Long-Term Nitrogen and Phosphorus Dynamics in Waters Discharging from Forestry-Drained and Undrained Boreal Peatlands

Contradictory results for the long-term evolution of nitrogen and phosphorus concentrations in waters discharging from drained peatland forests need reconciliation. We gathered long-term (10–29 years) water quality data from 29 forested catchments, 18 forestry-drained and 11 undrained peatlands. Trend analysis of the nitrogen and phosphorus concentration data indicated variable trends from clearly decreasing to considerably increasing temporal trends. While the variations in phosphorus concentration trends over time did not correlate with any of our explanatory factors, trends in nitrogen concentrations correlated positively with tree stand volume in the catchments and temperature sum. A positive correlation of increasing nitrogen concentrations with temperature sum raises concerns of the future evolution of nitrogen dynamics under a warming climate. Furthermore, the correlation with tree stand volume is troublesome due to the generally accepted policy to tackle the climate crisis by enhancing tree growth. However, future research is still needed to assess which are the actual processes related to stand volume and temperature sum that contribute to increasing TN concentrations.

Controls of Organic Carbon and Nutrient Export from Unmanaged and Managed Boreal Forested Catchments

Understanding the anthropogenic and natural factors that affect runoff water quality is essential for proper planning of water protection and forest management, particularly in the changing climate. We measured water quality and runoff from 10 unmanaged and 20 managed forested headwater catchments (7–12,149 ha) located in Finland. We used linear mixed effect models to test whether the differences in total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) export and concentrations observed can be explained by catchment characteristics, land use, forest management, soil fertility, tree volume and hydrometeorological variables. Results show that much of variation in TOC, TN and TP concentrations and export was explained by drainage, temperature sum, peatland percentage and the proportion of arable area in the catchment. These models explained 45–63% of variation in concentrations and exports. Mean annual TOC export in unmanaged catchments was 56.4 ± 9.6 kg ha−1 a−1, while in managed it was 79.3 ± 3.3 kg ha−1 a−1. Same values for TN export were 1.43 ± 0.2 kg ha−1 a−1 and 2.31 ± 0.2 kg ha−1 a−1, while TP export was 0.053 ± 0.009 kg ha−1 a−1 and 0.095 ± 0.008 kg ha−1 a−1 for unmanaged and managed, respectively. Corresponding values for concentrations were: TOC 17.7 ± 2.1 mg L−1 and 28.7 ± 1.6 mg L−1, for TN 420 ± 45 µg L−1 and 825 ± 51 µg L−1 and TP 15.3 ± 2.3 µg L−1 and 35.6 ± 3.3 µg L−1. Overall concentrations and exports were significantly higher in managed than in unmanaged catchments. Long term temperature sum had an increasing effect on all concentrations and exports, indicating that climate warming may set new challenges to controlling nutrient loads from catchment areas.

Management legacies and forest structure shape the root rot risk of coniferous forests in Finland

<p>Forest management and land use can strongly alter the forest ecosystem with long-lasting legacy effects by shaping e.g. species composition and age structure in stand and landscape scales. These changes may lead to changes in the local disturbance regime. In addition, forest management may directly affect the dynamics of disturbance agents. Heterobasidion root rot is one of the most important diseases of conifers in the Northern hemisphere. The epidemiology of the fungus relies heavily on the availability of fresh wood material which the spores need to cause an infection. In managed forests, fresh stump surfaces provide massive amounts of perfect growth media.  Once the fungus has infected a stand, the disease remains in there over tree generations slowly deteriorating the timber quality, killing trees and predisposing trees to subsequent disturbance agents such as wind. Thus, host availability in landscape scale, stand conditions and the management history all are assumed to play an important role in the epidemiology. The aim of this study was to analyze the drivers of current distribution of Heterobasidion root rot in Finland in order to understand the disease dynamics better and to manage the disease in the future. Specifically, we asked how important the legacies of different past management and land-use methods are. The National Forest Inventory (NFI) in Finland has recorded root rot observations since 1995 covering in total over 348 000 sample plots over four inventories. We combined that database with 20 different explanatory variables with a hypothetical relation to the biology and epidemiology of the fungus. The variables were categorized to three categories; (i) management legacies, (ii) landscape structure, and (iii) site conditions. Management legacies included for example the historical locations of sawmills and the share of forest pastures. Landscape structure combined structural characteristics, such as Norway spruce and old forest (120+ years) shares from different time periods. Site conditions were described with e.g. temperature sum and Shannon index for tree species richness. By using Boosted Regression Tree and Generalized Liner Models, we found that variables from all the three categories contributed to the presence of Heterobasidion root rot. The distance from an NFI plot to the nearest sawmill operating in 1910 (historical intensity of logging) and the distance to a waterway (timber rafting as main transportation methods) were shown to be one of the most important variables together with temperature sum and current Norway spruce share in landscape scale. This indicates that the management legacies, especially the past management intensity, has a significant effect on the epidemiology of Heterobasidion root rot.</p>

Morphological features of oat (Avena Sativa L.) shoots formation in the southern part of Ukraine

