Application of terrestrial laser scanning in forest inventory – an overview of selected issues

Precise determination of forest resources is one of the most important tasks in conducting sustainable forest management. Accurate information about the forest’s resources allows for a better planning of current and future management as well as conservation activities. Such precise information is needed by both, individual forest managers and for developing the national forest policy. In recent years, interest in the use of remote sensing in forest inventory has significantly increased. Remote sensing allows for non-invasive measurements and the automation of data processing. The most accurate source of remote sensing data at the level of the sample plot is terrestrial laser scanning (TLS). Its use in forest inventory has been studied for about two decades. This paper aims to introduce studies on state of the art TLS technology as well as provide an overview of research conducted in stands within the temperate climate zone. This article furthermore discusses issues such as TLS data acquisition, data processing and presents results for the estimation of tree biometric features.

Decline of Black Alder Alnus glutinosa (L.) Gaertn. along the Narewka River in the Białowieża Forest District

Black Alder Alnus glutinosa (L.) Gaertn. is an important tree commonly growing in Poland. Alders are actinorhizal plants that play an important ecological role in riparian ecosystems through atmospheric nitrogen fixation, filtration and purification of waterlogged soils as well as providing a refuge for terrestrial and aquatic organisms thus helping to stabilize stream banks. Black alder used to be considered a very pest and disease resistant species but, the situation changed in 2000, when an unprecedented decline of Alders was observed in Poland. In the Białowieża Forest District, this decline has been observed on wet meadow habitats and along rivers or watercourses. Currently, there are several hypotheses explaining Alder dieback, among them climatic changes and Phytophthora infections. In terms of climate, Black Alder requires a high atmospheric humidity during all phases of its reproductive cycle. It tolerates neither long-term summer flooding nor a significant decrease in the groundwater level. In terms of pests, oomycete pathogens of the genus Phytophthora are the most destructive plant pathogens known and many of them are present in forests and nurseries all over Europe. The aim of this study was to evaluate the health of Black Alder along the Narewka River in the Białowieża Forest District. Selected areas were monitored in 2012 and 2018, but no relationship between drought and alder health was found. A preliminary analysis of soil and water samples by real time PCR revealed the presence of two Phytophthora species: P. alni and P. cactorum. Further and more detailed research is required to elucidate the role of these pathogens in Alder dieback.

Quality of Scots pine, European beech and pedunculate oak grown from sowing on soil with different compaction levels

In this study, we explore the effect of soil compaction on the growth of seedlings of Scots pine Pinus sylvestris L., European beech Fagus sylvatica L. and pedunculate oak Quercus robur L. On the experimental plots, ground contact pressures ranging from 0 to 250 kPa was applied on the soil. The applied pressure resulted in an increase in soil compaction between 1.02 to 1.19 g cm–3, which reflected pressures exerted by the undercarriage of vehicles used in logging. We then measured the seedlings as well as the dry weight of the roots and the above-ground parts. Using this data, we calculated the following quality indicators for each seedling: SQ – sturdiness quotient, S/R – shoot to root dry mass, DQI – Dickson quality index. For pedunculate oak, the SQ value significantly improved with increasing soil compaction, whereas no differences in the other two indicators were observed. In case of the European beech, the best value of SQ and DQI were observed at a soil density of 1.11 g cm–3, whilst no significant difference for the S/R coefficient could be found. Completely different results were obtained for Scots pine. The most favorable growth was observed when no pressure was applied. However, the SQ and S/R ratios even exceeded the values commonly considered acceptable. Our results therefore indicate that the values of seedling quality indicators are indeed influenced by soil compaction. At a soil compaction of 1.11 g cm–3, the share of seedlings with the SQ value below the critical level was the highest, but a similar relationship could not be confirmed for the other indicators. The response of the seedlings to compaction is likely to be species specific.

Recreation in nature reserves – preferences and satisfaction of tourists visiting the Polesie National Park

