Forest fragmentation is a widespread phenomenon that directly or indirectly affects the processes that take place both in forest ecosystems and in their immediate surroundings. So far, many studies confirm its negative effects, especially on biodiversity. On the other hand, there are few studies that address the effects of forest fragmentation on the amount of accumulated biomass or carbon, as well as on the characteristics of wood resources in managed forests. Therefore, issues related to timber production, which are important from the point of view of multifunctional forest management, are omitted. The aim of our research was to add to the knowledge in this area. In particular, we focused on assessing the impact of forest fragmentation on wood resources based on an analysis of edge effects in forest patches (units formed by combining forest fragments characterized by structural connectivity). Vector data describing the topography of forest fragments in Poland and the results of the National Forest Inventory (NFI) from 2015–2019 were used as material for solving this problem. The results of our research showed that the effects of fragmentation on managed pine stands depend on the age of the stand and the fertility of the habitat. In young stands growing on barren or strongly barren habitats, growing stock volume turned out to be significantly higher in the edge zone. In older stands, especially on moderately fertile habitats, significantly higher resources were found in the interior zone of forest patches. Habitat quality also had a significant effect on the amount of carbon accumulated. In strongly barren habitats, higher carbon mass was found in edge zones, while in moderately fertile habitats, stands had higher carbon volume in the interior zone. Our results illustrate that forest fragmentation is a very complex process that can increase or reduce wood resources, depending on the age of the stand and the quality of the habitat. From the standpoint of measurable benefits, it was concluded that protection from the negative effects of fragmentation should focus primarily on older stands and more fertile habitats.

The Land and Property Register (LPR) of Poland contains information on land use for the entire country. Additionally, a sample-based National Forest Inventory (NFI) provides statistical data for forest areas and detailed information on numerous forest parameters. However, until 2014 NFI plots were established only on areas classified as forest in the LPR. In this article, we present results of an estimation of forest area by extending the NFI measurements on all theoretical points in a grid, and compare the results with LPR information for one province (the Podlaskie voivodeship). At each point, we assess land use with recent aerial photographs and verify the ambiguous points in the field. Forest area in Poland is increasing due to afforestation and natural expansion of forest. Delays in the updating process of the LPR, and unwillingness of the owners to agree to reclassification of their land, have led to an underestimation of overall forest area. Our results demonstrate that forest area estimates made by the improved NFI are higher than those based upon the LPR. The modified NFI may be an appropriate tool for monitoring forest area changes in Poland.

Over the years, various methods for estimating and projecting forest resources have been developed and are used by countries where the forest sector is important. Therefore, the obligation to report and account for forest resources, including changes in carbon stocks in a forest area, has gained attention. The latest regulations (Land Use, Land Use Change and Forestry—LULUCF) requires European Union (EU) members to annually report and publish national accounting plans estimating emissions and removals from managed forest areas (Regulation EU 2018/841). The major challenge is to choose and adapt a unique tool for this accounting. At the same time, they need to provide reliable estimates that are recognized by regulators and control authorities. This study focuses on comparing the adaptation of two accounting frameworks: the Operational-Scale Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) and the European Forest Dynamics Model (EFDM). Both tools are based on National Forest Inventory (NFI) data. It is assumed that the EFDM can provide similar results to the CBM-CFS3, which is already used in Poland. Implementing the EFDM and adapting it to Polish conditions could facilitate forest management decision-making and the preparation of forest policies. The main objective of this study was to compare and validate the accuracy of the results obtained with the EFDM framework. Metrics compared using both tools included growing stock volume, biomass of growing stock expressed in carbon units and age–class distribution over area. The comparison was based on the agreement of EFDM with CBM-CFS3 results. The volume of logging was taken from the EFDM and compared with the values obtained by Statistics Poland. This study also provides a guide for framework parameterization directly from the Polish National Forest Inventory data from the 2010–2015 cycle. Our main findings are that the results of the two models are reasonably comparable (the extent of deviation is acceptable). Moreover, the first implementation of the EFDM showed that it is an easy-to-use open-source program that allows forest managers to implement their own settings according to their needs. This document elucidates the concept of using both frameworks under Polish conditions and provides an impression of their performance for future modelers, students and researchers.

The United Nations Framework Convention on Climate Change and the Kyoto Protocol have committed member states to reduce greenhouse gas emissions by, among others, promoting the increase of carbon sequestration by carbon sinks (including woody biomass in forests). In order to achieve these objectives, an international reporting system was designed. The stock of woody biomass depends on several environmental and managerial factors, which determine species composition and age structure of a forest as well as characteristics of individual trees. Estimating aboveground woody biomass, especially on a nation-wide level, is generally based on the application of conversion factors to known characteristics such as the volume of the growing stock. The application of default conversion factors, as proposed by international guidelines, however, is questionable, since inventory systems for and definitions of growing stock differ from country to country. In this paper, the methods used in Poland to estimate woody biomass for the FAO and the UNFCC reporting, were presented and analysed. We also analysed the influence of some stand and tree characteristics, such as tree species composition and content of bark and its density, on the stock of woody biomass. We conclude that issues not addressed in the IPCC guidelines, such as big differences in wood and bark density, especially for pine, need to be taken into consideration when making estimations. Moreover, the results of this paper show that biomass conversion and expansion factors (BCEF) proposed by IPCC are not adequate for Polish conditions.

Long-term monitoring provides a unique opportunity to distinguish persistent ecological processes from short-term fluctuations in forest insect dynamics. However, the extent to which local insect populations persist through time and the mechanisms regulating their occupancy remain poorly understood. Using a 13-year dataset from the Polish ICP Forests network, we investigated temporal and spatial dynamics of insect occurrence in alder stands. We quantified persistence at tree and plot levels, evaluated signatures of density-dependent regulation, and assessed spatial structure using generalized additive models, logistic regression, transition analyses, and spatial autocorrelation metrics. Insect occurrence exhibited exceptionally strong temporal persistence. Occurrence in the previous year was the dominant predictor of current occurrence across all modeling approaches. Persistence patterns differed between plot and tree levels, with transition analyses revealing greater long-term stability at the level of monitoring plots, consistent with the long-term stability of local populations despite turnover among host trees. Occupancy dynamics were consistent with negative density-dependent regulation, with local populations fluctuating around a stable equilibrium occupancy of approximately 75%. Although year-to-year changes occurred regularly, most fluctuations were relatively small and rarely resulted in complete disappearance of populations from occupied locations. Insect occurrence also exhibited pronounced spatial structure. Occupancy remained significantly clustered throughout the study period, indicating persistent regional differences in local population abundance. In contrast, annual changes in occupancy showed only weak spatial autocorrelation, suggesting that short-term dynamics were driven primarily by local ecological processes rather than by highly synchronized regional fluctuations. Our results indicate that infestation patterns in alder stands are consistent with persistent and self-regulating local herbivore populations that remain associated with the same forest stands over extended periods. Long-term dynamics are governed primarily by temporal persistence, density-dependent feedback, and stable spatial structure rather than by repeated cycles of colonization and extinction. These findings highlight the importance of long-term monitoring for understanding population persistence and provide new insight into the processes maintaining herbivore populations in forest ecosystems.