Reference evapotranspiration estimates by means of Hargreaves-samani and Penman-monteith fao methods with missing data in the northwestern Mato Grosso do Sul / Estimativa da evapotranspiração de referência pelos métodos Hargreaves-samani e Penman-monteith fao com dados faltosos no noroeste sul-mato-grossense

We aimed to assess the performance of different methodologies to estimate the reference evapotranspiration (ET0) in different seasons for at 1, 3, 6 and 10 days for the Northwestern Mato Grosso do Sul. We used a set of daily data obtained from the networks of the Brazilian National Institute of Meteorology for Água Clara, Cassilândia, Chapadão do Sul, Paranaíba and Três Lagoas locations. The meteorological data used were: maximum and minimum air temperatures, wind speed, solar radiation, and relative humidity. The methodologies used for the ET0 estimation were Hargreaves-Samani and Penman-Monteith (PM-FAO) using all the meteorological data needed and missing data on relative humidity, solar radiation and wind speed. To compare ET0 values estimated by means of equations tested against the PM-FAO method we analyzed the parameters of linear regression equation "0" and "1", coefficient of determination (r²), standard-error of estimate (SEE) and coefficient of performance (c). The PM-FAO method with missing data (relative humidity and wind speed) were the best alternatives to estimate ET0, followed by the PM-FAO method with missing solar radiation data in all timescales during fall and winter seasons. The Hargreaves- Samani method is not recommended to be used in its original form to estimate ET0 in the Northwestern Mato Grosso do Sul, in none of the timescales and seasons.

Objetivou-se avaliar o desempenho de diferentes metodologias na estimativa da evapotranspiração de referência (ET0) nas distintas estações anuais e considerando as escalas de 1, 3, 6 e 10 dias para a região noroeste sulmato- grossense. Foi utilizado um conjunto de dados diários adquiridos de estações automáticas da rede do Instituto Nacional de Meteorologia das localidades de Água Clara, Cassilândia, Chapadão do Sul, Paranaíba e Três Lagoas. Os dados meteorológicos utilizados foram: temperaturas máximas e mínimas do ar, velocidade do vento, radiação solar e umidade relativa do ar. As metodologias utilizadas para a estimativa da ET0 foram: Hargreaves-Samani e Penman- Monteith FAO (PM-FAO) utilizando todos os dados meteorológicos necessários e com dados faltantes de umidade relativa do ar, radiação solar e velocidade do vento. Para comparar os valores de ET0 estimados por meio das equações testadas com os do método PM-FAO foram considerados os parâmetros da equação de regressão "0" e "1", coeficiente de determinação (r²), erro padrão de estimativa (EPE) e coeficiente de desempenho (c). Os métodos de PM-FAO com dados faltosos de umidade relativa e velocidade do vento são as melhores alternativas para a estimativa de ET0, seguido dos métodos de PM-FAO com dados faltosos de radiação solar em todas as escalas de tempo e para as estações outono e inverno. O método de Hargreaves-Samani não é recomendado para ser utilizado em sua forma original nas estimativas de ET0 na região noroeste sul-mato-grossense, em nenhuma das escalas de tempo e estações anuais.

Leaf traits in Chilean matorral: sclerophylly within, among, and beyond matorral, and its environmental determinants.

Studies of leaf traits often focus on tradeoffs between growth and resource conservation, but little is known about variation in the mechanical traits that influence resource conservation. This study investigates how leaf mechanical traits vary across matorral vegetation in central Chile, how they correlate with environmental factors, and how these trends compare at a broader geographic scale. Leaf toughness, strength, stiffness, and associated traits were measured in five matorral types in central Chile, and relationships with soil N and P and climate variables were assessed. Trends with soil and climate were then analyzed across shrubland and woodland in Chile, Western Australia, and New Caledonia. Chilean species varied in leaf mechanics and associated traits, both within and among matorral types, with more species in sclerophyll matorral having strong, tough, and stiff leaves than in arid and littoral matorral. Overall, leaves with high leaf dry mass per area were stiffer, tougher, stronger, thicker, denser, with more fiber, lignin, phenolics and fiber per unit protein and less protein: tannin activity and N and P per mass, forming a broad sclerophylly syndrome. Mechanical traits of matorral species were not correlated with soil N or P, or predictably with climate variables, except flexural stiffness (EI W) which correlated positively with annual reference evapotranspiration (ET 0). However, soil P made strong independent contributions to variation in leaf mechanics across shrublands and woodlands of Chile, Western Australia, and New Caledonia, either separately (strength) or together with ET 0 (toughness) explaining 46-90% of variation. Hence ET 0 was predictive of EI W in Chilean matorral, whereas soil P was highly predictive of variation in leaf strength, and combined with ET 0 was highly predictive of toughness, at a broader geographic scale. The biological basis of these relationships, however, may be complex.