LEDD issues

LEDD issues in forests & shrubland: general

2012-06-18T09:12:56+00:00

Authors: Agostino Ferrara, Guiseppe Mancino, Luca Salvati

{xtypo_alert}Editor's note 30 Apr 2012: Text source D311, section 3.1. {/xtypo_alert}

Although LEDD issues are primarily environmental problems, they generate associated socio-economic consequences. The LEDD issues in forests & shrubland that are examined in this deliverable are presented in Table 1. The table distinguishes between the environmental and the socio-economic aspects of these issues which are manifested at all spatial levels (global, national, regional, local).

Table 1. LEDD issues in forests and shrubland

Type of Issue	LEDD Issue
Environmental issues	Soil erosion Soil organic matter decline Loss of biodiversity Ecosystem (forest) fragmentation Soil compaction Soil salinisation Soil sealing Land desertification Forest productivity decline Water stress Phytosanitary deterioration of forest cover
Socio-economic issues	Rural depopulation Land use change Loss of traditional knowledge Poverty Unemployment Decrease in profitability of land Land abandonment Decline in property values

Source: LEDDRA Study Site Application Plan 2011.

LEDD issues in forest and shrublands are both of an environmental and human origin that increase the fragility and instability of these ecosystems and decrease their capability to provide ecosystem services. Human-induced issues can vary spatially and temporally. They are generally linked to the overexploitation of forest resources, land use change and air pollution. On the other hand, environmental pressures such as extreme climatic events (e.g. drought, ice, storms and floods); global warming; insects and phytosanitary diseases represent other relevant causes for the deterioration of forest ecosystem and for soil erosion and land desertification.

Forest productivity decline

One of the most important phenomena related to the degradation of forests & shrublands worldwide is the decline of forest productivity. The loss of forest ecosystem productive capacity, i.e. a reduction in the ability of forest soils to retain nutrients and a decline in soil water storage capability, results from a wide range of both human and biophysical factors. Biophysical factors such as climate change and increases in the frequency of extreme climatic events are responsible for long-term processes of forest productivity decline (Boisvenue and Running 2006). These drivers are often closely coupled to human drivers including grazing, forest fires, poor harvesting and management practices and they result in different levels of disturbance affecting nutrient cycling and soil properties. In particular, soil erosion and compaction together with reduction in soil organic matter content imply a simultaneous loss of nutrient and water storage capability (Pimentel et al. 1995; Lai 2000).

The effects of climate change vary at the regional scale due to general climatic conditions. Generally, forest productivity and ecosystem productivity at high latitudes show a positive feedback with an increase in carbon sequestration (Myneni et al. 2001). On the contrary, in the Mediterranean region, increasing temperature and related increasing evapotraspirative demand, lead to a general decline in forest ecosystem productivity (Peñuelas et al. 2008; Piovesan et al. 2008). An important phenomenon related to climate change is heat waves, affecting climate regimes worldwide with increasing frequency. These climate phenomena are mainly responsible for ecosystem productivity decline worldwide, with an associated increase in other disturbances including forest fires (Westerling et al. 2006) and desertification processes. In particular, as Ciais et al. (2005) showed, the European-wide heat and drought wave of 2003 has been responsible for a 30 percent reduction in forest assimilation process, which resulted in an ecosystem carbon dioxide release to the atmosphere equivalent to 4 years of European ecosystem productivity (Figure 1).

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Figure 1. European-wide anomaly of NPP during 2003. Source: (Ciais et al. 2005).

Loss of biodiversity

Loss of biodiversity represents an often irreversible process affecting the ecosystems at different levels, because it implies the extinction of genes, species and ecosystems. Although extinction is a natural process as testified by a number of past extinction crises, human activities have caused an exponential increase in extinction rates during the last century (Diaz et al. 2006). The principal drivers of biodiversity loss, such as habitat and land use change, overexploitation, pollution, invasive alien species and climate change, are constantly increasing in intensity on a global scale (Millennium Ecosystem Assessment 2005b) (Figure 2).

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Figure 2. Deforestation is land use conversion, not harvesting of timber. If a harvested forest is allowed to regenerate, the ecosystem effect of harvesting is carbon neutral; but if the forest is converted to another land use, carbon is released into the atmosphere (forest cleared for rice production, Indonesia). Source: (FAO/FO-5616/H. HIRAOKE).

