STUDY SITE 1: Caramulo Mountains, Portugal

Responsible partner: UAVR

1. General information

Following-up on prior work in the late 1980s-early 1990s, fire-related research by the UAVR team was “rekindled” by the summer-2003 fires and the subsequent submission and (national) funding of the EROSFIRE-I and PHOENIX projects, with the former focussing on post-fire hydrological and erosion processes and the latter on the recovery of vegetation structure and alpha diversity. Subsequent research projects and post-doctoral and PhD grants (details are given under point 6.) have allowed to intensify this work and widen its scope, namely by addressing: (i) social-economic and land-use planning aspects; (ii) land degradation risk in general, i.e. also in terms of soil nutrients, carbon and seedbank; (iii) effectiveness of emergency soil conservation measures; (iv) off-site effects on downstream aquatic habitats and flood zones, including with respect to potential eco-toxicological effects of ash-loaded runoff.
In the present context, the strong modelling component of the current work deserves special mention, as it will allow reconstruction of the land degradation processes following the past wildfires in the study area.

2. Geographical description

The study area is located in north-central Portugal, and is part of the Vouga River Basin which drains into the Ria de Aveiro coastal lagoon area. According Köppen’s system, the climate can be classified as Csb, i.e. as humid meso-thermal with a prolonged dry and warm summer - when the majority of the wildfires occur. Annual rainfall ranges from 1200 to over 2000 mm/year at the highest elevations, and is high for Mediterranean regions. The latter is also true for rainfall erosivity and, thus, erosion risk. The area belongs to the major physiographic unit of the Hesperic Massif, which is dominated by pre-Ordovician schists and greywackes and Hercynian granites. The terrain has a pronounced relief with steep slopes that are typically around 20-25o but steeper in places. The soils are mapped (scale of 1:1.000.000) as a complex of Humic Cambisols and, to a lesser extent, Dystric Litosols. Soils are typically shallow (<40 cm deep) and predominantly covered by commercial tree plantations of eucalypt (Eucalyptus globulus Labill.) and Maritime Pine (Pinus pinaster Ait.), which are both highly flammable species.
The map on the next page indicates the Caramulo study area. It also shows the location of the neighboring study sites that the UAVR team has been and is monitoring in the framework of its fire-related projects (see point 6. for details). In a nutshell: (i) all existing sites include recently burnt areas, except those of HIDRIA (last fire 15+ years ago); (ii) all existing sites include forest plantations, except that of Arouca (shrubland); (iii) the sites burnt in 2005, 2006, 2007 and 2009 are at plot and/or slope scale, whereas the sites burnt in 2008 and 2010 and before 1992 also include the catchment scale.

3. Main ecosystem(s) in the study area, and functions/services they provide

The main ecosystems in the study area are managed tree plantations of eucalypt and Maritime Pine, with the former increasingly having replaced the latter in the past few decades. Important differences between the two forest types are that: (i) the rotation cycle is much shorter for eucalypt than for Maritime Pine (roughly 12 vs. 40 years); (ii) following fire, mechanical ground operations like ploughing and, in recent times, especially terracing are frequent in eucalypt stands but hardly ever occur in pine stands (where natural regeneration prevails). Such operations can greatly reduce vegetation recovery and strongly enhance soil erosion rates.

Figure Location of the CASCADE study area and of the neighboring study sites of the UAVR team.

The principal ecosystem services provided by the two forest types include: (i) wood production, with eucalypt plantations assuming special relevance for the paper industry (a paper pulp plant exists in the Aveiro municipality); (ii) production of forest residues for biomass electricity centrals; (iii) protection against floods, which is particularly important in the case of the city centre of Águeda due to its location in a floodplain; (iv) attenuation of rainfall-runoff response, which will be fundamental for the dam complex that is currently being built in the lower Vouga river (Ribeiradio-Ermida) for generation of hydric electricity; (v) provision of good water quality, which is especially relevant for the capture of surface water for purpose of e.g. drinking water purposes like is the case of the Carvoeiro station in the lower Vouga river; (vi) preservation of natural values, especially in the Maritime Pine stands and the less-intensively managed eucalypt stands.

4. Ecosystem dynamics – are there indications for irreversible change in the area, and that critical thresholds and tipping-points regulate such changes? And what are the drivers for change?

