Showing papers by "Nikolaos M. Fyllas published in 2015"
Australian National University1, University of Western Sydney2, University of Minnesota3, Carnegie Institution for Science4, Institut national de la recherche agronomique5, Max Planck Society6, Commonwealth Scientific and Industrial Research Organisation7, James Cook University8, Pontifical Catholic University of Peru9, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto10, Purdue University11, National and Kapodistrian University of Athens12, Princeton University13, University of Leeds14, Lamont–Doherty Earth Observatory15, University of New Hampshire16, University of Edinburgh17, University of Western Australia18, Imperial College London19, University of Waikato20, Environmental Change Institute21, Macquarie University22, University of Exeter23, University of Toronto24, National Parks Board25, Estonian University of Life Sciences26, Wageningen University and Research Centre27, Colorado State University28, University of Florida29, Smithsonian Tropical Research Institute30, University of Canterbury31, University of Regina32, Spanish National Research Council33, University of Peradeniya34, Leipzig University35, Chinese Academy of Sciences36
TL;DR: A new global database of Rdark and associated leaf traits is analyzed and values at any given Vcmax or leaf nitrogen concentration were higher in herbs than in woody plants, and variation in Rdark among species and across global gradients in T and aridity is highlighted.
Abstract: Leaf dark respiration (R-dark) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of R-dark and associated leaf traits. Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in R-dark. Area-based R-dark at the prevailing average daily growth temperature (T) of each siteincreased only twofold from the Arctic to the tropics, despite a 20 degrees C increase in growing T (8-28 degrees C). By contrast, R-dark at a standard T (25 degrees C, R-dark(25)) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher R-dark(25) at a given photosynthetic capacity (V-cmax(25)) or leaf nitrogen concentration ([N]) than species at warmer sites. R-dark(25) values at any given V-cmax(25) or [N] were higher in herbs than in woody plants. The results highlight variation in R-dark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of R-dark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs).
310 citations
Nelson Mandela Metropolitan University1, National and Kapodistrian University of Athens2, Commonwealth Scientific and Industrial Research Organisation3, Royal Botanic Gardens4, University of Western Australia5, University of Cádiz6, University of KwaZulu-Natal7, University of California, Los Angeles8, California Institute of Technology9
TL;DR: In this article, the role of stable Pleistocene climate and Cenozoic topography in explaining variation in regional richness of Mediterranean-climate ecosystems (MCEs) was assessed.
Abstract: Aim
Although all five of the major mediterranean-climate ecosystems (MCEs) of the world are recognized as loci of high plant species diversity and endemism, they show considerable variation in regional-scale richness. Here, we assess the role of stable Pleistocene climate and Cenozoic topography in explaining variation in regional richness of the globe's MCEs. We hypothesize that older, more climatically stable MCEs would support more species, because they have had more time for species to accumulate than MCEs that were historically subject to greater topographic upheavals and fluctuating climates.
Location
South-western Africa (Cape), south-western Australia, California, central Chile and the eastern (Greece) and western (Spain) Mediterranean Basin.
Methods
We estimated plant diversity for each MCE as the intercepts of species–area curves that are homogeneous in slope across all regions. We used two down-scaled global circulation models of the Last Glacial Maximum (LGM) to quantify climate stability by comparing the change in the location of MCEs between the LGM and present. We quantified the Cenozoic topographic stability of each MCE by comparing contemporary topographic profiles with those present in the late Oligocene and the early Pliocene.
Results
The most diverse MCEs – Cape and Australia – had the highest Cenozoic environmental stability, and the least diverse – Chile and California – had the lowest stability.
Main conclusions
Variation in plant diversity in MCEs is likely to be a consequence not of differences in diversification rates, but rather the persistence of numerous pre-Pliocene clades in the more stable MCEs. The extraordinary plant diversity of the Cape is a consequence of the combined effects of both mature and recent radiations, the latter associated with increased habitat heterogeneity produced by mild tectonic uplift in the Neogene.
109 citations
James Cook University1, University of Leeds2, University of Edinburgh3, Karlsruhe Institute of Technology4, National Institute of Amazonian Research5, Forest Research Institute6, Commonwealth Scientific and Industrial Research Organisation7, Tropical Forest Research Institute8, Universidade do Estado de Mato Grosso9, Royal Botanic Garden Edinburgh10, University of Yaoundé11, University of Brasília12, Forestry Commission13, École Normale Supérieure14, World Wide Fund for Nature15, Conservation International16, University College London17, Imperial College London18
TL;DR: In this article, the authors present detailed stratified floristic and structural analyses for forest and savanna stands located mostly within zones of transition (where both vegetation types occur in close proximity) in Africa, South America and Australia.
Abstract: Through interpretations of remote-sensing data and/or theoretical propositions, the idea that forest and savanna represent "alternative stable states" is gaining increasing acceptance Filling an observational gap, we present detailed stratified floristic and structural analyses for forest and savanna stands located mostly within zones of transition (where both vegetation types occur in close proximity) in Africa, South America and Australia Woody plant leaf area index variation was related to tree canopy cover in a similar way for both savanna and forest with substantial overlap between the two vegetation types As total woody plant canopy cover increased, so did the relative contribution of middle and lower strata of woody vegetation Herbaceous layer cover declined as woody cover increased This pattern of understorey grasses and herbs progressively replaced by shrubs as the canopy closes over was found for both savanna and forests and on all continents Thus, once subordinate woody canopy layers are taken into account, a less marked transition in woody plant cover across the savanna–forest-species discontinuum is observed compared to that inferred when trees of a basal diameter > 01 m are considered in isolation This is especially the case for shrub-dominated savannas and in taller savannas approaching canopy closure An increased contribution of forest species to the total subordinate cover is also observed as savanna stand canopy closure occurs Despite similarities in canopy-cover characteristics, woody vegetation in Africa and Australia attained greater heights and stored a greater amount of above-ground biomass than in South America Up to three times as much above-ground biomass is stored in forests compared to savannas under equivalent climatic conditions Savanna–forest transition zones were also found to typically occur at higher precipitation regimes for South America than for Africa Nevertheless, consistent across all three continents coexistence was found to be confined to a well-defined edaphic–climate envelope with soil and climate the key determinants of the relative location of forest and savanna stands Moreover, when considered in conjunction with the appropriate water availability metrics, it emerges that soil exchangeable cations exert considerable control on woody canopy-cover extent as measured in our pan-continental (forest + savanna) data set Taken together these observations do not lend support to the notion of alternate stable states mediated through fire feedbacks as the prime force shaping the distribution of the two dominant vegetation types of the tropical lands
76 citations