Loss of biodiversity in forest ecosystems implies not only the extinction of species, but also the destruction of habitats and ecosystems. Logging activities also push roads into previously untouched forests. Even where logging is selective, access roads and tracks used to facilitate extraction damage soil (soil erosion and compaction), plants and other organisms (Lindenmayer and Noss 2006).

The conservation of biodiversity has become a pressing issue for the scientific community, involving the study of vulnerable as well as culturally valued species and ecosystems, conservation practices and policies. The conservation of biodiversity is also critical for economic systems and markets, due to its financial benefits and the costs of its loss. This represents an opportunity for the re-structuring of economies and financial systems following the global recession (Secretariat of the Convention on Biological Diversity 2010).

Forest fragmentation

Forest fragmentation is another important LEDD issue, occurring when habitats, landscapes and ecosystems become disconnected by human or non-human factors. Fragmentation results in a physical separation of habitat units in a previously continuous system. This phenomenon may occur naturally, after catastrophic geological events such as volcanic activity, geological faulting, tectonic movement, mass land slumping, major sea level rise and climate oscillation. However, human exploitation of forest ecosystems is one of the primary causes of landscape transformation and fragmentation. Local forest loss spatial processes include:

Attrition: the disappearance of patches,
Shrinkage: a decrease in the size of remaining patches,
Perforation: it occurs when holes or voids are made in a habitat, i.e. an extensive forest perforated by logged areas. Perforations are an ecologically important type of fragmentation because they introduce potential edge effects deeper into intact forests, compared to erosion of forest patch perimeters (Riitters and Coulston 2005);
Fragmentation: in the narrow sense of the term, is the breaking up of a habitat into smaller parcels. It includes the two processes of dissection and fragmentation.

Human-induced habitat fragmentation is mainly driven by agricultural land conversion processes, urbanisation, pollution, deforestation, introduction of alien species and forest fires. Fragmentation is the result of direct loss of forest area caused by land use change but it is also the result of “edge effects” of urban or agricultural land uses. Fragmented forest landscapes are characterised by more abrupt boundaries between native and non-native vegetation and are typically found in areas which have been developed for production forestry, where remnants of native vegetation are mixed with non-native tree species. In general, these processes transform isolated ecosystems from healthy forests into monocultures of timber production species, leaving only isolated historical remnants of native vegetation. Relict landscapes are also the result of urban/suburban development and expansion (urban sprawl). Fragmentation and dispersion of patches also induces loss of biodiversity. According to the Island Biogeography Theory, fragmented ecosystems have lower species richness per unit of area compared with contiguous habitats (MacArthur and Wilson 1963; Laurence 2008).

Soil erosion and deterioration

Healthy soil is an important component of the forest ecosystem providing water, nutrients and allowing exchange of carbon dioxide, oxygen, and other gasses that affect root growth and soil organisms. Soil erosion represents an often irreversible land degradation process affecting forest and shrubland ecosystems worldwide.

Soil erosion occurs naturally due to the interaction of the atmosphere and the water cycle with land surfaces. Although the distribution and intensity of natural erosion processes may be affected by climate change leading to land degradation, accelerated erosion due to unsuitable land uses and land management practices is a key LEDD issue in sloping areas. The main factors responsible for accelerated soil erosion are clearance of forests for expansion of agriculture and cultivation of steep slopes, changes in plant cover due to intensive cultivation, over-grazing, wildfires, levelling of land surfaces and poor maintenance of terracing land, amongst others. Soil is most susceptible to erosion processes after the removal of plant cover which protects it from wind and water, mainly from the splash effect of intense rainfall, while roots hold the soil together and anchor it in place.

Deforestation processes induced either by logging or forest fires cause a direct impact by reducing vegetation cover, and in many cases create a pre-condition for the increase of soil erosion rates. Forest fires produce large areas of bare soil, increasing soil loss particularly during the first year after a fire event (Shakesby 2011). However, the magnitude of soil erosion depends on many factors such as the frequency and magnitude of precipitation events after fire, soil texture and soil depth (Myronidis et al. 2010; Pardini et al. 2004).

Logging intensities directly influence surface runoff and eroded soil mass through timber felling, skidding trail establishment and log skidding and/or hauling from logging compartments through feeder roads to the temporary log yard. Logging activities are also responsible for soil compaction with changes in soil bulk density, penetration resistance and micro-topography as a result of several factors related to machine mass and type and traffic intensity (Ampoortera et al. 2010). At the same time, high rainfall and intensity increase the volume of surface water runoff and thus soil mass erosion. Microtopography (slope, aspect and length) also represents a key factor increasing soil erosion rate.

