Taking off the training wheels: the properties of a dynamic vegetation model without climate envelopes

Fisher, Rosie A.; Muszala, S.; Verteinstein, M.; Lawrence, P.; Xu, Chonggang; McDowell, N. G.; Knox, R. G.; Koven, Charles D.; Holm, Jennifer A.; Rogers, Brendan M.; Lawrence, David M.; Bonan, Gordon B.

doi:10.5194/gmdd-8-3293-2015

Cited by 49 publications

(104 citation statements)

References 144 publications

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“…Our simulated GPP reductions, if sufficient in magnitude and duration, could result in tree mortality in the teleconnected impacted areas. Future coupling of demography with existing global land model predictions could enable assessment of these potentially important die-off responses [44], as well as implementation of more realistic reductions in tree loss to drive scenarios (i.e., enabling assessments of ecological changes less drastic or occurring on shorter time-scales than conversion from forest to grassland biomes).…”

Section: Discussionmentioning

confidence: 99%

Synergistic Ecoclimate Teleconnections from Forest Loss in Different Regions Structure Global Ecological Responses

et al. 2016

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Forest loss in hotspots around the world impacts not only local climate where loss occurs, but also influences climate and vegetation in remote parts of the globe through ecoclimate teleconnections. The magnitude and mechanism of remote impacts likely depends on the location and distribution of forest loss hotspots, but the nature of these dependencies has not been investigated. We use global climate model simulations to estimate the distribution of ecologically-relevant climate changes resulting from forest loss in two hotspot regions: western North America (wNA), which is experiencing accelerated dieoff, and the Amazon basin, which is subject to high rates of deforestation. The remote climatic and ecological net effects of simultaneous forest loss in both regions differed from the combined effects of loss from the two regions simulated separately, as evident in three impacted areas. Eastern South American Gross Primary Productivity (GPP) increased due to changes in seasonal rainfall associated with Amazon forest loss and changes in temperature related to wNA forest loss. Eurasia’s GPP declined with wNA forest loss due to cooling temperatures increasing soil ice volume. Southeastern North American productivity increased with simultaneous forest loss, but declined with only wNA forest loss due to changes in VPD. Our results illustrate the need for a new generation of local-to-global scale analyses to identify potential ecoclimate teleconnections, their underlying mechanisms, and most importantly, their synergistic interactions, to predict the responses to increasing forest loss under future land use change and climate change.

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Section: Discussionmentioning

confidence: 99%

Synergistic Ecoclimate Teleconnections from Forest Loss in Different Regions Structure Global Ecological Responses

et al. 2016

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“…Scheiter et al, 2013;Fyllas et al, 2014;van Bodegom et al, 2014;Ali et al, 2015;Fisher et al, 2015;Meng et al, 2015;Sakschewski et al, 2015). Some trait-based modelling approaches have relied on empirical information on trait-trait and trait-environment covariation, but others (e.g.…”

Section: Implications For Modellingmentioning

confidence: 99%

Leaf nitrogen from first principles: field evidence for adaptive variation with climate

et al. 2017

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Abstract. Nitrogen content per unit leaf area (N area ) is a key variable in plant functional ecology and biogeochemistry. N area comprises a structural component, which scales with leaf mass per area (LMA), and a metabolic component, which scales with Rubisco capacity. The co-ordination hypothesis, as implemented in LPJ and related global vegetation models, predicts that Rubisco capacity should be directly proportional to irradiance but should decrease with increases in c i : c a and temperature because the amount of Rubisco required to achieve a given assimilation rate declines with increases in both. We tested these predictions using LMA, leaf δ 13 C, and leaf N measurements on complete species assemblages sampled at sites on a north-south transect from tropical to temperate Australia. Partial effects of mean canopy irradiance, mean annual temperature, and c i : c a (from δ 13 C) on N area were all significant and their directions and magnitudes were in line with predictions. Over 80 % of the variance in community-mean (ln) N area was accounted for by these predictors plus LMA. Moreover, N area could be decomposed into two components, one proportional to LMA (slightly steeper in N-fixers), and the other to Rubisco capacity as predicted by the co-ordination hypothesis. Trait gradient analysis revealed c i : c a to be perfectly plastic, while species turnover contributed about half the variation in LMA and N area .Interest has surged in methods to predict continuous leaftrait variation from environmental factors, in order to improve ecosystem models. Coupled carbon-nitrogen models require a method to predict N area that is more realistic than the widespread assumptions that N area is proportional to photosynthetic capacity, and/or that N area (and photosynthetic capacity) are determined by N supply from the soil. Our results indicate that N area has a useful degree of predictability, from a combination of LMA and c i : c a -themselves in part environmentally determined -with Rubisco activity, as predicted from local growing conditions. This finding is consistent with a "plant-centred" approach to modelling, emphasizing the adaptive regulation of traits. Models that account for biodiversity will also need to partition community-level trait variation into components due to phenotypic plasticity Published by Copernicus Publications on behalf of the European Geosciences Union. and/or genotypic differentiation within species vs. progressive species replacement, along environmental gradients. Our analysis suggests that variation in N area is about evenly split between these two modes.

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“…In a higher-fidelity land surface model, we might ideally allow numerous phenological algorithms to compete for light and water resources, and the ecosystem LAI profile would reflect the net behavior of the successful algorithms. This type of modeling is now theoretically possible (e.g., Fisher et al, 2010Fisher et al, , 2015, and will be investigated in future versions of the CLM.…”

Section: Impacts Of Modifications To the Modelmentioning

confidence: 99%

Environmental drivers of drought deciduous phenology in the Community Land Model

2015

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Abstract. Seasonal changes in plant leaf area have a substantial impact on global climate. The presence of leaves and the time when they appear affect surface roughness and albedo, and the gas exchange occurring between leaves and the atmosphere affects carbon dioxide concentrations and the global water system. Thus, correct predictions of plant phenological processes are important for understanding the present and future states of the Earth system. Here we compare plant phenology as estimated in the Community Land Model (CLM) to that derived from satellites in drought deciduous regions of the world. We reveal a subtle but important issue in the CLM: anomalous green-up during the dry season in many semi-arid parts of the world owing to rapid upwards water movement from wet to dry soil layers. We develop and implement a solution for this problem by introducing an additional criterion of minimum cumulative rainfall to the leafout trigger in the drought deciduous algorithm. We discuss some of the broader ecological impacts of this change and highlight some of the further steps that need to be taken to fully incorporate this change into the CLM framework.

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Taking off the training wheels: the properties of a dynamic vegetation model without climate envelopes

Cited by 49 publications

References 144 publications

Synergistic Ecoclimate Teleconnections from Forest Loss in Different Regions Structure Global Ecological Responses

Synergistic Ecoclimate Teleconnections from Forest Loss in Different Regions Structure Global Ecological Responses

Leaf nitrogen from first principles: field evidence for adaptive variation with climate

Environmental drivers of drought deciduous phenology in the Community Land Model

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