Paine, Charles Eliot Timothy

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Given Name
Charles Eliot Timothy
Charles Eliot Timothy
Surname
Paine
UNE Researcher ID
une-id:cpaine2
Email
cpaine2@une.edu.au
URI
Preferred Given Name
Tim
School/Department
School of Environmental and Rural Science

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Now showing 1 - 9 of 9
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    Publication
    Seed Predation by Neotropical Rain Forest Mammals Increases Diversity in Seedling Recruitment
    (John Wiley & Sons, Inc, 2007-12)
    Paine, C E Timothy 
    ;
    Beck, Harald
    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 pr?dation 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.
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    Publication
    Supplemental irrigation increases seedling performance and diversity in a tropical forest
    (Cambridge University Press, 2009-03)
    Paine, C E Timothy 
    ;
    Harms, Kyle E
    ;
    Ramos, Jess
    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.
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    Publication
    Tree Recruitment in an Empty Forest
    (John Wiley & Sons, Inc, 2008-06-01)
    Terborgh, John
    ;
    Nunez-Iturri, Gabriela
    ;
    Pitman, Nigel C A
    ;
    Valverde, Fernando H Cornejo
    ;
    Alvarez, Patricia
    ;
    Swamy, Varun
    ;
    Pringle, Elizabeth G
    ;
    Paine, C E Timothy 
    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.
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    Publication
    Seed predation by Neotropical rain forest mammals increases diversity in seedling recruitment
    (John Wiley & Sons, Inc, 2007-12)
    Paine, C E Timothy 
    ;
    Beck, Harald

    Seed dispersal and seedling recruitment (the transition of seeds to seedlings) set the spatiotemporal distribution of new individuals in plant communities. Many terrestrial rainforest 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), mediumsized 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.

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    Publication
    Quantifying the effects of seed arrival and environmental conditions on tropical seedling community structure
    (Springer, 2009-05)
    Paine, C E Timothy 
    ;
    Harms, Kyle E
    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 two years 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.
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    Diversity of the Volatile Organic Compounds Emitted by 55 Species of Tropical Trees: a Survey in French Guiana
    (Springer New York LLC, 2009-12)
    Courtois, Elodie A
    ;
    Blandinieres, Pierre-Alain
    ;
    Stien, Didier
    ;
    Bessiere, Jean-Marie
    ;
    Houel, Emeline
    ;
    Baraloto, Christopher
    ;
    Chave, Jerome
    ;
    Paine, C E Timothy 
    Volatile organic compounds (VOCs) are produced 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 (alpha-pinene and limonene) and two sesquiterpenes (beta-caryophyllene and alpha-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.
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    Regeneracion de arboles tropicales e implicaciones para el manejo de bosques naturales
    (Asociacion Espanola de Ecologia Terrestre, 2003)
    Harms, Kyle E
    ;
    Paine, C E Timothy 
    El reclutamiento exitoso desde semillas en bosques neotropicales implica una secuencia de etapas. La disponibilidad del polen y recursos consumibles por los arboles maternales puede limitar el numero de semillas producidas. La dispersion de semillas a un sitio determinado puede ser limitada por la densidad o la dispersion de arboles frutales, o por el agrupamiento impuesto por los procesos de dispersion 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 abioticos tales como la disponibilidad de agua, nutrientes y luz. Como la limitacion impuesta por estas etapas puede verse afectada por la explotacion forestal selectiva, es necesario investigar el efecto de las practicas selvicolas sobre cada etapa en la dinamica del bosque.
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    Publication
    Regeneración de los árboles tropicales e implicaciones para el manejo de bosques naturales
    (Asociacion Espanola de Ecologia Terrestre, 2003)
    Harms, Kyle E
    ;
    Paine, C E Timothy 

    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.

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    Publication
    Weak competition among tropical tree seedlings: Implications for species coexistence
    (Wiley-Blackwell Publishing, Inc, 2008-10)
    Paine, C E Timothy 
    ;
    Harms, Kyle E
    ;
    Schnitzer, Stefan A
    ;
    Carson, Walter P
    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.