The positive carbon stocks–biodiversity relationship in forests: co-occurrence and drivers across five subclimates

Lecina-Diaz J., Alvarez A., Regos A., Drapeau P., Paquette A., Messier C., Retana J. (2018) The positive carbon stocks–biodiversity relationship in forests: co-occurrence and drivers across five subclimates. Ecological Applications. 28: 1481-1493.
Link
Doi: 10.1002/eap.1749

Abstract:

Carbon storage in forests and its ability to offset global greenhouse gas emissions, as well as biodiversity and its capacity to support ecosystem functions and services, are often considered separately in landscape planning. However, the potential synergies between them are currently poorly understood. Identifying the spatial patterns and factors driving their co-occurrence across different climatic zones is critical to more effectively conserve forest ecosystems at the regional level. Here, we integrated information of National Forest Inventories and Breeding Bird Atlases across Europe and North America (Spain and Quebec, respectively), covering five subclimates (steppe, dry Mediterranean, humid Mediterranean, boreal, and temperate). In particular, this study aimed to (1) determine the spatial patterns of both forest carbon stocks and biodiversity (bird richness, tree richness, and overall biodiversity) and the factors that influence them; (2) establish the relationships between forest carbon stocks and biodiversity; and (3) define and characterize the areas of high (hotspots) and low (coldspots) values of carbon and biodiversity, and ultimately quantify their spatial overlap. Our results show that the factors affecting carbon and biodiversity vary between regions and subclimates. The highest values of carbon and biodiversity were found in northern Spain (humid Mediterranean subclimate) and southern Quebec (temperate subclimate) where there was more carbon as climate conditions were less limiting. High density and structural diversity simultaneously favored carbon stocks, tree, and overall biodiversity, especially in isolated and mountainous areas, often associated with steeper slopes and low accessibility. In addition, the relationship between carbon stocks and biodiversity was positive in both regions and all subclimates, being stronger where climate is a limiting factor for forest growth. The spatial overlap between hotspots of carbon and biodiversity provides an excellent opportunity for landscape planning to maintain carbon stocks and conserve biodiversity. The variables positively affecting carbon and biodiversity were also driving the hotspots of both carbon and biodiversity, emphasizing the viability of “win-win” solutions. Our results highlight the need to jointly determine the spatial patterns of ecosystem services and biodiversity for an effective and sustainable planning of forest landscapes that simultaneously support conservation and mitigate climate change. © 2018 by the Ecological Society of America

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Tree size and climatic water deficit control root to shoot ratio in individual trees globally

Ledo, A., Paul, K.I., Burslem, D.F.R.P., Ewel, J.J., Barton, C., Battaglia, M., Brooksbank, K., Carter, J., Eid, T.H., England, J.R., Fitzgerald, A., Jonson, J., Mencuccini, M., Montagu, K.D., Montero, G., Mugasha, W.A., Pinkard, E., Roxburgh, S., Ryan, C.M., Ruiz-Peinado, R., Sochacki, S., Specht, A., Wildy, D., Wirth, C., Zerihun, A., Chave, J. (2018) Tree size and climatic water deficit control root to shoot ratio in individual trees globally. New Phytologist. 217: 8-11.
Link
Doi: 10.1111/nph.14863

Abstract:

Atmospheric deposition of particulate matter between Algeria and France: Contribution of long and short-term sources

Lequy E., Avila A., Boudiaf Nait Kaci M., Turpault M.-P. (2018) Atmospheric deposition of particulate matter between Algeria and France: Contribution of long and short-term sources. Atmospheric Environment. 191: 181-193.
Link
Doi: 10.1016/j.atmosenv.2018.08.013

Abstract:

Large worldwide sources of dust, such as the Saharan desert, play a key role in the amounts and composition of atmospheric particulate deposition (APD), but their relative contribution compared to other sources remain unclear. Our study aimed to apportion Saharan, regional, and anthropogenic sources of APD in three sampling along a long transect affected by Saharan outbreaks. We quantified total APD, and analyzed its mineralogical and chemical composition between 2011 and 2012.. Strong markers of Saharan dust, such as large amounts of APD and of a low Al2O3:CaO ratio allowed identifying clear periods influenced by Saharan outbreaks. Nitrogen and phosphorus reflected soil affected by agricultural practices, while Cd, Pb, Sb and Sn tracked traffic and industrial sources – as confirmed by enrichment factors. Then, we designed a conceptual model including sensitivity analyses to estimate the contribution of unanalyzed (10–11%, likely chlorites or sulfates), organic (34–41%), anthropogenic (11–22%), mineral-regional (5–25%) and mineral-Saharan (10–38%) matter over our entire study period. Our study shows the rapidly decreasing contribution of Saharan outbreaks – and the decreasing flux of Ca and Mg, from 40 to 0.4 kg.ha−1 over the study period between Algeria and France. Yet, Saharan outbreaks were still noticeable in APD at a site 1500 km away. Our study also shows the large relative contribution of organic and anthropogenic sources to APD in the three sampling sites, and their possible influence on nutrient budgets. © 2018 Elsevier Ltd

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Preliminary growth functions for Eucalyptus gunnii in the UK

