Altitude and vegetation affect soil organic carbon, basal respiration and microbial biomass in apennine forest soils

Both altitude and vegetation are known to affect the amount and quality of soil organic matter (SOM) and the size and activity of soil microbial biomass. However, when altitude and vegetation changes are combined, it is still unclear which one has a greater effect on soil chemical and biochemical properties. With the aim of clarifying this, we tested the effect of altitude (and hence temperature) and vegetation (broadleaf vs pine forests) on soil organic carbon (SOC) and soil microbial biomass and its activity. Soil sampling was carried out in two adjacent toposequences ranging from 500 to 1000ma.s.l. on a calcareous massif in central Italy: one covered only by Pinus nigra J.F. Arnold forests, while the other covered by Quercus pubescens Willd., Ostrya carpinifolia Scop. and Fagus sylvatica L. forests, at 500, 700 and 1000 m a.s.l., respectively. The content of SOC and water-extractable organic carbon (WEOC) increased with altitude for the pine forests, while for the broadleaf forests no trend along the slope occurred, and the highest SOC and WEOC contents were observed in the soil at 700 m under the Ostrya carpinifolia forest. With regard to the soil microbial community, although the size of the soil microbial biomass (Cmic) generally followed the SOC contents along the slope, both broadleaf and pine forest soils showed similar diminishing trends with altitude of soil respiration (\u3a3CO2-C), and \u3a3CO2-C:WEOC and \u3a3CO2-C:Cmic ratios. The results pointed out that, although under the pine forests' altitude was effective in affecting WEOC and SOC contents, in the soils along the broadleaf forest toposequence this effect was absent, indicating a greater impact of vegetation than temperature on SOC amount and pool distribution. Conversely, the similar trend with altitude of the microbial activity indexes would indicate temperature to be crucial for the activity of the soil microbial community

Amido termoplástico.

bitstream/CNPDIA-2009-09/11042/1/DOC30_2007.pd

Utilização de fibras vegetais para reforço de plásticos.

bitstream/CNPDIA/9817/1/PA03_96.pd

Beef Heifers Performance under Continuous Grazing on Modified Grassland in Argentina Flooding Pampa

The Salado river basin is the main beef cattle breeding region of Argentina. It is a flat flooding area with poor slopes (\u3c 3%). Their soils are Natracuoles, Natraqualfes and Argiacuoles. The grasslands are predominately continuously grazed and with a set stocking rate cow – calf system. Stocking rate and grazing pressure are two core variables that directly affect animal production. Reduced animal performance is believed to be due to poor grazing management. During 2010, 2011 and 2012 an experiment on the effect of stocking rate on animal growth and body condition with Angus heifers continuously grazing annual winter grasses, was carried out. Previous studies have demonstrated the practicability of producing replacement females with this management (Carrillo 2001; Eirin et al. 2011; Agnelli et al. 2011) that involves mesothermic grasslands modification into self sown winter grasses by using glyphosate and other herbicides (Oyhamburu et al. 2000, Rodriguez and Jacobo 2010). The aim of this study was to establish the stocking rate that optimizes beef rearing heifer’s performance for early mating