Bonis Basin – Agro-forestry site

Monti della Sila

Region: CALABRIA

Location: Lat: 39°25’15’’ N, Long 16°12’38’’39°2N

Description of measurement site

Il Bonis Basin is located in the Cosentine Greek Sila and it is a sub-basin of the torrent Cino. Its surface is 139 hectares.

Bonis Basin is located in the Cosentine Greek Sila and it is a sub-basin of the torrent Cino. Its surface is 139 hectares.
The basin, which is publicly owned, was planned starting from 1984 and equipped in 1986 with the purpose to create a permanent lab to study the basin hydrological balance and the hydric processes of its versants (sub-basin), forestry population (laricio pine), in relation to also forestry management intervention (ie. shedding) and potential problem (ie. fires).

From the forest coverage point of view, 80% of the surface is covered by laricio pine (Pinus laricio Poiret), most of it is artificial, planted between 1955 and 1970. The original nuclei, whose age is close to the reforestation, occupy the highest part of the basin left and right (Picture 1).

Bonis1

Figura 1

Flows monitoring has been implemented, in its closing section, of a measurement building made up of a calming tank in reinforced concrete. The bed on top of the tank has been channeled for 32 meters and in its last parts broadens and is linked to a concrete check dam on one side and the tank on the other.

In order to have a measurement integrated system of the interactions among atmosphere ‐biosphere‐hydrosphere, in May 2003 a tower to measure exchanges of CO2, H2O and energy between forest and atmosphere with the eddy covariance technique has been installed, inside the basin, in Cozzarella – Don Bruno. The tower represents the most Southern forestry site in Italy and its purpose is to study the dynamics of the exchange between carbon and evaporation of 35-year-old pine forest, set on former pasture and got thinner in 1986, which represents the main ecosystem of the basin and one of the main ecosystems in Calabria. Its morphology is slightly wavy. The geological substrate is made up of granite rocks; soils are part of the Ultic Haploxeralfs association and are characterized by some clay, which often forms layers.

The pine forest has 637 trees per hectare, with base surface of 45.4 m2 ha-1, average diameter of 29 cm and average height of 21.5 m; leaf area index, measured with LAI‐2000 (LiCor, Lincoln, Nebraska ‐ USA) is 6.6±0.2 m2 m-2.

Among the data we already have and that will be studied further after the upgrading of the site, thanks to PON I-AMICA, we want to highlight the results on seasonal and performance of carbon exchanges through the years among pine forest and atmosphere and yearly balances.

Performances measured throughout the year 2006 are illustrated in picture 2a. It is an evergreen ecosystem and, even if it is situated in the mountains, it has rather favorable meteorological conditions. For this reason, the pine forest released carbon towards the atmosphere for only 36 (positive values in the picture). Maximum absorption values were around -8÷-10 gC m-2day-1 between beginning of May and half June. In the summer, which was rather dry and hot, absorption went down to -3÷-4 gC m-2 day-1 while in fall and the first months of winter, the ecosystem continues to be active but numbers are lower. On a yearly basis, pine forest has absorbed around 10 tC each hectare. These values are definitely higher and some studies will be carried out to verify this uncertainty. In particular, the topographic performance of the site could make us underestimate breathing nightly values because of the advection phenomenon.

Continuous and long term measurements can reveal the impact of climatic factors on carbon cycle. For instance, very hot summers, like in 2007 can highly limit carbon absorption. In that year, at the beginning of September, the pine forest showed values between 20 – 30% lower compared to 2005 and 2003-2004 (Picture 2b).

 

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