In the context of climate change, it is necessary to establish forest management by balancing more products, using less area, and minimizing environmental impacts. The use of different industrial bio-based by-products as soil conditioners in the last few decades has gain more interest, because it leads to an extended use time of these products and supports the circular economy. The aim of this study was to determine the effect of fertiliser made from cattle and pig manure biogas fermentation digestate and wood ash from two cogeneration plants, applied in different mixture ratios, to test its suitability for fertilisation of deciduous trees, using the physiological, morphological, and chemical parameters of the leaves as an indicator. We selected two poplar clones: foreign ‘OP42’ (syn. Hybrid 275) and local ‘AUCE’ annual shoot stem cuttings as planting materials. A negative control group with acidic forest mineral soil as substrate and four fertilised groups with different applied digestate and wood ash ratio mixtures to forest soil was established (ash:digestate 0:0 (Control), 1:1, 2:1, 3:1, 4:1). Mixture application improved growing conditions because all fertilised group poplars had longer growth periods and photosynthetic rates in August than the control group. Both local and foreign clones showed a good response to fertilisation in terms of leaf parameters. Poplar is a suitable culture to fertilise with bio-waste biogenic products, because of its capacity to absorb nutrients and fast response to fertilisation.

This study examines the spatial root development patterns of bareroot, containerized, and plug plus (plug+) saplings in hemiboreal forests of Latvia, focusing on the effects of two common soil preparation methods: mounding and disc trenching. In northern Europe, forest regeneration after clearcutting often involves planting, with soil preparation aimed at enhancing sapling survival and productivity. This study included four tree species: Pinus sylvestris, Picea abies, Betula pendula, and Alnus glutinosa. The results reveal that saplings planted in mounded sites developed more radially symmetrical root systems, while roots in trenched sites predominantly grew parallel to the furrow. This spatial root distribution was consistent across all forest types and did not show significant variation between stock types (containerized, bareroot, or plug+) or treatments (control or fertilized). Additionally, the number of main roots did not differ significantly between the soil preparation methods. These findings align with previous research and raise important questions regarding the impact of early root architecture on stand resilience at a mature stage, particularly in relation to windthrow, heavy snowfall, drought, and flooding resistance. The study underscores the need to consider root system development as a key factor in forest management practices aimed at ensuring long-term forest stability.

Short-rotation forest plantations on former agricultural land capture CO₂, provide bioeconomic materials, and mitigate climate change. This study aimed to enhance our understanding of the long-term effects of wood ash and wastewater sludge fertilization on various tree species (birch, hybrid aspen, grey alder, black alder, and hybrid alder) in short-rotation forestry plantations on abandoned agricultural land where tree growth measurements were taken over an 11-year period. After 11 years, the highest aboveground biomass (AGB) was observed for hybrid aspen clone No. 4 under wastewater sludge treatment (109.0 t ha⁻¹), birch under wood ash treatment (34.3 t ha⁻¹), black alder under wastewater sludge treatment (33.6 t ha⁻¹), grey alder under wastewater sludge treatment (40.9 t ha⁻¹), hybrid alder under control conditions (36.2 t ha⁻¹), and hybrid aspen clone No. 28 under wood ash treatment (37.2 t ha⁻¹). The average survival rate was 73% in control plots, 81% under wastewater sludge treatment, and 78% under wood ash treatment. Short-term positive impacts on tree growth were observed, effects that were not consistent over the long term. The impact of these treatments on tree growth varied between species, and the effects tended to diminish over time, which must be considered before fertilization.

Striving for climate neutrality and wider implementation of climate change mitigation measures including tree introduction in agricultural land, request for approaches and general allometric models for estimating carbon (C) stock in tree above-ground biomass (AGB) based on relatively easily obtainable remote sensing data is increasing. Here, we present estimates of individual trees’ crown diameters (CDs) for Betula pendula Roth (B. pendula) and Populus tremuloides Michx. × Populus tremula L. (P. tremuloides × P. tremula) in 11-year-old tree plantations (tree height ranged up to 12.8 and 18.1 m, respectively) in the hemiboreal region of Europe (in Latvia). Individual trees’ CDs were measured using a drone orthophoto map. Afterwards, linear equations were developed to predict individual trees’ stem diameters at breast height (DBHs) and, consequently, tree AGB (which was then converted to C stock) from remote-sensed tree CD data. RMSEs of the prediction models of tree stem DBH were in the ranges of 1.87–2.12 cm for B. pendula and 2.50–3.12 cm for P. tremuloides × P. tremula. This demonstrated approach is applicable to carry out, for instance, a self-assessment and approximate C stock in the AGB of selected tree species by land owners, managers, and other implementers of climate change mitigation measures.

Key words: forest regeneration, Conniflex, Trico, mechanical site preparationForest regeneration is crucial stage in commercial forest management because actions during this stage impact future forest productivity and value. Scots pine is one of the main tree species in forestry of the northern part of Europe. Foresters have to overcome different risk factors during regeneration process and two of them are seedling damage by Pine weevil (Hylobius abietis L) and browsing by herbivores of Cervidae family. Pine weevil is one of the main forest pests in Europe that damage regenerated coniferous stands. Damage caused by this pest can produce 70% mortality of planted seedlings. Another significant risk factor is browsing. With increase of deer (Cervidae) population the damaged forest area also increases to the extent that foresters choose other tree species for regeneration. The mitigation of these risks is possible with appliance of forest management practices.  There are used different repelents against Cervidae animals.  Regarding Pine weevil, due to restrictions on insecticide use in EU, different protective coating materials have been developed, and several studies show that soil preparation before planting reduce amount of damaged Pine seedlings and increase possibility of successful regeneration.  We evaluated if and how forest management methods - soil preparation techniques (spot mounding, disc trenching) in combination with different plant protection products (Conniflex, Trico) - affects the degree of damage caused by pine weevil and Cervidae animals to Scots pine seedlings one and two years after outplanting in four forest stands in Latvia. The results from this study shows that application of Conniflex reduce number of damaged trees by 16.8% first and 20.3% second year after outplanting compared to untreated seedlings. Soil preparation has significant impact on reduction of pine weevil damage. The best results have been achieved by planting with Conniflex treated seedlings on spot mounds (2.4% damaged trees compared to 48.9% in unprepared soil without treatment). Repellent Trico do not provide additional protection against Pine weevil and do not have long term protection effect against browsing. Overall conclusion is that combination of soil preparation and use of appropriate coating material (Conniflex) can provide sufficient protection without usage of insecticides, and Trico has to be applied before winter season to achieve effect of protection.

Briežu vajadzības saduras ar mežsaimniecības interesēm, it sevišķi meža atjaunošanā, jo ziemošanas periodā briežu dzimtas dzīvnieku barības bāzē egle un priede ir būtiska sastāvdaļa