Effects of stand features and soil enzyme activity on spontaneous pedunculate oak regeneration in Scots pine dominated stands – implication for forest management

Background:A challenge in current forestry is adaptation of managed forests to climate change,which is likely to alter the main processes of forest dynamics,i.e.natural regeneration.Scots pine will probably lose some parts of its distribution area in Europe.However,two native oaks,pedunculate and sessile may maintain or expand the area of their occurrence in central Europe.The utilization of spontaneous(not initialized by foresters)oak regeneration in Scots pine stands for the creation of next generation stands is one of the adaptation methods to climate change.Many factors influencing pedunculate oak regeneration are well known,but there is a lack of knowledge on the relation between soil enzyme activity and the establishment and development of the species.The aim of the study was to identify the relationships among stand characteristics,herb species composition,soil enzyme activity and the establishment or recruitment of oak regeneration in Scots pine-dominated stands.Results:The one of the most influential factors shaping the oak seedling count was dehydrogenase activity in the humus horizon.We found that plots without litter and fern cover had higher seedling density.The raspberry ground cover and birch crown projection area had a positive influence on oak seedling number.The factor indicating good conditions for high density of oak saplings was phosphatase activity in the organic horizon.The same enzyme activity but in humus horizon described conditions in which more numerous recruits were observed.Conclusions:The activity of soil enzymes can be used as the predictor of the establishment and advancement of oak regeneration but also could be seen as a new dimension of oak regeneration.The general density of spontaneous oak regeneration was not sufficient for the creation of new generation forest stands dominated by oak,but it is possible to use them as admixtures in new generation stands.

Changes in the growth of Scots pine(Pinus sylvestris L.)stands in an urban environment in European Russia since 1862

A century and a half ago,in the European part of Russia(Moscow),forest scientists established the first long-term observations of forests,many of which are under observation to the present day.In the twentieth century,climate changes and,due to industrial development,forest areas were under air pollution.Based on observations from 157 sites,this study shows that the growth and density of Scots pine(Pinus sylvestris L.)have decreased by the end of the twentieth century.The environment has changed,and the growth and development of plantations has slowed.Pine yields(-34%stand volume)and their life expectancy(on average 50 years)have decreased.These changes are critical for forestry and for the management of forests in urban centers.Due to the decline in growth,ecosystem functions by urban forests has decreased.In order to increase the sustainability of urban forests and the provision of ecosystem services,it is preferable to create multi-species stands with a complex structure.

Ice storm damage to oak forests in subtropical China

Ice storms,as important sources of frequent and injurious disturbances,drive forest dynamics in the Northern Hemisphere.However,stand-level differential vulnerability to ice storms and the associated factors that predispose forest stands remain unclear.This is particularly concerning in the subtropics where the frequency of ice storms is predicted to increase with global warming.Here we assessed how the impact on three forest stands(early and late secondary-growth forests,and old-growth forests)differed after an extreme ice storm during 20–21 March 2022,and identified the abiotic and biotic factors that determine the damage intensity in the Shennongjia World Natural Heritage Site,a biodiversity conservation hotspot in central China.We found a stand-specific‘middomain effect’where the late secondary-growth forest sustained the most severe damage,the early secondarygrowth forest sustained the least,and the old-growth forest suffered an intermediate amount.‘Crown broken’was the most severe damage type across all three forest stands,although the proportion of‘branch broken’was also high in the old-growth forest.Topography played a significant role in determining the vulnerability of the early secondary-growth forest to severe ice storms whereas the forest structure and composition were important factors in explaining the damage rates in the old-growth forest,although they differed among the damage categories.In contrast,topography,forest structure and composition generally explain the intensity of damage in the late secondary-growth forests.Our results highlight that,in subtropical forests,the intensity of damage caused by severe ice storms and related determining factors are stand-level dependent.We also suggest exploring potential management strategies(e.g.,slow-growing hardwood species that can resist storms should be the main species for reforestation in early secondary-growth forests)to mitigate the risk of future severe ice storms,as well as other wind-related climatic extremes.

Comparative analysis of thinning techniques in pine forests

Thinning is a necessary and complex forestry activity.The complexity increases due to theoretical disagreements,contradictory recommendations,and errors of modern practice,which require confirmation through longtime experiments.This article presents a summary of experimental results from plantations established 20–30 years ago and explains concepts of the theory,methods,and regime of thinning in permanent sample plots of pine stands in Gatchinsky forest of the Leningrad region.The research results allow for the clarification of growth patterns and age dynamics of pine stands subject to heavy,low thinning,as well as the results of applying the crown(high)thinning technique and a mixed treatment.A combined thinning and fertilization could improve wood quality and yield compared to conventional methods.Of particular scientific importance is the analysis of change in tree diameter classes during growth and after thinning.The research results allow for optimizing the treatment regime in pine plantations and reducing labor intensity by increasing the intensity of thinning and reducing the number of techniques.

Planted forest is catching up with natural forest in China in terms of carbon density and carbon storage

Over the last several decades,China has taken multiple measures for afforestation and natural forest protection,including setting the goal of carbon neutrality by the middle of 21th century.In order to support the practice of relevant policies from the scientific perspective,it is essential to precisely estimate the carbon storage of arbor forest,as it plays an important role in the carbon cycle of ecosystems.In this study,we first used the latest four phases of national forest inventory data to investigate the variation of carbon storage for both natural and planted arbor forest in China during the covered period(1999-2018).Then we used machine leaning methods to simulate the carbon density based on various kinds of environmental factors and analyzed the contribution of each influencing factor.Our results demonstrate that the total carbon storage for arbor forest in China kept increasing over the last two decades,but this increment was mainly brought about by the continuous expansion of forest land.The gap of carbon sequestration between natural forest and planted forest showed a significant trend of reduction.Additionally,tree age was identified as the dominant factor for influencing the spatiotemporal variation of carbon density among all the independent variables while the impact of climatic factor was limited.Therefore,the future improvement of carbon sequestration of arbor forest in should mainly rely on additional projects of afforestation,reforestation,green space conservation and reduction of emissions in China.Conclusions of this study have important implications for policy makers and other stakeholders to evaluate the previous achievement of environmental projects and can also help to set future plans and finally realize the goals of carbon neutrality.