Species substitution for carbon storage: Sessile oak versus Corsican pine in France as a case study
Introduction
Forest ecosystems can play a role in carbon storage to reduce atmospheric carbon dioxide in several ways. It is possible (i) to increase the areas covered by forests in order to increase the carbon stocks in terrestrial biomes, (ii) to change forest management options to store more carbon in already forested areas, and, (iii) to substitute fossil fuel by biomass or energy-intensive materials by construction timber (Cannell, 1995, Lindner, 1998). Species selection is one of the forest management options for increasing carbon stocks. Cannell (1996) pointed out that on the one hand fast-growing plantations would accumulate carbon more rapidly than slow-growing forest up to the time of harvest. On the other hand, for long time storage, slow-growing forests would be preferable as they have a higher time-averaged carbon stocks. Several studies have shown that species substitution induced by replacing primary or old-growth forests by plantations leads to a loss of carbon (Cropper and Ewel, 1987, Fleming and Freedman, 1998, Schroth et al., 2002, Erb, 2004), even when wood used in building structures is included in the models (Harmon et al., 1990). Beyond these general results, there is a lack of information about the carbon storage impact of species substitution in a large range of realistic situations of site productivities and silvicultural options.
Substituting species will imply changes in carbon stocks in both belowground and aboveground vegetation, but also in soil organic matter and in wood products. Carbon in wood products is complicated to assess (Karjalainen et al., 1994, Liski et al., 2001). Nevertheless, it has to be to taken into account since products from two different species have specific market destinations and lifespan (Dewar and Cannell, 1992, Karjalainen et al., 2002, Marland and Marland, 2003). The soil carbon content and changes with silviculture are also difficult to estimate as shows e.g. the review of Yanai et al. (2003). But the changes in soil carbon could be high (Liski et al., 2002, Peltoniemi et al., 2004) and also should be assessed.
The objective of this article is to assess the impact on carbon stocks due to species substitution. We studied the replacement of sessile oak (Quercus petraea Liebl.) high forests issued from natural regeneration by Corsican pine plantations (Pinus nigra subsp. laricio) in central France (Centre and Pays de la Loire regions). Within this area, according to the Inventaire Forestier National (National Forest Inventory, NFI), sessile oak is the main species, and occupies 327,000 ha, which represents 18% of the national resource for this species (Belouard, personal communication). This substitution is already practiced for production purposes. Corsican pine is appreciated by forest owners for several reasons. It is well adapted even on poor sites and yield can reach up to 20 m3/ha/year, with stems of remarkable straightness and good wood quality (Riou Nivert et al., 2001). If proven and substantial, carbon sequestration could be an additional benefit of this species substitution.
This article illustrates the utility of coupling models to address issues for which field measurements cover much too long a time interval to be useful for decision-making needed in the short-term. The study was carried out by coupling models that allowed estimating the changes in carbon of the four compartments for both species (below- and above-ground vegetation, soil organic matter and wood products). We focussed on the carbon stocks and their variations, and did not take into account the effects of energy-consuming building materials and fossil fuel substitution by wood, which would be a valuable continuation of our study. In order to help decision-making at the stand level, we needed to estimate the productivity of both species at the same site, and to consider silvicultural scenarios that are prescribed for either species. Productivity assessment has been carried out by using NFI data to estimate site index in relation to environmental factors and the indicator value of understorey vegetation as did Seynave et al. (2005) for Norway spruce. Silvicultural scenarios were chosen as recommended in guides.
Section snippets
Material and methods
Model chains were built for both sessile oak and Corsican pine to assess the changes in carbon stocks in the four following compartments: below- and above-ground vegetation, soil organic matter and wood products. Stand biomass is controlled by silviculture and predicted by stand growth models. At each growth cycle, models update the diameter distribution (through tree diameter growth and mortality) and individual heights. All tree and stand characteristics, including carbon stock in biomass,
Results and discussion
The impact of species substitution on carbon stocks in the abovementioned conditions can be analyzed for the steady state and transient state. The steady state is obtained when the same silviculture is repeated many times. The transient state is the dynamic that will occur after species substitution and that will lead to the steady state. We recall that for these two types of simulations the environmental conditions were regarded as stable.
Conclusion
The substitution of a slow-growing sessile oak even-aged forest by a fast-growing Corsican pine plantation would have effects on carbon storage depending on the time considered. As Cannell (1996) assumed in a previous work, we show here that during the first rotation, the Corsican pine plantation would have a higher carbon uptake, but that the time-averaged carbon stocks would be lower at steady state, in comparison with slow-growing oak stands spending decades at adult stages.
The additional
Acknowledgements
The authors wish to thank Christian Piedallu (ENGREF) for the work done on the GIS to get the climatic data, Vincent Badeau (INRA) for providing data from the European soil monitoring network, Marc Lanier and Erwin Ulrich from RENECOFOR for providing soil data, and Gilles Le Moguédec (INRA) for the basic density equation for sessile oak. The work was done during a PhD thesis with scholarships from ADEME and the Conseil Regional de Lorraine.
References (75)
- et al.
Decomposition of mediterranean leaf litters: a microcosm experiment investigating relationships between decomposition rates and litter quality
Soil Biology & Biochemistry
(1996) - et al.
A regional carbon storage simulation for large-scale biomass plantations
Ecological Modelling
(1987) - et al.
Decomposition dynamics of litters of various pine species in a Corsican pine forest
Soil Biology & Biochemistry
(1998) - et al.
Linking growth modelling to timber quality assessment for Norway spruce
Forest Ecology and Management
(1995) - et al.
An approach towards an estimate of the impact of forest management and climate change on the European forest sector carbon budget: Germany as a case study
Forest Ecology and Management
(2002) - et al.
Biomass expansion factors (BEFs) for Scots pine, Norway spruce and birch according to stand age for boreal forests
Forest Ecology and Management
(2004) - et al.
Increasing carbon stocks in the forest soils of western Europe
Forest Ecology and Management
(2002) - et al.
The treatment of long-lived, carbon-containing products in inventories of carbon dioxide emissions to the atmosphere
Environmental Science and Policy
(2003) - et al.
Forests for carbon sequestration or fossil fuel substitution? A sensitivity analysis
Biomass and Bioenergy
(1997) - et al.
Modeling carbon sequestration in afforestation, agroforestry and forest management projects: the CO2FIX V.2 approach
Ecological Modelling
(2003)