Using pixel and object based IKONOS image analysis for studying decay in silver fir stands

The problem of old silver fir stands decay has appeared in the lastdecades of the last century with symptoms such as defoliation, wood decay and parasites attacks. The problems in monitoring this phenomenon is that the defoliation and mistletoe attack appear on the crown top, triggering the coronation process - tree develop branches on their lower stem part in order to resist to the defoliation. Thisreaction makes the attack difficult to notice on aerial or satellite images, due to the reflection of light on the lower branches. The objective of the article is to find a research methodology for identifying and even mapping the mistletoe attack phenomenonat a tree or stand level. For a tree-level analysis, a comparison between the data obtained in a 1 ha sample plot and the data extracted from an IKONOS satellite image has been used. The simple spectral response is less correlated at tree level with the defoliation and mistletoe attacks. We found a very significant correlation in the infrared channel but with low correlation coefficients. Better results have been obtained in a stand-level analysis. In order to improve the separability, the methodologyfor extracting the remote sensing data did not resume only to the mean spectral response, but we also performed a variability and texture analysis. The obtained correlation coefficients were around 0.7, very significant for the data used in the research. The results obtained with the texture analysis are also related to the biometriccharacteristics of the stands, mistletoe attacks occurring in stands with a low canopy closure index and is usually accompanied by distorted crowns. The model of forest health analysis should also be tested in similar conditions in order to validate and apply on a large scale inventory

A Permanent Research Platform for Ecological Studies in Intact Temperate Mountainous Forests from Slătioara UNESCO Site and Its Surroundings, Romania

This paper describes a permanent research platform (PRP) designed and implemented in “Codrul secular Slătioara” and its surroundings (2205.85 ha), having also the role of introductory paper for future research articles based on data collected from this platform. “Codrul secular Slătioara” is known as one of the largest temperate mountainous intact forests of Europe and, in 2017, it was included in UNESCO World Heritage List, as part of the “Ancient and Primeval Beech Forests of the Carpathians and Other Regions of Europe”. Moreover, the PRP overlaps other three scientific reserves, the share of strictly protected forests exceeding 70%. This platform has a multiple role, being developed for research, conservation and educational activities. The PRP was designed for an ecological analysis of the intact forest ecosystems. It contains 193 circular sample plots, each of them of 500 m2, and it is structured on two levels. The first level contains 58 sample plots corresponding to a square grid of 500 × 500 m, stretching over the entire forested area, and the second level contains 135 plots, placed according to a square grid of 100 × 100 m, covering 136 ha within the core area of the UNESCO site. We measured the characteristics of 8296 living trees, 1743 standing dead trees, 1900 dead wood trunks, 3214 saplings, and the abundance–dominance indices of flora species. Thus, we identified 14 tree species, 17 shrub species, and 248 other cormophyte species forming the herbaceous layer. In terms of volume, the main tree species are Norway spruce, silver fir and European beech. The tallest species are Norway spruce (56 m) and silver fir (51 m). The average volume of living trees is 659 m3·ha−1, with a maximum of 1441 m3·ha−1. The mean total dead wood volume is about 158 m3·ha−1, with sample plots where the total dead wood volume exceeds 600 m3·ha−1. After presenting the results of preliminary data processing, the paper describes the main research topics to be further considered, based on the PRP, and the foresights related to the PRP’s monitoring and development