Browsing by Subject "comparative ecology"

Now showing 1 - 3 of 3
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    Fundamental tradeoffs generating the worldwide leaf economics spectrum
    (Ecological Society of America, 2006) Shipley, Bill; Lechowicz, Martin J; Wright, Ian; Reich, Peter B
    Recent work has identified a worldwide “economic” spectrum of correlated leaf traits that affects global patterns of nutrient cycling and primary productivity and that is used to calibrate vegetation–climate models. The correlation patterns are displayed by species from the arctic to the tropics and are largely independent of growth form or phylogeny. This generality suggests that unidentified fundamental constraints control the return of photosynthates on investments of nutrients and dry mass in leaves. Using novel graph theoretic methods and structural equation modeling, we show that the relationships among these variables can best be explained by assuming (1) a necessary trade-off between allocation to structural tissues versus liquid phase processes and (2) an evolutionary trade-off between leaf photosynthetic rates, construction costs, and leaf longevity.
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    A global method for calculating plant CSR ecological strategies applied across biomes world‐wide
    (Wiley, 2017) Pierce, Simon; Negreiros, Daniel; Cerabolini, Bruno E. L.; Kattge, Jens; Díaz, Sandra; Kleyer, Michael; Shipley, Bill; Wright, Stuart Joseph; Soudzilovskaia, Nadejda A; Onipchenko, Vladimir G.; van Bodegom, Peter M; Frenette-Dussault, Cedric; Weiher, Evan; Pinho, Bruno X; Cornelissen, Johannes H. C.; Grime, John Philip; Thompson, Ken; Hunt, Roderick; Wilson, Peter J,; Buffa, Gabriella; Nyakunga, Oliver C; Reich, Peter B; Caccianiga, Marco; Mangili, Federico; Ceriani, Roberta M; Luzzaro, Alessandra; Brusa, Guido; Siefert, Andrew; Barbosa, Newton P. U.; Chapin, Francis Stuart, III; Cornwell, William K; Fang, Jingyun; Fernandes, Geraldo Wilson; Garnier, Eric; Le Stradic, Soizig; Peñuelas, Josep; Melo, Felipe P. L.; Slaviero, Antonio; Tabarelli, Marcelo; Tampucci, Duccio
    Competitor, stress-tolerator, ruderal (CSR) theory is a prominent plant functional strategy scheme previously applied to local floras. Globally, the wide geographic and phylogenetic coverage of available values of leaf area (LA), leaf dry matter content (LDMC) and specific leaf area (SLA) (representing, respectively, interspecific variation in plant size and conservative vs. acquisitive resource economics) promises the general application of CSR strategies across biomes, including the tropical forests hosting a large proportion of Earth's diversity. We used trait variation for 3068 tracheophytes (representing 198 families, six continents and 14 biomes) to create a globally calibrated CSR strategy calculator tool and investigate strategy–environment relationships across biomes world-wide. Due to disparity in trait availability globally, co-inertia analysis was used to check correspondence between a ‘wide geographic coverage, few traits’ data set and a ‘restricted coverage, many traits’ subset of 371 species for which 14 whole-plant, flowering, seed and leaf traits (including leaf nitrogen content) were available. CSR strategy/environment relationships within biomes were investigated using fourth-corner and RLQ analyses to determine strategy/climate specializations. Strong, significant concordance (RV = 0·597; P < 0·0001) was evident between the 14 trait multivariate space and when only LA, LDMC and SLA were used. Biomes such as tropical moist broadleaf forests exhibited strategy convergence (i.e. clustered around a CS/CSR median; C:S:R = 43:42:15%), with CS-selection associated with warm, stable situations (lesser temperature seasonality), with greater annual precipitation and potential evapotranspiration. Other biomes were characterized by strategy divergence: for example, deserts varied between xeromorphic perennials such as Larrea divaricata, classified as S-selected (C:S:R = 1:99:0%) and broadly R-selected annual herbs (e.g. Claytonia perfoliata; R/CR-selected; C:S:R = 21:0:79%). Strategy convergence was evident for several growth habits (e.g. trees) but not others (forbs). The CSR strategies of vascular plants can now be compared quantitatively within and between biomes at the global scale. Through known linkages between underlying leaf traits and growth rates, herbivory and decomposition rates, this method and the strategy–environment relationships it elucidates will help to predict which kinds of species may assemble in response to changes in biogeochemical cycles, climate and land use.
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    Reinforcing loose foundation stones in trait-based plant ecology
    (Springer, 2016) Shipley, Bill; De Bello, Francesco; Cornelissen, J. Hans C; Laliberté, Etienne; Laughlin, Daniel C; Reich, Peter B
    The promise of “trait-based” plant ecology is one of generalized prediction across organizational and spatial scales, independent of taxonomy. This promise is a major reason for the increased popularity of this approach. Here, we argue that some important foundational assumptions of trait-based ecology have not received sufficient empirical evaluation. We identify three such assumptions and, where possible, suggest methods of improvement: (i) traits are functional to the degree that they determine individual fitness, (ii) intraspecific variation in functional traits can be largely ignored, and (iii) functional traits show general predictive relationships to measurable environmental gradients.