**3.3 Semideciduous Seasonal Forest**

116 The Dynamical Processes of Biodiversity – Case Studies of Evolution and Spatial Distribution

According to Köppen System, the climate of the Araucaria Rainforest region is Cfb, with annual average temperatures between 16 and 18 ºC and average annual rainfall generally

This forest formation shows structural variations related to environmental diversification, varying from dense formations with trees of ca. 25 to 35 m tall, to stunted formations consisting of variable density of trees and shrubs, associated with terrestrial ferns and bamboos (Leite & Klein, 1990). According to Maack (2002), *Araucaria angustifolia*, commonly known as the "Brazilian pine" or "Paraná pine" is the dominant tree of this region,

A compiled list of the Araucaria Rainforest tree flora of Southern Brazil, using data of the botanical collection of the Barbosa Rodrigues Herbaria, revealed 352 species. Almost 50% of

Castella & Britez (2004) analyzed satellite images from 1998 and concluded that Araucaria Rainforest communities at intermediate or advanced succession stages still covered 13420.6 km2 of the state of Paraná, representing about 16.2% of the original cover (Castella & Britez,

Two formations are presented in this section: Alluvial and Montane Araucaria Rainforests.

The Alluvial Araucaria Rainforest is associated mainly with the Montane formation and is easily distinguished by its typical physiognomy. This is a riparian forest that always

The physiognomy is structurally characterized by a high density of medium and small individuals, with the canopy ranging between 10 and 20 m in height. Communities can present different degrees of development. In the fairly homogeneous associations, subject to soils with considerable hydromorphy, such as some Fluvisols and Gleysols, *Sebastiania commersoniana* is the most relevant species. In more developed associations *Vitex megapotamica, Schinus terebinthifolius, Allophylus edulis, Luehea divaricata, Symplocos uniflora, Blepharocalyx salicifolius, Myrrhinium atropurpureum, Myrciaria tenella* and *Daphnopsis racemosa*  are present. Even *Araucaria angustifolia* can be observed where lower hydromorphy allows

occupies alluvial lands adjacent to watercourses (IBGE, 1992; Roderjan et al., 2002).

its growth (Leite & Klein, 1990; Roderjan et al., 2002; Barddal, 2002; Pires et al., 2005).

According to IBGE (1992), the altitudinal range of the Montane Araucaria Rainforest occurrence is between 400 and 1000 m a.s.l.. However, some authors, such as Leite & Klein (1990) and Roderjan et al. (2002), rightly argue that typical communities occur at altitudes higher than 800 m a.s.l. Below this altitudinal belt there is the beginning of the transition between the Montane Araucaria Rainforest and the Dense Atlantic Rainforest (on the east)

The typical physiognomy is marked by the dominance of *Araucaria angustifolia*, standing out over a continuous canopy that reaches on average 25-30 m height. The continuous strata is characterized by *Ocotea porosa*, *Nectandra lanceolata, Matayba elaeagnoides, Casearia decandra*, *Podocarpus lambertii, Cinnamodendron dinisii, Sloanea lasiocoma, Campomanesia xanthocarpa, Cedrela fissilis, Nectandra grandiflora, Jacaranda puberula, Drimys brasiliensis, Ilex paraguariensis*  and *Lithraea brasiliensis*. Species of Myrtaceae and Monimiaceae prevail in the dominated strata. Ferns, especially *Dicksonia sellowiana,* are also common (Leite & Klein, 1990; Durigan,

1999; Roderjan et al., 2002; Rondon Neto et al., 2002; Cordeiro & Rodrigues, 2007).

those species occur exclusively in this type of Atlantic Forest (Leite & Klein, 1990).

2004). However, primary remnants are much less representative.

between 1400 and 1600 mm (Caviglione et al., 2000).

distinguishing this landscape.

**3.2.1 Alluvial formation** 

**3.2.2 Montane formation** 

or the Semideciduous Seasonal Forest (on the west).

The Semideciduous Seasonal Forest region in the the state of Paraná occurs mainly in the Third Plateau (almost the entire North and West of the state) in altitudes generally between 200 and 600 m a.s.l. (Roderjan et al., 2002).

According to the Köppen system, the climate can be classified as Cfa, or meso-thermic, wet. Daily mean temperatures in the coldest month are under 18 ºC and the mean temperature of the warmest month is over 22 ºC (Maack, 2002). However, in this ecosystem the year can be divided into two distinct seasons: one tropical with intense summer rainfalls and short dry periods, and another subtropical with low winter temperatures and scarce precipitation. During this unfavorable cold and dry period, between 20 and 50% of the canopy trees are deciduous (Veloso et al., 1991; IBGE, 1992). In very specific locations this forest has as ingrown ecosystem the Savanna (Cerrado), which reaches its austral limit in this specified region, covering otherwise a major part of Brazil's Mid-West (Figure 1).

The Semideciduous Seasonal Forest shows succinct variations ranging from the evergreen to deciduous trees, which reach heights close to 30-40 m without forming a continuous superior canopy. This feature allows a great deal of sunlight to reach the forest ground, turning possible the development of a vigorous lower stratum (Silva & Soares Silva, 2000). There are also shrubs, lianas and epiphytes, although in lower abundance and richness compared to rainforests (Leite et al., 1986; Lamprecht, 1990; Leite & Klein, 1990; Roderjan et al., 2002).

A compiled list of the tree flora of the Semideciduous Seasonal Forest of Southern Brazil, using data of the botanical collection of the Barbosa Rodrigues Herbaria, presents at least 213 tree species (Leite & Klein, 1990). Silva & Soares Silva (2000), found 206 arboreal species in Godoy State Park.

Satellite images taken in 1998, indicate that 4174.7 km2 of Semideciduous Seasonal Forest communities at intermediate or advanced stages of succession covered only 5.4% of the original area of distribution in that year (SEMA, 2002). Some forests of the northern region were reduced to less than 1% in Maringá and 0.8% in Assaí municipalities (IPARDES, 1986). Forward are presented the characterizations for the Alluvial and Submontane formations of this forest type.
