scholarly journals Potential Transient Response of Terrestrial Vegetation and Carbon in Northern North America from Climate Change

Climate ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 113
Author(s):  
Steven A. Flanagan ◽  
George C. Hurtt ◽  
Justin P. Fisk ◽  
Ritvik Sahajpal ◽  
Maosheng Zhao ◽  
...  
Keyword(s):  
Climate Change ◽  
North America ◽  
Time Scales ◽  
Transient Response ◽  
Landscape Heterogeneity ◽  
Carbon Sink ◽  
Terrestrial Ecosystems ◽  
Ecosystem Model ◽  
Terrestrial Vegetation ◽  
Equilibrium Response

Terrestrial ecosystems and their vegetation are linked to climate. With the potential of accelerated climate change from anthropogenic forcing, there is a need to further evaluate the transient response of ecosystems, their vegetation, and their influence on the carbon balance, to this change. The equilibrium response of ecosystems to climate change has been estimated in previous studies in global domains. However, research on the transient response of terrestrial vegetation to climate change is often limited to domains at the sub-continent scale. Estimation of the transient response of vegetation requires the use of mechanistic models to predict the consequences of competition, dispersal, landscape heterogeneity, disturbance, and other factors, where it becomes computationally prohibitive at scales larger than sub-continental. Here, we used a pseudo-spatial ecosystem model with a vegetation migration sub-model that reduced computational intensity and predicted the transient response of vegetation and carbon to climate change in northern North America. The ecosystem model was first run with a current climatology at half-degree resolution for 1000 years to establish current vegetation and carbon distribution. From that distribution, climate was changed to a future climatology and the ecosystem model run for an additional 2000 simulation years. A model experimental design with different combinations of vegetation dispersal rates, dispersal modes, and disturbance rates produced 18 potential change scenarios. Results indicated that potential redistribution of terrestrial vegetation from climate change was strongly impacted by dispersal rates, moderately affected by disturbance rates, and marginally impacted by dispersal mode. For carbon, the sensitivities were opposite. A potential transient net carbon sink greater than that predicted by the equilibrium response was estimated on time scales of decades–centuries, but diminished over longer time scales. Continued research should further explore the interactions between competition, dispersal, and disturbance, particularly in regards to vegetation redistribution.

Inferring non-steady-state terrestrial vegetation carbon turnover times from multi-decadal space-borne observations on global scale

2020 ◽  
Author(s):  
Naixin Fan ◽  
Simon Besnard ◽  
Maurizio Santoro ◽  
Oliver Cartus ◽  
Nuno Carvalhais
Keyword(s):  
Climate Change ◽  
Steady State ◽  
Carbon Fixation ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Turnover Time ◽  
Terrestrial Vegetation ◽  
Time Step

<p>The global biomass is determined by the vegetation turnover times (τ) and carbon fixation through photosynthesis. Vegetation turnover time is a central parameter that not only partially determines the terrestrial carbon sink but also the response of terrestrial vegetation to the future changes in climate. However, the change of magnitude, spatial patterns and uncertainties in τ as well as the sensitivity of these processes to climate change is not well understood due to lack of observations on global scale. In this study, we explore a new dataset of annual above-ground biomass (AGB) change from 1993 to 2018 from spaceborne scatterometer observations. Using the long-term, spatial-explicit global dynamic dataset, we investigated how τ change over almost three decades including the uncertainties. Previous estimations of τ under steady-state assumption can now be challenged acknowledging that terrestrial ecosystems are, for the most of cases, not in balance. In this study, we explore this new dataset to derive global maps of τ in non-steady-state for different periods of time. We used a non-steady-state carbon model in which the change of AGB is a function of Gross Primary Production (GPP) and τ (ΔAGB = α*GPP-AGB/ τ). The parameter α represents the percentage of incorporation of carbon from GPP to biomass. By exploring the AGB change in 5 to 10 years of time step, we were able to infer τ and α from the observations of AGB and GPP change by solving the linear equation. We show how τ changes after potential disturbances in the early 2000s in comparison to the previous decade. We also show the spatial distributions of α from the change of AGB. By accessing the change in biomass, τ and α as well as their associated uncertainties, we provide a comprehensive diagnostic on the vegetation dynamics and the potential response of biomass to disturbance and to climate change.   </p><p></p><p></p><p></p><p></p><p></p><p></p>

scholarly journals Reduced resilience of terrestrial ecosystems locally is not reflected on a global scale