Oats is essential for agricultural production and processing industry due to the unique biochemical composition of its grain. Thus, it is very important to study the biological and morphometric features of oats. The length and area of the plant's organs can establish a degree of comfort of growing conditions and determine during which period of plant's life the external weather conditions changed. Phytomers are basic repetitive functional units of the oat shoot. This paper presents the description and parameters of development of oat shoot metamers, namely, the identification of growth patterns of terrestrial vegetative metamers of oat shoots and their parts. The experiments were conducted in 2013, 2014 and 2018. The weather conditions of the specified years varied greatly – 2013 and 2014 were the most favorable in terms of humidification and precipitation, while 2018 was a very dry one. The paper determines the absolute and relative growth rates of the oat shoot internode paper and the maximum growth rate of each metamer in the linear phase. According to our observations, the absolute growth rate of oats was negligible and increased from 0.01 to 0.5 mm/d when the air temperature varied from 15 °C to 20 °C. However, when the air temperature reached about 20 °C, the absolute growth rate increased from 0.5 mm/d to almost 2 mm/d. We also found the effective sum temperatures under which the beginning and the end of the growth of each internodes take place. Thus, the first internode starts to grow the effective temperature sum of up to 117 °C is with the accumulated while the panicle starts growing when the effective temperature sum of up to 668 °C is accumulated. The growth of both the seventh internode and the panicle stops at the same time when the effective temperature sum of up to 1173 °C is accumulated. The ontogeny of oat shoots has a regular sequence of growth and development of terrestrial vegetative shoot metamers and their parts. The average growth duration of oat stem internode duting the years of research constituted 9 days for the first internode, 30 days for the seventh internode and 26 days for the panicle .

Analyzing ingrowth using zero-inflated negative binomial models

Ingrowth is an important element of stand dynamics in several silvicultural systems, especially in continuous cover forestry. Earlier predictive models for ingrowth in Finnish forests are few and not based on up-to-date statistical methods. Ingrowth is here defined as the number of trees over 1.3 m entering a plot. This study developed new ingrowth models for Scots pine ( L.), (Picea abies (L.) H. Karst.) and birch ( Roth and Ehrh.) using data from the permanent sample plots of the Finnish national forest inventory. The data were over-dispersed compared to a Poisson process and had many zeros. Therefore, a zero-inflated negative binomial model was used. The total and species-specific stand basal areas, temperature sum and fertility class were used as predictors in the ingrowth models. Both fixed-effects and mixed-effects models were fitted. The mixed-effects model versions included random plot effects. The mixed-effects models had larger likelihoods but provided biased predictions. Also censored prediction was considered where only a certain maximum number of ingrowth trees were accepted for a plot. The models predicted most pine ingrowth in pine-dominated stands on sub-xeric and xeric sites where stand basal area was low. The predicted amount of spruce ingrowth was maximized when the basal area of spruce was 13 m ha. Increasing temperature sum increased spruce ingrowth. Predicted birch ingrowth decreased with increasing stand basal area and towards low fertility classes. An admixture of pine increased the predicted amount of spruce ingrowth.Pinus sylvestrisNorway spruceBetula pendulaB. pubescens2–1

Influence of mechanical site preparation on regeneration success of planted conifers in clearcuts in Fennoscandia – a review

In the Nordic countries Finland, Norway and Sweden, the most common regeneration method is planting after clearcutting and, often, mechanical site preparation (MSP). The main focus of this study is to review quantitative effects that have been reported for the five main MSP methods in terms of survival and growth of manually planted coniferous seedlings of Norway spruce ( (L.) Karst.), Scots pine ( L.) and lodgepole pine ( var. Engelm.) in clearcuts in these three countries. Meta analyses are used to compare the effects of MSP methods to control areas where there was no MSP and identify any relationships with temperature sum and number of years after planting. In addition, the area of disturbed soil surface and the emergence of naturally regenerated seedlings are evaluated. The MSP methods considered are patch scarification, disc trenching, mounding, soil inversion and ploughing. Studies performed at sites with predominately mineral soils (with an organic topsoil no thicker than 0.30 m), in boreal, nemo-boreal and nemoral vegetation zones in the three Fenno-Scandinavian countries are included in the review. Data from 26 experimental and five survey studies in total were compiled and evaluated. The results show that survival rates of planted conifers at sites where seedlings are not strongly affected by pine weevil ( L.) are generally 80–90% after MSP, and 15–20 percent units higher than after planting in non-prepared sites. The experimental data indicated that soil inversion and potentially ploughing (few studies) give marginally greater rates than the other methods in this respect. The effects of MSP on survival seem to be independent of the temperature sum. Below 800 degree days, however, the reported survival rates are more variable. MSP generally results in trees 10–25% taller 10–15 years after planting compared to no MSP. The strength of the growth effect appears to be inversely related to the temperature sum. The compiled data may assist in the design, evaluation and comparison of possible regeneration chains, i.e. analyses of the efficiency and cost-effectiveness of multiple combinations of reforestation measures.Picea abiesPinus sylvestrisPinus contortalatifoliaHylobius abietis