The aim of this study was to quantify the dynamics of herbaceous biomass and fine root productivity, and their relationship to stocks of carbon and nitrogen, in the Vertisols of two adjacent watersheds of a seasonally dry tropical forest (SDTF) under two different types of ground cover. The two watersheds are located in the county of Iguatu in the State of Ceará, Brazil. The control watershed of 2.1 ha, has been under regeneration for 35 years (RC 35 ), while the second watershed (1.1 ha) was subjected to thinning for a period of 5 years (TC 5 ). The sampled variables were herbaceous shoot biomass, fine roots, gravimetric moisture, the isotope δ 13 C (‰), total soil carbon (TSC) and total nitrogen (TN) in the 0 -20, 20 -40 and 40 -60 cm layers, between April 2013 and March 2014. To quantify herbaceous shoot biomass, samples were taken monthly. For TSC and TN, the campaigns were held every two months. The data underwent analysis of means and were compared by t-test (p < 0.05).Under TC 5 , there was an increase in the stocks of TSC and TN of 151 and 137% respectively in the 40 -60 cm layer, in relation to RC 35 . The implementation of thinning in a SDFT is seen as a management alternative to be considered in sustainability programs in the semi-arid region, contributing to maximising the production of herbaceous forage for feeding large and small ruminants, and for bee pasture, in addition to increasing the stock of carbon in the soil of SDFT and reducing global warming.

No abstract

No abstract

-The aim of this work was to identify and to investigate the determining factors of water table quality in the Irrigated Perimeter of Baixo Acaraú, Ceará, Brazil, using factor analysis/principal component analysis (FA/PCA). It was sampled nine shallow wells spread out on two different types of land: uncultivated area (A1) and irrigated area (A2 , HCO 3 -and CO 3 -2 . The PCA resulted in a model composed of three components that explained 93.06% and 83.72% of the total variance of the data set from A1 and A2, respectively. It was found that the determining factors of water quality were the mineralization processes and anthropogenic activities in both areas. The anthropogenic activities in the irrigated area were related to nitrogenous fertilizers, while those in the uncultivated area were associated with the presence of septic tanks (from the lack of sewage treatment). , NO 3 -, SO 4 -2 , HCO 3 -e CO 3 -2 . O emprego da AF/ACP resultou em um modelo composto por três componentes explicando 93,06 e 83,72%, da variância total, respectivamente, para as áreas A1 e A2. Os fatores que influenciam na qualidade das águas subterrâneas, em ambas as áreas, foram definidos pelo processo natural de intemperismo geológico do solo e da ação antrópica. Nas áreas de cultura irrigada, a ação antrópica foi determinada por um fator relacionado aos nutrientes nitrogenados e correções de acidez dos solos. Nas áreas não cultivadas, a ação antrópica foi definida por um fator de saneamento básico (uso de fossas sépticas com lançamentos diretos ao solo). O manejo adotado nas áreas irrigadas do Distrito de Irrigação do Baixo Acaraú está contribuindo para um aumento gradual nas concentrações de nitrato em águas do lençol freático. Keywords -Palavras-chave -Ação antrópica-fertilizantes. Poços rasos. Irrigação-contaminação hídrica.

A B S T R A C TThe material that is deposited throughout the year in forests has an important role in litter formation, especially in environments under stress, as occurs in the semi-arid. This study aimed to identify the inference of the vegetation cover in the production of leaf litter in tropical dry forest-Caatinga. The study was developed in the catchment area of the Alto Jaguaribe in Iguatu-CE. It was monitored two sub-basins, one with vegetation cover of caatinga in regeneration about 38 years, and another one under thinning management, maintaining the plant species with stem circumference ≤ 10 cm. Litter samples were taken monthly (January 2011 to December 2013). It was used 15 boxes of 1 m 2 randomly arranged in each hydrographic watershed. The average amount of leaf litter produced plots with regenerating and thinned caatinga were of the order of 4,277.2 and 2,248.0 kg.ha , respectively. Litter production presented a seasonal character, with peak production immediately after the rainy season, producing respectively 62.1% and 47.9% of all litter in the months of May to September. It shows that the caatinga in higher regeneration due to output the most individuals' ferns and most amount of species.