**7. Conclusion**

The analysis of the forest characteristics, the type of forest and its current location in the landscape of Portugal indicates that the silviculture and the landscape planning paradigm need to be changed.

Forest ecosystems involve biotic and abiotic processes occurring at different spatial and temporal scales, and at different levels of biological hierarchy. A relatively uniform management originates a pattern of relatively low diversity, which results in a loss of some processes and species. An excessive artificiality of the forest also increases their susceptibility to disturbances. Several studies show that complexity improves important forest attributes such as biodiversity, yield, resistance and resilience to several factors or disturbances (e.g., Hansen et al. [78]; Lindenmayer and Franklin [4]). Stand structural diversity, connectivity and landscape heterogeneity are important for ecosystem functioning and biodiversity.

Silviculture may be also related to the spatial and temporal scales in which the different ecological processes occur. It may be incorporated into a planned landscape, which can encompass different ecosystems and forms of intervention, seeking the sustainability of natural resources.

Diversity and landscape interactions can be promoted considering variations on the following main elements: site ecological conditions; composition and structural characteristics of the forest stands; forms of land use (forestry, agro-forestry, agriculture and pasture).

At the landscape level, management requires a spatial and temporal coordination of silviculture applied to different stands, trying the ecological maintenance or restoration of the landscape. At the forest stand level, according to the site conditions, objectives and assigned functions, silviculture suits the stand characteristics related to structure and composition. An integrated ecological-based silviculture provides a set of values that improve the economic efficiency and ecological conditions of the stand. In turn, at the landscape scale, forestry can be combined with other forms of land use, as well as with the variations of the site characteristics that might lead to forest patches with different characteristics and silviculture. In larger forest areas, units can be built differing by their characteristics and objectives, which may allow a diversification of interventions and operations, within a classified division and planning.

Biodiversity should also be evaluated in the spatial and temporal scales. For example, different units are viewed as interacting elements that continuously vary in space and time. Depending on the requirements of a given species, there may be a hierarchical space structuration for different groups, populations and metapopulations. The integration of biodiversity into the multifunctional silviculture is achievable considering a wide living space of habitats where the flora and fauna coexist and interrelate. Therefore, organizing communities and processes requires considering the spatial and temporal scales. Different habitat components can be managed in different scales (tree, stand and landscape). Ideally, various components of biodiversity are considered at different scales. Increasing structural diversity and spatial variability creates different ecological conditions that can promote biodiversity and resilience to disturbances (e.g., Turner et al. [79]).

Silviculture has a major influence on the presence and maintenance of microhabitats. The abundance and diversity of microhabitats considerably increase with

### *Spatial and Temporal Variability Regarding Forest: From Tree to the Landscape DOI: http://dx.doi.org/10.5772/intechopen.91701*

tree size and age. The existence of trees with cavities and dead wood is of particular interest to many specialist species. The tree species also plays an important role, and there is interest in certain species by their naturalness, kind of tree-related microhabitats and associated species. Silviculture should allow the maintenance of large trees, dead wood as well as certain species, which exhibit certain features of interest for biodiversity. Trees without economic value may be maintained by its biological value, without decreasing stand production, and avoiding harvesting costs, and, on the other hand, contribute to a better functioning of the ecosystem, with positive effects on the production of the stand.

Besides ecosystems and species diversity, biodiversity also involves genetic diversity. Genetic diversity in a given population of trees is determined by the long evolutionary history and population dynamics. A genetic diversity, in terms of intra- and interpopulation variability, is also an aspect to consider in silviculture given its importance to various levels as element of biodiversity in forest growth and production and survival and adaptability and as a vital part of the ecosystem functioning. This is important in terms of reproductive success, adaptability with implications for evolution, and climate change adaptation.

The tree regeneration is a key process that influences the genetic diversity of the stand population, affecting adaptation and demographic processes. The natural regeneration improves genetic diversity and enables continuous adaptation and evolution of the population in a given location. Evaluations conducted on the application of selective cuts show that natural regeneration has positive effects in genetic diversity [80, 81].

Habitat loss, overexploitation and inadequate silviculture are the main factors of the Mediterranean forest degradation (e.g., Chiatante et al. [82]). Some practices such as clearcutting and fragmentation might have negative effects for soil and water status, as well on the stand regeneration. In turn, an excessive fragmentation can have negative effects on the tree seed predation and dispersion as shown by Santos and Tellería [83] and Morán-López et al. [84].

