Landscapes Forest and Global Change - ESA - Escola Superior ...

A. Ruskule et al. 2010. Patterns of afforestation process in abandoned agriculture land in Latvia
101
Information from soil maps obtained from State Land Service as well as from soil sampling
carried out in the pilot areas mainly do not show direct impact of soil groups and its chemical
properties on spatial distribution and character of the ecological succession patches (see Figure
2). Nevertheless, relationship between soil groups and its chemical properties have been
recognized within the 3rd pilot area. There it was established that development of shrubs and
trees are faster on the soils characterized with poor nutrient status, but on fertile soils this
process could be considerably delayed.
4. Discussion
Figure 2: Soil conditions in pilot area 1 and 3.
The study shows that relation between character of landscape ecological succession and such
environmental factors as soil properties and species composition of surrounding forest are rather
ambiguous, if viewed separately. Development of ecological succession depends on interactions
of various factors like topography, geology, level of ground waters, soil and its chemical
properties. The previous land use and initial stage of succession prescribed by herbaceous
species colonising the abandoned fields also has significant role in this process (Prach et al
2001b; Kopecký and Vojta 2009; Rosenthal (in press)). For example in some cases higher soil
fertility can enhance the growth of shrubs, while in another it might increase density of herb
layer, thus solving down the course of succession by competitive exclusion of trees (Alard et al
2005).
Furthermore distribution of seeds of woody species depends on dominant winds as well as size
and configuration of the field. Although some studies highlight importance of distance from the
seed stand and species composition of the seed stand as decisive factor in development of
secondary succession (Daugaviete 2009), we consider that degree of influence of this factor
depends on size of the field as well as heterogeneity of environmental conditions. In very large
and fields with strait edges and plane topography having uniform environmental conditions the
afforestation process starts form the edge of forest and might develop into linear patches, while
in smaller fields with more complex shapes and hilly topography, where environmental
conditions are more diverse, the pattern of secondary succession is rather complex, usually
developing as mosaic patches, not always having direct connection to the forest edge. In very
small fields surrounded by forest continuous succession might develop covering simultaneously
all the area in rather short time.
Forest Landscapes and Global Change -New Frontiers in Management, Conservation and Restoration. Proceedings of the IUFRO Landscape Ecology
Working Group International Conference, September 21-27, 2010, Bragança, Portugal. J.C. Azevedo, M. Feliciano, J. Castro & M.A. Pinto (eds.)
2010, Instituto Politécnico de Bragança, Bragança, Portugal.