Ecological niche models (ENMs) can be used to investigate the shifts in geographical distributions and in productivity of cultivated species in future climatic scenarios. Such models can be classified in correlative, mechanistic or hybrid. The aim of this study was to investigate the relationship between productivity of Zea mays in Brazilian municipalities and crop suitability in current scenarios using the three different ENMs' types, as well as to predict the impacts of climate change on the geographic distribution of Z. mays in Brazil The mechanistic model used was Plantgro, the correlative one was Maxent, and to hybridize them we added the mechanistic model output as another predictor in a second Maxent model. The correlative and hybrid models were very similar, while the mechanistic model presented very distinct results from the other two models. The correlative (maxent) model was the best surrogate of maize productivity. The correlative model indicated that in the future there will be little change in environmental suitability in relation to the current climate.

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We offer a simple graphical representation for proofs of intuitionistic logic, which is inspired by proof nets and interaction nets (two formalisms originating in linear logic). This graphical calculus of proofs inherits good features from each, but is not constrained by them. By the Curry-Howard isomorphism, the representation applies equally to the lambda calculus, offering an alternative diagrammatic representation of functional computations

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Resumo -O objetivo deste trabalho foi apresentar alternativas para estimar o coeficiente de heterogeneidade do solo a partir do coeficiente de correlação intraclasse em diferentes estruturas de delineamentos experimentais. As estimativas dos coeficientes de heterogeneidade do solo obtidas por este método foram comparadas àquelas obtidas por meio de mínimos quadrados generalizados. Não houve diferenças entre as estimativas obtidas por ambos os métodos; nesse caso recomenda-se a estimativa com base no coeficiente de correlação intraclasse por ser mais simples e prática. Considerando-se o coeficiente de heterogeneidade do solo, obteve-se diversos tamanhos de parcela, para diferentes combinações de coeficiente de variação, número de repetições, grau de diferença que se espera detectar entre dois tratamentos e nível de significância.Termos para indexação: coeficiente de correlação intraclasse, precisão experimental, delineamento experimental, coeficiente de variação. Soil heterogeneity coefficient and plot sizeAbstract -The aim of this research was to present ways to estimate the coefficient of soil heterogeneity from the intraclass correlation coefficient for different structure of experimental designs. The coefficient of soil heterogeneity estimates obtained by this method were compared with those obtained by the generalized least square method. Practically, there was no difference between the estimates obtained from both methods, and thus it is recommended to use the estimate obtained from the coefficient of intraclass correlation due to its simplicity and practicability. Several plot sizes were obtained from the coefficient of soil heterogeneity estimates, for different combinations of variation coefficient, replicate number, expected difference between treatments and significance level.