Temperate Forest Zone Research Articles

Insight into the variation of soil hydraulic properties under beech and spruce forest—A case study in the forest of Tharandt, NE Germany

AbstractBackgroundThe increasing vulnerability of forests in the temperate zone due to climate change has led to modification in the forest structure to secure woody raw materials and ecosystem benefits. Such changes will influence hydrological processes both at the stand and catchment scale. Soil hydraulic properties (SHP) play an important role in assessing the water cycle in these ecosystems. Yet, knowledge regarding the effect of forest‐ and site‐specific conditions on SHP in temperate climates is scarce.AimsThis work addresses this research gap by assessing the variation of SHP under two common European forest stands, Fagus sylvatica and Picea abies (1) with comparable site conditions, and (2) across differing site conditions.MethodsWe determined the soil water retention curve (WRC) and the hydraulic conductivity curve (HCC) in several plots with the bimodal Kosugi–Mualem's hydraulic model. These functions were determined using combined field and laboratory measurements, including hydraulic conductivity and water content from soil samples.Results(1) We observed distinct variations in SHP between beech and spruce forest stands with comparable site conditions; however, no clear pattern in the variation was discernible. (2) A noticeable effect of the site‐specific characteristics on the SHP was detected. Moreover, SHP in each analysed forest type presented individual variations.ConclusionsThis study demonstrates that SHP present a wide range of variations in terms of both forest‐ and site‐specific conditions. Hence, due to its heterogeneity, we emphasise the need for more research to better characterise SHP in temperate zone forests. Moreover, this study underlines the urgent use of a minimum set of parameters in studies when addressing SHP (e.g., tree age, soil texture).

DISPERAL OF THE LILIACEAE REPRESENTATIVES IN RELATION TO THE STRUCTURE OF THEIR REPRODUCTIVE ORGANS

The Liliaceae family is a terminal one in the order Liliales sensu APG IV (2016) and consists of 15 genera with more than 700 species. The family’s geographical range covers most of the Northern hemisphere and extends through several natural zones, from forest tundra (Gagea species) to tropical forests (Tricyrtis imeldae Guthnick), within three continents, i. e. Eurasia, North America and Africa. Most Liliaceous genera occur both in Eurasia and North America. Representatives of Liliaceae develop coenocarpous fleshly indehiscent berries or dry dehiscent capsules. In most cases, multi-seeded berries themselves are a diaspore, whereas in the case of capsules, the seeds are normally a diaspora. The capsules play a vital role in seed dispersal. Structural adaptations of fruits allowed representatives of Liliaceae to spread into the territories that make up the modern range of the family.The aim of the study is to determine the principal patterns of fruit development for the representatives of Liliaceae with different types of dissemination. The study is based on the investigation of morphological and anatomical structure of fruits which is related to geography, ecology and biology of the Liliaceae taxa dissemination.The study has revealed that the wind is the most typical and widespread agent of dissemination for the investigated representatives of Liliaceae. The specialized capsules responsible for anemochory, i.e. auto-anemochory and anemochionochory (mainly in representatives of the ground cover of deciduous forests in temperate and subtropical climatic zones of the Holarctic Kingdom), are characteristic of representatives of the Lilioideae subfamily. Unlike the capsules supporting the anemochory, which actively participate in dissemination, the primary function of capsules of baromyrmecochorous representatives of Liliaceae is seed production rather than their dispersal, which is reflected in the anatomical structure of the capsules, with numerous intercellular spaces in the pericarp and almost complete lack of its lignification. The endozoochory of fleshly berries of Liliaceae is effective for dispersal by long-distance transport, primarily by birds. Supposedly, the ornitochory prevents dispersal among a large number of ecosystems, which is echoed in the ranges of Clintonia, Prosartes and Streptopus genera, representatives of the ground cover of coniferous and broadleaf forests of the Holarctic Kingdom.

Traces of Local Adaptive Acclimatization Response in the Tracheid Anatomical Traits between Dry and Wet Mesic Norway Spruce (Picea abies) Forests in Moravia, Czech Republic?