Water stress and phytosanitary deterioration of forest cover

In a globally changing climate, forests & shrublands are increasingly subject to environmental pressures like extreme climatic events or pests affecting the phytosanitary status of forest cover. Global climate change is reportedly making forest ecosystems more prone to damage by altering the frequency, intensity and timing of fire events, hurricanes, ice storms, and insect and disease outbreaks, together with possible changes of species distribution and shift of forest cover towards cooler and wetter conditions. The number of catastrophic climatic events over the past decade seems to go well beyond what could be considered normal meteorological oscillation (ECOSOC 2003). Climate-related shifts in the range of pest species, many of which are forest-dependent, can further exacerbate biophysical impacts on forest health.

Water stress, especially in Mediterranean forests & shrublands, seems to be the major cause of forest productivity decline and of forest deterioration more generally. It represents the direct consequence of extreme climatic events such as continuous heatwaves and drought events. The general deterioration of forests also determines favourable conditions for pest outbreaks contributing directly or indirectly to economic and environmental losses.

While insects and diseases are integral components of forests and often fulfil important functions, sporadic outbreaks can have adverse effects on tree growth and survival, yield and quality of wood and non-wood forest products, wildlife habitat and the recreational, scenic and cultural value of forests. The lack of effective quarantine measures, increased international trade in agricultural and forest products, exchange of plant materials and long-range air travel have introduced alien pathogens and insects into new environments leading, in some places, to significant forest damage. An example is the recent diffusion of the Pine Wood Nematode (PWN), Bursaphelenchus xylophilus, one of the most serious threats to pine forests worldwide (Harrington and Wingfield 1998).

Desertification

Desertification is a process of land and ecosystem degradation and loss of organic matter owing to a complex interaction among physical, biological, political, social, cultural and economic factors. Desertification can be considered a worldwide phenomenon affecting natural ecosystems and particularly Mediterranean Regions and semi-arid ecosystems. Since 1994, with the United Nations Convention to Combat Desertification (UNCCD), the desertification process has been considered as a key environmental issue closely correlated to other key issues such as increasing land demand for agriculture, land use changes and global change.

These land transformation processes are often associated with deforestation that is used to increase the land available for grazing or intensive monoculture to produce fuelwood and biofuels. In this way, desertification is the result of a land degradation process that starts with increasing soil fertility loss and eventually results in land abandonment. Furthermore, in semi-arid regions, global climate change increases the risk of desertification and accelerates the processes of land abandonment due to the increased frequency of extreme climatic events and, consequently, to a generalised loss of ecosystem productivity. This scenario implies deep transformations from a socio-economic point of view, with consequences for the distribution of the population and for the availability of food, water and resources for human populations.

Socio-economic issues

As discussed previously, forest and shrubland ecosystems provide a wide range of fundamental environmental, social and economic services to local communities. The continuous flow of ecosystem services ensures that the necessary conditions for the development of communities and human well-being are met (Daily 1997). Therefore, LEDD issues strongly impact the socio-economic system with consequences at both local and regional scales for activities related to land management, agriculture, grazing and forestry. As a consequence of LEDD issues, the loss of productivity and the associated reduction in the profitability of human activities represents an important factor determining the socio-economic dynamics at the local level. The loss of income generation potential and the consequent reduction in development opportunities pushes most of the younger people to look for other forms of employment outside of their home area, resulting in depopulation or outmigration and population aging.

These phenomena also involve other socio-economic processes that further exacerbate the problem. As an example, the reduction of the young population and rural population aging lead to a reduction in the availability of public services such as schools and health care. Furthermore, negative consequences for well-being can also propagate elsewhere, with emigrants increasing the population and environmental pressures in already stressed urban areas (Pereira et al. 2005).

Another socio-economic issue is the abandonment of forested land and the loss of traditional agricultural and land management practices, with a consequent increase in ecosystem degradation and loss of knowledge and cultural heritage. The decrease of land profitability is also responsible for land abandonment in mountainous areas, with consequences for land cover change driven by spontaneous afforestation. This phenomenon is particularly present in the mountainous areas of Europe, with an increase of forest cover over the last decades (Poyatos et al. 2003). According to a broadly accepted conviction, this process is seen as a positive phenomenon that leads to an increase of the ‘naturalness’ of an area. However, in many cases these ‘wilderness areas’ represent a net loss of cultural landscapes and also a loss of biodiversity during the succession process, due to the invasion of aggressive pioneer or dominant species (Höchtl et al. 2005). Furthermore, forest expansion in these areas requires the definition of new strategies in managing these new forest resources and services.