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Yuhao Feng ◽  
Haojie Su ◽  
Zhiyao Tang ◽  
Shaopeng Wang ◽  
Xia Zhao ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Vegetation Index ◽  
Global Climate ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Ecological Resilience ◽  
Terrestrial Vegetation ◽  
Ecosystem Resilience

AbstractGlobal climate change likely alters the structure and function of vegetation and the stability of terrestrial ecosystems. It is therefore important to assess the factors controlling ecosystem resilience from local to global scales. Here we assess terrestrial vegetation resilience over the past 35 years using early warning indicators calculated from normalized difference vegetation index data. On a local scale we find that climate change reduced the resilience of ecosystems in 64.5% of the global terrestrial vegetated area. Temperature had a greater influence on vegetation resilience than precipitation, while climate mean state had a greater influence than climate variability. However, there is no evidence for decreased ecological resilience on larger scales. Instead, climate warming increased spatial asynchrony of vegetation which buffered the global-scale impacts on resilience. We suggest that the response of terrestrial ecosystem resilience to global climate change is scale-dependent and influenced by spatial asynchrony on the global scale.

scholarly journals Soil nitrogen cycle unresponsive to decadal long climate change in a Tasmanian grassland

2019 ◽  
Vol 147 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Tobias Rütting ◽  
Mark J. Hovenden
Keyword(s):  
Climate Change ◽  
Atmospheric Carbon Dioxide ◽  
Carbon Sink ◽  
Vegetation Type ◽  
Terrestrial Ecosystems ◽  
Soil N ◽  
Mineral N ◽  
N Dynamics ◽  
Terrestrial Carbon Sink ◽  
Soil Nitrogen Cycle

AbstractIncreases in atmospheric carbon dioxide (CO2) and global air temperature affect all terrestrial ecosystems and often lead to enhanced ecosystem productivity, which in turn dampens the rise in atmospheric CO2 by removing CO2 from the atmosphere. As most terrestrial ecosystems are limited in their productivity by the availability of nitrogen (N), there is concern about the persistence of this terrestrial carbon sink, as these ecosystems might develop a progressive N limitation (PNL). An increase in the gross soil N turnover may alleviate PNL, as more mineral N is made available for plant uptake. So far, climate change experiments have mainly manipulated one climatic factor only, but there is evidence that single-factor experiments usually overestimate the effects of climate change on terrestrial ecosystems. In this study, we investigated how simultaneous, decadal-long increases in CO2 and temperature affect the soil gross N dynamics in a native Tasmanian grassland under C3 and C4 vegetation. Our laboratory 15N labeling experiment showed that average gross N mineralization ranged from 4.9 to 11.3 µg N g−1 day−1 across the treatment combinations, while gross nitrification was about ten-times lower. Considering all treatment combinations, no significant effect of climatic treatments or vegetation type (C3 versus C4 grasses) on soil N cycling was observed.

scholarly journals Plant-microbe Symbioses Reveal Underestimation of Modeled Climate Impacts

2018 ◽  
Author(s):  
Mingjie Shi ◽  
Joshua B. Fisher ◽  
Richard P. Phillips ◽  
Edward R. Brzostek
Keyword(s):  
Climate Change ◽  
Nitrogen Limitation ◽  
Climate Models ◽  
Climate Model ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Global Climate ◽  
Terrestrial Ecosystems ◽  
Climate Impacts ◽  
Microbial Symbionts