Norway spruce (Picea abies) forests in temperate zones are already reacting to short-term extreme summer heatwaves, threatening the vitality of trees and forest productivity, and can even lead to local and regional dieback events. Examining quantitative wood anatomy can provide helpful information in terms of understanding the physiology mechanisms and related responses of conifer trees to local environmental interactions in relation to tracheid adaptive capacity. This study analysed the tracheid functional anatomical traits (FATs) plasticity of six young Norway spruce trees growing in two mesic research plots with high annual precipitation (~43%) and air temperature differences during 2010–2017. The research plots are located in the sub-mountainous (Rájec Němčice) and mountainous (Bílý Kříž) belts of the Moravia region, Czech Republic. Vapour pressure deficit and cell wall reinforcement index (CWRI) were shown to be the most representative environmental parameters as proxies of dry conditions. Tracheid FATs indicated latewood phenological plasticity sensitivity, with more pronounced variability in the warmer and drier plots. Latewood tracheids of Norway spruce trees grown in the RAJ formed significantly thicker cell walls than BK during the studied period. The observed differences between the two research plots indicate additional support for tracheid cells’ hydraulic safety against cavitation and potential traces of adaptive acclimatization response.

Comparative Analysis of Machine Learning-Based Predictive Models for Fine Dead Fuel Moisture of Subtropical Forest in China

The moisture content of fine dead surface fuel in forests is a crucial metric for assessing its combustibility and plays a pivotal role in the early warning, occurrence, and spread of forest fires. Accurate prediction of the moisture content of fine dead fuel on the forest surface is a critical challenge in forest fire management. Previous research on fine surface fuel moisture content has been mainly focused on coniferous forests in cold temperate zones, but there has been less attention given to understanding the fuel moisture dynamics in subtropical forests, which limits the development of regional forest fire warning models. Here, we consider the coupled influence of multiple meteorological, terrain, forest stand, and other characteristic factors on the fine dead fuel moisture content within the subtropical evergreen broadleaved forest region of southern China. The ability of five machine learning algorithms to predict the moisture content of fine dead fuel on the forest surface is assessed, and the key factors affecting the model accuracy are identified. Results show that when a single meteorological factor is used as a forecasting model, its forecasting accuracy is less than that of the combined model with multiple characteristic factors. However, the prediction accuracy of the model is improved after the addition of forest stand factors and terrain factors. The model prediction ability is the best for the combination of all feature factors including meteorology, forest stand, and terrain. The overall prediction accuracy of the model is ordered as follows: random forest > extreme gradient boosting > support vector machine > stepwise linear regression > k-nearest neighbor. Canopy density in forest stand factors, slope position and altitude in terrain factors, and average relative air humidity and light intensity in the previous 15 days are the key meteorological factors affecting the prediction accuracy of fuel moisture content. Our results provide scientific guidance and support for understanding the variability of forest surface fuel moisture content and improved regional forest fire warnings.

Detection of Typical Forest Degradation Patterns: Characteristics and Drivers of Forest Degradation in Northeast China

The accurate identification of forest degradation and its driving factors is a prerequisite for implementing high-quality forest management. However, distinguishing degradation patterns is often neglected in large-scale forest quality assessments. The indicators were constructed to identify typical forest degradation patterns using remote sensing indexes, followed by an analysis of the spatiotemporal dynamics of forest degradation and quantification of the contributions from various driving factors. The results indicated that the constructed indicators could effectively distinguish typical forest degradation patterns, with a fire degradation identification accuracy of 90.0% and a fitting accuracy of drought and pest degradation higher than 0.7. The cold temperate conifer forest zone had the largest proportion of fire degradation, accounting for 67.7% of the area, and totals of 99.0% of the subtropical evergreen broadleaf forest zone and 92.8% of the temperate conifer and broadleaf mixed forest zone were moderately to severely affected by drought, with long-term stability. Additionally, 0.1% of the temperate grassland region and 0.1% of the cold temperate conifer forest zone underwent severe pest infestations, with a long-term stable trend. Meteorological factors were the primary contributors to all typical degradation patterns, accounting for 81.35%, 58.70%, and 82.29%, respectively. The research developed an index for assessing forest degradation and explained the importance of natural and anthropogenic factors in forest degradation. The results are beneficial for the scientific management of forest degradation and for improving forest management efficiency.