LEDD issues in forests & shrubland: Italy and Matera

2012-06-18T09:37:30+00:00

Authors: Agostino Ferrara, Guiseppe Mancino, Luca Salvati

{xtypo_alert}Editors note: text source D311 section 3.1.2{/xtypo_alert}

Forest productivity decline

Forest productivity decline in the Mediterranean region and thus in large areas of southern Italy represents an LEDD issue which is closely related to direct drivers of change, such as climate change, agriculture and tourism. The severity of the climate linked with forest mismanagement or the use of poor silvicultural practices and overgrazing are responsible for forest and ecosystem productivity decline at regional and local scales. In particular, these drivers affect nutrient cycling properties and physical properties such as soil characteristics. The Matera Study Site represents an area sensitive to forest productivity decline, due to its geomorphology, climate, and human activities. From a climate perspective, the Matera study site is particularly affected by frequent heat and drought waves during the summer season which dramatically reduce water availability, and thus the photosynthetic processes. This loss in productivity combined with forest fires and/or other practices like overgrazing in forest and shrubland is responsible for most of the loss of ecosystem productivity. At a local scale, forest mismanagement or poor silvicultural practices generally result in stand ageing.

Loss of biodiversity

In the Matera Study Site, loss of biodiversity represents a major LEDD issue affecting forests and shrublands, as is the case in the rest of the Mediterranean region of southern Italy. Recurrent anthropogenic and natural perturbations are responsible for this loss in biodiversity. As in the rest of the Mediterranean basin, the forests resources of the Basilicata region have long been exploited, leading to deforestation and forest fragmentation in past centuries. In many areas, important re-forestation projects carried out during the last century have produced even-aged pure conifer stands. Another case is the transformation of natural forests into coppices, with a simplification of forest structure and species composition. In forest stands characterized by good soil fertility, forest management has been oriented towards maximizing wood production, with even-aged structures and the prevalence of one or few tree species. Figure 1 shows the distribution of forest types with different biodiversity levels for the Matera study site.

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Figure 1. Distribution of forest types with different biodiversity levels for Matera study site. Source: (Spatial analysis of the Basilicata Region Forest Map and Regional Biodiversity Map produced by the authors).

Forest fragmentation

As in the rest of Mediterranean region, forest fragmentation represents an important threat to forests and shrublands in the Matera study site. Human activities such as agricultural land conversion, overgrazing, forest fires, urbanisation and tourism represent the main drivers of forest fragmentation at the study site level.

Soil erosion and degradation

Soil erosion processes are widely distributed within the forest environment of the Matera study site. The geomorphology of the area provides favourable conditions for land degradation processes.

In the study area, repeated fire events have led to devolution of forest succession stages. Thus, the Holm oak high forest degrades to a sparse forest and then to a shrubland mixed with Phillyrea, Cystus, amongst other species. Further impact from fire or excessive grazing will lead to a further reduction of trees and shrubs and the area will eventually become grassland, dominated by geophytes such as the Asphodelus. The spreading of fire, which reduces the amount of biomass, has negative effects on the soil with an increase in erosion, deterioration of chemical and physical characteristics and increased risk of landslides. In particular, alterations of soil chemical and physical characteristics involve changes in porosity with a general reduction in soil ventilation and infiltration capacity, reduction in organic matter content and development of a waterproof layer to a depth of 10-15 cm.

In the Calanchi (“badlands”) area, the particular conditions of microtopography (slope, aspect and length) represent key factors increasing the soil erosion rate (Figure 2).

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Figure 2. Afforestation in Calanchi areas. Source: (Spatial analysis of the Basilicata Region Forest Map and Calanchi “Badlands” Map by the authors).

Water stress and phytosanitary deterioration of forest cover

The Mediterranean coastal and upland study site of the Matera prefecture is an area prone to water stress events, due to its climatic characteristics, with repeated drought events occurring during the year.

In this context, the main forest areas affected by water stress and phytosanitary deterioration are the coastal pinewood forests and coniferous forests in the Calanchi area. In these areas, poor seasonal climatic conditions and soil degradation create a high sensitivity to water stress and induce poor quality vegetation, increasing vulnerability to parasitic attack (most often processionary moth and scolytus).

