Pine Sites Research Articles

Influence of Structure from Motion Algorithm Parameters on Metrics for Individual Tree Detection Accuracy and Precision

Uncrewed aerial system (UAS) structure from motion (SfM) monitoring strategies for individual trees has rapidly expanded in the early 21st century. It has become common for studies to report accuracies for individual tree heights and DBH, along with stand density metrics. This study evaluates individual tree detection and stand basal area accuracy and precision in five ponderosa pine sites against the range of SfM parameters in the Agisoft Metashape, Pix4DMapper, and OpenDroneMap algorithms. The study is designed to frame UAS-SfM individual tree monitoring accuracy in the context of data processing and storage demands as a function of SfM algorithm parameter levels. Results show that when SfM algorithms are properly tuned, differences between software types are negligible, with Metashape providing a median F-score improvement over OpenDroneMap of 0.02 and PIX4DMapper of 0.06. However, tree extraction performance varied greatly across algorithm parameters, with the greatest extraction rates typically coming from parameters causing increased density in dense point clouds and minimal point cloud filtering. Transferring UAS-SfM forest monitoring into management will require tradeoffs between accuracy and efficiency. Our analysis shows that a one-step reduction in dense point cloud quality saves 77–86% in point cloud processing time without decreasing tree extraction (F-score) or basal area precision using Metashape and PIX4DMapper but the same parameter change for OpenDroneMap caused a ~5% loss in precision. Providing reproducible processing strategies is a vital step in successfully transferring these technologies into usage as management tools.

Wet and dry spell induced changes in the soil CO2 effluxes of Pine and Oak ecosystems of Central Himalaya: a comparative assessment for monsoon and winter seasons.

Soil efflux of CO2( ) is known to be dependent on natural drying and rewetting of the soil. Although the central Indian Himalayan region is predominantly occupied with two ecosystems, i. e. Pine (Pinus roxburghii) and Oak (Quercus leucotrichophora), differences in their dynamics and responses of to varying wet and dry spells were hardly known. To address this knowledge gap, this study provides a comparative assessment of variability from Pine and Oakecosystems of central Himalaya as a response to rainfall induced wet and dry spells of monsoon and winter seasons. The data presented in this study are collected for242 days of 2021-22 that include monsoon and winter seasons from a Pine and an Oak sites. The mean sof Pine and Oak sites are found to be 3.95(± 0.02) and 3.61(± 0.01) μmol.m-2.s-1, respectively. We find that the winter reduction in the in comparison to monsoon at the Pine site (78%) is more substantial than at Oak site (64.6%). The cross wavelet spectra of and monsoon rainfall amount at the Oak site, unlike the Pine site, indicate a negative relationship. The rainfall spell duration and amount of monsoon wet spells are noted to have an inverse relationship with at both sites, although, increasing rainfall spell duration in winter is noted to increase at Pine and Oak sites. Similarly, increasing is observed with increasingdry spells of monsoon at both sites. Results of this study indicate that in comparison to Oak, variability at Pine ecosystem is primarily driven by abiotic factors wherein wet spell is a major determinant.

Ash fertilization increases long-term timber production in drained nitrogen-poor Scots pine peatlands

Wood ash fertilization remarkably increases tree growth and hence, carbon sequestration in drained boreal peatland forests, particularly in nitrogen (N)-rich Scots pine sites with limited phosphorus (P) and potassium (K). Because ash lacks N, N-deficient ombrotrophic and poor oligotrophic sites are generally considered unsuitable for ash fertilization. In this study, timber production was investigated in six field experiments in N-poor, drained Scots pine dominated peatlands in central Finland, where ash fertilization was applied 15–85 years earlier. Ash significantly increased tree growth in all the study sites. Unfertilized plots showed long-term average mean annual increment (MAI) of 2.01 m3·ha−1·a−1, whereas in fertilized plots MAI was 4.46 m3·ha−1·a−1. An analysis with nonlinear mixed effects model revealed a faster volume yield development and higher asymptote of the mean curve in fertilized plots. Higher amount of K in the ash significantly increased the response. Fertilizations were financially lucrative: on average, the break-even cost surpassed the ash fertilization cost (390 € ha−1) more than two-fold at 5% interest rate. The current nutrient status of fertilized trees was rather balanced. The results proved that the long-term growth response to ash fertilization in poor drained peatland sites is comparable to N-rich sites, but the response time is distinctively longer.