Abstract. The extent to which terrestrial ecosystems slow climate change by sequestering carbon hinges in part on nutrient limitation. We used a coupled carbon–climate model that accounts for the carbon cost to plants of supporting nitrogen-acquiring microbial symbionts to explore how nitrogen limitation affects global climate. The carbon costs of supporting symbiotic nitrogen uptake reduced net primary production, with the largest absolute effects occurring at low-latitudes and the largest relative changes occurring at high-latitudes. The largest impact occurred in high-latitude ecosystems, where such costs were estimated to increase temperature by 1.0 °C and precipitation by 9 mm yr−1. Globally, our model predicted that nitrogen limitation enhances temperature and decreases precipitation; as such, our results suggest that carbon expenditures to support nitrogen-acquiring microbial symbionts have critical consequences for Earth’s climate, and that carbon–climate models that omit these processes will over-predict the land carbon sink and under-predict climate change.

scholarly journals Past and future global transformation of terrestrial ecosystems under climate change

Science ◽  
2018 ◽  
Vol 361 (6405) ◽  
pp. 920-923 ◽  
Author(s):  
Connor Nolan ◽  
Jonathan T. Overpeck ◽  
Judy R. M. Allen ◽  
Patricia M. Anderson ◽  
Julio L. Betancourt ◽  
...  
Keyword(s):  
Climate Change ◽  
Structural Changes ◽  
Global Climate ◽  
Terrestrial Ecosystems ◽  
Terrestrial Vegetation ◽  
Emission Scenarios ◽  
Last Glacial ◽  
Alternative Future ◽  
High Emission ◽  
The Last Glacial

Impacts of global climate change on terrestrial ecosystems are imperfectly constrained by ecosystem models and direct observations. Pervasive ecosystem transformations occurred in response to warming and associated climatic changes during the last glacial-to-interglacial transition, which was comparable in magnitude to warming projected for the next century under high-emission scenarios. We reviewed 594 published paleoecological records to examine compositional and structural changes in terrestrial vegetation since the last glacial period and to project the magnitudes of ecosystem transformations under alternative future emission scenarios. Our results indicate that terrestrial ecosystems are highly sensitive to temperature change and suggest that, without major reductions in greenhouse gas emissions to the atmosphere, terrestrial ecosystems worldwide are at risk of major transformation, with accompanying disruption of ecosystem services and impacts on biodiversity.

scholarly journals Ecological restoration and rising CO2 enhance carbon sink, counteracting climate change in northeastern China

2021 ◽  
Author(s):  
Binbin Huang ◽  
Fei Lu ◽  
Xiaoke Wang ◽  
Xing Wu ◽  
Lu Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
Ecological Restoration ◽  
Carbon Sink ◽  
Remote Sensing Data ◽  
Terrestrial Ecosystems ◽  
Source Control ◽  
Impact Of Climate Change ◽  
The Individual ◽  
Business As Usual ◽  
The Impact

Abstract The impact of climate change, rising CO2, land use/land cover change (LC) and land management (LM) on carbon cycle in terrestrial ecosystems has been widely reported. However, rare studies have been conducted to clarify the impact of climate change and rising CO2 on carbon sink contributed by ecological restoration projects (ERPs). To better understand the impact of climate change and rising CO2 on ERPs, we took the Beijing-Tianjin Sand Source Control Project (BTSSCP) zone as an example to set different scenarios to distinguish the confounding effects of these factors on regional carbon budget based on remote sensing data-driven model. Compared with business as usual (BAU), our results showed climate change caused carbon loss of 78.97 Tg. On the contrary, ERPs contributed approximately 199.88 Tg C sink in forest and grassland. Furthermore, rising CO2 also contributed an additional 107.80 Tg C sink. This study distinguished the individual effects of different factors, and clarified the net carbon sink contributed by ERPs and rising CO2 and their significance to enhance regional carbon sink and reverse adverse effects of climate change on carbon sink. Furthermore, ERPs can sequester carbon dioxide faster and more effectively compared with rising CO2.

scholarly journals Behavioral modifications by a large-northern herbivore to mitigate warming conditions

