Limits...
Long tree-ring chronologies provide evidence of recent tree growth decrease in a Central African tropical forest.

Battipaglia G, Zalloni E, Castaldi S, Marzaioli F, Cazzolla-Gatti R, Lasserre B, Tognetti R, Marchetti M, Valentini R - PLoS ONE (2015)

Bottom Line: As many factors affect tree growth patterns, short -term studies might be influenced by the confounding effect of several interacting environmental variables on plant growth.Our results provided no evidence for a fertilization effect of CO2 on tree growth.The effect of other changing environmental factors, like temperature, may have overridden the fertilization effect of CO2.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Second University of Naples, Caserta, Italy; Ecole Pratique des Hautes Etudes, Centre for Bio-Archaeology and Ecology, Institut de Botanique, University of Montpellier 2, Montpellier, France.

ABSTRACT
It is still unclear whether the exponential rise of atmospheric CO2 concentration has produced a fertilization effect on tropical forests, thus incrementing their growth rate, in the last two centuries. As many factors affect tree growth patterns, short -term studies might be influenced by the confounding effect of several interacting environmental variables on plant growth. Long-term analyses of tree growth can elucidate long-term trends of plant growth response to dominant drivers. The study of annual rings, applied to long tree-ring chronologies in tropical forest trees enables such analysis. Long-term tree-ring chronologies of three widespread African species were measured in Central Africa to analyze the growth of trees over the last two centuries. Growth trends were correlated to changes in global atmospheric CO2 concentration and local variations in the main climatic drivers, temperature and rainfall. Our results provided no evidence for a fertilization effect of CO2 on tree growth. On the contrary, an overall growth decline was observed for all three species in the last century, which appears to be significantly correlated to the increase in local temperature. These findings provide additional support to the global observations of a slowing down of C sequestration in the trunks of forest trees in recent decades. Data indicate that the CO2 increase alone has not been sufficient to obtain a tree growth increase in tropical trees. The effect of other changing environmental factors, like temperature, may have overridden the fertilization effect of CO2.

No MeSH data available.


Sampling area.Sampling area (black circle) (2°14ʹ59˝N and 16°9ʹ59˝E), located in the Lobeke National Park, in south-eastern of Cameroon (grey area), within the Congo basin.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4373839&req=5

pone.0120962.g001: Sampling area.Sampling area (black circle) (2°14ʹ59˝N and 16°9ʹ59˝E), located in the Lobeke National Park, in south-eastern of Cameroon (grey area), within the Congo basin.

Mentions: The sampling area is Libongo (2°14ʹ59˝N and 16°9ʹ59˝E), located in the proximity of the Lobeke National Park, in south-eastern of Cameroon, within the Congo basin (Fig. 1). It is bounded on the east by the Sangha River, which serves as Cameroon’s international border with the Central African Republic and the Republic of the Congo. The area is covered by a semi-evergreen forest of 2178.54 km2, which ranges from 300 to 750 m in altitude above sea level. The soil is a red or yellowish-red oxisol with a high content of clay and oxides of iron and aluminum. The average annual rainfall is 1400 mm, with the dry season occurring from December through February, and an annual average temperature of 24°C. The annual average air humidity varies between 60 and 90% [43].


Long tree-ring chronologies provide evidence of recent tree growth decrease in a Central African tropical forest.

Battipaglia G, Zalloni E, Castaldi S, Marzaioli F, Cazzolla-Gatti R, Lasserre B, Tognetti R, Marchetti M, Valentini R - PLoS ONE (2015)

Sampling area.Sampling area (black circle) (2°14ʹ59˝N and 16°9ʹ59˝E), located in the Lobeke National Park, in south-eastern of Cameroon (grey area), within the Congo basin.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4373839&req=5

pone.0120962.g001: Sampling area.Sampling area (black circle) (2°14ʹ59˝N and 16°9ʹ59˝E), located in the Lobeke National Park, in south-eastern of Cameroon (grey area), within the Congo basin.
Mentions: The sampling area is Libongo (2°14ʹ59˝N and 16°9ʹ59˝E), located in the proximity of the Lobeke National Park, in south-eastern of Cameroon, within the Congo basin (Fig. 1). It is bounded on the east by the Sangha River, which serves as Cameroon’s international border with the Central African Republic and the Republic of the Congo. The area is covered by a semi-evergreen forest of 2178.54 km2, which ranges from 300 to 750 m in altitude above sea level. The soil is a red or yellowish-red oxisol with a high content of clay and oxides of iron and aluminum. The average annual rainfall is 1400 mm, with the dry season occurring from December through February, and an annual average temperature of 24°C. The annual average air humidity varies between 60 and 90% [43].

Bottom Line: As many factors affect tree growth patterns, short -term studies might be influenced by the confounding effect of several interacting environmental variables on plant growth.Our results provided no evidence for a fertilization effect of CO2 on tree growth.The effect of other changing environmental factors, like temperature, may have overridden the fertilization effect of CO2.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Second University of Naples, Caserta, Italy; Ecole Pratique des Hautes Etudes, Centre for Bio-Archaeology and Ecology, Institut de Botanique, University of Montpellier 2, Montpellier, France.

ABSTRACT
It is still unclear whether the exponential rise of atmospheric CO2 concentration has produced a fertilization effect on tropical forests, thus incrementing their growth rate, in the last two centuries. As many factors affect tree growth patterns, short -term studies might be influenced by the confounding effect of several interacting environmental variables on plant growth. Long-term analyses of tree growth can elucidate long-term trends of plant growth response to dominant drivers. The study of annual rings, applied to long tree-ring chronologies in tropical forest trees enables such analysis. Long-term tree-ring chronologies of three widespread African species were measured in Central Africa to analyze the growth of trees over the last two centuries. Growth trends were correlated to changes in global atmospheric CO2 concentration and local variations in the main climatic drivers, temperature and rainfall. Our results provided no evidence for a fertilization effect of CO2 on tree growth. On the contrary, an overall growth decline was observed for all three species in the last century, which appears to be significantly correlated to the increase in local temperature. These findings provide additional support to the global observations of a slowing down of C sequestration in the trunks of forest trees in recent decades. Data indicate that the CO2 increase alone has not been sufficient to obtain a tree growth increase in tropical trees. The effect of other changing environmental factors, like temperature, may have overridden the fertilization effect of CO2.

No MeSH data available.