How good is TanDEM-X 50 m forest/non-forest map? Product validation using temporally corrected geo-browser supplied imagery through Collect Earth

TanDEM-X Forest/Non-Forest (FNF) map(s) have been one such data focusing on the status of global forest coverage, which has played an essential role in combating climate change. Although the producers have carried out verification and comparison analyses, the need for accuracy assessments in a broader sense creates uncertainties for the users to approve the new data. For this purpose, TanDEM-X 50 m FNF maps were exclusively examined visually through 66,000 test grids within 30 geocells selected from temperate, boreal, and tropical forest zones. Thus, it was aimed to provide product accuracy utilizing visual inspections to the end users of TanDEM-X FNF maps. In addition, Collect Earth (CE) software was used to evaluate the dataset visually, and its advantages or disadvantages were compared with similarly designed studies. Consequently, even though the producers’ data sets were found to have an accuracy of around 85%, it was observed that there were some issues, especially in the definition of the “non-forest” class. CE software was found to be helpful in such studies. However, the dependence of the analyses on geo-browser supplied imagery had some limitations in estimating the accuracy of a new dataset.

The Fine Root Distribution and Morphology of Mature White Poplar in Natural Temperate Riverside Forests under Periodically Flooded or Dry Hydrological Conditions

Fine roots are a key component of carbon turnover in the terrestrial environment. Therefore, their distribution allows for the estimation of areas of carbon in the soil. The vertical distribution of roots is the result of both the tree species and various environmental factors. Research on the architecture of root systems most often includes seedlings and young trees growing under experimental conditions; however, little is known about trees in their natural habitats. The aim of this study is to analyze the fine root distribution of mature white poplar trees in natural riverside temperate zone forests of Central Europe (Poland) periodically flooded and in dry hydrological conditions. The length, diameter, and area of the fine roots, as well as the specific root length (SRL) and specific root area (SRA) of white poplar were measured in three layers of the soil, 0–10 cm, 10–20 cm, and 20–30 cm depths, in three forest sites. Two of the sites experience periodic floods, and one has been without flooding for 80 years, due to the construction of a flood embankment. The highest values of the lengths and surface areas of the poplar fine roots were observed at a depth of 0–10 cm at all sites. Soil moisture was positively correlated with the analyzed root parameters. The presence of understory plant roots contributed to the reduction in the fine root length of poplar in the subsurface layer, compared to the site that was not affected by the presence of plants other than poplar. The distribution of fine roots, the most dynamic part of the plant root system, reflects the most active areas in the soil profile. The presented research will allow for a better understanding of the functioning of natural riverside ecosystems, as well as show the great adaptability of white poplar fine roots to various conditions in the soil.

Vegetation and biotopes of the regional botanical natural monument «Kashtak Pine Forest» (Sosnovskiy District of Chelyabinsk Oblast)

The vegetation and biotopes of the regional botanical natural monument Kashtak Pine Forest have been characterized in this paper. By multivariate statistics and a dominant approach 13 pine and birch-pine plant associations have been identified. But in most cases the associations are detected by dominance or co-dominance of Fragaria vesca L. in the herbage in spite of high biodiversity. The difference of associations is identified by shrub species dominance mainly. The biotopes of the regional botanical natural monument Kashtak Pine Forest are not characterized by principal abiotic factors of high variation while the differences are determined by coenotic factors. The classification of Kashtak Pine Forest biotopes is identified by soil acidity and soil nitrogen regimes in the first place. For Kashtak Pine Forest three ordination axes have been detected: 1) boreal pine forests of Boreal zone, 2) temperate pine and birch-pine forests of Temperate Forest and Forest-Steppe zones and 3) axe of soil moistening and cryoregime. Three coenotic series have also been detected: hydrosere of Fragaria vesca associations and two trophoseries of boreal pine forests of Boreal zone. These series form an integrated biotopical sere and succession of South-Urals pine forests from temperate forest-steppe pine forests to boreal pine forests of Boreal zone.

