Mixed Forest Research Articles

Texas Water Observatory: A Distributed Network for Monitoring Water, Energy, and Carbon Cycles Under Variable Climate and Land Use on Gulf Coast Plains

Abstract In the Gulf Coastal Plains of Texas, a state-of-the-art distributed network of field observatories, known as the Texas Water Observatory (TWO), is developed to better understand the water, energy, and carbon cycles across the critical zone (encompassing aquifers, soils, plants, and atmosphere) at different spatiotemporal scales. Using more than 300 advanced real-time / near-real-time sensors, this observatory monitors high-frequency water, energy, and carbon storage and fluxes in the Brazos River corridor, which are critical for coupled hydrologic, biogeochemical, and land-atmosphere process understanding in the region. TWO provides a regional resource for better understanding and/or managing agriculture, water resources, ecosystems, biodiversity, disasters, health, energy, and weather/climate. TWO infrastructure spans common land uses in this region, including (traditional/aspirational cultivated agriculture, rangelands, native prairie, bottomland hardwood forest, and coastal wetlands). Sites represent landforms from low-relief erosional uplands to depositional lowlands across climatic and geologic gradients of central Texas. We present the overarching vision of TWO and describe site design, instrumentation specifications, data collection, and quality control protocols. We also provide a comparison of water, energy, and carbon budget across sites, including evapotranspiration, carbon fluxes, radiation budget, weather, profile soil moisture and soil temperature, soil hydraulic properties, hydrogeophysical surveys, groundwater levels and groundwater quality reported at TWO primary sites for 2018-2020 (with certain data gaps). In conjunction with various earth-observing remote sensing and legacy databases, TWO provides a master testbed to evaluate process-driven or data-driven critical zone science, leading to improved natural resource management and decision support at different spatiotemporal scales.

Seasonal and interspecific variations in the water uptake depth of trees in a moist cool-temperate mixed forest in Japan

ABSTRACT The water uptake depth of trees affects their overall water use and the water cycle of forest ecosystems. However, empirical data on the depth from which water is drawn are lacking for many moist forests. In this study, we estimated the water uptake depths of 24 coexisting tree species in a moist cool-temperate mixed forest in Japan using stable oxygen isotopes. Our goal was to clarify the factors influencing water uptake depth including season, species, slope position, and tree height under moist conditions. Water uptake depth was determined during three periods in which temperatures differed but soil moisture levels remained similar. Season was shown as one of the factors affecting water uptake depth, which was shallowest in August, when temperatures reached maximum values, and deepest during May, when temperatures were lowest. This seasonal variation is likely to be related to physiological processes such as increasing transpiration which leads to water uptake shifting to the water-rich shallow soil layer and/or activation of fine root production at the soil surface, where temperatures are high. Water uptake depth also varied with tree species, suggesting the occurrence of belowground resource segregation among moist forest tree species. Slope position and tree height did not affect water uptake depth. This study highlights the importance of considering temperature-driven physiological processes when examining water uptake depth in moist forests, which could have implications for predicting the responses of these ecosystems to climate change.

Climatic and disturbances influence on tree-rings of Larix gmelinii in the southeast coastal area