Leslie, A.D., Mencuccini, M., Perks, M.P. (2018) Preliminary growth functions for Eucalyptus gunnii in the UK. Biomass and Bioenergy. 108: 464-469.
Link
Doi: 10.1016/j.biombioe.2017.10.037

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Long-term experimental drought combined with natural extremes accelerate vegetation shift in a Mediterranean holm oak forest

Liu D., Ogaya R., Barbeta A., Yang X., Peñuelas J. (2018) Long-term experimental drought combined with natural extremes accelerate vegetation shift in a Mediterranean holm oak forest. Environmental and Experimental Botany. 151: 1-11.
Link
Doi: 10.1016/j.envexpbot.2018.02.008

Abstract:

Increasing drought combined with natural extremes are expected to accelerate forest die-off and shifts in vegetation in the Mediterranean Basin. However, fewer studies have explored these climate-driven changes in forest ecosystems. A long-term (17-year) experimental drought (−30% precipitation) was established in a Mediterranean holm oak forest with high (H) and low (L) canopies to determine the changes in stem mortality, recruitment and composition shifts. Experimental drought increased annual stem mortality rate at the community level for both H- and L-canopies. Natural drought amplified the effects of experimental drought on stem mortality at the community level and of Q. ilex for H- and L-canopies. The timescales of natural drought, however, varied substantially with canopy types and species, with shorter timescales in L- than H-canopy and for Q. ilex than P. latifolia. Furthermore, experimental drought combined with natural extremes amplified the increases in stem mortality and decreases in growth for L-canopy. Contrasting responses between Q. ilex and P. latifolia for the relative in abundance and growth were observed in L-canopy and drought treatment reinforced the vegetation shift favoring P. latifolia. These findings suggest continuous drought regimes accelerated a vegetation shift, implying potential consequences for the functions and services for water-limited forest ecosystems. © 2018 Elsevier B.V.

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Decelerating Autumn CO2 Release With Warming Induced by Attenuated Temperature Dependence of Respiration in Northern Ecosystems

Liu D., Piao S., Wang T., Wang X., Wang X., Ding J., Ciais P., Peñuelas J., Janssens I. (2018) Decelerating Autumn CO2 Release With Warming Induced by Attenuated Temperature Dependence of Respiration in Northern Ecosystems. Geophysical Research Letters. 45: 5562-5571.
Link
Doi: 10.1029/2018GL077447

Abstract:

Feedbacks from the carbon cycle in boreal and arctic ecosystems can significantly affect climate change, but the effects of climate change on the high-latitude carbon cycle during the dormant period remain uncertain. By analyzing the long-term atmospheric CO2 concentration record from Point Barrow in Alaska, we show that warming significantly boosts net CO2 release in autumn over the period 1974–2014. But this warming-stimulated effect has been attenuated since 1997. This deceleration of net CO2 release with warming is ascribed to the attenuation in respiration response to temperature rather than changing relationship between temperature and productivity or changes in atmospheric transport, fossil fuel emissions, or air-sea CO2 exchanges. The attenuated respiration response is likely due to decoupling between temperature and plant-derived carbon inputs to soil for decomposition. Contrary to previous suggestions, warming no longer results in a higher autumn net CO2 release. ©2018. American Geophysical Union. All Rights Reserved.

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Extension of the growing season increases vegetation exposure to frost

Liu, Q., Piao, S., Janssens, I.A., Fu, Y., Peng, S., Lian, X., Ciais, P., Myneni, R.B., Peñuelas, J., Wang, T. (2018) Extension of the growing season increases vegetation exposure to frost. Nature Communications. 9: 0-0.
Link
Doi: 10.1038/s41467-017-02690-y

Abstract:

Historical and event-based bioclimatic suitability predicts regional forest vulnerability to compound effects of severe drought and bark beetle infestation

Lloret F., Kitzberger T. (2018) Historical and event-based bioclimatic suitability predicts regional forest vulnerability to compound effects of severe drought and bark beetle infestation. Global Change Biology. 24: 1952-1964.
Link
Doi: 10.1111/gcb.14039

Abstract:

Vulnerability to climate change, and particularly to climate extreme events, is expected to vary across species ranges. Thus, we need tools to standardize the variability in regional climatic legacy and extreme climate across populations and species. Extreme climate events (e.g., droughts) can erode populations close to the limits of species' climatic tolerance. Populations in climatic-core locations may also become vulnerable because they have developed a greater demand for resources (i.e., water) that cannot be enough satisfied during the periods of scarcity. These mechanisms can become exacerbated in tree populations when combined with antagonistic biotic interactions, such as insect infestation. We used climatic suitability indices derived from Species Distribution Models (SDMs) to standardize the climatic conditions experienced across Pinus edulis populations in southwestern North America, during a historical period (1972–2000) and during an extreme event (2001–2007), when the compound effect of hot drought and bark beetle infestation caused widespread die-off and mortality. Pinus edulis climatic suitability diminished dramatically during the die-off period, with remarkable variation between years. P. edulis die-off occurred mainly not just in sites that experienced lower climatic suitability during the drought but also where climatic suitability was higher during the historical period. The combined effect of historically high climatic suitability and a marked decrease in the climatic suitability during the drought best explained the range-wide mortality. Lagged effects of climatic suitability loss in previous years and co-occurrence of Juniperus monosperma also explained P. edulis die-off in particular years. Overall, the study shows that past climatic legacy, likely determining acclimation, together with competitive interactions plays a major role in responses to extreme drought. It also provides a new approach to standardize the magnitude of climatic variability across populations using SDMs, improving our capacity to predict population's or species' vulnerability to climatic change. © 2018 John Wiley & Sons Ltd