Dynamics of radioactive contamination of lingonberry (Vaccinium vitis-idaea L.) in the forests of Zhytomyr Polissia (Ukraine) since the Chernobyl Nuclear Accident

The article presents results of study of levels of radioactive soil contamination and 137Cs activity concentration in the aboveground part of lingonberry (Vaccinium vitis-idaea L.) phytomass and berries on permanent experimental plots in different years since the Chernobyl Nuclear Power Plant accident (forest site type conditions — moist fairly infertile pine site type (B3), soils — soddy-podzolic sandy-loam on fluvioglacial sands). The research was conducted at the Poliskyi Branch of the Ukrainian Research Institute of Forestry and Forest Melioration named after G.M. Vysotsky over the years 1998–2021, utilized methods generally accepted in forest science and radioecology were used. Results were processed using statistical analysis. To substantiate the research, an official reporting data from forestry enterprises of the Volyn, Rivne and Zhytomyr regions were used. An analytical review of the state of research on this problem revealed that at the last 10–15 years there were no scientific publications on the study of 137Cs contamination of lingonberry. It was demonstrated that there was significant reduction in the density of radioactive soil contamination and 137Cs activity concentration in the aboveground part of lingonberry phytomass and berries in the forests of the research region over the observation period. It was found that the main part of the total 137Cs activity is currently located in the upper (10 cm) layer of the mineral part of the soil — 74.7% where root systems of herbaceous and dwarf-shrub species are concentrated in forest ecosystems. It was established that a considerable content of the radionuclide is retained in the aboveground part of lingonberry phytomass even with low density of radioactive soil contamination. It was found that in 1998, at relatively low value of soil 137Cs contamination density (49±5.6 kBq∙m–2), specific activity of 137Cs in aboveground phytomass of lingonberry was 8043±511 Bq∙kg–1, while in 2021 (value of soil 137Cs contamination density 22±0.3 kBq∙m–2) — 1046±182 Bq∙kg–1. The values of radionuclide transfer coefficients in 1998 were quite significant and varied within wide range: in the air-dry aboveground phytomass from 33.4 to 164.1 m2∙kg–1∙10–3 and in the fresh berries, from 9.5 to 26.0 m2∙kg–1∙10–3. Dependencies between density of radioactive soil contamination and the content of 137Cs in the aboveground part of lingonberry phytomass and berries were calculated, which can be applied in the practice of their harvesting. It was found that lingonberry belongs to the group of plants characterized by the high content of 137Cs in the aboveground vegetative phytomass. Harvesting of lingonberry leaves for the production of medicinal products should be restricted in all areas contaminated with 137Cs. Lingonberry fresh berries can be harvested in areas with a radioactive soil contamination density up to 74 kBq∙m–2.

The University of West Florida Campus Ecosystem Study: effects of forest vegetation on light availability and soil processes.

College and university campuses with a notable arboreal component provide unique opportunities for carrying out ecological research. The University of West Florida Campus Ecosystem Study (UWF CES) was established in 2019 as interconnected research to take advantage of the extensive arborescent nature of the UWF campus, particularly concerning longleaf pine (Pinus palustris). One of these investigations established permanent plots in forested sites of two contrasting types, one dominated by longleaf pine ("pine site") and the other dominated by hardwoods ('hardwood site'). This study used these plots to examine the influence of forest vegetation on light availability and soil processes. Light was measured as photosynthetically active radiation (and expressed as photon flux density-PFD) with a handheld meter in each plot. Soil was sampled to 5 cm in each plot; texture was measured with the hydrometer method. Identical sampling methods were carried out in a persistent canopy opening to assess light and soil conditions under maximum solar radiation. Mean PFD was ~4× higher in pine stands than in hardwood stands; PFD was 12.8 and 3.5% of full light in the pine and hardwood stands, respectively. All soils were dominated by coarse-textured sands, but silt was significantly higher in pine stand soil and higher still in the canopy opening. Among forest stand plots, sand was negatively related to PFD, whereas clay was positively related to PFD. Across the three sites, silt was positively related to PFD. These relationships are consistent with the importance of solar radiation as one of many drivers of soil weathering.