The vast region of North East Asia is covered by primary mixed conifer-broadleaved forests which include a range of different tree species. A key factor in the dynamics of these ecosystems is wind disturbance. According to reports, this factor will be increasingly important as a result of the poleward migration of tropical cyclones, a characteristic of which is strong wind. At the same time, global climate change may reduce the recovery potency of some species and lead to new combinations of species. Gmelin Larch is one of the key early succession species in the north of the region. In the southeastern part of its range (Russian Far East), this species has not been widely studied by dendroclimatologists and there are no dendroecological studies available. This study shows how the seasonal growth of Larix gmelinii responds to changes in climate, specifically to variations in precipitation and temperature. The study has established that these trees are more affected by rising temperatures than by consistent precipitation levels, provided there is no shortage of water. Interestingly, after the 1970s there was a change in the climate sensitivity of Larix gmelinii in June (the month with the strongest correlation). It went from a negative correlation with temperature to a positive correlation with precipitation. By using tree ring data, we were able to reconstruct the past history of forest disturbance. The peaks in this chronology coincide with those in earlier published dendroecological reconstructions for other species. They indicate that the radial growth of larch is sensitive to canopy changes. We recorded two release peaks in the 1960s and 2000s, during the period of meteorological observations. We attributed the first peak to the most powerful tropical cyclone Emma (1956). We assume also that the second peak reflects the recent intensification of tropical cyclones in the region. In our opinion, the change in microclimate as a result of disturbance has altered the relationship to climate in such a way that disturbance may cause tree growth to be dependent on precipitation. At the same time, such low correlations do not support a conclusion about the strong negative influence of the current climate on the trees.

Pine woodland fire dynamics mirror industrial history at New River Gorge National Park and Preserve, West Virginia, USA

Fire is an important biophysical process in pine (Pinus) and mixed pine-oak (Quercus) forests and woodlands across the Central Appalachian Mountains. Decades of fire exclusion, however, particularly on public lands, have resulted in a well-documented homogenization of species composition and forest structure. Our objective was to inform management and restoration efforts by expanding on previous dendroecological research at New River Gorge National Park and Preserve and adjacent Babcock State Park in southern West Virginia. Specifically, we assessed pine woodland fire activity in the context of local industrial history, land management, and regional drought. Samples cut from 110 fire-scarred pine trees, distributed across four sites, were used to develop a fire-scar record that spans the period 1842–2010; however, sample depth diminishes rapidly before the 1860s. Fires occurred frequently and extensively in the early–mid 20th century, coinciding with peak coal production and population density. Eleven major fires, or years when at least two trees and 25 % of samples recorded a fire scar at an individual site, were documented in the tree-ring record, but none occurred during the federal land management era (1978–present). Synchronous fire events recorded at two or more sites were associated with drier than average September–May (‘dormant season’) climate conditions. Our results indicate that, since the late 19th century, fire activity in pine woodlands at the New River Gorge has been driven primarily by human ignitions associated with industrial activities, and that periods of drought have amplified landscape-scale fire occurrence. Land managers should consider these historical fire patterns when developing restoration strategies that may include prescribed fire, thinning treatments, and managed wildfires.

Distribution and Biology of Protaetia fieberi (Coleoptera, Scarabaeidae)-Is Protection Status Required?

Studies on saproxylic species of Coleoptera have garnered significant attention due to the rarity of some of them. To investigate the distribution and biology of Protaetia fieberi (Kraatz, 1880) (Scarabaeidae: Cetoniinae) in European Russia, we analyzed data from 16 regions collected between 2018 and 2024. This species has been reliably recorded in 26 regions. We describe the species' distribution area boundaries and discuss limiting factors that inhibit its spread to the north, south, and southeast of European Russia. The primary limiting factor is the lack of suitable biotopes. Within its distribution, Protaetia fieberi prefers deciduous and mixed forests of various types. These habitats include both old-growth forest ecosystems and secondary forests that have regenerated following logging. The species also inhabits man-made forest ecosystems, such as field protection forest belts, old parks, and gardens. In forest ecosystems, Protaetia fieberi tends to occupy the upper levels and is rarely found on the ground layer. Conversely, in open areas such as glades, the species is more commonly found at ground level. This distribution pattern is linked to the adults' feeding preferences, which include consuming sap on tree trunks in forests and feeding on flowering plants in open ecosystems. The seasonal activity of Protaetia fieberi peaks from the third decade of June to the second decade of July. It is hypothesized that the perceived rarity of Protaetia fieberi in research samples is due to the specific baiting methods used, with beer traps being the most effective. The status of the species is re-evaluated in light of new data, suggesting that Protaetia fieberi is common rather than rare in European Russia.