First record of the swallowtail moth Epiplema adamantina Inoue, 1998 (Lepidoptera: Uraniidae: Epipleminae) from western Himalaya, India

This record of Epiplema adamantina Inoue, 1998 from Mussoorie is the first confirmed record of this species from the Western Himalaya outside Nepal, which is ~800kmwest from vill. Bagmati, Mt. Phoolchauki in Eastern Nepal, the nearest known site record of this species. The species prefers ‘Monsoon season’ as its flight period in ‘Moist temperate oak forest zone’ of Western and Central Himalayas. The paper discusses distinguishing features of E. adamantina with its congeners E. morataria and E. arcuata found in the same region.

The Effects of Different Management Methods on Restored Grasslands in Potential Temperate Forest Zones

The European temperate forest zone has great importance, in terms of maintaining the habitats of not only forests but also anthropogenous grasslands, which were formed as a result of habitat reconstruction. These habitats have great importance, by means of nature conservation, landscape use, economy, and forest and grassland use. The mosaic-like habitat complexes that consist of these grasslands and forest patches help to increase biodiversity and supply the habitat for forest game. In this survey, changes in the vegetation of the temperate forests (Fagetum) of the Mátra Mountains of Hungary were investigated after reconstruction. In 2012, shrub cutting was carried out in the area of Parádóhuta, and then three different management methods (abandoning, mowing, and grazing) were utilized. Our goals were the following: to perform a vegetation survey of the sample areas (i); surveying the natural regeneration of the grassland and analyzing its biodiversity, nature conservation, and economical value (ii); and analyzing the vegetation in terms of nature conservation and valuing its life form spectrum, economy values, and livestock-feeding ability (iii). According to our results, systematic mowing and a less-intensive grazing had a significantly positive effect on biodiversity and the coverage of species, thus increasing the naturalness of the studied grassland habitats, while wild game were able to act as ecological engineers.

Bioecofunge-C preparation impact on growth and development of pine planting material (Pinus sylvestris L.)

Pine plantations drying has been observed during the last decade. Mass drying occurs in the temperate climate zone forests. Scots pine has been signifcantly weakened in recent years, which may further result in a change in the type of forests in Zhytomyr Polissia. This article covers the issue of growing Scots pine seedlings treated with Bioecofunge-C. A study of the biological preparation effect on the germination and growth of Scots pine seedlings in the conditions of Zhytomyr Polissia was conducted. It was proved that the germination energy of Scots pine seeds was signifcantly higher in the areas where Bioecofunge-C was applied compared to the control and amounted to 95 %. An average increase in the height of the seedlings by 34.2 % and root length by 34.9 % was noted during the cultivation of one-year-old Scots pine seedlings in the forest nursery of the Korbutiv Forestry, where the seeds were treated with the preparate. Scots pine seedlings were treated (root dosing) during the growth and development of Scots pine seedlings. The obtained results showed positive dynamics in terms of height in comparison with the control treated with water. The preparate use is promising for obtaining high-quality planting material since the treatment with Bioecofunge-C ensure the preservation, obtaining high-quality planting material and the yield of seedlings. It has been established that obtaining high-quality planting material is one of the most important components of the technologies for growing tree and shrub plants at forestry enterprises of Ukraine. However, obtaining and high-quality planting material resistant to adverse factors requires improvement of existing or development of new measures and methods. It has been proven that the artifcial restoration of the Zhytomyr Polissia forests depends on the cultivation of high-quality planting material. Key words: forest plantations, height, growth technology, planting material, seeds, growth, Zhytomyr Polissia.

