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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.

The increasing worldwide interest in renewable energy and carbon storage has led to the development of relatively fast solutions to obtain wood biomass. The cultivation of fast-growing tree species in short-rotation crops, such as hybrid poplar clones, is one such solution, at least in temperate areas. Sometimes these monocultures are affected by disturbing factors, including severe insect defoliation, with strong destructive effects. The impact of defoliation on the growth and productivity of poplar crops is often estimated in the context of artificial defoliation. There have been few studies in which the effect of defoliation was calculated after natural defoliation. Among defoliating insect species, Clostera anastomosis L. is one of the most important defoliators of young poplars. This species developed severe defoliation in a 4-year-old poplar clone AF8 crop, from the northeastern part of Romania, in the spring and summer of 2017. The study aimed to assess the impact of defoliation both on the growth and mortality of defoliated trees and the productivity of the affected crop. To reach this goal, the height and radial growth of 150 trees with different defoliation rates (50 non-defoliated, 50 partially defoliated, and 50 completely defoliated) were measured and the defoliation symptoms and mortality were also evaluated for 4780 poplars (10% of the analyzed population). The defoliation caused a significant decrease in the annual height growth (28.6% of the partially defoliated trees and 38.5% of the completely defoliated trees) and a severe decrease in the radial growth, between 82.2% and 90.4%, respectively, depending on the defoliation rate. These strong decreases led to a significant decline in tree-level biomass accumulation, approximately 74.8% for partially defoliated trees and 83.1% for completely defoliated trees, for the year of defoliation. As a result, the loss in total biomass (for the four years of the rotation) was between 28.1% and 34.6%, respectively, depending on the defoliation rate. Therefore, the total biomass loss was 5 t·ha−1, representing approximately 70% of the forecasted production for 2017 only (approximately 7 t·ha−1).