Tilia trees are preferred hosts of several ectomycorrhizal Ascomycota – New insights supported by the first community study of the endemic Tilia kiusiana

Asia is the center of Tilia (Malvaceae) species diversity. However, the ectomycorrhizal (ECM) relations of Asian Tilia are scarcely studied. This study provides the first description of ECM communities of Tilia kiusiana, a rare tree endemic to southwestern Japan. Across the natural distribution of T. kiusiana, ECM fungal communities hosted by the species were investigated in three study sites: Hyōgo (H) and Yamaguchi (Y) on Honshu Island, and Ōita (O) on Kyushu Island. Using molecular methods, T. kiusiana was revealed to host a high diversity of fungi belonging to 25 ECM lineages (16, 17, and 14 lineages on sites H, Y, and O, respectively). The ECM communities of T. kiusiana and the previously studied endemic T. japonica were compared to the available data on other ECM tree genera in Japan, revealing that three Ascomycota ECM lineages (/genea-humaria, marcelleina-peziza gerardii, /tuber-helvella) show a preference towards Tilia hosts. While the total lineage richness did not differ among the compared host tree genera, Tilia communities exhibited higher effective lineage richness at higher (less sensitive to rare taxa) diversity orders. Despite their relative rarity, Tilia trees might play an important role in mixed forests: maintaining the diversity of ECM Ascomycota and potentially buffering the ECM fungal biodiversity loss in cases of ECM tree host diversity decline.

Late Holocene vegetation history and monsoonal climate change from the Core Monsoon Zone of India

To understand the vegetation response to climate change and the Indian Summer Monsoon rainfall (ISMR) variability during the Late Holocene (approx. 2.5 ka), pollen analysis was conducted on a 1.2-m-long lacustrine sediment profile from the Korba District of Chhattisgarh, central India, within the core monsoon zone (CMZ). The pollen evidence suggest that between approx. 2500 and 1950 cal yr BP, open tropical deciduous forest vegetation occupied the landscape under a warm and relatively less humid climate, coupled with decreased ISMR. Between approx. 1950 and 1035 cal yr BP, a warm and relatively more humid climate prevailed, along with moderate ISMR, leading to the transition of the existing vegetation to an open mixed tropical deciduous forest. Between approx.1035 and 220 cal yr BP (CE 915–1730), the mixed tropical deciduous forest became established under a warm and humid climate with increased ISMR, coinciding globally with the Medieval Climatic Anomaly (MCA). Mixed tropical deciduous forest expanded and transformed into a dense mixed tropical deciduous forest between approx. 220 cal yr BP to the present (CE 1730 onwards). This transformation occurred under a warm and relatively more humid climate, accompanied by intensified ISMR, aligning with the Current Warm Period (CWP). Gradual forest transformation from open vegetation to dense mixed tropical deciduous forests, as well as in the ISMR has been observed since the last approx. 2.5 ka in central India. Cereal-based agricultural practices and other anthropogenic activities have been documented in the study area since approx. 2.5 ka, with an accelerated pace observed from 1035 cal yr BP to the present.

Dendrobium namdongense (D. sect. Dendrobium), a new miniature orchid from limestone mountains of northern Vietnam

Dendrobium namdongense is described here as a new species from limestone areas of the Nam Dong Conservation Area, Thanh Hoa Province, Quan Hoa District (northern Vietnam). This species inhabits primary evergreen broad-leaved and mixed forests on karstic limestone at elevations of 900–1100 m a.s.l. in a zone of humid, cool tropical climate. A detailed illustrated description and comparison of the discovered plant with the morphologically closest species, D. fuscifaucium and D. hekouense is provided, along with data on its distribution, ecology, and phenology. The new species has a potential in ornamental horticulture. According to the criteria of the IUCN Red List, the conservation status of the species is determined as Critically Endangered (CR).

Restoration of stand on the site of burnt spruce forest in the Central Forest reserve

With the warming of the climate, the intensification of droughts and the drying up of coniferous forests, the number of forest fires is also increasing. Therefore, the study of the post-fire dynamics of stands and prospects for reforestation on burnt areas is especially relevant. The research was carried out in the Central Forest State Natural Biosphere Reserve (southern taiga) on the burnt area formed in 1999 as a result of a thunderstorm. The purpose of the work was: to describe the state of vegetation 22 years after burnout; to find out the characteristics of the stand formed on the burnt area and the possibility of their use for reconstructing the history of disturbancies in old spruce forests. The objectives of the study included: monitoring vegetation changes in the 1999 burnt area; studying the growth of spruce undergrowth in the burnt area; finding out the number and ratio of preliminary and subsequent renewal of tree species; analyzing the distribution and amount of coals in the sample plots (depending on the intensity of burnout and the state of the pre-fire stand). To study the state of vegetation after the burnout of the blueberry-wood sorrel and wood sorrel – nemoral-herb spruce (Picea abies (L.) H. Karst.) forests, 14 sample plots (100 m2 each) were laid in the northwestern part of the burnt area. The sample plots covered 1.5 hectares. 22 years after the fire, a mixed small-leaved forest with a predominance of birch and a significant participation of spruce has been forming on the site of burnt spruce forests. Spruce is represented mainly by post-fire renewal. In the undergrowth, the ratio of pre- and post-renewal spruce is about 1 : 3. In the ground cover, a small number of nemoral herb species is recorded, and in the stand and undergrowth – almost complete absence of broad-leaved species. A lot of coals were found in soil digs in 4 sample plots (30%); there were no coals in 3 (20%) sample plots, and small coals in small amount were found in 7 (50%) sample plots. Assessing the possibilities of identifying the first post-fire generation of spruce in old stands, it must be said that none of the characteristics of a post-fire spruce stand is universal for its recognition. Only a set of features allows to identify the history of the stand. Distinctive features of the first post-old generation: the presence of coals in 30% of samples or more; a large admixture of birch and aspen; a large diversity of the aspen part of the stand; if there are broad-leaved species, they will be much younger than the spruce; the presence of a sharp decline, and then a rise in growths in a significant part of the oldest spruce trees; the main generation of spruce has initial radial growths on an average of 2.1 mm/year, and the absence of synchronous sharp rises of the growths at the beginning of life. The age of aspen most accurately corresponds to the year of the fire.

Trait-based community assembly and functional strategies across three subtropical karst forests, Southwestern China.

Variations in community-level plant functional traits are widely used to elucidate vegetation adaptation strategies across different environmental gradients. Moreover, studying functional variation among different forest types aids in understanding the mechanisms by which environmental factors and functional strategies shift community structure. Based on five plant functional traits, including four leaf and one wood trait, for 150 woody species, we analyzed shifts in the community-weighted mean trait values across three forest types in a karst forest landscape: deciduous, mixed, and evergreen forests. We also assessed the relative contributions of stochastic processes, environmental filtering, and niche differentiation to drive community structure using a trait-based null model approach. We found marked changes in functional strategy, from resource acquisition on dry, fertile soil plots in deciduous forests to resource conservation on moist, infertile soil conditions in evergreen forests. The trait-based null model showed strong evidence of environmental filtering and convergent patterns in traits across three forest types, as well as low niche differentiation in most functional traits. Some evidence of overdispersion of LDMC and LT occurred to partially support the recent theory of Scheffer and Van Nes that competition could result in a clumped pattern of species along a niche axis. Our findings suggest a change in environmental gradient from deciduous to evergreen forest, together with a shift from acquisitive to conservative traits. Environmental filtering, stochastic processes, niche differentiation, and overdispersion mechanisms together drive community assembly in karst forest landscapes. These findings will contribute to a deeper understanding of the changes in functional traits among karst plants and their adaptive strategies, with important implications for understanding other community assemblies in subtropical forest systems.

Allometry and biomass dynamics in temperate mixed and monospecific stands: Contrasting response of Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea (Matt.) Liebl.)

Mixed forests generally outperform monospecific forests in terms of productivity, stability, and resilience and are becoming increasingly important for sustainable forest management. However, accurate estimates of tree biomass allocation, as well as aboveground and component biomass in mixed forests, remain scarce. Our study addressed three different objectives to identify differences in biomass between mixed and monocultures and develop biomass models: (1) identification of biomass growth patterns in mixed and monoculture stands using analysis of covariance (ANCOVA), (2) investigation of the best fitting approach to modeling aboveground biomass using logarithmic regression and nonlinear mixed-effects models, and (3) fitting compartment biomass proportion models by Dirichlet regression, considering the additivity property. We analyzed 52 harvested trees from six plots within an experimental triplet in northern Spain, consisting of mixed and single-species stands of Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea (Matt.) Liebl.). Moreover, diameter at breast height and tree height were used as covariate variables to determine the most accurate and unbiased models. The research findings showed that (i) allometric patterns of individual-tree biomass in mixed stands significantly differed from those in monospecific stands for sessile oak, while those in Scots pine did not change; (ii) nonlinear mixed-effect models demonstrated a better fit – indicated by lower Furnival index values – than logarithmic regression models in predicting aboveground biomass; and (iii) the fitted biomass equations provided good performance and accurate estimates of biomass component proportions compared to those of existing models. Consequently, our results offer a better understanding of biomass and carbon storage within mixed and monoculture forests in the context of climate change.

Pollen source affects acorn production in pedunculate oak (Quercus robur L.)

Acorn production in oaks (Quercus spp.) shows considerable inter-annual variation, known as masting. The effects of pollen sourced from trees within or outside the stand on acorn production were investigated in pedunculate oak (Quercus robur L.) in an ancient mixed woodland during two moderate masting years. Comparisons were made between natural pollination, hand pollinations with out-of-stand pollen, in-stand pollen or a 1:1 combination of the two pollen sources, and for bagged flowers left unpollinated. After all treatments, > 85% of the flowers or developing acorns were aborted between May and August of both years. When flowers were protected with pollen bags and no pollen added, no acorns were produced. In contrast, hand pollination with out-of-stand pollen produced the most acorns both years and significantly more than within-stand pollen or natural pollination in 2022. Hand pollination with out-of-stand or within-stand pollen provided significantly more acorns than natural pollination in 2023. In 2022, hand pollination with a 1:1 mixture of out-of-stand and within-stand pollen yielded an intermediate number of mature acorns between those for the out-of-stand and within-stand pollination treatments. The study provides clear evidence of maternal choice during acorn development in pedunculate oak and of the benefits of pollen supplementation. It also confirms that pedunculate oak is a fruit-maturation masting species; abortion of pollinated flowers and immature acorns determines a mast year (rather than the number of flowers produced) at this site.

Climate change ecological vulnerability and hotspot analysis of himalayan forests in North-Eastern region, India

The Himalayan forests are vulnerable to climate change leading to disturb the current flow of critical ecosystem services to the dependent population. Present study attempts to evaluate the current vulnerability status of major forest types in Nagaland, India due to climate change along with identifying the hot spots for mitigating the vulnerability of the forests. Vulnerability of mixed moist deciduous, pine, wet hill and wet temperate forests were evaluated using the IPCC framework. Local Moran's I analysis, hot spot analysis and a histogram analysis of the vulnerability were made in QGIS. Field data such as Shannon-Wiener Index and Importance Value Index along with secondary data such as edaphic factors, vegetation factors and climatic variables were used for vulnerability analysis. Analysis results that mixed moist deciduous forests had the highest area in under high-high clusters, hot spots and was highly vulnerable. The result suggests that very dense or moderately dense forest cover were less vulnerable than low density forests in the region. The study provides baseline information along with identification of vulnerable hot spot forests for future climate change policy and management of resources at the division level. The study suggests strengthening the less dense forests along with increasing the biodiversity through suitable strategy for mitigating the vulnerability.

Geoinformation analysis of the vegetation cover of the northern regions of the Irkutsk region and its changes under the impact of fires

The northern regions of the Irkutsk oblast have been prone to fires in recent decades as a result of oil and gas and infrastructure development, as well as changing climatic conditions. Geoinformation mapping and analysis of the spatial structure of the vegetation cover of two key areas located in the area of the Vershina Khandy village and the village of Tokma for two time slices: 2013–2014 and 2018–2019 (before and after active forest fires, mainly in 2016 and 2017) was carried out. Mapping was done using the Random Rorest supervised classification method, Landsat 8 space images. As a result, 10 classes of vegetation cover were identified on the territory. It is shown that in the territories in 2013–2014 coniferous (light coniferous – pine-larch, larch-pine, less often dark coniferous – cedar and spruce) forests prevailed, as well as mixed coniferous-deciduous and deciduous forests and swamps. From 2013 to 2019, more than 20% of Tokma and more than 5% of Khanda key area was covered by fires. Mostly coniferous forests, as well as ernik bogs in the Tokma area were burning.

Predictions of Carbon Stock in the Southern Moscow Region Forests Under Different Forest Use Scenarios

The results of forest simulation modelling of the dynamics of carbon pools and fluxes in forest ecosystems under different forest management scenarios were considered on the example of the Dankovsky forest enterprise (south of the Moscow region, subzone of coniferous-broadleaved mixed forests). The impact of such changes in forest management practices, as the reserve regime, the reduction in the proportion of forest lands as a result of residential development, and zoning of the territory with an emphasis on increasing the recreational use of forests on the carbon balance was analysed. In computational experiments, a set of Russian models was used: the dynamic model of a forest stand FORRUS-S, the model of soil organic matter dynamics Romul_Hum, the model of the hydrothermal regime of soils SCLISS. Calculations were performed for a time period of 100 years at the forestry unit level, and were also aggregated at the level of the entire forestry district. The diversity of types of forest growth conditions (FGC), together with the species diversity and the initial different ages of stands, determined significant variations of the calculated indicators of forest stands’ production, the quantity and quality of plant litter entering the soil. For all cases, model estimates of changes in carbon reserves occurred in the forest stands within the initial 40–60 years with a subsequent decrease in the calculated values. Under the conservation scenario, an increase in the organic substances reserves in forest litter and soil was observed: for FGCs C2 and C3, an increase over 100 years was approximately 5–10 kg m–2, for the remaining FGCs — at the level of 2–3 kg m–2 in terms of carbon. Under the economic use scenarios, a relative “levelling” of forest enterprise area towards the lower end of the spectrum was shown in terms of soil carbon reserves. The maximum ecosystem carbon stock was calculated for FGC C2 and C3, the minimum — for A5 and C4. Depending on the scenario, over 100 years, the total net sequestration of carbon by the forests of the Dankovsky forest enterprise (with a total area of forested land of 6836 ha) was estimated within the range of 0.15–0.57 Tg.

Different drought-tolerance strategies of tree species to cope with increased water stress under climate change in a mixed forest.

