The bioclimatological analysis of a region or an area is based on the premise that one can find more or less evident relationships between climatic variables, especially temperature and precipitation, and the spatial distribution of plants and consequently vegetative communities.
The Serra da Gardunha is situated in a zone of indefinite transiton between two macrobioclimatic units which vary according to orographic exposure:
- Mediterranean – on the slopes exposed to the South and East and on the lowest hillsides to the South, which is the hottest area in the summer and the least cold in the winter. From the agricultural perspective, there are vineyards, orange groves and olive groves.
- Temperate – dominates the Northern and Western slopes and the lowest zones of the Cova de Beira depression, in which the winter is more rigorous and the summer milder. Agriculture is dominated by pastures and orchards (Cherry, apple, peach)
The evidence of transition between these bioclimates is easily noted in some locations in Gardunha where the change in the landscape is so accentuated that one can make out the boundary between two bioclimatic units. The Portela da Gardunha – Alpedrinha is a good example of a bioclimatic boundary that separates two units, as described by Orlando Ribeiro which marks the boundary between Atlanic-Portugal and Mediterranean-Portugal.
The landscape moves brusquely between the mixed forests of cork and black oak and the scrubland with gum rockrose and holly mixed with olive and orange groves and Solomon’s seal and mixed oak forests and Portuguese broom interspersed with cereals.
The mean annual precipitation for the weather station at Fundão, is 943.7 mm despite its inclusion in a sub-humid ombroclimate. In order to establish when the vegetation suffers from lack of water, one has to find the “dry months”.
Consider that drought occurs when the monthly pluviosty(mm) is less than double the value of the mean monthly temperature (ºC) P< 2T.
As such, it is noted in the ombrothermic diagram the existence of a dry season from the middle of June to the middle of September, or easily three months. This is due to the fact that summer precipitation registered in these months is very low, while the temperatures reaches its annual maximum.
The geographic distribution of organisms on the ground’s surface (Biogeography) permits the definition of areas that are more or less characteristic according to the grouping of species of a particular (endemisms) or global (cosmopolitan species) distribution which occur in a determined zone. One can characterize the geographic pattern of the distribution of plants (Phytogeograhy) for a determined area, and idenfity the pecularities and characteristics of the local flora. In this case, the pecularities of the Gardunhinian flora.
Given the geographical situation and the geomorphological characteristics that are present, the area studied reveals a huge biogeographical diversity, according to Rivaz-Martinez, (1987). With regard to its biogeography, the Serra da Gardunha is situated in the Holarctic kingdom, in the Mediterranean Region, the Sub-region Western Mediterranean Superprovince Ibero-Atlantic Mediterranean, Sub-province Luso-Extremadurense, Sector Toledano-Tagano, Sub-sector Hurdano-Zezerense, Superdistrict Zezerense.
The Toledano-Tagano sector is one of the sectors of the sub-province Luso-Extremadurense. It is characterized by a mosaic subsoil of granite and slate, with interspersed quartzite crystals, under the dry and humid mesomeditarranean influence, where the Portuguese brooms Cytiso multiflori - Retametum sphaerocarpae and the heathers Halimio ocymoidis – Ericetum umbellatae (Rivaz-Martínez, 1987) stand out.
Given the position of transition of Gardunha from the climatic point of view and given its reduced orogrphy, the Gardunhian flora captures Atlantic/Eurosiberian and markedly Mediterranean characteristcs and even strictly endemic species.