Ecological and coenotic groups of Southern Trans-Urals vascular plants flora and biotopes phytoindication

The expert and statistical assessment of ecological and coenotic groups of Southern Trans-Urals vascular plants flora has been done for A.L. Belgards coenomorphs scheme and scheme of vascular plants flora of temperate forest zone of European Russia. Both suggested schemes of groups give adequate and similar assessment of biotopes. The proposed groups of vascular plants flora are identified in phytometer scales space definitely and can be used for regional assessment of biotopes. The best assessment of ecological flora of region is realized by combined coenomorphs and coenotic group schemes approach at the same time. The authors have established regimes of principal ecological factors that identified differentiation flora by coenotic groups and ultimate for specific groups forming in Southern Trans-Urals habitats. Sylvant coenomorph has been formed by boreal (acidic soils phytometers) and nemoral sciophytes and heliosciophytes, moreover a nemoral group must be understood as a group of shady forests on rich soils. The sylvant pine forest group is heterogeneous and not coenoticaly specific. The steppe coenotic group has been formed of obligate and facultative heliophytes of mostly dry biotopes, pratal coenomorph is heterogeneous and not coenoticaly specific and made up of humidity-meadow flora, dry-meadow coenotic group is not specific. For Southern Trans-Urals region it is recommended to use unite paludal coenomorphs but with a separation of coenotic group of oligotrophic bogs. The separation of ruderal coenomorph (phytometers of dry-meadow moistening and rich of nitrogen soils) is confirmed statistically. The authors have established regimes of principal ecological factors for stenotopic ecological and coenotic groups of Southern Trans-Urals region. For coenotic groups of Southern Trans-Urals region the authors have identified biotopical centres and biotopic and coenotic series which are associated with moistening, aeration and saline soil conditions and brightness regime.

Factors affecting winter damage and recovery of newly planted Norway spruce seedlings in boreal forests

In boreal and temperate forest zones, snowless winters and springs with varying temperature conditions are becoming more common with climate change. In the spring of 2020, extensive winter damage in Norway spruce (Picea abies (L.) Karst.) seedlings, which had been planted the previous year in Central Finland, was observed. In most cases, the probable reason was winter desiccation. This provided a good opportunity to study the regeneration site, seedling, and weather factors that affect winter damage and the recovery of seedlings from damage. In the study, systematic plot sampling was done in 60 selected regeneration sites where damage was known to have occurred. The prediction models for the probabilities of winter damage and the recovery of seedlings were fit to the data. The risk of winter damage was higher in seedlings packed in a closed package than in seedlings stored in open trays. The risk was especially high if seedlings packed in a closed package were stored for more than a week before planting in the middle of June or later. In open trays, the risk of damage was highest in seedlings planted in September, but even then, the risk was lower than in seedlings packed in a closed package. Long storage duration also increased the damage risk in seedlings stored in open trays and planted in September. Other factors that increased damage were coarse soil and the sample plot being on top of a hill. Factors reducing the risk were a fast chain from clear-cutting to planting, planting in good-quality mounds, a sample plot position on the north slope, and the shading of the forest edge on the southern side of a plot. Recovery of seedlings was weaker when seedlings were stored in a closed package and planted in the fall, in too shallow planting depth, or in humus-covered mounds. Recovery improved when seedlings were planted at a depth of at least 5 cm, or when the coniferous forest edge was on the southern or western side of a plot. Winter damage reduced seedling growth and induced the formation of multiple leaders. In practice, the most important factors to be taken into account were avoiding long storage duration and planting seedlings packed in a closed package after the middle of June. Good-quality site preparation and planting were also important for minimizing the risk of damage and improving recovery.