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Non-structural carbohydrate dynamics associated with drought-induced die-off in woody species of a shrubland community

Lloret F., Sapes G., Rosas T., Galiano L., Saura-Mas S., Sala A., Martínez-Vilalta J. (2018) Non-structural carbohydrate dynamics associated with drought-induced die-off in woody species of a shrubland community. Annals of Botany. 121: 1383-1396.
Link
Doi: 10.1093/aob/mcy039

Abstract:

Background and Aims The relationship between plant carbon economy and drought responses of co-occurring woody species can be assessed by comparing carbohydrate (C) dynamics following drought and rain periods, relating these dynamics to species' functional traits. We studied nine woody species coexisting in a continental Mediterranean shrubland that experienced severe drought effects followed by rain. Methods We measured total non-structural carbohydrates (NSC) and soluble sugars (SS) in roots and stems during drought and after an autumn rain pulse in plants exhibiting leaf loss and in undefoliated ones. We explored whether their dynamics were related to foliage recovery and functional traits (height [H], specific leaf area [SLA], wood density [WD]). Key Results During drought, NSC concentrations were overall lower in stems and roots of plants experiencing leaf loss, while SS decreases were smaller. Roots had higher NSC concentrations than stems. After the rain, NSC concentrations continued to decrease, while SS increased. Green foliage recovered after rain, particularly in plants previously experiencing higher leaf loss, independently of NSC concentrations during drought. Species with lower WD tended to have more SS during drought and lower SS increases after rain. In low-WD species, plants with severe leaf loss had lower NSC relative to undefoliated ones. No significant relationship was found between H or SLA and C content or dynamics. Conclusions Our community-level study reveals that, while responses were species-specific, C stocks overall diminished in plants affected by prolonged drought and did not increase after a pulse of seasonal rain. Dynamics were faster for SS than NSC. We found limited depletion of SS, consistent with their role in basal metabolic, transport and signalling functions. In a scenario of increased drought under climate change, NSC stocks in woody plants are expected to decrease differentially in coexisting species, with potential implications for their adaptive abilities and community dynamics. © The Author(s) 2018.

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Remote sensing of canopy nitrogen at regional scale in Mediterranean forests using the spaceborne MERIS terrestrial chlorophyll index

Loozen Y., Rebel K.T., Karssenberg D., Wassen M.J., Sardans J., Peñuelas J., De Jong S.M. (2018) Remote sensing of canopy nitrogen at regional scale in Mediterranean forests using the spaceborne MERIS terrestrial chlorophyll index. Biogeosciences. 15: 2723-2742.
Link
Doi: 10.5194/bg-15-2723-2018

Abstract:

Canopy nitrogen (N) concentration and content are linked to several vegetation processes. Therefore, canopy N concentration is a state variable in global vegetation models with coupled carbon (C) and N cycles. While there are ample C data available to constrain the models, widespread N data are lacking. Remotely sensed vegetation indices have been used to detect canopy N concentration and canopy N content at the local scale in grasslands and forests. Vegetation indices could be a valuable tool to detect canopy N concentration and canopy N content at larger scale. In this paper, we conducted a regional case-study analysis to investigate the relationship between the Medium Resolution Imaging Spectrometer (MERIS) Terrestrial Chlorophyll Index (MTCI) time series from European Space Agency (ESA) Envisat satellite at 1ĝ€km spatial resolution and both canopy N concentration (%N) and canopy N content (Nĝ€gĝ€mĝ'2, of ground area) from a Mediterranean forest inventory in the region of Catalonia, in the northeast of Spain. The relationships between the datasets were studied after resampling both datasets to lower spatial resolutions (20, 15, 10 and 5ĝ€km) and at the original spatial resolution of 1ĝ€km. The results at higher spatial resolution (1ĝ€km) yielded significant log-linear relationships between MTCI and both canopy N concentration and content: r2ĝ€ Combining double low line ĝ€0.32 and r2ĝ€ Combining double low line ĝ€0.17, respectively. We also investigated these relationships per plant functional type. While the relationship between MTCI and canopy N concentration was strongest for deciduous broadleaf and mixed plots (r2ĝ€ Combining double low line ĝ€0.24 and r2ĝ€ Combining double low line ĝ€0.44, respectively), the relationship between MTCI and canopy N content was strongest for evergreen needleleaf trees (r2ĝ€ Combining double low line ĝ€0.19). At the species level, canopy N concentration was strongly related to MTCI for European beech plots (r2ĝ€ Combining double low line ĝ€0.69). These results present a new perspective on the application of MTCI time series for canopy N detection. © Author(s) 2018.

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