Differences in Soil Fungal Communities between Forested Reclamation and Forestry Sites in the Alberta Oil Sands Region.

Fungi play key roles in forest soils and provide benefits to trees via mycorrhizal symbioses. After severe disturbance, forest regrowth can be impeded because of changes in fungal communities. In 2013-2014, soil fungi in forest floor and mineral soil were examined by Roche 454 pyrosequencing in undisturbed, harvested, and burned jack pine stands in a forested area near Fort Chipewyan, Alberta. These fungal communities were compared with jack pine, white spruce, and larch stands in Gateway Hill, a nearby certified reclaimed area. In 2014, a more detailed sampling of forestry and reclamation jack pine sites examined fungi in soil fractions using two high-throughput sequencing platforms and a sporocarp survey. The significances of compositional and functional differences in fungal communities between the forested and reclamation sites were assessed using permutation tests of partially constrained ordinations, accounting for confounding factors by variance partitioning. Taxa associated with the forestry area were primarily ectomycorrhizal. Fungal richness and diversity were greater in soils from the reclamation sites and included significantly more pathogenic taxa and taxa with unknown functional properties. Fungal community dissimilarities may have been artefacts of historical legacies or, alternatively, may have resulted from contrasting niche differentiation between forestry and reclamation sites.

Carbon Stocks and Transfers in Coniferous Boreal Forests Along a Latitudinal Gradient

Carbon (C) sequestrated in the boreal forest ecosystems plays an important role in climate regulation. This study’s objectives were to quantify the differences in the components of the forest C cycle along a 1000 km latitudinal gradient within the boreal region and between dominant coniferous species in Fennoscandia. The study included seven xeric–sub-xeric and eight mesic–herb-rich heath forests dominated by Scots pine and Norway spruce, respectively. The total site carbon stock (CS) ranged from 81 to 260 Mg ha−1. The largest ecosystem component CSs were tree stems, mineral soil, and humus layer, representing 30 ± 2%, 28 ± 2%, and 13 ± 1% of total CS, respectively. On average, the spruce sites had 40% more C than the pine sites, and CS stored in most compartments was higher on spruce than on pine sites. As exceptions, understorey vegetation and litter layer had a larger CS on pine than on spruce sites. The northern sites had an average of 58% less C than the southern sites. Humus layer CS was the only compartment showing no latitudinal trends. Northern sites had a significantly larger fine and small root CS and understorey CS than southern sites. Most CS compartments were significantly correlated with litterfall C transfer components. Dissolved organic carbon (DOC) flux in throughfall was positively correlated with the aboveground tree compartment CS. Our study revealed patterns of C distribution in major boreal forest ecosystems along latitudinal and fertility gradients, which may serve as a reference for Earth system models and in the evaluation of their projections.

Evaluating Close-Range Photogrammetry for 3D Understory Fuel Characterization and Biomass Prediction in Pine Forests

Understory biomass plays an important role in forests, and explicit characterizations of live and dead understory vegetation are critical for wildland fuel characterization and to link understory vegetation to ecosystem processes. Current methods to accurately model understory fuel complexity in 3D rely on expensive and often inaccessible technologies. Structure-from-motion close-range photogrammetry, in which ordinary photographs or video stills are overlaid to generate point clouds, is promising as an alternative method to generate 3D models of fuels at a fraction of the cost of more traditional field surveys. In this study, we compared the performance of close-range photogrammetry with field sampling surveys to assess the utility of this alternative technique for quantifying understory fuel structure. Using a commercially available GoPro camera, we generated 3D point cloud models from video-derived image stills of 138 sampling plots across two western ponderosa pine and two southeastern slash pine sites. We directly compared structural metrics derived from the photogrammetry to those derived from field sampling, then evaluated predictive models of biomass calibrated by means of destructive sampling. Photogrammetry-derived measures of occupied volume and fuel height showed strong agreements with field sampling (Pearson’s R = 0.81 and 0.86, respectively). While we found weak relationships between photogrammetry metrics and biomass 0 to 10 cm in height, occupied volume and a novel metric to characterize the vertical profile of vegetation produced the strongest relationships with biomass above the litter layer (i.e., >10 cm) across different fuel types (R2 = 0.55–0.76). The application of this technique has the potential to provide managers with an accessible option for inexpensive data collection and can lay the groundwork for the rapid collection of input datasets to train landscape-scale fuel models.

