Coupled long-term summer warming and deeper snow alters species composition and stimulates gross primary productivity in tussock tundra

Oecologia ◽  
2016 ◽  
Vol 181 (1) ◽  
pp. 287-297 ◽  
Author(s):  
A. Joshua Leffler ◽  
Eric S. Klein ◽  
Steven F. Oberbauer ◽  
Jeffrey M. Welker
2006 ◽  
Vol 141 (2-4) ◽  
pp. 118-132 ◽  
Author(s):  
Kevin Black ◽  
Phill Davis ◽  
Peter Lynch ◽  
Mike Jones ◽  
Michael McGettigan ◽  
...  

2020 ◽  
Author(s):  
Sinkyu Kang ◽  
Wenping Kang

<p>Changes in vegetation productivity and species composition have been used as conventional indicators of land degradation and rehabilitation assessments. The two biophysical parameters vary nonlinearly during land change process with various time lags, which provide, as a whole, a useful framework to diagnose degree of land degradation and rehabilitation. In this study, the net primary productivity (NPP) and water use efficiency (WUE), which are the proxies of vegetation productivity and ecophysiological properties related to species composition, were combined to develop an eco-physiological framework to assess the degree of land degradation in the Northeast-Asia dryland regions (NADR) from 1982 to 2012. Results from long-term trends analysis showed early, middle or late degradation stages occurred in northern grassland and central barren or sparsely vegetated regions, respectively, while the rehabilitation prevailed in eastern croplands and forest, southern, and western grassland. In contrast, short-term trend analysis illustrated the recent rehabilitation in mideastern Mongolia and Loess Plateau, which was unseen in long-term trend analysis. The spatial patterns and temporal changes of land degradation and rehabilitation could be explained partly by either or both natural and anthropogenic factors. Longterm drying and warming might induce land degradation in northern and central NADR, respectively, while the recovery projects and wetting conditions after 2000s promoted the land rehabilitation in Loess Plateau and mid-eastern Mongolia. Here, our NPP–WUE framework may contribute further conceptual development and rapid assessments on land degradation and rehabilitation in wide geographic regions.</p>


2021 ◽  
Author(s):  
Anne Holtmann ◽  
Andreas Huth ◽  
Felix Pohl ◽  
Corinna Rebmann ◽  
Rico Fischer

<p>Forests play an important role in climate regulation due to carbon sequestration. However, a deeper understanding of forest carbon flux dynamics are often missing due to a lack of information about forest structure and species composition, especially for non-even-aged and mixed forests. In this study, we combined field inventory data of a mixed deciduous forest in Germany with an individual-based forest gap model to investigate daily carbon fluxes and to examine the role of tree size and species composition for the overall stand productivity. Simulation results show that the forest model is capable to reproduce daily eddy covariance measurements (R<sup>2</sup> of 0.73 for gross primary productivity and of 0.65 for ecosystem respiration). The simulation results showed that the forest act as a carbon sink with a net uptake of 3.2 t<sub>C</sub> ha<sup>-1</sup> yr<sup>-1</sup>  (net ecosystem productivity) and an overall gross primary productivity of 18.2  t<sub>C</sub> ha<sup>-1</sup> yr<sup>-1</sup>. At the study site, medium sized trees (30-60cm) account for the largest share (66%) of the total productivity. Small (0-30cm) and large trees (>60cm) contribute less with 8.5% and 25.5% respectively. Simulation experiments showed, that species composition showed less effect on forest productivity. Stand productivity therefore is highly depended on vertical stand structure and light climate. Hence, it is important to incorporate small scale information’s about forest stand structure into modelling studies to decrease uncertainties of carbon dynamic predictions. Experiments with such a modelling approach might help to investigate large scale mitigation strategies for climate change that takes local forest stand characteristics into account.</p>


2012 ◽  
pp. 66-77 ◽  
Author(s):  
I. A. Lavrinenko ◽  
O. V. Lavrinenko ◽  
D. V. Dobrynin

The satellite images show that the area of marshes in the Kolokolkova bay was notstable during the period from 1973 up to 2011. Until 2010 it varied from 357 to 636 ha. After a severe storm happened on July 24–25, 2010 the total area of marshes was reduced up to 43–50 ha. The mean value of NDVI for studied marshes, reflecting the green biomass, varied from 0.13 to 0.32 before the storm in 2010, after the storm the NDVI decreased to 0.10, in 2011 — 0.03. A comparative analysis of species composition and structure of plant communities described in 2002 and 2011, allowed to evaluate the vegetation changes of marshes of the different topographic levels. They are fol­lowing: a total destruction of plant communities of the ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae on low and middle marches; increasing role of halophytic species in plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. typicum on middle marches; some changes in species composition and structure of plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. festucetosum rubrae on high marches and ass. Parnassio palustris–Salicetum reptantis in transition zone between marches and tundra without changes of their syntaxonomy; a death of moss cover in plant communities of the ass. Caricetum mackenziei var. Warnstorfia exannulata on brackish coastal bogs. The possible reasons of dramatic vegetation dynamics are discussed. The dating of the storm makes it possible to observe the directions and rates of the succession of marches vegetation.


2021 ◽  
Vol 307 ◽  
pp. 108456
Author(s):  
Marcelo Sacardi Biudes ◽  
George Louis Vourlitis ◽  
Maísa Caldas Souza Velasque ◽  
Nadja Gomes Machado ◽  
Victor Hugo de Morais Danelichen ◽  
...  

2015 ◽  
Vol 72 (9) ◽  
pp. 2600-2608 ◽  
Author(s):  
Dimitrios Damalas ◽  
Christos D. Maravelias ◽  
Giacomo C. Osio ◽  
Francesc Maynou ◽  
Mario Sbrana ◽  
...  

Abstract Discarding of commercially important fish species in the bottom trawl fisheries in the northern Mediterranean Sea was investigated by soliciting the long-term recollections of fishers engaged or formerly engaged in such fisheries. The main aim of our investigation was to describe the prevalence of discarding and its evolution over the past 70 years using information gathered through individual questionnaire-based interviews with fishers from ports in Spain, Italy, and Greece, following a standardized sampling protocol. Although it proved impossible to derive absolute estimates of the volume of discarded catches over the period investigated, we conclude that over the past 70 years, discarding as a practice has gradually increased in the northern Mediterranean trawl fisheries and has been accompanied by a shift in the species composition of the discarded catch. While discarding can occur for a number of reasons, our investigations indicate that discarding in the past was mostly driven by market demand, but recent legal and regulatory constraints have led to changes in fishing strategies and became a significant reason for discards.


2021 ◽  
Vol 307 ◽  
pp. 108527
Author(s):  
Ning Chen ◽  
Changchun Song ◽  
Xiaofeng Xu ◽  
Xianwei Wang ◽  
Nan Cong ◽  
...  

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