Scientists recommend using larch in multi-phase forest regeneration on calamity clearings
Following the bark beetle crisis from 2017 to 2023, restoring approximately 60,000 hectares of forest remains essential. Research and practical experience in restoring areas affected by calamities have consistently shown that a multi-phase approach to forest regeneration is effective for large open spaces.
Photo: Preparatory larch stand for two-phase regeneration; FGMRI archive
Using various “preparatory” tree species to quickly restore forest environments in clearings offers biological, production, and economic advantages. One such tree species that can thrive in a relatively wide range of habitat conditions is the European larch.
The preparatory stand is designed to quickly establish a canopy, which will help mitigate the climate extremes often found in bare areas. It reduces direct sunlight and temperature fluctuations, lowers wind speed, and limits weed competition. Additionally, it helps maintain or improve the upper soil layers, regulate the water regime, and promote rooting. This stand also reduces the risk of soil erosion and adjusts the physical and chemical conditions of the soil. Furthermore, weed control through shading lessens the habitat’s appeal to mouse-like rodents.
Photo: Artificially established preparatory larch stand for two-phase renewal (7 years after planting); FGMRI archive
Historically, the use of European larch as a preparatory forest tree species was not widely accepted. However, attitudes toward larch are changing. Recent experiences from pollution-affected areas and specific locations established in the last decade demonstrate its high potential for use as a preparatory tree species.
Today, European larch is considered one of the most promising options for creating preparatory stands as part of two-phase forest regeneration. Its ability to promote good natural regeneration and rapid regrowth in large calamity clearings further supports its value in this context.
Scientists from the Opočno Research Station, VÚLHM, v. v. i., working on the NAZV project QK21010335 titled “Possibilities of using European larch in Czech forests under the impact of global climate change” (Možnosti využití modřínu opadavého v českých lesích pod dopadem globální klimatické změny) have developed a certified methodology Využití přípravných porostů modřínu při vícefázové obnově kalamitních holin (The use of larch preparatory stands during the two-phase regeneration of calamity clearings).
The methodology outlines silviculture practices involving larch as a component of the tree species composition for restoring areas affected by calamities. European larch can be a suitable tree species for various stages of regeneration, depending on the ecological conditions of specific clearings. By considering the unique characteristics of each habitat and optimising the technical processes for establishing and managing mixed stands with larch, this methodology provides users with an alternative to traditional one-time forest regeneration methods.
Photo: Use of larch in combined regeneration – planting of the future skeleton of stands; FGMRI archive
The positive outcomes of implementing these procedures include improved environmental conditions, reduced costs for the regeneration process, and the subsequent economic benefits of using woody biomass throughout the various stages of developing new forest stands. Ultimately, these strategies can lead to greater differentiation and stabilisation of forest stands on a broader scale.
Utilising preparatory tree species helps mitigate the negative impacts of extreme climatic conditions in clearings, creating more favourable growth environments for the introduction and cultivation of target woody plants. Their incorporation in a two-phase regeneration approach can also enhance the overall productivity and economic sustainability of forestry management.
Preparatory stands enhance the quality parameters of target tree species. Without the protection of these preparatory stands, the quality of the trunk can decline, leading to the formation of thick branches.
European larch is a valuable tree species known for its high-quality wood. Even when silvicultured as a preparatory tree species, it can yield profitable, marketable assortments if the stand training is executed properly.
Photo: Left – natural regeneration of larch at the edge of a calamity clearing (Heraltice Forest Reserve); right – the use of larch as a preparatory tree species in rows mixed with beech; FGMRI archive
Larch is an appropriate choice as a preparatory tree species in natural pine habitats and in exposed, acidic, and nutrient-poor locations, spanning a wide range of altitudes from lowlands to mountainous areas. However, in glued habitats, larch is less suitable as a primary preparatory tree species. It can still be used as a mixed or scattered species, depending on the specific ecological conditions of the site. It is important to note that floodplain forests and all waterlogged habitats are completely unsuitable for larch.
When there are significant clearings, one effective approach is to implement combined regeneration in a “new” concept. This involves first conducting artificial regeneration with tree species that thrive well in large open areas and then leveraging the potential for natural regeneration within these established stands.
Combined regeneration is best applied in moderately rich and water-affected sites, provided the terrain conditions are favourable. In such areas, we can expect natural regeneration of species that are suitable for inclusion in the species composition of new forest stands. Using European larch in combined regeneration offers both biological and economic advantages. One of the key benefits of larch is its potential to serve as both a preparatory and target tree species.
Photo: Artificially established preparatory larch stand for two-phase renewal (3 years after planting); FGMRI archive
The procedures outlined in the methodology for forest regeneration in calamity areas will have significant positive impacts on stabilising forests and enhancing their resilience to climate change. Additionally, these procedures will allow the regeneration process to be extended over a longer period, making more effective use of natural processes in areas where the potential for recovery exists.
According to scientists, implementing procedures that use larch in calamity clearings can lead to cost savings in forest regeneration, estimated between 10,000 and 50,000 CZK per hectare. Following the bark beetle calamity, approximately 60,000 hectares of forest still require regeneration. If these procedures are applied to 20% of the affected areas, the annual economic benefit for the forestry sector in the Czech Republic could reach up to 600 million CZK. Furthermore, the costs of regeneration can be distributed over a longer period after the calamity occurs.
The methodology “Using preparatory larch stands in multi-phase regeneration of calamity clearings” (Využití přípravných porostů modřínu při vícefázové obnově kalamitních holin) can be downloaded here.
Authors: Ing. Jan Leugner, Ph.D., Ing. Dušan Kacálek, Ph.D., Mgr. Nikola Švorc Štěpánová; Research Station Opočno, VÚLHM, v. v. i., Strnady, e-mail: leugner@vulhmop.cz
Prepared based on the original by Ing. Jan Řezáč, VÚLHM, v. v. i., e-mail: rezac@vulhm.cz