Carbon storage in the Mediterranean upland shrub communities of Montesinho Natural Park, northeast of Portugal

Abstract

Carbon storage is one of the several important functions of shrub communities in terrestrial ecosystems and could represent an effective way to mitigate climate change. Accordingly, biomass carbon (above and belowground), litter carbon, and soil organic carbon (SOC) were studied in three shrub species: Cistus ladanifer (C. ladanifer), Cytisus multiflorus (C. multiflorus), and Erica australis spp. Aragonensis (E. australis)-representing dominant shrub communities found in Montesinho Natural Park (PNM), NE Portugal. The experimental design envisaged testing the effects of species and topography on variables mentioned and procedures carried out included assessments in areas covered by the three communities mentioned, in different topographic conditions (gentle slope, about 5 %; moderate, around 15 %; steep, around 25 %), with three replicates. Above and belowground biomass and litter were collected in 1 m2 plots, where soil samples at depths of 0-5, 5-10, and 10-20 cm were taken (disturbed for C mass concentration, undisturbed for bulk density determinations). The aboveground biomass was separated in stems, branches, branchlets, leaves, and fruits. Carbon mass concentrations determined in biomass, litter, and soil were converted to kg C m -2 ground area. Results showed that: (1) under the conditions studied, over 80 % of carbon is stored in the soil; (2) the contribution of biomass is higher in E. australis, representing about 20 % of carbon storage in the system; (3) for total carbon storage in the whole system, species followed the pattern E. australis (12.8 kg C m ); (4) effects of topographic conditions were not significant in the global C storage, with 10.6, 11.6, and 11.7 kg C m -2 in gentle slope, moderate, and steep, respectively.

Effect of prescribed fire on soil properties and soil erosion in a Mediterranean mountain area

“…The sum of exchangeable bases (SEB) generally decreased after the fire at all depths, which would be expected, since this parameter reflects the variation of the base cations, and these also suffered reductions by fire effect, which is in agreement with Fonseca et al (2011). The values of this parameter (SEB) are considered low (LQARS (Laboratório Químico Agrícola Rebelo da Silva), 2006).…”

“…Extractable potassium decrease two and six month after the fire, as reported for phosphorus, these losses can be attributed to the processes of leaching and erosion (Fonseca et al, 2011), as well as to vegetation root uptake which fastly grew up in this period. Thirty-six months after the fire the potassium content is identical to pre-fire situation and it is Chemical properties Depth 0 -5 cm 5 -10 cm 10 -20 cm…”

“…There are many reasons to apply prescribed fire in forest management as, for instance, it reduces hazardous fuels and breaks up fuel continuity (Fernandes and Botelho, 2004;Fernandes and Loureiro, 2010), it prepares sites for seeding or planting of forest species, and controls the competing vegetation (Brooks and Lusk, 2009), it improves habitat and creates diversity needed by wildlife (Wasserman, 2015), it controls insects and diseases (Parker et al, 2006), it improves pasture quality for cattle (Fonseca et al, 2011), it improves access into forest stands, and it contributes to preserve fire-dependent plant species, particularly important in Mediterranean environments (Pausas and Keeley, 2009). Prescribed fire in shrublands applied to protect forests stands is a relatively common practice in Montesinho Natural Park (PNM), Northeast Portugal (IPB/ ICN, 2007;Fonseca et al, 2011). Soil is a qualitatively scarce resource in this region and even more scarce in the marginal areas where the shrubs dominate (Figueiredo, 2002).…”

“…Soil is a qualitatively scarce resource in this region and even more scarce in the marginal areas where the shrubs dominate (Figueiredo, 2002). The protection of this resource is essential due to its key role in ecosystem services provision, associated to the hydrological cycle, nutrient cycles and carbon dynamics and storage (Rashid, 1987;Thomas et al, 1999;Pardini et al, 2004;Bompastor et al, 2009;José, 2009;Fonseca et al, 2011;Fonseca et al, 2012). The knowledge of soil degradation processes and the context factors that determine them is a basic condition for the design of strategies, actions and practices focused in the soil resource protection.…”

“…A direct effect of fire on soil surface is the formation of a continuous water-repellent film, which reduces permeability and increases runoff (Imeson et al, 1992). In Mediterranean ecosystems, where the torrential rainfall events are frequent in autumn and winter, October to March is a critical period when soil susceptibility to water erosion processes is increased after the summer wildfires (Andreu et al, 2001;Fonseca et al, 2011;Francos et al, 2016). Higher frequency of fire and intense rainfalls represents a large potential to reduce soil fertility by erosion and nutrient loss, therefore limiting burnt areas recovery and enhancing soil degradation (Thomas et al, 1999).…”