Land use change
Tropical forests are important biomes due to several reasons. Tropical forests are major reservoirs of carbon, nitrogen and water. The exchanges of them with the atmosphere make the tropical forests essential biomes in the global climate and global biogeochemical cycles (Melillo et al., 1993; Field et al., 1998; Cleveland et al., 1999; Bonan, 2008). Additionally, the tropical forests are characterized by having a high number of tree species, which led to a high biogeochemical heterogeneity with large variability in the limiting nutrient (N and P) concentrations as well as in the ratios of these nutrients among them and in relation to carbon.
The Atlantic Forest (Ombrophyllus Dense Forest) is located mainly along the Brazilian coast and it is characterized by a high diversity and endemism of plants (MORELATTO; HADDAD, 2000; TALORA; MORELLATO, 2000). Variation in edaphic and microclimatic conditions due mainly to differences in latitude and altitude are responsible for create such variability in the flora and fauna of these forests. The Atlantic Forest is considered one of the priorities hotspots for conservation of the global biodiversity (MYERS et al., 2000). This is especially important if we considered that only 12% of the Atlantic Forest is left of the 1.5 million km2 of its original area (RiBEiRO; LiMA, 2009). in the coast of the State of São Paulo the sharp difference in the air temperature due to the a altitudinal gradient that occurs along a short distance offers an unique opportunity to evaluate the effects of global warming on the basic biogeochemical processes that control the carbon and the nitrogen cycle of the coastal Atlantic Forest.
Preliminary results have shown that the Montana Atlantic Forest (1,000 m above sea level) located in the Serra do Mar State Park, branch Santa Virginia it is a forest that despite the fact that soil nitrogen stocks are relatively high, transference nitrogen flux among different reservoirs are low, and probably limited due to lower air temperatures (SOUSA NETO, 2010; GROPPO, 2010). On the other hand, in the Lowland Atlantic Forest (100 m below sea level) the soil nitrogen stocks are lower than at 1000 m, but the nitrogen transference fluxes are higher, probably due to the higher air temperature (SOUSA NETO, 2010; GROPPO, 2010).
The main objective of this project is investigate how the temperature differences among along an altitudinal gradient control the dynamic of carbon and nitrogen in the coastal Atlantic Forest in the north portion of the Serra do Mar State Park, branches of Picinguaba (100 m above sea level) and Santa Virgínia (1000 m above sea level).
in order to reach such objective the biomass and soil carbon and nitrogen stocks will be determined in the two branches of the coastal Atlantic Forests. The carbon and nitrogen exchanges among major reservoirs will also be investigated.
Study Area and Methodology
As already mentioned our study will be conducted at two branches of the Serra do Mar State Park – the branch Picinguaba where the Lowland Atlantic Forest is located and the branch Santa Virginia where the Montane Atlantic Forest is located.
The Picinguaba branch has an area of 8,000 ha (23°31'-23°34'S; 45°02'-45°05'W) (NÚCLEO PiCiNGUABA, 2010).The relief of this area encompass either the Coastal Plains as well as steeps slopes of the Serra do Mar itself (PONÇANO et al., 1981). As a consequence the altitudes of this area vary from sea level up to 1,340 m. The climate is tropical with temperatures around 21°C and rainfall of approximately 2,600mm most of them falling in the summer period from October to April (TALORA; MORELLATO, 2000).
The Santa Virgínia branch has a larger area than Picinguaba encompassing 17,000 ha. The relief is hilly with steep slopes; the altitude varies from 850 to 1200 m. The climate is tropical with an annual average rainfall of 2,200 mm and annual average temperature of 19°C. The bedrock of both areas is formed by Pre-Cambrian granites that led to the formation of shallow and infertile inceptissols soil types.
The study will be conducted in four 1ha-parcels in each altitude. in this parcels trees were tagged and botanically identified in accordance with the BiOTA/FAPESP project entitled "Composição florística, estrutura e funcionamento da Floresta Ombrófila Densa dos Núcleos Picinguaba e Santa Virgínia do Parque Estadual da Serra do Mar" (FAPESP #2003/12595-7). This Project has as its main objective to investigate how the structure and functioning of the coastal Atlantic Forest along an altitudinal gradient.
Main Goals and Outcomes
We anticipate that two master students and two doctoral students will conclude their programs in this project. We also anticipate the publication of four articles in peer-reviewed scientific journals.