Current 137Cs accumulation by mushrooms in different site types of scots pine forests of Ukrainian Polissia

The study of 137Cs radioactive contamination of fruiting bodies of mushrooms was carried out in September - October 2022 in 18 sampling sites laid out in the Korosten district of Zhytomyr region in 3 of the most widespread forest site types (FST): fresh infertile pine site type (А2), fresh fairly infertile pine site type (В2) and moist fairly infertile pine site type (В3). It was found that the highest levels of 137Cs content in investigated FST were characteristic of symbiotrophic mushroom species - Сortinarius mucosus, Сortinarius caperatus, Sarcodon imbricatus, Imleria badia, Tricholoma equestre, Paxillus involutus, Hygrophorus hypothejus, and the lowest - for xylotrophes-saprotrophes such as Armillaria mellea and Tapinella atrotomentosa. When analyzed, it was shown that interspecific differences of average values of 137Cs aggregated transfer coefficient (Tag) among mushrooms in each FST varied in a wide range: they reached 1.1⋅103 times in FST-A2 - from 435 in Cortinarius mucosus to 0.4 m2⋅kg-1⋅10-3 in Armillaria mellea; 71.4 times - in FST-B2 - from 162 in Sarcodon imbricatus to 2.3 m2⋅kg-1⋅10-3 in Armillaria mellea; and 12 times - in FST-B3 - from 111 in Imleria badia to 9.2 m2⋅kg-1⋅10-3 in Leccinum scabrum. Also, it was shown that in genus Russula even in the same FST-B2 among five studied species a 24-fold change in average values of 137Cs Tag are observed - from 67 in Russula vinosa to 2.8 m2⋅kg-1⋅10-3 in Russula aeruginea. The results of ANOVA were discussed as well as the essentiality of the difference of the average values of Tag in mushroom species in different FST.

Viscum album subsp. austriacum (Santalaceae R. Br.) in Volyn Polissia and Zhytomyr Polissia (Ukraine): current distribution, ecology and prediction of future spread

Background. One of the subspecies of the European mistletoe, the so called pine mistletoe (Viscum album subsp. austriacum (Wiesb.) Vollm.) is a hemiparasitic, evergreen, epiphytic phanerophyte that parazitizes predominantely on the Scots pine (Pinus sylvestris L.) in Ukraine. The pine trees infested with V. album subsp. austriacum lack moisture for transpiration and photosynthesis, which reduces their primary productivity, viability and health. The purpose of this study was: 1) to determine the current distribution of V. album subsp. austriacum in Volyn and Zhytomyr Polissia regions using GIS-technology; 2) study the main taxation parameters of pine stands infested with V. album subsp. austriacum; 3) predict the possible further spread of V. album subsp. austriacum in the studied Region. Materials and Methods. The grid mapping method based on GIS technology, with a grid size of 10×10 km and 20×20 km, was used to create the map of the species distribution. The spatial distribution of soil moisture in the forest soils of Drevlyanskyi Nature Reserve was determined using satellite images and data on soil moisture from the Earth Engine Data Catalog. The taxation parameters of the mistletoe-infested pine stand (i.e., participation of the Scots pine in the stand composition, area distribution of pine stands by age, relative completeness, stand quality class, trophotope, and hygrotope) were obtained from standard taxation descriptions. Results and Discussion. The study found that V. album subsp. austriacum is more widespread in Volyn Polissia than in Zhytomyr Polissya – 87 and 20 localities respectively. It was shown that the forest plantations colonized by V. album subsp. austriacum in Drevlyansky Nature Reserve are located in areas with the lowest moisture content, with a moisture reserve of 16–70 mm in the 0–100 cm soil layer, which corresponds to dry and fresh hygrotopes. Conclusions. V. album subsp. austriacum is more widely distributed in such nature reserves of the region as Shatskyi National Nature Park and Drevlianskyi Nature Reserve, and less so in Rivne, Cheremskyi, Polissia Nature Reserves and Pripyat-Stokhid National Nature Park. In the region under study, V. album subsp. austriacum mostly affects pure pine forests aged 80‒140 years, of medium completeness (0.5‒0.7), and relatively high and high stand quality classes – Ic–II, in fresh hygrotopes – 67.3 % of the area and in fairly infertile pine site type (trophotope B) – 51.5 %. Based on the distribution of forest site types in the region and their susceptibility to V. album subsp. austriacum, the possibility of its further intensive spread in the study region can be predicted.