Reducing fragmentation through appropriate silviculture helps to maintain biodiversity and the ability of forest natural adaptation. The recommended solutions resulting from specific studies vary depending on the biological groups, the forest type, the site characteristics, the distribution pattern and targets [55, 85]. Measures to solve fragmentation should also be combined with actions for forest fire prevention, particularly: actions at the social level; forest partitioning or segregation with other forms of land use (agriculture, agro-forestry and pasture); utilization of forest species more resistant to fire, with a lower combustibility and fire propagation.

Several programs related to the conservation and promotion of biodiversity have highlighted the importance of an integrated approach in silviculture. Some studies have shown that biodiversity conservation involves combining different types of strategies and measures applied at different scales. The level of integration of conservation measures will depend on several factors, namely, related to the ecosystem characteristics, conservation needs and forest management objectives. Several authors (e.g., Kohm and Franklin [86]; Lindenmayer and Franklin [4]) indicate the promotion or maintenance of the following key elements for the biodiversity conservation and its relationship with the landscape: stand structural complexity, connectivity and landscape heterogeneity. Continuity in space and time is an essential element to support populations, since there is a wide range of life strategies and habitat requirements.

Silviculture should enable the development of these elements at the tree, stand and landscape levels. Different values can be achieved or involve different spatial scales. This can create heterogeneity and spatial variability.

It is now necessary to reverse this landscape organization model, through a new

paradigm that will take at least three decades to implement and that has to be

*Spatial Variability in Environmental Science - Patterns, Processes, and Analyses*

The analysis of the forest characteristics, the type of forest and its current location in the landscape of Portugal indicates that the silviculture and the land-

Forest ecosystems involve biotic and abiotic processes occurring at different spatial and temporal scales, and at different levels of biological hierarchy. A relatively uniform management originates a pattern of relatively low diversity, which results in a loss of some processes and species. An excessive artificiality of the forest also increases their susceptibility to disturbances. Several studies show that complexity improves important forest attributes such as biodiversity, yield, resistance

Lindenmayer and Franklin [4]). Stand structural diversity, connectivity and landscape heterogeneity are important for ecosystem functioning and biodiversity. Silviculture may be also related to the spatial and temporal scales in which the different ecological processes occur. It may be incorporated into a planned landscape, which can encompass different ecosystems and forms of intervention, seek-

Diversity and landscape interactions can be promoted considering variations on the following main elements: site ecological conditions; composition and structural characteristics of the forest stands; forms of land use (forestry, agro-forestry,

At the landscape level, management requires a spatial and temporal coordination

of silviculture applied to different stands, trying the ecological maintenance or restoration of the landscape. At the forest stand level, according to the site conditions, objectives and assigned functions, silviculture suits the stand characteristics related to structure and composition. An integrated ecological-based silviculture provides a set of values that improve the economic efficiency and ecological conditions of the stand. In turn, at the landscape scale, forestry can be combined with other forms of land use, as well as with the variations of the site characteristics that might lead to forest patches with different characteristics and silviculture. In larger forest areas, units can be built differing by their characteristics and objectives, which may allow a diversification of interventions and operations, within a

Biodiversity should also be evaluated in the spatial and temporal scales. For example, different units are viewed as interacting elements that continuously vary in space and time. Depending on the requirements of a given species, there may be a

Silviculture has a major influence on the presence and maintenance of microhabitats. The abundance and diversity of microhabitats considerably increase with

hierarchical space structuration for different groups, populations and metapopulations. The integration of biodiversity into the multifunctional silviculture is achievable considering a wide living space of habitats where the flora and fauna coexist and interrelate. Therefore, organizing communities and processes requires considering the spatial and temporal scales. Different habitat components can be managed in different scales (tree, stand and landscape). Ideally, various components of biodiversity are considered at different scales. Increasing structural diversity and spatial variability creates different ecological conditions that can promote

biodiversity and resilience to disturbances (e.g., Turner et al. [79]).

and resilience to several factors or disturbances (e.g., Hansen et al. [78];

actively funded by the government.

scape planning paradigm need to be changed.

ing the sustainability of natural resources.

agriculture and pasture).

classified division and planning.

**134**

**7. Conclusion**