Trees' functional strategies to cope with extreme drought are essential under climate change. In a mixed Mediterranean forest, we analyzed the functional strategy in response to drought of four co-occurring species (Pinus pinea, Pinus pinaster, Juniperus oxycedrus, and Quercus ilex) during two years. Specifically, we assessed functional traits related to tree water status, leaf water relations, and gas exchange. Different trait-syndrome metrics and the functional strategies under water stress observed suggested a species drought-tolerance differentiation, with the more anysohidric Q. ilex and J. oxycedrus showing a much higher drought tolerance than the more isohydric P. pinea and P. pinaster. All species recovered from negative leaf turgor reached during peak water stress in summer. Q. ilex and J. oxycedrus kept lower leaf osmotic potentials and lower sensitivity of leaf gas exchange and leaf photochemistry to water stress. In contrast, the pine species exhibited more drought-avoidant and water-conservative strategies, yet this behavior was less effective in mitigating water stress's impact on their physiology. The pine species were the most affected by drought, with prolonged near-zero net photosynthesis during summer. P. pinaster was more isohydric than P. pinea and exhibited a lower capacity to maintain leaf turgor. Physiological processes regulating leaf turgor under drought constitute a key functional strategy involved in the carbon and water-related mechanisms, ultimately inducing mortality under hot drought. The currently observed mortality dynamics for P. pinaster, and to a lower extent in P. pinea, may be exacerbated by loss of functional homeostasis.

The sources of nitrate exported from a watershed containing mixed forest, paddy fields, and urban areas in Japan: differences between baseflow conditions and rainfall events

The sources of nitrate exported from a watershed containing mixed forest, paddy fields, and urban areas in Japan: differences between baseflow conditions and rainfall events

The vascular plant species of different protection levels in the ecosystems of the regional landscape parks of the Ukrainian Polissia

The Ukrainian Polissia is a distinctive region in terms of biodiversity, with a significant number of northern and boreal species and communities, as well as Central European species in the Western Polissia. The research region stretches from west to east for 750 km, and from north to south for 120–150 km. In the northeast direction, its territory gradually narrows to 50–80 km and constitutes a significant part of the important ecological corridor of Eastern Europe. Background. The natural conditions of the Ukrainian Polissia are favorable for the formation of coniferous, broadleaf and mixed forests, which are zonal communities here. The widespread distribution of fluvioglacial sediments causes the predominance of sandy sod-podzolic soils and associated pine forests. The high groundwater table and the low surface area contribute to the development of eutrophic peat bogs. All this leads to the formation of a diverse vegetation cover, which contributes to the representativeness and significant preservation of floristic and coenotic diversity. One of the key roles in the protection of rare species of phytodiversity in the Polissia region of Ukraine belongs to multifunctional protected areas, including the category of “regional landscape parks”. They cover more than 200 species of vascular plants of the Polissia region, with diffe­rent conservation statuses – from the international level of protection to the regional one. Materials and Methods. The study was conducted using conventional field (route-based, geobotanical descriptions of key areas) and desk methods. The species names are given according to the International Plant Names Index, and their belonging to the protected categories is based on the conservation criteria and protection levels accor­ding to the regulatory documents. Results and Discussion. The materials of the research of phytodiversity of five regional landscape parks (Prypiat-Stokhid, Nadsluchanskyi, Ptashynyy Rai, Mizhrichenskyi, Yalivshchyna), in particular rare species, are presented, as evidenced by their diversity, including a number of glacial relics, endemics and borderline species located at the southern or eastern border of the distribution area. Conclusions. The study has revealed that the rare vascular plant flora of the Polissia regional landscape parks is represented by 56 species included in the Red Data Book of Ukraine, 145 species under regional protection of three oblasts of the Polissia region, nine species from Appendix I of the Bern Convention, four species from Appendix II of CITES, and three species included in the European Red List. Two RLPs are the most sozologically representative in the study area: Nadsluchansky (six species of international protection statuses, 30 species of the Red Data Book of Ukraine, 107 species of regional protection level) and Mizhrichynsky (14 species with international protection statuses, 28 species of the Red Data Book of Ukraine, 51 species of regional protection level), which is determined by the peculiarity of natural conditions, habitat diversity and area of the territories. regional landscape parks as a category of nature reserve fund of regional status within the Polissia region of Ukraine cover most of the representative habitats, which include a corresponding number of rare species of different levels of protection, namely: forest (87 species), herbaceous (85 species), marsh (36 species) and aquatic (30 species) habitats.

