Resumo em Inglês:

ABSTRACT Seasonal variation of temperature could place physiological constraints on the distribution and performance of tropical forest plants, associated with light and water availability. A simple way to assess the relationship between temperature and plant physiology is through the characterization of leaf traits. The main aim of this study was to evaluate, through foliar parameters, the responses of plants to inherent seasonality. A 0.09 ha plot was installed near the flux tower and albedo sensors at Montane Ombrophilous Dense Forest (MODF) - Santa Virgínia Nucleus. At the peak of the dry and wet seasons, the electron transport rate (ETR) and photosynthetic pigments were measured. The results indicated that in MODF, cold and light availability are the main factors that could be influencing the physiology of species, demonstrated by high ETR in the wet season (197.4 µmol e-m-2s-1) compared to the dry season (87.4 µmol e-m-2s-1). Photosynthetic pigments varied between seasons, we observed higher chlorophyll b content (p<0.05), and lower content of carotenoids and xanthophylls (p<0.01) and Chl a/b (p<0.01) in the dry season. The low temperatures and irradiance influenced metabolic activity.

Resumo em Inglês:

ABSTRACT Light Detection and Ranging (LiDAR) derived individual tree crown attributes can potentially serve as a tool for ecology and forest dynamics studies and reduce field inventory costs. In this study, four methods of individual tree detection (ITD), Watershed, Silva et al. (2016), Dalponte and Coomes (2016), and Coomes et al. (2017), were evaluated in a tropical forest under sustainable forest management, situated in the State of Rondônia, Brazil. An automated tree matching procedure was developed in order to minimize the error when matching individual tree count from LiDAR and field data. In order to compare the four methods, results were expressed in recall, precision, and F score. Silva et al. (2016) outperformed the other methods, detecting 48% of trees with 46% of precision. Omission of trees was the leading source of error, caused primarily by overlapped trees in lower vegetation. However, errors of over-segmentation were relevant, caused by large and heterogeneous crowns that had multiple detections. Current canopy height model-based methods are ineffective to tropical forests, due to its complexity, which present a challenge for ITD algorithms. We believe that future studies that use complete 3D information from the point cloud, and multi-layer approaches should help to improve the accuracy of individual tree detection.

Resumo em Inglês:

ABSTRACT It is know that many plants live in symbiosis with microorganisms that can be found on their interior, the endophytes. Environment and tissue type are modulating factors of this community, in which most of these microorganisms produce important antimicrobial molecules and they may be powerful biocontrol agents in agriculture. Thus, the aim of this study was to evaluate the community of Endophytic fungi from Eremanthus erythropappus in anthropogenic and natural areas (with human interaction, natural habitat and planned planting) of Minas Gerais State, Brazil, through cultivation-based approach and verify their antimicrobial activity against phytopathogenic fungal and pathogenic bacteria. The endophytic fungi isolated were identified by sequencing of the ITS region and subjected an in vitro antagonism test. The antagonisms that show antibiosis were submitted to tests on split plates to verify the volatile compound production. In the pairing testes, the endophytic fungi of the genera Cryptosporiopsis, Diaporthe, Xylaria, Paraconiothyrium and Camarosporium presented antibiosis against phytopathogenic fungi by releasing compounds in the medium. To our knowledge, this paper is the first report on the isolation of twelve genera fungi in E. erythropappus besides verifying their antagonist capacity, which opens the way for discovery of bioactive substances produced by endophytic fungi that inhibit pathogens.

Resumo em Inglês:

ABSTRACT The objective of this study was to establish multivariate models for the prediction of wood basic density with reference to the values of average density of trees and near infrared (NIR) spectra measured in the breast height. The wood basic density of 39 Eucalyptus clones was determined in the laboratory by means of the mean longitudinal positions of 0%, 2%, 10%, 30%, 50% and 75% of the commercial height of the tree by the gravimetric method. NIR spectra were recorded using a spectrometer using optical fiber probe and integrating sphere directly on the transverse plane of the solid wood in disks collected from diameter at breast height and later in the sawdust. The performance of the NIR based models was evaluated according to the spectral acquisition method and sample preparation. The results showed that the best model for basic density estimation using indirect measurements was developed from the average spectra per clone measured in solid wood disks (R2cv of 0.77 and RMSEcv of 15 kg.m-³).

Resumo em Inglês:

ABSTRACT The imbalace between the increase in the demand and the decrease in the supply of products from natural forests, partly explains the on-going development of exotic tree plantations. In northwestern Patagonia of Argentina, Pinus ponderosa (Pinaceae) afforestation plays a key role in ameliorate degraded soils, but may also reduce biodiversity. The ecological sustainability of this activity was assessed in Aguas Frías (38°46´ W, 70°54´ S) and Litrán (38°54´ W, 71°01´ S) forest stations, where species richness and life form diversity of plants were compared in vegetation units, fenced and unfenced against livestock. Eleven vegetation units were identified, including natural herbaceous-shrubby steppes, xerophilous and hygrophilous meadows, pure and mixed forests of Nothofagus pumilio (Nothofagaceae) and Araucaria araucana (Araucariaceae), and P. ponderosa planted forests of dissimilar canopy cover. Xerophilous meadows on rocky outcrops held 1/3 of total richness in an extremely restricted area. Hygrophilous meadows exhibited the largest number of families and native and exotic species, and lower diversity of life forms. Dense pine stands exhibited low values of light in the undergrowth, water in the topsoil, cover of undergrowth plants, frequency of hemicriptophytes and richness and diversity of life forms. As canopy cover decreased, values for these indicators resembled those of the steppe of reference. Within a plantation, greater compatibility between conservation of diversity and wood production requires maintenance of fencing, reduced tree spacing over long rotations and the development of buffer zones and biological corridors. Although such a project may represent a decline in productivity, it will promote enhanced ecosystem and aesthetic values, increasing the likelihood of further economic support from society.

Resumo em Inglês:

ABSTRACT Paratecoma peroba is a native Brazilian forest species of great economic and ecological interest, which is currently at risk of extinction owing to excessive wood exploration. The use of the mini-cutting technique could facilitate the vegetatively propagation of this species. The objective of the present study was to establish a vegetative propagation protocol for P. peroba using the mini-cutting technique. In the first experiment, were tested five concentrations of indolbutiric acid (IBA; 0, 1, 2, 4 and 8 g.L-1) and two types of substrates (sand and a commercial substrate based on ground Pinus bark, coconut powder, and mineral additives). In the second experiment, were tested three types of mini-cuttings (apical of 6 cm and 10 cm, and intermediary of 4 cm) and two leaf area sizes (total leaf area and reduced to 50% of leaf area). The results showed that P. peroba could be vegetatively propagated using the mini-cutting technique with up to 82.5% rooting. There was only 5.6% of mini-cutting rooted in sand. High concentrations of IBA promotes decrease in rooting and number of roots. The 10 cm apical mini-cuttiing tend to form clones with better quality standards. The maintenance of the leaf area promotes the attainment of roots with greater root surface area, volume and dry mass of P. Peroba plants.