PROJECT DESCRIPTION
BACKGROUND
Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are the most important greenhouse gases (GHGs) emitted from agricultural and forest soils, contributing 60%, 15% and 5%, respectively, towards global warming. Forest ecosystems commonly act as a net sink for CO2, contributing to climate change mitigation by removing atmospheric CO2 and storing it in different carbon pools (i.e. biomass, soil, dead organic matter, litter). Moreover, forests comprise an important carbon reservoir, since they store about twice the amount present in the atmosphere. The capacity of ecosystems to store carbon depends on the balance between net primary productivity (NPP) and heterotrophic respiration. Whether a particular ecosystem is functioning as sink or source ofGHG emission may change over time, depending on its vulnerability to climate change and other stressors and disturbances.
Deforestation and forest degradation are significant contributors to global GHG emissions, but if these processes are controlled, forests can significantly contribute to climate change mitigation. To reverse current forest degradation, an innovative management plan is required that supports and facilitates all the functionalities of peri-urban forests in the context of climate change mitigation. The reduction in the capacity of these forests to provide goods and services is often related to the absence of appropriate silviculture practices, which increases the risk of fires and compromises their value for recreational purposes.
OBJECTIVES
The LIFE FoResMit project aimed to draw up guidelines for good silvicultural practices for the restoration of peri-urban degraded coniferous forests in Italy and Greece with native broadleaved species. These would improve the ecological stability and climate change mitigation potential of these ecosystems.
The project also planned to test and verify in the field the effectiveness of management options for the conversion of degraded coniferous forests in meeting climate change mitigation objectives. It would provide data on vegetation structure, biomass increment, carbon accumulation in all relevant pools of vegetation and soil, and CO2 and other greenhouse gas emissions, thus giving a complete picture of mitigation potential of management practices.
RESULTS
The LIFE FoResMit project collected data over four years (2015-2018) to monitor the impact of silvicultural interventions, including data on:
The project clearly demonstrated that selective thinning, compared to traditional thinning, increases the forest stand stability and enhances its capacity to mitigate climatic change by increasing the sequestration capacity of carbon in above and below ground living biomass as a consequence of an increase of the net primary production.
The reformed thinning operations resulted in a short-term variation of GHG fluxes, which increased more strongly in Monte Morello than Xanthi, because of the use of heavy machinery and the consequent soil disturbance. Both sites are methane sinks, independent of management. Moreover, through selective thinning it was possible to increase CH4 uptake even after thinning. Overall, during the six months after silvicultural operations at the two sites, selective thinning saved 439 kg CO2eq ha-1 with respect to the control traditional thinning, which produced 2,512 kg CO2eq ha-1. Hence, selective thinning appeared to have the best performance in terms of GHG emissions. Short-term effects of thinning on CO2 emissions were dependent on the timing of logging operations and organic matter inputs. After thinning CH4 uptake increased significantly under selective treatment, independent of specific site-induced effects. N2O fluxes were characterised by low emissions in both sites and were not affected by treatments. The increase of CO2 emissions during thinning operations and in the short-term after thinning operations was expected. The project team observed a stabilisation of fluxes six months after thinning compared to control plots for CO2 and N2O.
Both methods of thinning lead to a loss of carbon stock in the short term, due to biomass harvesting, which is recovered because of increased primary productivity and consequent carbon sequestration. The better performance is shown from the traditional thinning scenario in absolute terms. Nonetheless, in relative terms (i.e. carbon sequestration/biomass released after the thinning) the two scenarios have the same performances at around 12%.
Another success of the project was the involvement of several categories of stakeholders. The local community was involved in the process of drawing up forest management guidelines. The views of forest users were canvassed by questionnaire, while semi-structured interviews were held with organised groups and public meeting were organised. Also, local authorities, managers, decision-makers and public administration officials were informed about the silvicultural approach and its impact.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
