Featured Research

from universities, journals, and other organizations

Global Warming Bringing Early Spring Seasons To Eurasian Forests

Date:
April 1, 2008
Source:
Centre National De La Recherche Scientifique
Summary:
With the help of satellite data, researchers from laboratories in France(1), the UK, Japan and Russia have completed the accurate and large-scale mapping of leaf appearance dates in boreal forests. Their work has revealed a remarkable trend towards earlier foliation, which occurred between 1987 and 1990, over a large part of northern Eurasia, caused by the unprecedented increase in spring temperatures since 1921.

The boreal forest, Siberia.
Credit: Copyright CESBIO

With the help of satellite data, researchers from laboratories in France(1), the UK, Japan and Russia have completed the accurate and large-scale mapping of leaf appearance dates in boreal forests. Their work has revealed a remarkable trend towards earlier foliation, which occurred between 1987 and 1990, over a large part of northern Eurasia, caused by the unprecedented increase in spring temperatures since 1921. By comparing these results with the previous studies available, they were able to reconstruct the foliation trend over the whole 20th century. Their work, published the journal Global Change Biology, enables the effects of global warming on these forests to be measured.

Related Articles


Phenology studies the climate-dependent variations of seasonal phenomena of plant life. In this study, the researchers particularly focused on the date of leaf appearance in boreal forests. In the northern hemisphere at high latitudes, foliation depends essentially on temperature. It is, therefore, considered direct evidence of the warming of the climate observed during the 20th century, which is especially marked in these regions. In addition, it also sets the pace for exchanges of carbon between vegetation and the atmosphere, which have an impact on the climate.

Before 1982, two techniques were used to analyze temporal variations in foliation:  modeling based on meteorological measurements, which is not very precise, and measurements in the field, which make for a more precise analysis, but only at the local level. 1982 saw the beginning of observations from space (remote sensing), which are necessary for this type of study.  Since then, a considerable amount of research based on these observations has shown that leaves in deciduous forests in boreal regions have tended to appear earlier and earlier due to warming. However, these measurements only provided rough trends, which were averaged out considerably over space and time.

In their work published in Global Change Biology, the researchers refined their interpretation of satellite data(2), especially by taking into account the effect of snow on the radiometric signal(3). They also calibrated their model for leaf appearance based on temperature, thus enabling remote sensing observations and modeling to be in close agreement.

They were able to show that foliation had generally occurred at an increasingly early date from 1982 until the present, on average around 5 days earlier for the Eurasian boreal forest. Variations in leaf appearance dates since 1982 have not been linear over time, and have not been identical for the whole of boreal Eurasia: the trend to increasingly early foliation dates accelerated between 1987 and 1990, and was more marked in Central Siberia.

Besides improved methods, the novel feature of this work consisted in studying foliation trends over the whole 20th century, by comparing the new results with those for the period before 1982 (with the help of field and modeling data).

The major trend observed in Central Siberia was connected to two events:

  1. abnormally high spring temperatures in the 1990s, with leaf appearance in Central Siberia at its earliest since 1921,
  2. especially low spring temperatures in the region in 1983 and 1984, with leaf appearance during these two years at its latest since 1921; results which confirm that the trends observed by remote sensing should be analyzed with great care.

Earlier this century, boreal Eurasia was affected by other periods of warming during which leaves appeared earlier and earlier (for instance from 1936 to 1944 in Central Siberia and on several occasions in Western Russia), as well as cooler periods which gradually led to increasingly late leaf appearance (especially between 1945 and 1960 in central and eastern Siberia. However these trends always occurred on a local or regional scale.

The recent trend towards increasingly early foliation observed by remote sensing is therefore striking when compared to similar events which have occurred since 1921, in that it has simultaneously affected the greater part of boreal Eurasia and has given rise to the earliest leaf appearance dates in the region for almost a century. With regard to global warming, it shows that there has been a large-scale increase of spring temperatures during this period.

Notes:

1) Center for the study of the biosphere from space (Centre d'études spatiales de la biosphère) (CESBIO/OMP, CNRS, Université Toulouse 3, IRD, CNES), Laboratory for Environmental Geophysics and Glaciology (Laboratoire de glaciologie et géophysique de l'environnement) (LGGE/OSUG, CNRS and Université Grenoble 1), JAMSTEC-Frontier research center for global change (Yokohama, Japan), Centre for terrestrial carbon dynamics (Sheffield, GB), University of Sheffield (Sheffield, GB) and Komarov institute of botany (St Petersburg, Russia)
2) Data from CNES's SPOT VEGETATION satellite and NOAA's AVHRR satellite.
3) Snow melt can be erroneously interpreted as the beginning of foliation.


Story Source:

The above story is based on materials provided by Centre National De La Recherche Scientifique. Note: Materials may be edited for content and length.


Cite This Page:

Centre National De La Recherche Scientifique. "Global Warming Bringing Early Spring Seasons To Eurasian Forests." ScienceDaily. ScienceDaily, 1 April 2008. <www.sciencedaily.com/releases/2008/03/080330213008.htm>.
Centre National De La Recherche Scientifique. (2008, April 1). Global Warming Bringing Early Spring Seasons To Eurasian Forests. ScienceDaily. Retrieved October 30, 2014 from www.sciencedaily.com/releases/2008/03/080330213008.htm
Centre National De La Recherche Scientifique. "Global Warming Bringing Early Spring Seasons To Eurasian Forests." ScienceDaily. www.sciencedaily.com/releases/2008/03/080330213008.htm (accessed October 30, 2014).

Share This



More Earth & Climate News

Thursday, October 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Mudslide in Sri Lanka Buries Houses

Deadly Mudslide in Sri Lanka Buries Houses

AP (Oct. 29, 2014) — A mudslide triggered by monsoon rains buried scores of workers' houses at a tea plantation in central Sri Lanka on Wednesday, killing at least 10 people and leaving more than 250 missing, an official said. (Oct. 29) Video provided by AP
Powered by NewsLook.com
Galapagos Tortoises Bounce Back, But Ecosystem Lags

Galapagos Tortoises Bounce Back, But Ecosystem Lags

Newsy (Oct. 29, 2014) — The Galapagos tortoise has made a stupendous recovery from the brink of extinction to a population of more than 1,000. But it still faces threats. Video provided by Newsy
Powered by NewsLook.com
Saharan Solar Project to Power Europe

Saharan Solar Project to Power Europe

Reuters - Business Video Online (Oct. 29, 2014) — A solar energy project in the Tunisian Sahara aims to generate enough clean energy by 2018 to power two million European homes. Matt Stock reports. Video provided by Reuters
Powered by NewsLook.com
Obama: The US Will Not 'run and Hide' From Ebola

Obama: The US Will Not 'run and Hide' From Ebola

AP (Oct. 29, 2014) — Surrounded by health care workers in the White House East Room, President Barack Obama said the U.S. will likely see additional Ebola cases in the weeks ahead. But he said the nation can't seal itself off in the fight against the disease. (Oct. 29) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:  

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile iPhone Android Web
    Follow Facebook Twitter Google+
    Subscribe RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins