ORCID Profile
0000-0002-1345-4138
Current Organisation
Indiana University Bloomington
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Publisher: Elsevier BV
Date: 09-2018
Publisher: American Association for the Advancement of Science (AAAS)
Date: 25-05-2018
Abstract: Hülsmann and Hartig suggest that ecological mechanisms other than specialized natural enemies or intraspecific competition contribute to our estimates of conspecific negative density dependence (CNDD). To address their concern, we show that our results are not the result of a methodological artifact and present a null-model analysis that demonstrates that our original findings—(i) stronger CNDD at tropical relative to temperate latitudes and (ii) a latitudinal shift in the relationship between CNDD and species abundance—persist even after controlling for other processes that might influence spatial relationships between adults and recruits.
Publisher: Elsevier BV
Date: 2021
Publisher: Wiley
Date: 28-07-2022
DOI: 10.1002/ECY.3790
Abstract: The microbial priming effect-the decomposition of soil organic carbon (SOC) induced by plant inputs-has long been considered an important driver of SOC dynamics, yet we have limited understanding about the direction, intensity, and drivers of priming across ecosystem types and biomes. This gap hinders our ability to predict how shifts in litter inputs under global change can affect climate feedbacks. Here, we synthesized 18,919 observations of CO
Publisher: Wiley
Date: 07-10-2020
DOI: 10.1111/GCB.15353
Publisher: Wiley
Date: 02-06-2017
DOI: 10.1111/GCB.13752
Abstract: Rising levels of atmospheric CO
Publisher: Wiley
Date: 08-05-2018
DOI: 10.1111/GEB.12747
Publisher: Springer Science and Business Media LLC
Date: 19-08-2019
DOI: 10.1038/S41559-019-0958-3
Abstract: Direct quantification of terrestrial biosphere responses to global change is crucial for projections of future climate change in Earth system models. Here, we synthesized ecosystem carbon-cycling data from 1,119 experiments performed over the past four decades concerning changes in temperature, precipitation, CO
Publisher: Springer Science and Business Media LLC
Date: 25-02-2021
DOI: 10.1038/S41597-021-00851-9
Abstract: A Correction to this paper has been published: 0.1038/s41597-021-00851-9.
Publisher: Wiley
Date: 19-08-2013
DOI: 10.1111/NPH.12440
Abstract: The rhizosphere priming effect ( RPE ) is a mechanism by which plants interact with soil functions. The large impact of the RPE on soil organic matter decomposition rates (from 50% reduction to 380% increase) warrants similar attention to that being paid to climatic controls on ecosystem functions. Furthermore, global increases in atmospheric CO 2 concentration and surface temperature can significantly alter the RPE . Our analysis using a game theoretic model suggests that the RPE may have resulted from an evolutionarily stable mutualistic association between plants and rhizosphere microbes. Through model simulations based on microbial physiology, we demonstrate that a shift in microbial metabolic response to different substrate inputs from plants is a plausible mechanism leading to positive or negative RPE s. In a case study of the Duke Free‐Air CO 2 Enrichment experiment, performance of the PhotoCent model was significantly improved by including an RPE ‐induced 40% increase in soil organic matter decomposition rate for the elevated CO 2 treatment – demonstrating the value of incorporating the RPE into future ecosystem models. Overall, the RPE is emerging as a crucial mechanism in terrestrial ecosystems, which awaits substantial research and model development. Contents Summary 31 I. Introduction 31 II. Magnitude and driving variables of the rhizosphere priming effect 32 III. Will global environmental change alter the RPE? 34 IV. A game theoretic model: is priming the result of evolutionarily stable strategies? 35 V. A microbial physiology‐based model: simulating positive and negative RPEs 37 VI. A case study: matching simulation results with observations at the Duke FACE 38 VII. Research needs and future perspectives 39 Acknowledgements 41 References 41
Publisher: American Association for the Advancement of Science (AAAS)
Date: 25-05-2018
Abstract: Chisholm and Fung claim that our method of estimating conspecific negative density dependence (CNDD) in recruitment is systematically biased, and present an alternative method that shows no latitudinal pattern in CNDD. We demonstrate that their approach produces strongly biased estimates of CNDD, explaining why they do not detect a latitudinal pattern. We also address their methodological concerns using an alternative distance-weighted approach, which supports our original findings of a latitudinal gradient in CNDD and a latitudinal shift in the relationship between CNDD and species abundance.
Publisher: Springer Science and Business Media LLC
Date: 09-07-2020
DOI: 10.1038/S41597-020-0534-3
Abstract: The FLUXNET2015 dataset provides ecosystem-scale data on CO 2 , water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible.