Contribution to the Study of The Pedofauna In Southern Algeria (Djelfa Forest, Algeria)

This study compares the soil fauna populations of two Aleppo pine sites in the semi-arid bioclimatic zone. One is located at Moudjbara, and the other at Senalba Chergui in the steppe of the Wilaya of Djelfa. Analysis of the soil sample inventories revealed a total of 479 specimens belonging to 9 classes, 16 orders, 38 families and 41 species. The Moudjbara fauna remains the best represented in terms of abundance, with a rate of 53% of the total number, as well as in terms of richness for all taxa combined, 23 families and 26 species compared with 15 for each of the above-mentioned ranks. On the basis of the data collected, it is clear that the Moudjbara forest seems to offer ecological conditions that are more conducive to the establishment of a more diversified community of soil fauna than the Sénalba Chergui forest. The Sénalba Chergui forest is the least rich in species and the least abundant in terms of numbers of individuals. The equitability values for the two biotopes surveyed tend to approach the value of 1, which implies that all the species are more or less equally distributed between them.

Poor regeneration of pine after mountain pine beetle attack in colder boreal regions of Canada

The recent expansion of mountain pine beetle (MPB, Dendroctonus ponderosae) from its native range in western North America into northern boreal pine forests in Alberta, Canada has resulted in conditions for tree regeneration that are dramatically different from those after wildfire, the predominant natural disturbance in these forests. We assessed natural regeneration post-MPB for northern boreal lodgepole pine sites in Alberta, Canada via intensive surveys of small plots at 33 severely attacked pine stands and using data from 205 permanent sample plots representing various site types and levels of MPB mortality. We used model selection to identify factors explaining regeneration. Overall, pine regeneration was very poor 6–9 years post-MPB; only 42% of the 33 intensively surveyed plots and only 9% of the 205 permanent plots had pine seedlings. This poor regeneration is attributed to high levels of cone serotiny in these populations, unsuitable regeneration microsites due to undisturbed litter or feathermoss layers, and competition from the residual canopy and understory vegetation. Other species (aspen, birch, poplar, and black and white spruce) were found on most sites, either as post-attack regeneration or regeneration established in advance. Without intervention, many of these stands will likely transition away from pine, to broadleaf and other conifer species.

Widespread regeneration failure in ponderosa pine forests of the southwestern United States

As climate changes in coming decades, ponderosa pine forest persistence may be increasingly dictated by their regeneration. Sustained regeneration failure has been predicted for forests of the southwestern US (SWUS) even in absence of stand-replacing wildfire, but regeneration in undisturbed and lightly disturbed forests has been studied infrequently and at a limited number of locations. We characterized 77 ponderosa pine sites in 7 SWUS locations, documented regeneration occurring over the past ∼20 years, and utilized gridded meteorological estimates and water balance modeling to determine the climate and environmental conditions associated with regeneration failure (R0). Of these sites, 29% were R0, illuminating that regeneration failure in these forests is widespread. R0 sites were distinguished by high above- and belowground heat loading, loss of cool-season climate, and high soil moisture variation. Explanatory variables had high accuracy in identifying R0 sites, and illustrate the climate-driven pathway by which regeneration failure has occurred in the SWUS. Regeneration failure has high potential to increase in a warmer, more hydrologically variable climate, and expand regionally from lower to higher latitudes. Yet, we also found that human management interventions were associated with environmental conditions that avoided regeneration failure. To counteract regeneration-associated forest declines, interventions will need to influence climate-driven environmental change by adjusting forest characteristics at local scales. Regeneration failures are a major threat to ponderosa pine forest persistence, and they have potential to intensify and expand in a changing climate.

