Ábrahám Levente (szerk.): Válogatott tanulmányok VIII. - Natura Somogyiensis 23. (Kaposvár, 2013)
Salamon-Albert É.: Climatic conditions and habitats in Belső-Somogy, Külső-Somogy and Zselic as vegetation-based landscape regions IV. Precipitation envelopes of mesic deciduous woodlands
76 Natura Somogyiensis tal point of view. Climate classification of the vegetation is mainly computed at different spatial scales, according to bioms, continents, countries and regions leading to be constructed spatial or ecological patterns and distributions (Ozenda and Borel 2000, Hőssel et al. 2003, Piovesan et al 2005, Thompson et al 2005, Attore et al. 2007). Requirements for small-scale studies are discussed and demonstrated by more and more authors nowadays (e.g. Lindner et al. 2010), but their conclusions as the scientific results have to be applied with caution. Quantifying significant ecological factors influencing range and threshold values of species or habitat existence or distribution is an ongoing challenge for scientists nowadays, especially under current changing climate conditions (Guisan and Thuiller 2005, Colwell and Rangel 2009). A lot of measures have been used to quantify distribution characteristics leading to construct environmental niches and analyse their overlap (e.g. Fitzpatrick et al. 2008; Peterson and Nakazawa 2008), differences in niches using observed occurrences of the objects can reflect to their unknown conjunction (Soberón 2007, Colwell and Rangel 2009). Ecologically appropriate subset of environmental conditions that is actually occupied by the species or habitats corresponds to the realized niche (Hutchinson 1957). Long term climatic conditions resulting the realized environmental envelopes described by a set of geographically referenced variables come from the widely used, systematic climatic databases (Hossell et al. 2003, Beaumont et al. 2005, Humans et al. 2005, Attorre et al. 2007, Czúcz et al. 2009). Novel analyses connecting distribution models with other ecological phenomena can provide novel capacities for understanding specific and general drivers of occurrence and distribution. Transdanubia of Hungary is one of the most significant regions for lowland and colline mesic woodlands under high level of climatic and geographic variability (Molnár Zs. et al. 2008, www.met.hu). For this reason the region can be a suitable object for ecological modelling and passing out spatial studies at regional scale. Bioclimatic variables as the adequate macro-ecological environmental predictors representing annual trends, short or long term extreme or limiting abiotic factors of the sorrounding, therefore they are more suitable for studying climatic niches and interactions among them (e.g. Hijmans et al. 2005). These ecological phenomena, especially the precipitation components do play a significant role in the long term existence of mesic woodlands that are consensually regarded to be a macro-climate adapted vegetation in Europe, even though of their geographical or regional diversity (e.g. Marinsek et al. 2013). The aims of our study is 1) to characterize and compare climate envelopes of mesic deciduous woodlands by mean, minimum, maximum and range of monthly, quarterly and yearly precipitation variables, 2) to analyse relationships between climatic niches of mesic woodland habitats by summarized and multipeak distributions and comparing to semi-natural habitats furtherly, and 3) to detect bioclimatic variable(s) that could be the most significant for niche segregation providing an essential contribution to quantify precipitation performance of mesic woodlands in the studied regions. Material and method Study area The study area is Külső-Somogy, Belső-Somogy and Zselic as the three significant vegetation based landscape regions of South Transdanubia in Hungary, defined on their actual macro-climatic, dominant extrazonal or edaphic vegetation types (Molnár Cs. et al. 2008). Elevation varies in a moderate range from lowlands (96 m a.s.l.) to hills (300
