Browsing by Author "Shipley, Bill"
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Item ‘‘Diminishing returns’’ in the scaling of functional leaf traits across and within species groups(National Academy of Sciences, 2007) Niklas, Karl J; Cobb, Edward D; Niinemets, Ulo; Reich, Peter B; Sellin, Arne; Shipley, Bill; Wright, Ian JMore than 5,000 measurements from 1,943 plant species were used to explore the scaling relationships among the foliar surface area and the dry, water, and nitrogen/phosphorus mass of mature individual leaves. Although they differed statistically, the exponents for the relationships among these variables were numerically similar among six species groups (ferns, graminoids, forbs, shrubs, trees, and vines) and within 19 individual species. In general, at least one among the many scaling exponents was <1.0, such that increases in one or more features influencing foliar function (e.g., surface area or living leaf mass) failed to keep pace with increases in mature leaf size. Thus, a general set of scaling relationships exists that negatively affects increases in leaf size. We argue that this set reflects a fundamental property of all plants and helps to explain why annual growth fails to keep pace with increases in total body mass across species.Item Fundamental tradeoffs generating the worldwide leaf economics spectrum(Ecological Society of America, 2006) Shipley, Bill; Lechowicz, Martin J; Wright, Ian; Reich, Peter BRecent 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.Item Gallery Talk with Bill Shipley - Asymmetry: Three-Dimensional Works from the Tweed Collection (2019-09-07)(2019) Shipley, Bill; University of Minnesota Duluth. Tweed Museum of ArtItem 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, DuccioCompetitor, 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.Item The global spectrum of plant form and function(2016) Díaz, Sandra; Kattge, Jens; Cornelissen, Johannes H C; Wright, Ian J; Lavorel, Sandra; Dray, Stéphane; Reu, Björn; Kleyer, Michael; Wirth, Christian; Prentice, I. Colin; Garnier, Eric; Bönisch, Gerhard; Westoby, Mark; Poorter, Hendrik; Reich, Peter B; Moles, Angela T; Dickie, John; Gillison, Andrew N; Zanne, Amy E; Chave, Jérôme; Wright, S. Joseph; Sheremet’ev, Serge N; Jactel, Hervé; Baraloto, Christopher; Cerabolini, Bruno; Pierce, Simon; Shipley, Bill; Kirkup, Donald; Casanoves, Fernando; Joswig, Julia S; Günther, Angela; Falczuk, Valeria; Rüger, Nadja; Mahecha, Miguel D; Gorné, Lucas DEarth is home to a remarkable diversity of plant forms and life histories, yet comparatively few essential trait combinations have proved evolutionarily viable in today’s terrestrial biosphere. By analysing worldwide variation in six major traits critical to growth, survival and reproduction within the largest sample of vascular plant species ever compiled, we found that occupancy of six-dimensional trait space is strongly concentrated, indicating coordination and trade-offs. Three-quarters of trait variation is captured in a two-dimensional global spectrum of plant form and function. One major dimension within this plane reflects the size of whole plants and their parts; the other represents the leaf economics spectrum, which balances leaf construction costs against growth potential. The global plant trait spectrum provides a backdrop for elucidating constraints on evolution, for functionally qualifying species and ecosystems, and for improving models that predict future vegetation based on continuous variation in plant form and function.Item Partitioning the effect of composition and diversity of tree communities on leaf litter decomposition and soil respiration(Wiley, 2016) Jewell, Mark Davidson; Shipley, Bill; Low-Décarie, Etienne; Tobner, Cornelia M; Paquette, Alain; Messier, Christian; Reich, Peter BThe decomposition of plant material is an important ecosystem process influencing both carbon cycling and soil nutrient availability. Quantifying how plant diversity affects decomposition is thus crucial for predicting the effect of the global decline in plant diversity on ecosystem functioning. Plant diversity could affect the decomposition process both directly through the diversity of the litter, and/or indirectly through the diversity of the host plant community and its affect on the decomposition environment. Using a biodiversity experiment with trees in which both functional and taxonomic diversity were explicitly manipulated independently, we tested the effects of the functional diversity and identity of the living trees separately and in combination with the functional diversity and identity of the decomposing litter on rates of litter decomposition and soil respiration. Plant traits, predominantly leaf chemical and physical traits, were correlated with both litter decomposition and soil respiration rates. Surface litter decomposition, quantified by mass loss in litterbags, was best explained by abundance-weighted mean trait values of tree species from which the litter was assembled (functional identity). In contrast, soil respiration, which includes decomposition of dissolved organic carbon and root respiration, was best explained by the variance in trait values of the host trees (functional diversity). This research provides insight into the effect of loss of tree diversity in forests on soil processes. Such understanding is essential to predicting changes in the global carbon budget brought on by biodiversity loss.Item 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 BThe 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.Item A traits-based test of the home-field advantage in mixed-species tree litter decomposition(Oxford University Press, 2015) Jewell, Mark Davidson; Shipley, Bill; Paquette, Alain; Messier, Christian; Reich, Peter BBackground and Aims Litter often decomposes faster in its environment of origin (at ‘home’) than in a foreign environment (‘away’), which has become known as the home-field advantage (HFA). However, many studies have highlighted the conditional nature of the HFA, suggesting that current understanding of this phenomenon is not yet sufficient to generalize across systems. Methods The HFA hypothesis was tested for mono-specific and mixed-species litter using a tree-based experiment that manipulated the functional identity and diversity of the host tree community. Litter types of varying quality were transplanted between several host tree communities and decomposition rates were measured using litterbags. Since the decomposer community should respond to traits of the litter input and not their taxonomic identity, a traits-based index of litter–tree similarity was developed. Key Results Mono-specific litter exhibited HFA, but when the same litter was decomposed in mixture, this trend was not observed. Mixed-species litter decomposed on average no faster or slower than monoculture litter and exhibited both positive and negative species interactions. These non-additive interactions of decomposition rates in mixture were influenced by the degree of similarity between litter and tree traits. Both synergistic and antagonistic interactions decreased in magnitude with increasing litter–tree similarity such that mixture rates were predictable from monocultures. Conclusions The HFA occurred more strongly for mono-specific litter than for the litter types mixed together because interactions between species may have masked this effect. However, when expressed as a function of trait similarity between litters and tree communities, the HFA was not detected.Item Tweevenings: Talk about Art at Tweed! (2013-10-01)(2013) Shipley, Bill; Biederman, Charles; University of Minnesota Duluth. Tweed Museum of Art