Біотопи існування та живлення зубра в Національному природному парку Цуманська Пуща (Україна)

The conservation and restoration of the bison (Bison bonasus L.) is one of the fundamental issues of international importance in the Tsumanska Pushcha National Nature Park, Ukraine. The distribution of bison in the territory of the park and adjacent areas is associated with the specific requirements of the species regarding food and protective properties of the terrain. In spring, with the beginning of the growing season, the grass cover is thin and the amount of food is insufficient, so bison prefer swampy biotopes. In March–April, birch–alder and aspen–birch–alder stands provide optimal feeding conditions for the animals. Within the territory of spring distribution of bison, the biotopes they inhabit are represented by wet and fairly fertile sites (types C3 and C4,), as well as moist and fairly infertile pine site (type B3). Biotopes these animals inhabit during the spring–summer period (March–August) cover an area of about 1640 hectares, of which 350 hectares are within the national park, and the rest are part of the territory of the Muravyschensky and Sokyrychivsk forests of the Kivertsi Forestry State Enterprise. The territory of the forest districts is characterised by a mosaic structure of stands, alternating areas of broad-leaved and coniferous species, wetlands and grass glades with good feeding conditions for the animals. The animals have adapted to almost all types of forest biotopes. During the entire growing season, the trophic activity of bison is particulary high in pastures, forest clearings, and swampy meadows adjacent to woodlands. The main bison biotopes are located at a large distance from human settlements and characterised by poorly developed road network, low level of disturbance, and favourable living conditions. The current size of the bison population in the national park is 21 individuals, and the presence of calves and young animals is a sign of favourable conditions and positive population dynamics that may lead to further increase in the future. In order to minimise the impact of negative factors, relevant measures should be implemented to maintain the stability of the subpopulation, to protect the habitats of the animals, and to conduct active educational and informational activities in the park. The technologies of forest felling, harvesting of minor forestry products, and other forestry works must include elements aimed at preventing negative effects on bison.

Rapid shift of soil fungal community compositions after clear-cutting in hemiboreal coniferous forests

Clear-cutting is the main forest management method in boreal and hemiboreal forests, but recently its implementation has raised concerns due to its effects on biodiversity, including the soil fungal biota. Forest soil fungi have an important role as mycorrhizal symbionts, decomposers of organic material and root pathogens. There is conflicting information about the effect of clear-cutting and related management practices on fungal assemblages. We aimed to assess the factors that affect the assemblages of major fungal functional guilds (ectomycorrhizal, saprotrophic, pathogenic and yeast fungi) and the changes in soil fungal diversity and community composition after clear-cutting in Norway spruce and Scots pine (retention trees > 5 m3 per ha) stands, and compared the outcomes with alongside control sites (uncut stands). In addition, we tested the effect of the size of the clear-cut area, soil scarification and the forest regeneration method (planting and sowing) on soil fungi. The samples were collected from 50 different clear-cut sites and 50 control sites on two repeated sampling occasions: recently (0–6 months) cut and one year after clear-cutting. Based on high-throughput Illumina sequencing soil fungal communities were affected immediately after clear-cutting, resulting in significantly different fungal structure composition. Soil fungal diversity in both spruce and pine stands increased after one year post-cut compared to control sites, except the richness of ectomycorrhizal fungi in spruce sites. However, the fungal communities showed the highest similarity between control and one year post-cut sites based on principal coordinates (PCO) and Permanova analyses. Nonetheless, relative abundance of ectomycorrhizal (EcM) fungi declined, whereas that of saprotrophs and pathogens increased. In spruce sites, saprotrophic fungi were negatively affected by soil scarification, but this was not evident in pine sites. Forest regeneration by planting after clear-cutting in pine sites resulted in higher ectomycorrhizal fungal richness compared to sowing. Size of the clear-cut area (ranging from 0.4 to 3.1 (5.0) ha) did not affect soil fungal diversity in spruce- and pine-dominated sites. We demonstrated that fungal community composition may recover within one year after clear-cutting in pine- and spruce-dominated hemiboreal forest stands. However, understanding the long-term effects of management on patterns and shifts in fungal biota needs a long-term study.

Effects of pre-commercial thinning on soil respiration and some soil properties in black pine (Pinus nigra) stands

Forestry practices may cause significant changes in soil characteristics as related to their properties and size. Although chemical attributes of the soil respond to the applications in the mid- or long-term while changes in soil respiration can react rapidly to forestry practices. Therefore, determining changes in soil attributes is needed to identify how the management practices would affect forest ecosystem function. Although there is much information on the effect of thinning practices on tree growth, there is a lack of knowledge on the impacts of pre-commercial thinning on soil properties, especially soil respiration. We aimed to determine pre-commercial thinning effects on some soil attributes in black pine sites. Four treatments with different intensities were applied to the stands studied. These practices were control (no pre-commercial thinning), 2000 (heavy), 4000 (moderate), and 6000 (light) individuals per hectare left, respectively. Measurements of soil respiration and soil temperature were carried out between 2014 and 2017 in spring, summer, autumn, and winter months. Soil characteristics, including pH, organic matter, nitrogen, and phosphor content, were measured just after and three years after the thinning. As a result, thinning increased soil respiration rate and soil temperature while decreased soil pH values. Results of the study showed that carbon balance in the ecosystem was significantly affected by thinnings, and adjusting the thinning intensity may be an efficient carbon management tool for reducing carbon emission from the soil.

Restoration of woody plant communities in red pine plantations on abandoned agricultural land in northern Minnesota, USA

While tree plantations have increased globally, there is growing interest in restoring plantations to native ecosystems. Restoration efforts may be more successful when tree species native to original ecosystems are planted instead of species that are either introduced or native, but off site.Plantations of red pine (Pinus resinosa Ait.) in the western Great Lakes region of North America were commonly established on red pine sites, often after agricultural clearing and abandonment. Red pine is the only species in the overstory, compared to 10 or more species in red pine woodlands. Plantations differ in structure from woodlands, being single-aged versus multi-cohort and having high and spatially-uniform density versus lower and variable density.Our aim was to contrast changes in structure and woody species composition over a 15-year period in response to two silvicultural approaches in red pine plantations on the Red Lake Wildlife Management Area in northwestern Minnesota, USA. Approaches included: 1) uniform thinning followed by a dispersed retention harvest (dispersed treatment) and 2) variable density thinning followed by an expanding gap irregular shelterwood (aggregated treatment).Basal area of trees ≥10 cm dbh was reduced similarly in both treatments to 9 m2 ha−1, but there was high within-stand variability (coefficient of variation) in the aggregated treatment (>100%) compared to the dispersed treatment (20%). Understory woody species abundance increased with both treatments, including sapling, large regeneration, and small regeneration layers, with >100% increases. In the sapling layer, the increased abundance (to 2.5 m2 ha−1) reflected new recruitment into this layer, as there were few saplings before treatment (<0.5 m2 ha−1). By year 15, the majority of saplings were canopy capable species, while lower regeneration layers contained mixtures of canopy trees, sub-canopy trees, and shrubs.Composition in the understory changed, but was similar between treatments, including increases in woody shrubs in the small regeneration layer and increases in red pine regeneration in the large regeneration layer. The sapling layer had increased importance of several native tree species, especially in the aggregated treatment.Both of our silvicultural approaches moved structurally simple, species poor red pine plantations toward a condition reflecting native red pine woodlands, which had mixed-species composition and variably open canopy cover. The treatment using variable density thinning and an irregular shelterwood resulted in greater spatial variability of structure and greater importance of shade-intolerant tree species, both characteristics of native woodlands. While focused on red pine, this approach should have application to conifer restoration more generally.