Desertification

The study site of the Matera prefecture can be considered very representative of the Mediterranean region’s main characteristics. It is particularly prone to land degradation and loss of organic matter and, thus, to desertification. The increasing frequency of extreme climatic events, ecosystem overexploitation and, in some cases, land abandonment represents the main causes of the desertification process.

In particular, desertification can be considered as the result of two main opposing processes: 1) land overexploitation; and 2) land abandonment. The first process is generally driven by poorly managed agriculture and grazing that result in land and ecosystem degradation such as soil erosion and deterioration, loss of organic matter, loss of water holding capacity, ecosystem fragmentation and loss of ecosystem productivity. The second process is generally driven by socio-economic factors such as small farm size and property fragmentation, low income from agricultural activities and socio-cultural change driving rural migration towards urbanised areas. In this context, global climate change accelerates the biophysical processes which underlie the main LEDD issues.

Socio-economic issues

The Mediterranean coastal and upland study site of the Matera prefecture presents most of the socio-economic issues related to forest ecosystem and shrubland degradation processes. In the last few decades, the study area has been characterized by continuous depopulation, generally related to the loss of profitability of agricultural and forestry activities (Regione Basilicata 2008b). LEDD issues affecting the Mediterranean region in general also affect the Matera Prefecture study site, with loss in ecosystem productivity which results in loss of income. This situation also worsens due to a generalised lack of technological assistance, the types of farms present and the land property fragmentation. A main consequence of depopulation and migration of younger people to urban areas is population ageing, land abandonment and loss of cultural heritage (Fuccella et al. 2010).

LEDD issues in forests & shrubland: Spain, Portugal and Baixo Guadiana

2012-06-18T09:52:36+00:00

Authors: Michiel Curfs, Anton Imeson

{xtypo_alert}Editors note: Text source D311 section 3.1.3{/xtypo_alert}

Land desertification

The main function of 88 percent of Spanish forests is to protect against soil erosion and desertification, and to regulate the hydrological cycle (FAO 2011). Dehesa and montado forests protect the soil from the drying effects of wind and solar radiation (shadow and windblocks). This type of forest also facilitates the condensation of fog (natural fog harvesting effect). Deep root systems extract nutrients from the lower layers of soil and through leaf litter, return these nutrients to soil surface horizons. Furthermore, litter works as mulch, shading the soil and helping to create favourable moisture conditions which protect the soil from erosion. Livestock manure is also introduced to the system via agroforestry practices (Olea and San Miguel-Ayanz 2006). This increases soil organic matter and makes the soil less vulnerable to erosion.

Just as in other areas, however, Dehesa and Montado forests are degrading into shrublands with thinner and hotter soils. As the forest canopy becomes more open, there is positive feedback which leads to more runoff, less infiltration and degradation of the hydrological cycle and other ecosystem functions and services. As degradation increases, there is an associated progressive decline in natural and economic capital. This general degradation of the forests is exacerbated by specific issues that include inappropriate soil conservation issues (poor construction of terraces), introduction of exotic tree species such as eucalypts that produce toxic substances in the soil, local contamination from mining and a drop in groundwater levels.

Forest productivity decline

The 12 percent of forests in Spain that are used for production purposes suffer from many degradation issues. Issues include the use of floodplains for growing trees that use phreatophytic water, so that less water is available for other river functions. A major issue in many forests in Spain and Portugal is the use of bulldozers and heavy machinery and as a result the soil profile is inverted, placing sensitive soil on the surface. This issue is present in a number of regions in Spain. This issue occurs where the main source of income is subsidies for planting trees on land that has been burned or used for other agri-environmental schemes. Trees fail to grow because of the way they are planted and managed, and entire landscape eventually becomes desertified. The land loses its natural soil and water regulation function because of soil compaction from heavy machinery.

Loss of biodiversity

The loss of biodiversity in relation to plant species is discussed below, as most of the key LEDD issues and their drivers impact directly on biodiversity. For example, it is clear that forest fires lead to biodiversity loss, particularly in the short term. Fragmentation and soil deterioration are also directly linked to biodiversity loss (COST 341 2003). A special emphasis must be given to indirect loss of biodiversity in dehesa and montado systems. These systems are an important habitat for a number of endangered animal and bird species, such as the Spanish imperial eagle (Aquila adalberti) and the Iberian Lynx (Lynx pardinus). As the area of dehesa and montado declines, so does the available habitat for these threatened species (Olea and San Miguel-Ayanz 2006).