High temperatures constrain latewood formation in Larix gmelinii xylem in boreal forests

In trees, both radial growth and earlywood or latewood differentiation of xylem can reflect responses not only to internal stimuli but also to changes in the external environment. Here, we examined the effect of age and environment on the proportion of latewood to earlywood (PLE) in Larix gmelinii (Dahurian larch) from boreal forests in Eurasia to gain a better understanding of the influence of climate change on genetically controlled characteristics of tree growth. Distinctive differentiation and interannual changes in growth divergences were dependent on age, whereas the influence of environmental factors was also limited. The low-frequency change in the PLE has a juvenile effect, and the variation is unstable. The proportions of latewood to earlywood changed significantly with age during the first 100 years of life (p < 0.05), and environmental factors had a limited impact on the PLE during this stage. However, environmental effects on the PLE became statistically significant when trees were over 100 years old. The average temperature in June–August had a significantly negative correlation with the PLE with temporal changes. The PLE increased significantly with decreased annual mean temperature (p < 0.05) with geospatial variations. After 100 years of tree age, temperature played a crucial role in PLE changes. This suggests that the abnormal radial growth of Larix gmelinii, as indicated by the PLE, will occur in response to rising temperatures. Therefore, PLE-related supporting structures and intrinsic physiological processes in trees can be expected to undergo complex changes, the nature of which is uncertain, as temperatures rise globally. The variation in the PLE could lead to significant changes in the growth of the dominant tree species and hence in the structure and function of boreal forests in cold temperate zones.

A detailed reconstruction of changes in the factors and parameters of soil erosion over the past 250 years in the forest zone of European Russia (Moscow region)

Accelerated soil erosion is a major threat to soil, and there are great variations in the rate of soil erosion over time due to natural and human-induced factors. The temperate forest zone of Russia is characterized by complex stages of land-use history (i.e. active urbanization, agricultural development, land abandonment, etc.). We have for the first time estimated the rates of soil erosion by the WaTEM/SEDEM model (rainfall erosion) and by a regional model (snowmelt erosion) over the past 250 years (from 1780 to 2019) for a 100-km2 study site in the Moscow region of Russia. The calculations were made on the basis of a detailed historical reconstruction of the following factors: the location of the arable land, crop rotation, the rain erosivity factor, and the maximum snow water equivalent. The area of arable land has decreased more than 3.5-fold over the past 250 years. At the end of the 20th century, the rates of gross erosion had declined more than 5.5-fold (from 28 × 103 to 5 × 103 tˑha−1ˑyr−1) in comparison with the end of the 18th century. Changes in the boundaries of arable land and also the relief features had led to a significant intra-slope accumulation of sediments. As a result of sediment redeposition within the arable land, the variation in net soil erosion was significantly lower than the variation in gross soil erosion. The changes in arable land area and in crop composition are the factors that have to the greatest extent determined the changes in soil erosion in this territory.

Critical temperatures controlling the phenology and radial growth of Pinus sylvestris var. Mongolica on the southern margin of a cold temperate coniferous forest

Temperature plays a key role in phenology and growth of dominant tree species and hence in the structure and function of coniferous forests in cold temperate zones. We used a dendrochronological method to determine the critical temperatures of Pinus sylvestris var. mongolica (Mongolian pine) radial growth and the xylem growing season. Results showed that Mongolian pine radial growth is sensitive to daily mean temperatures of 4.0–5.5 °C in early spring, 14.0 °C in summer and 2.0–2.5 °C in autumn. A temperature of 4 °C might be the initial temperature required for sap flow, photosynthesis and tree germination in this area in early spring, and 5.5 °C is the most critical temperature for earlywood onset growth. The advance and extension of temperature 14.0 °C in summer can exacerbate water stress for trees and inhibit earlywood growth under the condition of insufficient precipitation. In autumn, 2.0–2.5 °C may be the minimum temperature for the xylem growth. These critical temperatures are important in predicting the changes in the phenology of cambial activity and the growth of conifers in cold temperate regions under a scenario of a warming climate. We defined the mean xylem growing season of pines in this region as 151 days from early May to early October. With the increase in temperatures during 1972–2015, the start date of the xylem growing season advanced by 0.24 days/year, the duration of the xylem growing season increased by 0.27 days/year and the basal area increment of Mongolian pine increased significantly (P < 0.01). The influence of the earlier and longer xylem growing season compensated the negative effect of high initial temperature (14.0–15.0 °C) in some months, resulting in an increase in tree radial increment in this area. The warmer climate will lead to a longer xylem growing season, resulting in greater wood production with an adequate supply of water available.

