Luís César Rodrigues da Silva

Comparison of methods for estimating heights from complete stem analysis data for Pinus taeda .

The objective of this research was to compare actual heights at known ages with those estimated by the methods proposed by Graves (1906), Carmean (1972), Lenhart (1972), Newberry (1978), and the Ratio and Graphic methods, in order to identify the most accurate one for Pinus taeda from Southern Brazil. That way, six trees aged at least 11 years were used. Cross-sections with 5 cm thickness were collected at heights of 0.10 meters, 0.70 meters, 1.30 meters and so on at every 1 meter along the bole. True height growth for a given age was measured on the section itself by dividing it in two parts along the pith and looking for the exact point where the true annual height growth took place. The accuracy analyses were based on residuals between true heights and those estimated by the tested methods for each age. For this analysis, the relative mean deviation (D % ), relative mean absolute deviation (AbsD % ), standard deviation of differences (S d ) and sum of squared relative residuals (SSRR) were calculated. These 4 statistics evaluated together, allowed for the identification of the most accurate method for every age. Complementarily, the non paired t 0.05 test for data was applied to evaluate whether the residuals from each method were significant or not. The results of the analysis indicated that Carmean (1972) and Lenhart (1972) were identical owing to the fact that they estimated the same height value for sections where there was only one growth ring finishing in the same section. This situation occurred for most of the results in this current study. It was concluded that Carmean (1972) and Lenhart (1972) were the best methods for estimating height growth because both produced non-significant residuals for the majority of the trees studied.

Efeito da árvore marginal nos estimadores populacionais obtidos por métodos de amostragem de área variável

Nesta pesquisa, objetivou-se avaliar o efeito da arvore marginal nos estimadores populacionais obtidos pelos metodos de amostragem de Bitterlich (1948), Prodan (1968) e Strand (1958). A base de dados foi um censo realizado em fragmento de Floresta Ombrofila Mista Montana situado no Campus III da UFPR, Curitiba - PR. Todas as arvores com DAP ≥ 10 cm foram medidas, identificadas, georreferenciadas, e consideradas como possiveis centros das unidades amostrais dos metodos. De todas as arvores, 185 foram sorteadas, aleatoriamente, como inicio dos pontos amostrais para a estimativa de N.ha-1, G.ha-1 e V.ha-1 para os tres tratamentos distintos: sem a influencia da arvore marginal, contagem de meia arvore e contagem da arvore marginal corrigida pelo Fator P de Pellico Netto (1994). Independente do metodo e do tratamento utilizado ocorreu superestimativa do N.ha-1. Para a estimativa da area basal, bem como do volume por hectare, o metodo de Bitterlich apresentou os melhores resultados, seguido de Strand e Prodan, respectivamente. A aplicacao do fator P nas arvores marginais nao melhorou expressivamente os estimadores populacionais a ponto de se diferenciar satisfatoriamente da estimativa gerada com as arvores marginais, contadas como meia arvore ou sem a sua influencia.

Floristic evolution in an agroforestry system cultivation in Southern Brazil

Bracatinga (Mimosa scabrella Bentham) is an important pioneer tree species in Ombrophylous Mixed Forest of Brazil and is widely used as an energy source. In traditional agroforestry systems, regeneration is induced by fire, then pure and dense stands known as bracatinga stands (bracatingais) are formed. In the first year, annual crops are intercalated with the seedlings. At that time the seedlings are thinned, then the stands remain at a fallow period and cut at seven years old. The species is very important mainly for small landowners. We studied the understory species that occur naturally during the succession over several years in order to manage them rationally in the future and maintain the natural vegetation over time. Three to 20 year-old Bracatinga stands were sampled between 1998 and 2011. All tree species with diameter at breast height (DBH) ≥ 5 cm were measured.The floristic evolution was assessed with respect to Sociability Index, the Shannon Diversity Index and the Pielou Evenness Index. Graphs of rank/abundance over different age groups were evaluated using the Kolmogorov-Smirnov test. We identified 153 species dispersed throughout the understory and tend to become aggregated over time.

EVOLUÇÃO ESTRUTURAL DE BRACATINGAIS DA REGIÃO METROPOLITANA DE CURITIBA, PARANÁ, BRASIL

The objective of this research was to study the structural evolution of tree species in stands of bracatinga, along twenty years. The bracatinga (Mimosa scabrella Bentham) is a short-lived pioneer species that characterizes its stands. Under the bracatingas it is formed an understory with other tree species which will replace bracatinga over the years and it is too treated as if it were bracatinga´s firewood, when the area is submitted to clear cutting at every 7 years and bracatinga regeneration is again induced by burning the area. The succession process in stands of bracatinga has not been studied yet and is useful to identify the age when other trees species dominate the stands. The data for this research came from 320 sample plots measured between 1998 and 2011, distributed in stands of bracatinga aged 3 to 20 years. The DBH (diameter at breast height) and total height of all species with a DBH ≥ 5 cm were measured. It was observed that, at age 11, the set of others species outnumber bracatinga. At age 19 tree species already have a diameter distribution similar to that one of a forest in a more advanced stage. Generally speaking it was observed that after age 10, the stands of bracatingastart toshow a configuration of a desne pole stand.

Comparação entre análise de tronco digital e convencional em árvores de mimosa scabrella bentham e pinus taeda L.

Complete stem analysis is largely used in studies on the growth of commercial tree species that have distinguishable growth rings. Rings are manually measured, using a millimetric ruler and that is established as standard procedure. However, Rosot et al (2003) developed procedures for these measurements to be made by computer programs, improving significantly the application of this technique. Thus, the objective of this study was to compare manual measurements with digital ones on stem analysis of Mimosa scabrella and Pinus taeda. Six trees of each species were used and the differences between the two procedures for DBH (cm), total height (m), cross-sectional area (cm 2) and volume (cm 3) of each growth ring were compared by the t test (0.05) for paired data. The differences between digital and manual measurements were significant only for the volume of P. taeda in some ages. The results indicate that digital stem analysis is a good alternative to the conventional one, demanding skilled person to use the tools of GIS (Geographic Information System).