results affirmed each of these predictions.
Interpreted at face value, the evidence suggests that few species are demographically stable at BM and that up to 28% are increasing and 72% decreasing. Loss of dispersal function allows species dispersed abiotically and by small birds and mammals to substitute for those dispersed by large birds and mammals. Although we regard these conclusions as preliminary, over the long run, the observed type of directional change in tree composition is likely to result in biodiversity loss and negative feedbacks on both the animal and plant communities. Our results suggest that the best, and perhaps only, way to prevent compositional change and probable loss of diversity in tropical tree communities is to prohibit hunting.
Paine, CET, and H Beck. 2007. Seed predation by Neotropical rainforest mammals increases diversity in seedling recruitment. Ecology 88:3076-3087. abstract pdf
Seed dispersal and seedling recruitment (the transition of seeds to seedlings) set the spatiotemporal distribution of new individuals in plant communities. Many terrestrial rain forest mammals consume post-dispersal seeds and seedlings, often inflicting density-dependent mortality. In part because of density-dependent mortality, diversity often increases during seedling recruitment, making it a critical stage for species coexistence. We determined how mammalian predators, adult tree abundance, and seed mass interact to affect seedling recruitment in a western Amazonian rain forest. We used exclosures that were selectively permeable to three size classes of mammals: mice and spiny rats (weighing ,1 kg), medium-sized rodents (1-12 kg), and large mammals (20-200 kg). Into each exclosure, we placed seeds of 13 tree species and one canopy liana, which varied by an order of magnitude in adult abundance and seed mass. We followed the fates of the seeds and resulting seedlings for at least 17 months. We assessed the effect of each mammalian size class on seed survival, seedling survival and growth, and the density and diversity of the seedlings that survived to the end of the experiment. Surprisingly, large mammals had no detectable effect at any stage of seedling recruitment. In contrast, small- and medium-sized mammals significantly reduced seed survival, seedling survival, and seedling density. Furthermore, predation by small mammals increased species richness on a per-stem basis. This increase in diversity resulted from their disproportionately intense predation on common species and large-seeded species. Small mammals thereby generated a rare-species advantage in seedling recruitment, the critical ingredient for frequency dependence. Predation by small (and to a lesser extent, medium-sized) mammals on seeds and seedlings significantly increases tree species diversity in tropical forests. This is the first long-term study to dissect the effects of various mammalian predators on the recruitment of a diverse set of tree species.
Harms, KE and CET Paine. 2003. Regeneración de árboles tropicales e implicaciones para el manejo de bosques naturales. Ecosistemas 2003/3. abstract pdf
El reclutamiento exitoso desde semillas en bosques neotropicales implica una secuencia de etapas. La disponibilidad del polen y recursos consumibles por los árboles maternales puede limitar el número de semillas producidas. La dispersión de semillas a un sitio determinado puede ser limitada por la densidad o la dispersión de árboles frutales, o por el agrupamiento impuesto por los procesos de dispersión de semillas. El establecimiento de semillas dispersadas puede ser limitado por la mortalidad debida a enemigos naturales, por ejemplo depredadores de semillas y herbivoros, o por factores abióticos tales como la disponibilidad de agua, nutrientes y luz. Como la limitación impuesta por estas etapas puede verse afectada por la explotación forestal selectiva, es necesario investigar el efecto de las prácticas selvícolas sobre cada etapa en la dinámica del bosque.
Paine, CET 2007. Seedling Recruitment in a Tropical Rain Forest: Ecological factors that maintain diversity and shape community structure. 80 pp. VDM Verlag Dr. Müller, Saarbruken, Germany. ISBN: 978-3-8364-2926-9 Available at Barnes & Noble or Amazon
Paine, CET and P Alvarez, Manuplants.org. Photos detailing the flowers, fruit, seeds, and seedlings of 967 species of trees from Southeastern Peru. http://manuplants.org
Paine, CET 2007. Ecological factors affecting the diversity of tropical tree seedlings. 134 pp. Ph.D. Dissertation, Louisiana State University, Baton Rouge, LA. abstract english español
Seed dispersal and seedling establishment - the two stages in seedling recruitment - set the spatiotemporal distribution of new individuals in plant communities. Diversity often increases at the seed to seedling transition, making it critical for species coexistence. Debate continues regarding the effects of each stage on the community structure of diverse forests. Neutral theories postulate a strong role of dispersal, whereas niche-differentiation theories suggest that environmental conditions may be more important. This dissertation tested the effects of dispersal, competition and predation on the structure of the seedling layer in a pristine Amazonian rainforest.
Seed-addition experiments broadly tested the relative importance of dispersal and environmental conditions on seedling community structure. Dispersal treatments explained more variance in community structure than did environmental conditions. This was the first variance-partitioning study to show that dispersal affects not only seedling density, but also diversity and species composition. Two more narrowly focused studies tested the intensity of competition among seedlings, and examined the effects of various mammalian predators on seedling recruitment. Evidence for inter-seedling competition was weak: individual growth and survival rates were generally unrelated to stem density, and seedlings' zones of influence rarely overlapped substantially. As predators, small and medium-sized mammals reduced seedling density, whereas large mammals had no detectable effects. Furthermore, small mammals generated a rare-species advantage, the fundamental element of frequency dependence.