Components explain, but do eddy fluxes constrain? Carbon budget of a nitrogen-fertilized boreal Scots pine forest.

Nitrogen (N) fertilization increases biomass and soil organic carbon (SOC) accumulation in boreal pine forests, but the underlying mechanisms remain uncertain. At two Scots pine sites, one undergoing annual N fertilization and the other a reference, we sought to explain these responses. We measured component fluxes, including biomass production, SOC accumulation, and respiration, and summed them into carbon budgets. We compared the resulting summations to ecosystem fluxes measured by eddy covariance. N fertilization increased most component fluxes (P < 0.05), especially SOC accumulation (20×). Only fine-root, mycorrhiza, and exudate production decreased, by 237 (SD = 28) g C m-2 yr-1 . Stemwood production increases were ascribed to this partitioning shift, gross primary production (GPP), and carbon-use efficiency, in that order. The methods agreed in their estimates of GPP in both stands (P > 0.05), but the components detected an increase in net ecosystem production (NEP) (190 (54) g C m-2 yr-1 ; P < 0.01) that eddy covariance did not (19 (62) g C m-2 yr-1 ; ns). The pairing of plots, the simplicity of the sites, and the strength of response provide a compelling description of N effects on the C budget. However, the disagreement between methods calls for further paired tests of N fertilization effects in simple forest ecosystems.

Harvest Intensity Impacts Nutrient Status and Young Stand Development in Latvian Hemiboreal Forest

This study aimed to compare the effects of whole-tree and stem-only harvesting in hemiboreal forests in Latvia. Chemistry of soil solution, precipitation, litter and needles, as well as tree parameters in regenerated stands were measured from 2012 to 2021 in oligotrophic and mesotrophic Scots pine sites with mineral soils and a eutrophic Norway spruce site with drained peat soil. Compared to the undisturbed control, the soil solution pH was significantly lower and N-NO3− and K+ concentrations were significantly higher after stem-only harvesting at the oligotrophic site, stem-only and whole-tree harvesting at the mesotrophic site and whole-tree harvesting at the eutrophic site. The height growth of the regenerated stands in all sites was similar for both harvesting methods six years after planting. More slender trees were observed after whole-tree harvesting than after stem-only harvesting at the eutrophic site. Whole-tree harvesting produced significant negative short-term effects on height growth in the oligotrophic site four to six years after harvest. The nutrient levels of needles differed with harvest intensity but did not indicate insufficient nutrient availability with any type of harvesting.

Initiating the transition from open-canopy lichen woodland to productive forest by transplanting moss, results from a 10-year experiment

Background and aimsLow productivity open lichen (Cladonia spp.) woodlands have been rapidly expanding in the closed-crown feather moss (Pleurozium schreberi (Brid.) Mitt.) boreal forest of eastern Canada. While open-woodland areas are progressing, there is little information on the recoverability of open lichen woodlands back to closed-canopy forests.MethodsAn experimental set-up using moss transplantation was installed on a poor jack pine (Pinus banksiana Lamb.) stand with a lichen ground cover in 2011. Treatments included: 1) lichen cover removed, 2) lichen cover removed and transplantation of a feather moss cover, 3) lichen control, and 4) a natural jack pine site with feather moss cover (moss control). We extracted tree stem increment cores and collected needles and soil samples for nutrient analysis.ResultsThe transplanted-moss treatment can counteract the adverse effects of lichen on jack pine growth. This treatment enhanced foliar nutrition and soil nutrients, especially ammonium (N-NH4+) and nitrate (N-NO3−). With this treatment, the soil conditions (e.g., soil nutrients, soil moisture) and foliar nutrition were closer to that of moss control. Surprisingly, lichen removal treatment did not improve growth and resulted in poorer jack pine growth and harsher soil conditions.ConclusionFeather moss can establish, survive, and remain healthy in an environment previously occupied by lichen. The replacement of lichen by feather moss establishes soil conditions that appear conducive to better tree growth and have the potential of restoring the productivity of boreal forests in open-canopy lichen woodlands.