Publisher: Wiley
Date: 19-04-2018
DOI: 10.1111/GEB.12738
Publisher: Wiley
Date: 13-09-2021
Abstract: Mycorrhizal fungi play a central role in plant nutrition and nutrient cycling, yet our understanding on their effects on free‐living microbes, soil carbon (C) decomposition and soil CO 2 fluxes remains limited. Here we used trenches lined with mesh screens of varying sizes to isolate mycorrhizal hyphal effects on soil C dynamics in subtropical successional forests. We found that the presence of mycorrhizal hyphae suppressed soil CO 2 fluxes by 17% in early‐successional forests, but enhanced CO 2 losses by 20% and 32% in mid‐ and late‐successional forests respectively. The inhibitory effects of mycorrhizal fungi on soil CO 2 fluxes in the young stands were associated with changes in soil nitrogen (N) mineralization and microbial activities, suggesting that competition between mycorrhizae and saprotrophs for N likely suppressed soil C decomposition. In the mid‐ and late‐successional stands, mycorrhizal enhancement of CO 2 release from soil likely resulted from both hyphal respiration and mycorrhizal‐induced acceleration of organic matter decay. Synthesis . Our results highlight the sensitivity of mycorrhizal fungi‐saprotroph interactions to shifts in nutrient availability and demand, with important consequences for soil carbon dynamics particularly in ecosystems with low nutrient conditions. Incorporating such interactions into models should improve the simulations of forest biogeochemical cycles under global change.
Publisher: Wiley
Date: 30-05-2019
Publisher: American Association for the Advancement of Science (AAAS)
Date: 30-06-2017
Abstract: Negative interaction among plant species is known as conspecific negative density dependence (CNDD). This ecological pattern is thought to maintain higher species ersity in the tropics. LaManna et al. tested this hypothesis by comparing how tree species ersity changes with the intensity of local biotic interactions in tropical and temperate latitudes (see the Perspective by Comita). Stronger local specialized biotic interactions seem to prevent erosion of bio ersity in tropical forests, not only by limiting populations of common species, but also by strongly stabilizing populations of rare species, which tend to show higher CNDD in the tropics. Science , this issue p. 1389 see also p. 1328
Publisher: Springer Science and Business Media LLC
Date: 22-09-2021
DOI: 10.1038/S41586-021-03939-9
Abstract: The leaf economics spectrum 1,2 and the global spectrum of plant forms and functions 3 revealed fundamental axes of variation in plant traits, which represent different ecological strategies that are shaped by the evolutionary development of plant species 2 . Ecosystem functions depend on environmental conditions and the traits of species that comprise the ecological communities 4 . However, the axes of variation of ecosystem functions are largely unknown, which limits our understanding of how ecosystems respond as a whole to anthropogenic drivers, climate and environmental variability 4,5 . Here we derive a set of ecosystem functions 6 from a dataset of surface gas exchange measurements across major terrestrial biomes. We find that most of the variability within ecosystem functions (71.8%) is captured by three key axes. The first axis reflects maximum ecosystem productivity and is mostly explained by vegetation structure. The second axis reflects ecosystem water-use strategies and is jointly explained by variation in vegetation height and climate. The third axis, which represents ecosystem carbon-use efficiency, features a gradient related to aridity, and is explained primarily by variation in vegetation structure. We show that two state-of-the-art land surface models reproduce the first and most important axis of ecosystem functions. However, the models tend to simulate more strongly correlated functions than those observed, which limits their ability to accurately predict the full range of responses to environmental changes in carbon, water and energy cycling in terrestrial ecosystems 7,8 .
Publisher: Wiley
Date: 27-01-2015
DOI: 10.1111/NPH.13303
Abstract: Although it is increasingly being recognized that roots play a key role in soil carbon (C) dynamics, the magnitude and direction of these effects are unknown. Roots can accelerate soil C losses by provisioning microbes with energy to decompose organic matter or impede soil C losses by enhancing microbial competition for nutrients. We experimentally reduced belowground C supply to soils via tree girdling, and contrasted responses in control and girdled plots for three consecutive growing seasons. We hypothesized that decreases in belowground C supply would have stronger effects in plots dominated by ectomycorrhizal ( ECM ) trees rather than arbuscular mycorrhizal ( AM ) trees. In ECM ‐dominated plots, girdling decreased the activity of enzymes that break down soil organic matter ( SOM ) by c . 40%, indicating that, in control plots, C supply from ECM roots primes microbial decomposition. In AM ‐dominated plots, girdling had little effect on SOM ‐degrading enzymes, but increased the decomposition of AM leaf litter by c . 43%, suggesting that, in control plots, AM roots may intensify microbial competition for nutrients. Our findings indicate that root‐induced changes in soil processes depend on forest composition, and that shifts in the distribution of AM and ECM trees owing to climate change may determine soil C gains and losses.
Publisher: Springer Science and Business Media LLC
Date: 24-03-2021
DOI: 10.1038/S41586-021-03306-8
Abstract: Terrestrial ecosystems remove about 30 per cent of the carbon dioxide (CO
No related grants have been discovered for Richard Phillips.