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Jyoti S. Jennewein ◽  
Mark Hebblewhite ◽  
Peter Mahoney ◽  
Sophie Gilbert ◽  
Arjan J. H. Meddens ◽  
...  
Keyword(s):  
Climate Change ◽  
Habitat Selection ◽  
North America ◽  
Ambient Temperature ◽  
Landscape Heterogeneity ◽  
Thermal Environment ◽  
Selection Response ◽  
Behavioral Thermoregulation ◽  
Selection Function ◽  
High Northern Latitude

Abstract Background Temperatures in arctic-boreal regions are increasing rapidly and pose significant challenges to moose (Alces alces), a heat-sensitive large-bodied mammal. Moose act as ecosystem engineers, by regulating forest carbon and structure, below ground nitrogen cycling processes, and predator-prey dynamics. Previous studies showed that during hotter periods, moose displayed stronger selection for wetland habitats, taller and denser forest canopies, and minimized exposure to solar radiation. However, previous studies regarding moose behavioral thermoregulation occurred in Europe or southern moose range in North America. Understanding whether ambient temperature elicits a behavioral response in high-northern latitude moose populations in North America may be increasingly important as these arctic-boreal systems have been warming at a rate two to three times the global mean. Methods We assessed how Alaska moose habitat selection changed as a function of ambient temperature using a step-selection function approach to identify habitat features important for behavioral thermoregulation in summer (June–August). We used Global Positioning System telemetry locations from four populations of Alaska moose (n = 169) from 2008 to 2016. We assessed model fit using the quasi-likelihood under independence criterion and conduction a leave-one-out cross validation. Results Both male and female moose in all populations increasingly, and nonlinearly, selected for denser canopy cover as ambient temperature increased during summer, where initial increases in the conditional probability of selection were initially sharper then leveled out as canopy density increased above ~ 50%. However, the magnitude of selection response varied by population and sex. In two of the three populations containing both sexes, females demonstrated a stronger selection response for denser canopy at higher temperatures than males. We also observed a stronger selection response in the most southerly and northerly populations compared to populations in the west and central Alaska. Conclusions The impacts of climate change in arctic-boreal regions increase landscape heterogeneity through processes such as increased wildfire intensity and annual area burned, which may significantly alter the thermal environment available to an animal. Understanding habitat selection related to behavioral thermoregulation is a first step toward identifying areas capable of providing thermal relief for moose and other species impacted by climate change in arctic-boreal regions.

Nutrient constraints on the Amazon carbon sink: from field measurements to model projections

2020 ◽  
Author(s):  
Katrin Fleischer ◽  
Carlos Alberto Quesada ◽  
David Lapola ◽  
Lucia Fuchslueger ◽  
Laynara Lugli ◽  
...  
Keyword(s):  
Climate Change ◽  
Atmospheric Carbon Dioxide ◽  
Amazon Basin ◽  
Carbon Sink ◽  
Soil Phosphorus ◽  
Field Measurements ◽  
Ecosystem Model ◽  
Future Research ◽  
The Future ◽  
Increasing Demand

<p>The Amazon rainforest faces immense pressures from human-induced deforestation and climate change and its future existence is largely indeterminate. Accurately projecting the forest’s response to future conditions, and thus preparing for the best possible outcome, requires a sound process-based understanding of its ecological and biogeochemical functioning. The intact forest acts as a sink of atmospheric carbon dioxide (CO<sub>2</sub>), however, this invaluable function is slowing down for unclear reasons, according to long-term plot measurements of tree growth. Earth system models, on the other hand, assume a continuous sink of carbon into the 21<sup>st</sup> century, predominantly driven by CO<sub>2</sub> fertilization, concurrently buffering against adverse effects by climate change. Advancing empirical and experimental evidence points to strong nutrient constraints on the Amazon carbon sink, foremostly by phosphorus and other cations, so that the projected strength of the future carbon sink is certainly unrealistic. It is highly uncertain, however, to which degree nutrients are and will diminish elevated CO<sub>2</sub>-induced productivity, and to which extent plant-based mechanisms may upregulate phosphorus supply or optimize phosphorus use to facilitate the increasing demand by elevated CO<sub>2</sub>. Site-scale ecosystem model ensemble analysis underscores the diverging hypotheses on phosphorus feedbacks we are currently facing. In addition, heterogeneous soil phosphorus availability across the Amazon basin, in combination with a hyperdiverse plant community, challenges current efforts to project phosphorus constraints on the future of the Amazon carbon sink. We here give an outlook of current progress and future research needs of model-experiment integration to tackle this pressing question.</p>

Predicted and observed multidecadal variations of tree physiological responses to climate and rising  CO2: insights from tree-ring carbon isotopes in temperate forests.