The past and present research by the UAVR team has found erosion rates to be low compared to those reported by post-fire studies in the rest of the Iberian Peninsula but especially in Australia and the USA. This is linked to the fact that erosion rates in north-central Portuguese forests are markedly sediment-limited. This, in turn, is taken to reflect the long land-use history in the area, probably exacerbated by the widespread planting of Maritime Pine by the national forest services during the first half of the 19th century and the intensified management following their increasing conversion to eucalypt plantations during the past few decades.
Nonetheless, wildfires and poor land management following wildfire often increase sediment losses markedly, selectively removing the fines and organic matter (ashes). Therefore, they are regarded as the key drivers in furthering the degradation of the soil functions of these managed ecosystems to possibly irreversible levels (in the human time frame). The current, fragile state of many soils in the study area is clearly indicated by the frequent occurrence of extensive stone layers as well as their shallow depth (a key limiting factor in root development and plant water availability), and by the often slow and contracted recovery of spontaneous vegetation after fire and forest management.

5. Relevant end-users of knowledge in the region / country (like natural resource and biodiversity managers, local/regional/national authorities, users or beneficiaries of ecosystem services

  • Forestry land owners, especially through associations like the Baixo Vouga Forestry Association
  • Technical Forestry Offices of the municipalities of Águeda, Albergaria-a-Velha and Sever do Vouga in particular
  • RAIZ – Research Institute for Forestry and Paper
  • Administration of the Centre Hydrographic Region (ARH Centro)
  • Associação de Municípios do Carvoeiro (Carvoeiro water capture station)
  • Greenvouga (Ribeiradio-Ermida dam complex)

6. Past and on-going projects on ecosystem functioning, thresholds, and related aspects

  • EROSFIRE (2005-2008) - erosion risk assessment & modeling following wildfire
  • PHOENIX (2005-2009) - vegetation recovery with time after fire
  • RECOVER (2007-2010) - effectiveness of emergency soil conservation measures
  • EROSFIRE-II (2007-2010) - on- & off-site wildfire effects on runoff and erosion
  • DESIRE (2007-2011) - stakeholder-based land conservation strategies against desertification
  • HIDRIA (2009-2012) - rainfall-runoff modeling of long unburnt forest catchments 
  • FORESTAKE (2010-2013) - role of stakeholders in forest policy success in fire-prone areas
  • FIREREG (2010-2013) - mid-term post-fire regeneration in eucalypt & pine forest 
  • FIRECNUTS (2010-2013) - on- & off-site wildfire effects on runoff and soil, organic matter, carbon and nutrient losses
  • 4 post-doctoral grants and 8 PhD grants on fire-related research

7. Key references about ecosystem dynamics in the study area or wider spatial setting.

  • Ferreira A.J.D., Silva J.S., Coelho C.O.A., Boulet A.K, Keizer J.J. 2009 The Portuguese experience of managing fire effects. In: Robichaud P. & Cerdà A. (eds.), Fire effects on soils and restoration strategies,,pp 401-422. Science Publishers, Enfield, U.S.A.
  • Maia P., Pausas J., Arcenegui V., Guerrero C., Pérez-Bejarano A., Mataix-Solera J., Varela M.E.T., Fernandes I., Pedrosa E.T., Keizer J. accepted. Wildfire effects on the seed bank of a Maritime Pine stand, central Portugal. In: VI International Conference on Forest Fire Research (Coimbra, 15-18/11/2010), 7 pg
  • Maia, P. Lacmane, D., Cartei, L. Pinho, R., Silva, J., Keizer, J., 2007. Efeitos do fogo sobre a estructura e compoisição florísticsa de pinhais e eucaliptais nos concelhos de Albergaria-a-Velha e Águeda. In: Borrego, C., Miranda, A.I., Figueiredo, E., Martins, F., Arroja, L. & Fedélis, T. (eds.), 9ª Conferência Nacional do Ambiente (Aveiro; 18-20/04/2007), Vol.4, pp. 1418-1421. (U.Aveiro, Dept. Ambiente).
  • Malvar M.C., Prats S.A., Nunes J.P., Keizer J.J. in press. Post-fire overland flow generation and inter-rill erosion under simulated rainfall in two eucalypt stands in north-central Portugal. Environmental Research (doi:10.1016/j.envres.2010.09.003)
  • Shakesby, R.A., Boakes, D., Coelho, C.O.A., Gonçalves, A.J.B., Walsh, R.P.D., 1996. Limiting the Soil Degradational Impacts of Wildfire in Pine and Eucalyptus Forests in Portugal. Applied Geography 16 (4), 337-355