Influence of photosynthetic active radiation on sap flow dynamics across forest succession stages in Dinghushan subtropical forest ecosystem

With the intensification of global change, forests are subjected to varying degrees of drought or high-temperature stress, which has an indelible impact on the growth of trees. However, knowledge on the response of sap flow to environmental changes in different types of forests is still rare, especially in China's subtropical forest ecosystem. Consequently, studying how different tree species regulate their sap flow in response to shifting environmental conditions is essential for understanding forest transpiration, water use efficiency, and drought stress resilience. Therefore, this study aimed to investigate the sap flow dynamics of seven tree species in five forest plots, i.e., pine forest (PF), two types of mixed conifer-broadleaf forests (MF1+MF2), monsoon evergreen broadleaved forest (MEBF), and montane monsoonal evergreen broad-leaf forest (MOBF) at Dinghushan National Reserve in Southern China, using the heat dissipation probe technique and synchronous environmental factor recordings. Results demonstrated a significant influence of photosynthetic active radiation (PAR) on sap flow across all tree species, with mean PAR values ranging from over 1200 to 425 μmol m−2 s−1, establishing it as the principal driving factor. This observation underscores the heightened responsiveness or sensitivity of tree species to variations in PAR as the forest undergoes development and maturation. The correlation between vapor pressure deficit (VPD) and tree sap flow decreased as succession progressed. Moreover, the influence of soil water content (SWC) on sap flow stability against environmental changes increased. Similar patterns were also found between the two MF, with MF-2 displaying ecological characteristics and environmental conditions more closely aligned with those of the late-successional MEBF. The study reveals the intricate relationship between environmental factors and sap flow regulation in tree species within a subtropical forest ecosystem. Addressing a comparative gap in sap flow correlation among dominant tree species at Dinghushan, it establishes a hydro-physiological foundation for understanding tree species substitution during forest succession. The results provide key insights for forest management and climate-related research. Future studies should delve into the long-term implications of observed sap flow dynamics, exploring their impact on tree species adaptability amid ongoing environmental changes.

Global analysis of forest tipping points leading to changing water cycle dynamics

Forest cover loss is increasing at unprecedented rates, affecting the hydrologic systems of major freshwater-producing regions of the world. However, quantification of the tipping points of forest cover loss before hydrologic changes manifest and their impact in water yield and climatic conditions has remained elusive. In this study, we aim to systematically document the critical thresholds of tree cover loss leading to changing hydrologic functioning within regions that experienced extensive drought, fire, or clear-cutting events spanning different climates during the period from 2001 to 2016. Using the Hydrologic Sensitivity Index based on Budyko’s curve, we analyzed the changes in hydrologic responses to climate variability as landcover changes across the affected forests. Critical thresholds were derived by fitting Richard’s Curve function to the observed relationship between growing sensitive area and tree cover loss. Our analysis reveals decrease in water yields and warming trends during the early stages of tree cover loss in tropical forests (c = 16 %), with negative anomalies observed in rainforests of Central Africa and Maritime Southeast Asia. Boreal forests also show low thresholds (c = 18 %) with a strong tendency toward a warmer climate state and no clear tendency in water yields. Mixed forests show moderate thresholds (c = 25 %) with unclear water yield and climate trends. Conversely, Temperate forests exhibit the most resilience to hydrologic regime shifts with high critical thresholds of tree cover loss (c = 46––54 %), but a rapid alteration once their threshold is surpassed resulting primarily in increased water yields and a shift toward cooler climate conditions. As the potential for additional tree cover loss heightens, due to expected increases in the frequency and intensity of droughts and wildfires, the analyses presented provides a quantitative framework to monitor and assess the impacts of changing forest cover conditions on the water cycle behavior of some of the largest freshwater producing regions of the world.