Detecting turnover among complex communities using null models: a case study with sky-island haemosporidian parasites.

Turnover in species composition between sites, or beta diversity, is a critical component of species diversity that is typically influenced by geography, environment, and biotic interactions. Quantifying turnover is particularly challenging, however, in multi-host, multi-parasite assemblages where undersampling is unavoidable, resulting in inflated estimates of turnover and uncertainty about its spatial scale. We developed and implemented a framework using null models to test for community turnover in avian haemosporidian communities of three sky islands in the southwestern United States. We screened 776 birds for haemosporidian parasites from three genera (Parahaemoproteus, Plasmodium, and Leucocytozoon) by amplifying and sequencing a mitochondrial DNA barcode. We detected infections in 280 birds (36.1%), sequenced 357 infections, and found a total of 99 parasite haplotypes. When compared to communities simulated from a regional pool, we observed more unique, single-mountain haplotypes and fewer haplotypes shared among three mountain ranges than expected, indicating that haemosporidian communities differ to some degree among adjacent mountain ranges. These results were robust even after pruning datasets to include only identical sets of host species, and they were consistent for two of the three haemosporidian genera. The two more distant mountain ranges were more similar to each other than the one located centrally, suggesting that the differences we detected were due to stochastic colonization-extirpation dynamics. These results demonstrate that avian haemosporidian communities of temperate-zone forests differ on relatively fine spatial scales between adjacent sky islands. Null models are essential tools for testing the spatial scale of turnover in complex, undersampled, and poorly known systems.

Environmental Risks from Pollution and Climate Change: An Updated Review

Climate change expected for the next century could occur in an ecosystem already stressed by UV-B amplification, air pollution, and rising nutrient fluxes. We investigated the relationships among these many environmental challenges by focusing on specific habitats, temperate zone forests, freshwater lakes, and estuaries. The increase in oxidant levels across the lower atmosphere and hydrosphere is a significant chemical consequence of atmospheric change. These changes may result in net nutrient transfer from land to coastal ocean, resulting in forest degradation and coastal eutrophication. Local adjustments may already be occurring, but the synergistic nature of the pressures threatens to speed up the process over the next few decades. Aside from any direct effects of climate change, the worsening of current environmental problems is a significant indirect effect.

