Raúl Vicente Pezzutti

Quantificação das perdas no desenvolvimento de Pinus taeda após o ataque de formigas cortadeiras.

In this study, the main purpose was to quantify the diameter, height and productivity index losses in initial development in Pinus taeda seedlings in stands in Argentine, after leaf cutting ants attack. The treatments were: T1 = control without attack; T2 = attacked by ants; and T3 = sequential artificial deneedling. The three development stages of the plants in two distinct slopes were also evaluated. The results allow concluding that there is a significant reduction in Pinus taeda development when attacked by leaf cutting ants during the first 24 months. In the artificially deneedled plants, there was a significant reduction related to the ones deneedled by the ants, for all the analyzed variables.

Plano de amostragem de Acromyrmex spp. (Hymenoptera: Formicidae) em áreas de pré-plantio de Pinus spp

A study was conducted to elaborate a sampling plan to leaf cutting ants in forest pre-planting areas, at Bosques del Plata company, located in Santo Tome, Corrientes province, Argentine. The research had as object of study the spatial distribution of Acromyrmex nests in Pinus spp. pre-planting areas to determine the adequate plots size and to estimate the sampling intensity to this genus of ants. It was concluded that the Acromyrmex spp. nests spatial distribution in Corrientes-Argentine, adjusts to the randomized model, the adequate plot size to sample the nests density (hole. ha-1) is 700m2 (10x70m) and the adequate sampling intensity is 10.5% for a predicted error of 24%.

Efeito do manejo de plantas daninhas no desenvolvimento inicial de Pinus taeda em várzeas na Argentina

Realizou-se um estudo sobre o efeito de cobertura e periodos de manejo de plantas daninhas em plantios no ano de 1999 de Pinus taeda, localizados na Provincia de Corrientes, Argentina. Em razao das caracteristicas da area, varzeas, foram construidos camalhoes de 1,80 m de largura por 0,60 m de altura para o plantio das mudas e, a seguir, instaladas parcelas com tres fileiras de 12 plantas em cada uma no espacamento de 1,75 m entre as mudas e 4,0 m entre o centro dos camalhoes. Foram medidas somente as 10 plantas do camalhao central, com o objetivo de avaliar o efeito de diferentes modalidades e intensidades de manejo de plantas daninhas na sobrevivencia (%), no desenvolvimento inicial em altura (cm), no diâmetro do colo (cm) e no fator de produtividade (cm3) das mudas de Pinus taeda. Avaliaram-se as modalidades de controle: controle quimico na linha do plantio (camalhao) e controle quimico em area total sendo avaliados por dois periodos: um ano e dois anos de controle, tendo ainda uma testemunha, sem nenhum controle. O delineamento estatistico do experimento foi em blocos ao acaso, com tres repeticoes. Diferencas significativas foram obtidas entre os tratamentos de controle quimico em relacao ao sem controle. Os resultados levaram a conclusao de que e benefico o controle por dois periodos e que nao houve diferenca quanto as modalidades de controle (camalhao e area total). As mudas de Pinus taeda foram submetidas ao teste de Tukey para analise da sobrevivencia e nao apresentaram diferenca significativa a 5% de probabilidade de erro nas medias.

ESTUDO E MODELAGEM DO CRESCIMENTO EM DIÂMETRO DE POVOAMENTOS DE Pinus taeda L. SUBMETIDOS A PODAS E DESBASTES NA ARGENTINA

The aim of this research was to study and to model the effect of pre-commercial thinning and pruning on diameter growth, on a 15 th year old stand of Pinus taeda L. in northeastern Argentina. The study was established in a deep red clay soil, with a systematic design of blocks for thinning intensity and sub-blocks for pruning intensity. The thinning treatments, performed at 3 year old were: 1666 (without thinning); 833; 416 and 208 trees ha -1 . The pruning were done annually, starting at 3 year old, and applied by 2, 3 or 4 consecutive years removing 30, 50 and 70 % of the living crown, respectively. The general model obtained by linear regression allowed to estimate, with good precision (mean absolute deviation as a percentage equal to 5.71), the quadratic mean diameter (QMD) in function of age. The variable remnant trees, remnant crown, and number of prunings were considered to estimate the general function coefficients. At 15 year old, the QMD varied from 25.6 to 41.5 cm to 1666 and 208 trees ha -,1 respectively, without pruning. The QMD growth was negatively affected by pruning and positively affected by thinning.

Sobrevivência e crescimento inicial de mudas de Pinus taeda L. com diferentes diâmetros do colo

The aim of this research was to evaluate the survival and growth of Pinus taeda seedlings produced in containers and bare root with different collar diameters. Two trials were established in a poor drained area located in the Corrientes province, Argentina. The experimental design was randomized complete blocks, with 3 replications and experimental units with 64 seedlings with double lines buffer. The treatments evaluated on the trial 1 were seedlings produced in containers with collar diameter of 1,6 mm; 2 mm; 3mm and 4 mm and on the trial 2 were bare root seedlings with collar diameters of 3 mm; 4 mm; 5 mm and 6 mm. At 4-year-old the seedlings produced in containers did not showed significant differences in survival and growth however in the bare root seedlings production, the seedlings with 4 and 5 mm showed the best survival. No significant differences in growth were detected for all the treatments. For both types of seedling production the collar diameter did not showed significant influence in field growth.