2021 ◽  
Author(s):  
Soumaya Belmecheri ◽  
R. Stockton Maxwell ◽  
Alan. H Taylor ◽  
Kenneth. J Davis ◽  
Rossella Guerrieri ◽  
...  
Keyword(s):  
Carbon Isotopes ◽  
Time Scales ◽  
Tree Ring ◽  
Water Loss ◽  
Optimality Theory ◽  
Temperate Forests ◽  
Carbon Sink ◽  
Theory Model ◽  
Carbon Gain ◽  
Terrestrial Vegetation

<p>Increasing water-use efficiency (WUE), the ratio of carbon gain to water loss, is a key mechanism that enhances carbon uptake by terrestrial vegetation under rising atmospheric CO<sub>2 </sub>(c<sub>a</sub>). Existing theory and empirical evidence suggest a proportional increase of WUE in response to rising c<sub>a</sub> as plants maintain a relatively constant ratio between the leaf internal (c<sub>i</sub>) and ambient (c<sub>a</sub>) partial CO<sub>2</sub> pressure (c<sub>i</sub>/c<sub>a</sub>). This has been hypothesized as the main driver of the strengthening of the terrestrial carbon sink over the recent decades. However, proportionality may not characterize CO<sub>2</sub> effects on WUE on longer time-scales and the role of climate in modulating these effects is uncertain. We evaluated the long-term WUE responses to c<sub>a</sub> and climate from 1901-2012 CE by reconstructing intrinsic WUE (iWUE, the ratio of photosynthesis to stomatal conductance) using carbon isotopes in tree rings across temperate forests in the northeastern USA. We further replicated iWUE reconstructions at eight additional sites for the 1992-2012 period-overlapping with the common period of the longest flux-tower record at Harvard Forest to evaluate the spatial coherence of recent iWUE variation across the region. Finally, we compared tree-ring based and modelled c<sub>i</sub>/c<sub>a</sub> over the 1901-2012 period to examine whether temporal patterns of c<sub>i</sub>/c<sub>a</sub> reconstructions are consistent with predictions based on the optimality principle of balancing the costs of water loss and carbon gain.</p><p>We found that iWUE increased steadily from 1901 to 1975 CE but remained constant thereafter despite continuously rising c<sub>a</sub>. This finding is consistent with a passive physiological response to c<sub>a</sub> and coincides with a shift to significantly wetter conditions across the region. Tree physiology was driven by summer moisture at multi-decadal time-scales and did not maintain a constant c<sub>i</sub>/c<sub>a </sub>in response to rising c<sub>a</sub> indicating that a point was reached where rising CO<sub>2</sub> had a diminishing effect on tree iWUE.  The c<sub>i</sub>/c<sub>a</sub> derived from tree-ring d<sup>13</sup>C and the predicted values based on the optimality theory model had similar median values over the 1901-2012 CE period, though with a modest agreement (R<sup>2</sup><sub>adj </sub>= 0.22, p < 0.001). The reconstructed and predicted c<sub>i</sub>/c<sub>a </sub>trends were not statistically different from 0 when estimated over the 1901-2012 CE period; however, isotope-based reconstruction of the c<sub>i</sub>/c<sub>a </sub>trend<sub></sub>showed distinct multidecadal variation while the predicted c<sub>i</sub>/c<sub>a </sub>remained nearly constant. Our results challenge the mechanism, magnitude, and persistence of CO<sub>2</sub>’s effect on iWUE with significant implications for projections of terrestrial productivity under a changing climate.</p>

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