Forest fragmentation

As reported in the COST 341 report ‘Wildlife and traffic’ (2003), one of the major impacts of infrastructure development is habitat fragmentation and associated biodiversity loss. Transportation, agriculture and urbanisation are three key causes of fragmentation. Spain and Portugal have seen a significant expansion of the road network over the past 20 years, with a 640 percent increase in its road network (Eurostat 2009). Urban expansion is also causing significant forest fragmentation in Portugal and Spain (MAOTDR 2007).

Most dehesa and montado forests are located in rural areas with low populations, or in mountainous areas used for hunting grounds. In Portugal, ecological corridors or green bands are being created in order to prevent forest ecosystem fragmentation. In the Spanish part of the Baixo Guadiana study area, solutions are being sought to enable these green corridors to be expanded from Portugal into Spain.

Soil erosion

In the Baixo Guadiana area, soils in general are shallow. Dehesa and montado land use management includes ploughing between trees. This happens, in general, twice per year and causes accelerated (tillage) erosion. The main reason for ploughing is to clear undergrowth as a fire prevention tool. This leads to excessive erosion rates in the form of sheet, wind, rill and gully erosion and soil deterioration. On the Spanish side of the study area, landowners are held responsible for any fires starting on their land. As a result, preventative ploughing is deeply entrenched as a cultural activity, to prevent severe fires.

Soil sealing

In Portugal, there is a generalised and increasing trend in soil sealing. Between 2000 and 2006, soil sealing increased by 10 percent, mainly as a result of dispersed urbanisation. An important issue is the impact of surfaced and unsurfaced roads on surface water drainage. Hard surfaces lead to rapid runoff and the loss of the water that trees require. Rapid runoff also leads to soil erosion and the sedimentation of water courses, which can contribute to flooding downstream.

The forest can also provide a protection function (See Doran et al. 2005) which protects people from rockfall and landslides. The disturbance of the forest because of road building or agriculture leads to the loss of this function.

Water stress and phytosanitary deterioration of forest cover

A recent study by Garcia et al. (2003) showed that all Mediterranean forests suffer from a permanent shortage of water. Large areas of cork and holm oak mortality have been observed in Spain in recent years. Early symptoms of impending mortality range from progressive signs of defoliation with partial or total dead branches to rapid death in a short period of time (sudden oak death or ´seca´). Surviving trees appear unhealthy for a considerable length of time. Mortality occurs in pockets with no apparent geographic patterns.

At the Evora conference in 2006 on the vitality of cork and holm oak stands and forests, it was stated that in Portugal, data suggests that the area of cork and holm oak (montados) increased between 1902 and 1956, from approximately 800,000 ha to 1,200,000 ha following a relatively stable period (with cork oak areas occupying a slightly larger area than holm oaks). Analysis of the health of these areas in Portugal suggests that area and tree densities are in relatively fair condition but health status, such as levels of defoliation at the plot level, suggest that a high proportion of plots may be in poor condition.

Among the main causes of mortality, pests, fungi and water stresses were found to be the most critical. Pests such as Phytophthora spp. occur in association with all Quercus species and are perhaps an important factor of cork and holm oak decline. This process is called ´seca´ in Spain (Figure 1). Oak endophytic fungi can act as pathogens to their host.

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Figure 1. La ‘Seca’ affecting holm oaks in the Baixo Guadiana. Source: (Author Michiel Curfs).

The lower Guadiana basin, represents a typical semi-arid region where human activity and modification of the hydrological regime over previous decades have led to increasing water scarcity and the identification of water shortage as a ‘structural characteristic’ of the system. Future climate change will act to amplify existing water stress, with important consequences for the availability and distribution of water between different land uses (ADAM 2009). Water stress is related to irregular rainfall patterns, which are predicted to worsen on the Iberian Peninsula as a result of climate change scenarios. The decline of forest productivity of the montado and dehesa forest type is likely to be negatively affected as a result of changing climatic conditions and biological pest attack.

Socio-economic issues

Economic and social issues that affect the forest include reductions in the value of forest products such as cork, and the labour and knowledge needed to produce it. Crops that were sustainable and integrated into the economy and social structure are replaced by eucalyptus for cellulose production, which provides some labour but which degrades the hydrological functions of the soils.