Integrating the three studies, we suggest that dispersal is more important for seedling community structure than are environmental conditions. Given the low density of seedlings in Neotropical forests, we infer that competition among tree seedlings is largely irrelevant to their recruitment. Seed predators operated in a distinctly non-neutral manner, preferentially removing seeds of common and large-seeded species. Despite the powerful effects of predation, dispersal explained more variance in seedling recruitment than did all aspects of environmental variation (including predation). Taken together, the results of these three experiments support a view that, at least for young plants, and at small scales, dispersal may more strongly influence the species composition of tropical trees than environmental conditions, consistent with predictions from neutral models.
Paine, CET 1999. Holocene water quality and climate fluctuations in the New World District, Montana. 37 pp. Senior Honors Thesis, Dartmouth College, Hanover, NH. abstract
The question of remediating Fisher Creek to pre-mining conditions assumes importance with the closing of the New World District, Montana (NWD). Fisher Creek, which drains the area, currently has high acidity and metal concentrations. As well, there is a lack of local, temporally detailed descriptions of Holocene climate for the NWD. Both issues are addressed in this study, through the analysis of metal concentrations preserved in four 14C-dated wetland core profiles. In wetlands downwind of the NWD, metal concentrations, especially Fe, are found to increase with age. This strongly suggests that Fisher Creek has been contaminated throughout the Holocene, and that remediation is neither possible nor necessary for Fisher Creek. The 4,000 yr metal concentration record from a wetland upwind of the NWD suggests that the area was warmer and drier 3,000-1,000 ybp than earlier or later. The agreement of this depositional record with other published climate records for the region suggests that it could serve as an additional paleoclimate proxy.
| 2002–2007 | Ph.D. | Department of Biological Sciences |
| Louisiana State University | ||
| Baton Rouge, Louisiana USA | ||
| 2005 | Likelihood Methods in Forest Ecology | |
| Cary Institute for Ecosystem Studies | ||
| Millbrook, New York USA | ||
| 1995–1999 | B.A. | Departments of Biology and Earth Sciences |
| Dartmouth College | ||
| Hanover, New Hampshire USA | ||
| 1999 | Dartmouth Field Course in Tropical Ecology | |
| Costa Rica and Jamaica |
| 2009 | Biotropica Award for Excellence in Tropical Biology and Conservation |
| CNRS Amazonie grant, Co-PI with Chris Baraloto €9,000 | |
| 2008 | CNRS Amazonie grant, Co-PI with Natalia Norden €5,660 |
| 2007 | Daisy and William Luke Botany Teaching Assistant Award $500 |
| 2004 | OAS LASPAU Fellowship $2,500 |
| 2003 | Sigma Xi Grant-in-Aid of Research $1,000 |
| 2002–2006 | LSU Board of Regents Graduate Fellowship and enhancement $23,000 per year for four years |
| 1999 | Undergraduate Thesis with Honors ‘Holocene water quality and climate fluctuations in the New World District, Montana’ |
| 2008–Present | Postdoctoral Researcher with the BRIDGE Project, Kourou, French Guiana |
| 2003–2007 | Manu National Park and Los Amigos Biological Station, Peru. Dissertation research: ‘Ecological factors affecting the diversity of tropical tree seedlings’ |
| 2002 | Brownsberg Nature Park, Surinam. Initiated a vegetation-monitoring program, emphasizing the fruiting phenology of canopy trees |
| 2000 | Museo de Historia Natural, Santa Cruz, Bolivia. Collected, identified, and accessioned botanical specimens in Parque Nacional Noel Kempff Mercado |
| 2007 | Plant Taxonomy (Biol 4041) |
| 2006 | Mycology (Biol 4054) |
| 2008 | ESA Annual Meeting. Milwaukee, Wisconsin. ‘Quantifying habitat filtering in the forests of French Guiana using functional traits’ |
| 2008 | ATBC Annual Meeting. Paramaribo, Suriname. ‘Water availability, seedling performance, and diversity in a tropical forest’ |
| 2007 | ESA Annual Meeting. San Jose, California. ‘What shapes tropical seedling community structure? Seed dispersal versus environmental conditions’ |
| 2006 | ESA Annual Meeting. Memphis, Tennessee. ‘Predation, more than water availability, limits seedling recruitment’ |
| 2005 | ESA Annual Meeting. Montreal, Quebec. ‘Restricted zones of influence limit competition among seedlings of a tropical tree’ |
| 2005 | Museum of Natural Science, Louisiana State University. Baton Rouge, Louisiana. ‘Mammals, not competition, affect seedling recruitment’ |
| Reviewer for | Actualidades Biológicas, American Journal of Botany, Ecological Research, Ecology, Evolutionary Ecology, Journal of Ecology, Journal of Tropical Ecology, Journal of Vegetation Science, National Science Foundation, Oecologia |
| Professional Memberships | Ecological Society of America, Association for Tropical Biology and Conservation, Sigma Xi – The Scientific Research Society |
| Languages |
Native: English Fluent: French, Spanish, R, HTML, PHP, MySQL Studying: Portuguese, German, C |