The aim of this study was to evaluate the stock of total organic carbon (TOC) and to perform the physical-granulometric fractionation of soil organic matter (SOM) in different management systems (MS). Three MS and one reference area of Native Forest (NF) were studied, and the three systems were sugarcane (SC), permanent pasture (PP) and no-tillage system (NTS). Soil samples were collected in the 0–0.05, 0.05–0.10, 0.10–0.20-m layers. Soil density (Sd), TOC, stratification index (SI), carbon stock (StockC), variation in StockC (∆StockC), carbon content of particulate organic matter (C-POM) and mineral organic matter (C-MOM), carbon stock index (CSI), lability (L), lability index (LI), and carbon management index (CMI) were determined. The MS presented higher Sd than the NF area. The NF area had higher TOC contents in the first layers, reaching 25.40 g kg-1 in the 0–0.05-m layer, with the PP area having higher values than the NF in the 0.10–0.20-m layer. The NF area showed the highest levels of C-POM (15.25 g kg-1) and C-MOM (10.15 g kg-1) in the first layer. In the 0.10–0.20-m layer, the PP and NTS systems were superior to the others. Regarding the C-MOM content, SC and PP showed higher levels in the 0.10–0.20-m layer. The highest CMI values were observed in the NTS and PP areas in the 0.10–0.20-m layer. The MS increased the Sd and reduced the TOC levels. The different MS modified the POM fraction, and the MOM fraction was most impacted by the SC area. The lability of the SOM was altered by the MS in the most superficial layers.
This work had as main objective to verify the existence of hysteresis in the Brazilian exportations of manufactured products. For this objective, a descriptive analysis of exporting industrial firms was initially carried through and the estimate of a tree of classification for the period of 1989-1997. These first analyses had demonstrated that existence of an asymmetry between the number of incoming firms in the period favorable to the exportations and the number of desisting firms in the not favorable period, giving evidences of the permanence/persistence of the exporting firms in the period of 1989-1997. Moreover, one evidenced an trend of "wait and see" of the firms in the export market for the period of 1990-1993 and induction to the exit of firms for the period of 1994-1997. After that, from aggregated data for the period of 1985-2003, a time serial analysis was carried through. These results had been corroborated that evidenced the of hysteresis hypothesis for some selected sectors, as much in the long-run as for short-run. Words keys: hysteresis, real exchange rate, exportation.. O termo constante (cte) é inversamente relacionado à elasticidade da demanda das indústrias, e essa por sua vez, está diretamente relacionada à estrutura do mercado.
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