林下植被和凋落物对寒温带森林生长季土壤CH4通量的影响

为进一步探究林下植被和凋落物管理对我国寒温带森林生长季土壤CH₄通量的影响，采用静态箱-气相色谱法对大兴安岭北部4种林型（白桦林、山杨林、樟子松林和兴安落叶松林）4种处理（自然状态、去除凋落物、去除林下植被以及去除林下植被和凋落物）的土壤CH₄通量排放特征进行观测研究。结果表明：该地区森林生长季土壤均表现为CH₄的汇，4种林型不同处理后土壤CH₄通量表现为单峰变化趋势，吸收峰值出现在7月或8月。自然状态4种林型土壤CH₄平均吸收通量表现为白桦林（-79.23±14.92）μg m^-2 h^-1>山杨林（-64.27±9.60）μg m^-2 h^-1>樟子松林（-62.54±15.48）μg m^-2 h^-1>兴安落叶松林（-48.73±12.26）μg m^-2 h^-1，兴安落叶松土壤CH₄平均吸收通量显著小于其他三种林型（P<0.05）。相比于自然状态，4种林型在去除凋落物后土壤CH₄吸收通量提高了2.12%-12.15%，但变化幅度均没有达到显著水平（P>0.05）。去除林下植被后4种林型CH₄吸收通量提高了0.84%-20.55%，且只有山杨林吸收增加达到显著水平（P<0.05）。同时去除林下植被和凋落物后，对白桦林和樟子松土壤CH₄通量影响不显著（P>0.05），但对山杨林和兴安落叶松林影响显著（P<0.05）。总之，去除凋落物或林下植被均会提高土壤对CH₄吸收，去除林下植被对土壤CH₄通量的影响要大于去除凋落物的影响，但不同林型不同处理之间还存在差异。;In order to explore the impacts of understory vegetation and litter management on soil CH₄ flux of cold temperate zone forest during the growth season, the characteristics of soil CH₄ flux emission under different treatments were analyzed and studied, which provides a scientific basis and theoretical reference for the management of the forest ecosystem in the Greater Xing'an Mountains in China. The static chamber-gas chromatography was used to analyze the characteristics of soil CH₄ flux emission in four forest types (Betula platyphylla forest, Populus davidiana forest, Pinus sylvestris var. mongolica forest, and Larix gmelini forest) with 4 kinds of treatments (natural state, removal of litter, removal of understory vegetation, and removal of understory vegetation and litter). The results showed that the soil of the four forest types all appeared as CH₄ sinks in this area during growth season. The soil methane showed a single-peak change trend in the four forest types with different treatments, and the absorption peak appeared in July and August. In the natural state, the average soil CH₄ absorption flux of the four forest types showed the trend of Betula platyphylla forest (-79.23±14.92) μg m^-2 h^-1> Populus davidiana forest (-64.27±9.60) μg m^-2 h^-1> Pinus sylvestris var. mongolica forest (-62.54±15.48) μg m^-2 h^-1> Larix gmelini forest (-48.73±12.26) μg m^-2 h^-1. The average absorption flux of soil CH₄ in Larix gmelini forest was significantly smaller than the other three forest types (P<0.05). Compared with the natural state, the soil CH₄ absorption flux increased by 2.12%-12.15% after the removal of litter in the four forest types, but the change range did not reach a significant level (P>0.05). After removing the understory vegetation, the CH₄ absorption flux of the four forest types increased by 0.84%-20.55%, of which only the Populus davidiana forest showed a significant (P<0.05) increase in the soil CH₄ absorption flux. The removal of understory vegetation and litter had no significant effects on the soil CH₄ flux of Betula platyphylla forest and Pinus sylvestris var. mongolica forest (P>0.05), but had significant effects on Populus davidiana forest and Larix gmelini forest (P<0.05). In short, the removal of litter and understory vegetation both increased the soil's absorption of CH₄. The removal of understory vegetation had a greater impact on soil CH₄ flux than the removal of litter, but there were still differences between different forest types and different treatments. Therefore, a scientific and reasonable forest management method is the prerequisite for regulating the absorption of CH₄ by forest soil in this area and the ecological environment protection.

Research Trends and Methodological Approaches of the Impacts of Windstorms on Forests in Tropical, Subtropical, and Temperate Zones: Where Are We Now and How Should Research Move Forward?

Windstorm is one of the destructive natural disturbances, but the scale-link extent to which recurrent windstorms influenced forests ecosystems is poorly understood in a changing climate across regions. We reviewed the synergistic impacts of windstorms on forests and assessed research trends and methodological approaches from peer-reviewed articles published from 2000 to 2020 in tropical (TRF), subtropical (SUF), and temperate (TEF) forests/zones, based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Overall, the majority of the reviewed studies were conducted in TRF (i.e., 40%), intermediate in SUF (i.e., 34%), and the lowest in TEF (i.e., 26%). Among the four levels of biological organization, the species-population and community-ecosystem levels had the highest number of study cases, while the molecular-cellular-individual and landscape levels had the lowest study cases in all forest types. Most of the articles reviewed dealt largely on tree mortality/survival and regeneration/succession for TRF, tree mortality/survival and species composition/richness/diversity for SUF, and stem density, gap dynamics, and regeneration/succession for TEF. However, research on the effects of windstorms on mycorrhizal symbioses, population genetics, and physiological adaptation, element fluxes via litterfall, litter decomposition, belowground processes, biological invasion, and tree health are less common in all forest types. Further, most of the studies were conducted in permanent plots but these studies mostly used observational design, while controlled studies are obviously limited. Consequently, more observational and controlled studies are needed on the topic reviewed, particularly studies at the molecular-cellular-individual and landscape levels, to help inform forest management decision-making about developing sustainable and resilient forests amid climate change.