The aim of this work was to determine preferences and satisfaction of tourists visiting the Polesie National Park (PPN). Preferences were defined in terms of the motives for visiting, ways of spending leisure time, the length and frequency of visits, knowledge of tourist attractions and awareness of the Park’s financing. A survey was conducted in July–August 2019 gathering responses from 125 adults visiting the PPN tourist and bicycle paths. 100 correctly completed questionnaires were analysed using the CART method to determine the respondents’satisfaction with spending leisure time in the Park. The most frequently mentioned reasons for visiting were the beautiful landscape (28%) and the species richness (27%) of the PPN. 39% of respondents visited the area for the first time and 47% came for one day. Most visitors (65%) had very good knowledge of the tourist attractions in the PPN. Walking was the most common way (37%) for visitors to spend theirleisure time in the Park. More than half of the respondents (58%) would be willing to accept additional fees in order to help maintain and protect the PPN. The vast majority of the respondents indicated that they are satisfied (42%) or very satisfied (48%) with their visit to this area. Our statistical analysis indicated that asking the question about financing the Park greatly impacted the responses to the question about visitor satisfaction, but was also correlated with the respondent’s place of residence as well as their knowledge of tourist attractions. The unique character, landscape as well as the natural, historical and cultural richness of the PPN combined with the well-maintained infrastructure are crucial to ensure a high level of visitor satisfaction.

Multiplex detection of Phytophthora spp. using the Fluidigm platform

The genus Phytophthora plays an important role not only in agriculture but also in forest ecosystems. As the number of known Phytophthora species continues to grow, identifying new isolates in this genus has become increasingly challenging even by DNA sequencing. Therefore, the development of proper techniques for detection and identification is crucial for monitoring and control of these pathogens in the forestry sector. In recent years, new molecular methods using innovative approaches have indeed been developed. However, the majority of these methods was designed to detect single Phytophthora species. Techniques that are able to target multiple species would offer advantages, especially for the assessment of Phytophthora diversity in the environment. This paper describes a multiplex assay for the identification of eight Phytophthora isolates, down to the species level, based on a Fluidigm platform employing pyrosequencing. The obtained results showed that for an accurate determination of the species, it is sufficient to know the sequence of two markers, ITS and COX1. The sensitivity of this test is sufficient to identify Phytophthora in a pure culture. Unfortunately, analysis based on a pyrosequencing platform does not provide enough data to simultaneous identify multiple Phytophthora species in samples collected in the field. This problem could be resolved in the future by sequencing using more efficient platforms like Illumina or IonTorrent.

Fungi associated with Armillaria spp. rhizomorphs on Populus tremula L.

The economic significance of aspen Populus tremula l. is only marginal, which is the main reason for its low share in the structure of stands. however, aspen can play a decisive ecological role as a pioneer tree in the succession of forest communities and may decrease the occurrence of pathogenic fungi. Aspen is also dying out and in order to determine possible biotic causes, we examined taxa of fungi using classical and molecular methods in the area of the Czerwony Dwór Forest District, Subdistrict Rogale, compartments 74b and 75j. The health of aspen trees and the quantitative and qualitative structure of microorganisms associated with Armillaria spp. was evaluated. Based on our health assessment of the aspen, we conclude that the main reason for its dying out is the intensification of root rot, which is a result of Armillaria spp weakening the trees. In the general pool of Armillaria-associated microorganisms, saprotrophs were dominating, and the fungus Fomitopsis pinicola commonly inhabited the poplar stems, whereas pathogen antagonists comprised the lowest proportion. In the quantitative and qualitative structure of fungi found in rhizomorphs, the composition of ecological groups inhabiting stumps was found to be favourable nevertheless. The increasing frequency of pathogens on the logs is a major premise for removing trees affected by Armillaria, because aspen stumps are a good food base for A. cepistipes and A. ostoyae which ultimately spread within the stand. Treatment of stumps with preparations stimulating the decomposition of wood is not recommended for logs that form the food base for pathogenic fungi.

The influence of stand and habitat characteristics on the occurrence of pine sawflies Diprion pini L. and Gilpinia virens (Klug) (Hymenoptera, Diprionidae) in selected areas of northern Poland

Pine sawflies (Hymenoptera: Diprionidae) belong to the most common pests of Scots pine Pinus sylvestris L. in the area of the Regional Directorates of State Forests in Toruń and Gdańsk. The two most destructive species, Diprion pini L. in the area of Puszcza Bydgoska and Gilpinia virens (Klug) in Bory Tucholskie, were investigated in this study. Our main aim was to characterise the two species in the Bydgoszcz Forest District in RDSF in Toruń and Kaliska in RDSF in Gdańsk, respectively, based on data gathered during outbreaks between 1991 and 2011. For this purpose, a geometric database was created, containing information about the year of outbreak, number of larvae observed after tree felling as well as selected stand and site features including stand age and species composition, stocking index, canopy closure, site index, humidity and fertility. By analysing the occurrence of both species in relation to stand and site features, we were able to determine their environmental requirements, which are quite different from one another. D. pini preferred older stands, with a stocking index between 0.8–0.9, growing on fresh and dry coniferous sites, while species composition (share of pine), canopy closure or site index did not have any influence on its abundance. G. virens preferred middle-aged pure pine stands, with relatively open canopies, on fresh coniferous sites and poorer soils. The stocking index did not affect its occurrence.

