ABSTRACT Fragmentation is one of the main causes of biodiversity loss in tropical forests through consequences on their different components. Beta diversity patterns across fragments have been studied across multiple spatial scales, but comparisons with intact landscapes and in a variety of vegetation types are scarce. In order to address this issue of anthropogenic landscape disturbance, we tested two hypotheses relating to fragmentation and beta diversity: 1. Floristic homogenization at patch-level scale and 2. Floristic differentiation at landscape-level scale. The study was conducted in the Espinhaço Range biosphere reserve, Brazil. Three landscapes encompassing a broad range of vegetation types were sampled in 115 plots. Two landscapes were fragmented due to mining activities (Sabará and Brumadinho) and one is protected (Parque Estadual Serra do Rola-Moça). Results showed high overall beta diversity both between landscapes (conserved and fragmented) and vegetation types (forest, Brazilian savanna “campos rupestres”, ecotone and ironstone “canga”) with high turnover and species losses, even in highly disturbed vegetation types. The conserved landscape was most diverse in terms of richness. Thus, fragmentation effects differed from the expected with a main role of differentiation processes, and we argue that high beta diversity is not always a good predictor of ecosystem health.

Resumo Para verificar a influência da altitude na estrutura anatômica de folhas e do xilema secundário de galhos de indivíduos da espécie Clethra scabra Pers. (Clethraceae) ocorrentes na Serra da Mantiqueira, estado de Minas Gerais, realizaram-se coletas de amostras nas cotas altitudinais de 1500, 1700, 1900 e 2100 m (metros). As folhas e galhos coletados foram fixados e preparados seguindo procedimentos usuais de microtécnica vegetal. Procederam-se análises anatômicas quantitativas utilizando software de análise de imagem. As folhas de C. scabra são hipoestomáticas com epiderme trisseriada e tricomas estrelados, mesofilo dorsiventral, parênquima paliçádico com uma a duas camadas celulares e o parênquima esponjoso com quatro. A nervura central com xilema desenvolvido e o feixe vascular envolvido pela bainha esclerenquimática. Análises de variância (ANOVA) e teste de Scott-Knott demonstraram que as espessuras do limbo foliar, mesofilo e parênquima paliçádico não apresentaram diferenças estatísticas significativas entre as altitudes avaliadas. O xilema secundário apresentou diminuição no comprimento dos elementos de vaso com o aumento da altitude na cota de 2100 m e o diâmetro tangencial dos elementos de vaso aumentaram nas duas menores altitudes e depois reduziram. Índices de vulnerabilidade de Carlquist e de mesomorfia diminuíram ao longo do gradiente altitudinal. Comprimento e diâmetro das fibras diminuíram com elevação da altitude. Assim, a altitude influencia nas modificações anatômicas apresentadas por folhas e galhos de C. scabra, que podem ser relacionadas a sua plasticidade fenotípica em resposta às diferentes condições ambientais.

Abstract To verify the influence of altitude on the anatomical structure of leaves and the secondary xylem of branches of individuals of the species Clethra scabra Pers. (Clethraceae) occurring in the Serra da Mantiqueira, state of Minas Gerais, samples were collected at altitudes of 1500, 1700, 1900 and 2100 m (meters). The collected leaves and branches were fixed and prepared following usual plant microtechnical procedures. Quantitative anatomical analyzes were performed using image analysis software. The leaves of C. scabra are hypoestomatic with triseriate epidermis and stellate trichomes, dorsiventral mesophyll, palisade parenchyma with one to two cell layers and the spongeous parenchyma with four. The central rib with developed xylem and the vascular bundle involved by the sclerenchyma sheath. Analysis of variance (ANOVA) and Scott-Knott test demonstrated that the thickness of the leaf blade, mesophyll and palisade parenchyma did not present statistically significant differences between the evaluated altitudes. The secondary xylem showed a decrease in the length of the vessel elements with increasing altitude at the 2100 m elevation and the tangential diameter of the vessel elements increased at the two lowest altitudes and then reduced. The Carlquist and the mesomorphic vulnerability indices decreased along the altitudinal gradient. Fiber length and diameter decreased with increasing altitude. Thus, altitude influences the anatomical changes presented by leaves and branches of C. scabra, which can be related to its phenotypic plasticity in response to different environmental conditions.

RESUMEN Este estudio tuvo como objetivo evaluar el crecimiento, producción y nutrición de algodón de color natural (cultivar BRS Verde) regado con agua salina en diferentes etapas de crecimiento. El ensayo se realizó en un diseño de bloques al azar en el que los tratamientos consistieron en tres niveles de salinidad del agua de riego aplicados a lo largo del ciclo del cultivo o alternativamente en tres etapas de crecimiento. El agua de menor salinidad se extrajo del acuífero Arenito Açu en el estado de Rio Grande do Norte, Brasil; el agua de mayor salinidad se preparó para obtener una salinidad similar a la del agua extraída del acuífero Calcário Jandaíra, y la salinidad intermedia se obtuvo de la mezcla de volúmenes iguales de las aguas de menor y mayor salinidad. Se recomienda la aplicación de agua de menor salinidad en todas las etapas de crecimiento debido a los incrementos de aproximadamente 19% en el crecimiento del algodón y 40% en el rendimiento comparado con la aplicación de agua de intermedia o mayor salinidad. La aplicación de agua de menor salinidad en la etapa vegetativa y de agua de salinidad intermedia en las siguientes etapas es una alternativa al uso de agua de buena calidad durante todo el ciclo, a pesar de las disminuciones de alrededor de 7% en el crecimiento y 16% en el rendimiento. La nutrición de las plantas de algodón regadas con agua salina durante todo el ciclo o en algunas etapas de crecimiento estuvo marcada por un aumento de hasta un 86% en el contenido de sodio de la hoja de algodón, una disminución del contenido de potasio de la hoja de hasta un 21% y aumentos entre un 24 y 188% en el contenido de micronutrientes de las hojas cuando el agua de mayor salinidad reemplazó a la de menor salinidad.

ABSTRACT This study aimed to evaluate the growth, production, and nutrition of naturally colored cotton (cultivar BRS Verde) irrigated with saline water in different growth stages. The trial was conducted with a randomized block design in which the treatments consisted of three irrigation water salinity levels applied throughout the crop cycle or alternately in three growth stages. The lowest-salinity water was drawn from the Arenito Açu aquifer in the state of Rio Grande do Norte, Brazil; the highest-salinity water was prepared to obtain salinity similar to the water drawn from the Calcário Jandaíra aquifer, and an intermediate salinity was obtained from the mixture of equal volumes of the lowest and highest-salinity waters. The application of the lowest-salinity water is recommended in all growth stages due to the increases of about 19% in cotton growth and 40% in yield compared to the application of intermediate or highest-salinity water. The application of the lowest-salinity water in the vegetative stage and the intermediate-salinity water in the following stages is an alternative to using good quality water throughout the cycle, despite the decreases of about 7% in growth and 16% in yield. The nutrition of cotton plants irrigated with saline water throughout the cycle or in some growth stages was marked by an increase of up to 86% in the cotton leaf sodium content, a decrease in the leaf potassium content of up to 21% and increases between 24% and 188% in leaf micronutrient content when the highest-salinity water replaced that with the lowest salinity.