Effects of seasonal and interannual climate variability on net ecosystem productivity of boreal deciduous and conifer forests

2002 ◽  
Vol 32 (5) ◽  
pp. 878-891 ◽  
Author(s):  
M A Arain ◽  
T A Black ◽  
A G Barr ◽  
P G Jarvis ◽  
J M Massheder ◽  
...  
Keyword(s):  
Populus Tremuloides ◽  
Land Surface ◽  
Black Spruce ◽  
Climatic Variability ◽  
Flux Measurement ◽  
Canopy Conductance ◽  
Net Ecosystem Productivity ◽  
Spruce Forest ◽  
Ecosystem Productivity ◽  
Aspen Forest

The response of net ecosystem productivity (NEP) and evaporation in a boreal aspen (Populus tremuloides Michx.) forest and a black spruce (Picea mariana (Mill.) BSP) forest in Canada was compared using a newly developed realistic model of surface-atmosphere exchanges of carbon dioxide (CO2), water vapor, and energy as well as eddy covariance flux measurements made over a 6-year period (1994-1999). The model was developed by incorporating a process-based two-leaf (sunlit and shaded) canopy conductance and photosynthesis submodel in the Canadian Land Surface Scheme (CLASS). A simple submodel of autotrophic and heterotrophic respiration was combined with the photosynthesis model to simulate NEP. The model performed well in simulating half-hourly, daily, and monthly mean CO2 exchange and evaporation values in both deciduous and coniferous forests. Modeled and measured results showed a linear relationship between CO2 uptake and evaporation, and for each kilogram of water transpired, approximately 3 g of carbon (C) were photosynthesized by both ecosystems. The model results confirmed that the aspen forest was a weak to moderate C sink with considerable interannual variability in C uptake. In the growing season, the C uptake capacity of the aspen forest was over twice that of the black spruce forest. Warm springs enhanced NEP in both forests; however, high mid-summer temperatures appear to have significantly reduced NEP at the black spruce forest as a result of increased respiration. The model suggests that the black spruce forest is a weak C sink in cool years and a weak C source in warm years. These results show that the C balance of these two forests is sensitive to seasonal and interannual climatic variability and stresses the importance of continuous long-term flux measurement to confirm modeling results.

Link between continuous stem radius changes and net ecosystem productivity of a subalpine Norway spruce forest in the Swiss Alps

2010 ◽  
Vol 187 (3) ◽  
pp. 819-830 ◽  
Author(s):  
R. Zweifel ◽  
W. Eugster ◽  
S. Etzold ◽  
M. Dobbertin ◽  
N. Buchmann ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Swiss Alps ◽  
Net Ecosystem Productivity ◽  
Spruce Forest ◽  
Ecosystem Productivity ◽  
Norway Spruce Forest

scholarly journals Changes in net ecosystem productivity of boreal black spruce stands in response to changes in temperature at diurnal and seasonal time scales

2009 ◽  
Vol 29 (1) ◽  
pp. 1-17 ◽  
Author(s):  
R.F. Grant ◽  
H.A. Margolis ◽  
A.G. Barr ◽  
T.A. Black ◽  
A.L. Dunn ◽  
...  
Keyword(s):  
Time Scales ◽  
Black Spruce ◽  
Net Ecosystem Productivity ◽  
Ecosystem Productivity ◽  
Spruce Stands

scholarly journals Carbon uptake and water use in woodlands and forests in southern Australia during an extreme heat wave event in the ‘Angry Summer’ of 2012/2013

2016 ◽  
Author(s):  
Eva van Gorsel ◽  
Sebastian Wolf ◽  
Peter Isaac ◽  
James Cleverly ◽  
Vanessa Haverd ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Wave ◽  
Forest Ecosystem ◽  
Land Surface ◽  
Bowen Ratio ◽  
Terrestrial Ecosystems ◽  
Carbon Uptake ◽  
Temperature Extremes ◽  
Net Ecosystem Productivity ◽  
Ecosystem Productivity

Abstract. As a result of climate change warmer temperatures are projected through the 21st century and are already increasing above modelled predictions. Apart from increases in the mean, warm/hot temperature extremes are expected to become more prevalent in the future, along with an increase in the frequency of droughts. It is crucial to better understand the response of terrestrial ecosystems to such temperature extremes for predicting land-surface feedbacks in a changing climate. During the 2012/2013 summer, Australia experienced a record-breaking heat wave with an exceptional spatial extent that lasted for several weeks. We synthesized eddy-covariance measurements from seven woodland and forest sites across climate zones in southern Australia, which we combined with model simulations from the CABLE land surface model to investigate the effect of this summer heat wave on the carbon and water exchange of terrestrial ecosystems. We found that the water-limited woodlands and the energy-limited forest ecosystem responded differently to the heat wave. During the most intense part of the heat wave, the woodlands experienced decreased latent heat flux, an increased Bowen ratio and a reduced carbon uptake while the forest ecosystem had increased latent heat flux, reduced Bowen ratio and increased carbon uptake. Ecosystem respiration was increased at all sites resulting in reduced net ecosystem productivity in the woodlands and constant net ecosystem productivity in the forest. Importantly all ecosystems remained carbon sinks during the event. Precipitation after the most intense first part of the heat wave and slightly cooler temperatures led to a decrease of the Bowen ratio and hence increased evaporative cooling. Carbon uptake in the woodlands also recovered quickly but respiration remained high. While woodlands and forest proved relatively resistant to this short-term heat extreme these carbon sinks may not sustainable in a future with an increased number, intensity and duration of heat waves.

