Short-term effects of thinning on soil CO2, N2O and CH4 fluxes in Mediterranean forest ecosystems.

In Mediterranean ecosystems an increasing demand for in situ trace gas exchange data is emerging to enhance the adaptation and mitigation strategies under forest degradation. Field-chamber green-house gas fluxes and site characteristics were analysed in two Mediterranean peri-urban pine forests showing degradation symptoms. We examined the effect of different thinning interventions on soil CO2, CH4 and N2O fluxes, addressing the relationships with the environmental variables and C and N contents along forest floor-soil layers. Soil temperature resulted as the main driving variable for CO2 efflux and CH4 uptake. Soil moisture content and organic matter availability affected CO2 emission patterns in the two sites. N2O fluxes showed a positive correlation with soil moisture under wetter climatic conditions only. GHG fluxes showed significant correlations with C and N content of both forest floor and mineral soil, especially in the deepest layers, suggesting that it should be considered, together with environmental variables when accounting GHG fluxes in degraded forests. Short-term effects of thinning on CO2 emissions were dependent on disturbance induced by logging operations and organic matter inputs. After thinning CH4 uptake increased significantly under selective treatment, independently from specific site-induced effects. N2O fluxes were characterized by low emissions in both sites and were not affected by treatments. Soil CO2 efflux was the largest component of global warming potential (GWP) from both sites (11,553 kg ha-1 y-1 on average). Although it has a large global warming potential, N2O contribution to GWP was about 131 kg CO2eq ha-1 y-1. The contribution of CH4-CO2 equivalent to total GWP showed a clear and significant CH4 sink behaviour under selective treatment (36 kg ha-1 y-1 on average). However, in the short-term both thinning approaches produced a weak effect on total GWP.

Intra-annual raw basal area increments (early-wood and late-wood) of Pinus nigra subsp. laricio Poiret trees from southern Italy at the pines׳ mesic to xeric distribution range.

This article contains tree rings data related to the research article entitled "An intra-stand approach to identify intra-annual growth responses to climate in Pinus nigra subsp. laricio Poiret trees from southern Italy" (Mazza et al., 2018). Most dendroclimatological studies on black pine have been conducted on the P. nigra subsp. nigra, while only few results on climate-growth relationships are available for other taxa such as P. nigra subsp. laricio, which has the narrowest distribution range of the collective species P. nigra. This data article provides tree rings data for the subsp. laricio at an intra-annual growth level, distinguishing early-wood (EW) and late-wood (LW), from an even aged forest stand from the Sila mountain area within the subspecies mesic to xeric distribution range.