SITES DEFINITION IN Pinus elliottii Engelm. POPULATION AT ENCRUZILHADA DO SUL REGION, RS

Abstract

The present work was developed in “Ipiranga VII”, located at the Boa Vista farm, in Encruzilhada do Sul, RS town.  Project began in 1987, with a total area of 311.59 ha and an effective planting area of 200 ha. The objective of this work is to determine distinct characteristics of the studied area (sites) as a function of edaphic, dendrometric, and vegetative factors. Site I presents a dark reddish brown colour (humid, 5YR 3/4), according to Munsell"s chart, at a depth of 0-10 cm.  This site has shallow soils, with a depth  smaller than 20 cm, its soil surface presents lots of stones and little stones, with a sandy to clay loam texture and a grumous granular structure.  Site II has a very dark collor, what makes it sharp different from site I; at the depth of 20-40 cm, it presents a dark reddish brown collor (humid, 5YR 2,5/2,0), according to Munsell"s chart.  At this site, soil has a large to medium depth, being the most of the drilling points with a soil depth bigger than 40.0 cm.  Soil surface at this site almost presented no  stones and little stones and it has  a poliedric granular to subangular blocks structure, and a sandy loam texture.  Although site I has less trees per hectare,  i.e., about 120 trees / ha less than site II, the trees have a media of basal tree diameter smaller than site II, according to the well known statement that diameter is influenced, directly, by the population density, what means the most dense the population, the smaller the diameter of it. Media basal area per hectare in site I was 32,40 m2/ha, and 37,91 m2/ha in site II, what makes a difference of 5.51 m2/ha between them. Once “Ipiranga VII” has two sites, the total area was covered with the objective to collect soil samples in different depths, i.e., site I at 0-20 cm and 20-40 cm depths, and site II at 0-20 and 20-40 cm depths.  Soil analysis showed site II has a larger percentage of organic matter in both depths, what may justify the darker collor of the soil and a larger Nitrogen, as well as other nutrients, availability to plants.  Both sites, at both depths, are very acid, with a lime media necessity of 4,9 t/ha, according to SMP table, in order to get a 5,5 pH, what is considered ideal to Pinus and Eucalyptus. Such acidity is reflected by Aluminium content, what is arround 1,0 meq / 100 ml of soil, with the trend to grow as sample depth grows.  The largest clay percentage was found in the 20-40 cm depth in both sites I and II, ensuring the region soil type ( B textural horizon, Yellow-Red Podzolic ).