Impact of changing soil moisture distribution on net ecosystem productivity of a boreal aspen forest during and following drought

2006 ◽  
Vol 139 (3-4) ◽  
pp. 208-223 ◽  
Author(s):  
Praveena Krishnan ◽  
T. Andrew Black ◽  
Nicholas J. Grant ◽  
Alan G. Barr ◽  
E. (Ted) H. Hogg ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Distribution ◽  
Net Ecosystem Productivity ◽  
Ecosystem Productivity ◽  
Aspen Forest ◽  
Soil Moisture Distribution

Greenhouse gas fluxes from boreal forest soils during the snow-free period in Quebec, Canada

2009 ◽  
Vol 39 (3) ◽  
pp. 666-680 ◽  
Author(s):  
Sami Ullah ◽  
Rebeccah Frasier ◽  
Luc Pelletier ◽  
Tim R. Moore
Keyword(s):  
Forest Soil ◽  
Forest Soils ◽  
Pinus Banksiana ◽  
Deciduous Forest ◽  
Black Spruce ◽  
Jack Pine ◽  
Wetland Soil ◽  
Spruce Forest ◽  
Soil N Mineralization ◽  
Aspen Forest

This paper presents soil fluxes of methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) from 12 sites located in four major forest types, black spruce ( Picea mariana (Mill.) BSP), jack pine ( Pinus banksiana Lamb.), aspen ( Populus spp.), and alder ( Alnus spp.) stands, in the Eastmain and Chibougamau regions of Quebec. Fluxes were determined with closed chambers during the snow-free period from May to October 2007. Well-drained black spruce, jack pine, and aspen forest soils were net sinks of atmospheric CH4 (–0.33 ± 0.11 mg·m–2·day–1), while alder-dominated wetland soils were sources of CH4 (0.45 ± 0.12 mg·m–2·day–1). The cut-over alder wetland soil produced 131 times more CH4 than the undisturbed wetland soil. Soil moisture and temperature mainly regulated CH4 fluxes. N2O fluxes from these forest soils were highly variable and smaller (1.6 ± 0.33 µg N·m–2·h–1) than those from deciduous forest soils. N2O emission from the cut-over black spruce forest soil was 2.7 times greater than that from the mature black spruce forest soil. Large C/N ratios (27 to 78) and slow soil N mineralization and nitrification rates in these forest soils may have led to small N2O fluxes. CO2 emissions from these forest soils, ranging from 0.20 to 2.7 g·m–2·day–1, were mainly controlled by soil temperature.

scholarly journals Soil characteristics mediate the distribution and response of boreal trees to climatic variability

2014 ◽  
Vol 44 (5) ◽  
pp. 487-498 ◽  
Author(s):  
Sylvie Gewehr ◽  
Igor Drobyshev ◽  
Frank Berninger ◽  
Yves Bergeron
Keyword(s):  
Populus Tremuloides ◽  
Black Spruce ◽  
Climatic Variability ◽  
Basal Area ◽  
Organic Layer ◽  
Dormant Period ◽  
Study Region ◽  
Growing Period ◽  
Soil Organic Layer ◽  
The Relationship

We studied the effects of the soil organic layer (SOL) accumulation on growth and distribution of black spruce (Picea mariana (Mill.) BSP) and trembling aspen (Populus tremuloides Michx.) within the Quebec Clay Belt. At the landscape scale, spruce was present over a much larger gradient in SOL thickness (∼1 to 100 cm) than aspen (∼1 to 30 cm). For trees between 60 and 100 years old, SOL thickness had no effect on the basal area increment (BAI) of spruce but showed a strong and negative correlation with BAI in aspen. Radial growth of black spruce was favored by higher precipitation in June of the previous growing season, higher temperatures in early winter and in spring, and by low temperatures in summer. SOL thickness had statistically significant but moderate effects on the climate–growth relationships in spruce, apparently affecting root insulation during the dormant period and water availability during the growing period. In aspen, current-year June temperature was the most important factor positively correlated with growth. The SOL thickness affected the relationship between the aspen growth and (i) January temperature and (ii) June–August monthly drought code. We predict that the response of black spruce to climate change should be rather uniform across the study region, while the response of aspen is likely to be strongly mediated by SOL thickness.

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