Forest management plan in Poland – problems and development directions

Nowadays, improving forest management is done by way of amendments to the forest management instructions, silvicultural rules and forest protection instructions. From the point of view of forest management, the most important is the forest management plan, the basic document prepared for a specific object, containing a description and assessment of the state of the forest, as well as the objectives, tasks and ways of forest management. Before each subsequent revision of the forest management guidelines, new instructions are developed in consultation with the public, based on discussions on the proposed changes that are in each case to serve as the best plan for forest management. The forest management plan is vital as it ties together silviculture, conservation, production and non-production purposes as well as social forestry tasks, but only if the primary and operational nature of the objectives considered at the stage of creating the plan are recognized. Therefore, the role of forest management in shaping and protecting the environment cannot be overestimated. In this work, we outline the basic principles and rights related to both, forest management under various forms of ownership, as well as detailed guidelines for the content of the forest management plan. We found that the specificity of mountain forests requires the use of different rules and methods. Taking into account the existing rich scientific achievements, it is tempting to attempt to develop forest management instructions specifically for mountain forests, whether in the form of a separate chapter or a separate publication. The basic problem with forest management under other forms of ownership (urban, experimental, private forests) is the lack of a detailed legal basis accounting for their specific nature. Therefore, appropriate steps should be taken towards introducing appropriate new or supplementary provisions into the forest legislation, which would allow for the development of modern standards. For the State Forests, forest management instructions should be prepared by a team of experts appointed by the Minister of the Environment who will approve the finished document for official use. The forest management plan should include an economic annex focused on the forecast of the expected financial result, including costs associated with a deviation from the optimal due to social or protective reasons.

Forest – the photosphere of life in the Earth’s atmosphere

The evolution of the vertical, long distance water transport, overcoming gravitation, by trees during the Devonian, initiated the emerging of forest ecosystems extending the photosphere of life further into the Earth's atmosphere. The origin of woody tissues is likely associated with genome mutations in primitive green plants, which inhabited the land about 350 million years ago. Most probably, only two mutations were required – one allowing the synthesis of lignin and the second, enabling the autolysis of protoplast in the maturing cellular woody elements. Developing forest ecosystems formed the most productive environments, in which sunlight-dependent metabolic processes of life reached further into the atmosphere while at the same time allowing more water to be stored on the land surface, which in turn allowed for the evolution of numerous heterotrophic organisms. This property of the forest could therefore be considered an important factor in the evolution of hominids, which eventually contributed to the development of the Homo sapiens culture.

The impact of fertilisers and fungicides on seed germination and the initial phase of seedling growth in black alder Alnus glutinosa (Gaertn.)

To test the influence of selected fertilisers and fungicides on the germination of black alder seeds and the initial phase of seedling growth, we conducted a laboratory experiment outlined in this paper. Six treatments were applied on petri dishes each containing 30 seeds. The substrate for germination was sterile filter paper wetted with an aqueous solution of either one of two fungicides, two organic fertilisers, a mineral fertiliser or distilled water (control). Fungicides and fertilisers were applied according to the manufacturers' recommendations. In order to keep genetic variability to a minimum, seeds originated from a single tree in a seed stand located in the Chotyłów Forest District, eastern Poland. Germination and growth took place at a temperature of 23°C ± 2°C with a 14 h/10 h day/night cycle. Seeds began to germinate as early as the second day after sowing, except for the mineral fertiliser treatment, in which the first sprouting was observed on day 3. Seedling length was measured daily from the day of germination of a given seed through to day 15. Germination was found to proceed most rapidly in the control, while the largest increments in length and dry mass occurred in the control and fertiliser treatment with the so-called N1 fertiliser (solely comprising growth stimulators in the form of humic acids, chitosan and silicon). The most limited growth was observed under the influence of the F1 fungicide (active compound Thiram) as well as the organic fertiliser N2 (a mixture of mineral components and organic growth stimulators). Roots were found to develop most rapidly in the control and in the treatment with N1 (no mineral components). These are also the only two treatments in which the roots were longer than the stems after 15 days. Fertiliser N2 was found to have the most unfavourable influence on both, germination and the first phase of seedling development. The fact that selected fertilizers and fungicides affected black alder seeds and seedlings under laboratory conditions does not mean that they will have an impact under field conditions or on other forest tree species. Therefore, this type of research will need to be conducted individually for each forest tree species.