Comparable diameter resulted in larger leaf area and denser foliage in the park trees than in street trees: A study on Norway maples of Karlsruhe city, Germany.

The leaf area of trees is the main surface of energy and matter exchange between the plant canopy and the atmosphere. A better understanding of canopy structure variations in cities is a prerequisite to evaluating leaf area and ecosystem services. We selected 58 single-standing and healthy Norway maple trees (Acer platanoides L.), equally distributed between the park and street at the same tree size for canopy structure and leaf area measurements. The canopy structures of street trees and park trees were different. Street trees had significantly higher dieback (p < 0.01), crown damage (p < 0.01), and branch-free bole length (p < 0.001) than park trees. Even though we sampled trees with similar diameters, park tree crowns tended to be healthier and denser than street trees. The crown volume, crown projection area (CPA), light availability (Crown Light Exposure or CLE), and foliage density were lower in street trees than in park trees. The average foliage density of street trees is 20 % lower than park trees. All the above differences in crown volume and foliage density lead to a significantly lower leaf area in street trees. The total leaf area of a single street tree was only 83 m2 on average, compared to 186 m2 among park trees. We demonstrated that crown volume and growing habitats (i.e., park or street) are important explanatory variables for leaf area. We conclude that a precise and site-specific evaluation of leaf areas is a prerequisite for accuracy in quantifying ecosystem services from urban trees.

Crown die-back of peri-urban forests after combined heatwave and drought was species-specific, size-dependent, and also related to tree neighbourhood characteristics.

The Rhine River valley of Germany has been facing recurrent and intense spells of drought and heatwaves threatening the health of trees in peri-urban forests. Crown damage intensified by climate change accelerates tree mortality, threatening its ecological, economic, and social benefits; however, the pattern of crown die-back in peri-urban forests remained unclear. We performed a field inventory to estimate the crown die-back of 2578 trees of 51 species from 68 randomly selected peri-urban forest plots in Karlsruhe region on the right bank of the Rhine, after the catastrophic summer heatwave and drought of 2018. We related crown die-back to species-specific drought tolerance, wood anatomical traits, tree size, canopy surface temperature, tree density, Shannon's diversity and Gini coefficient for tree height. Regression results indicate that small-size trees were found to be more susceptible to canopy damage than large trees, with a 1-meter increase in tree height associated with a 0.8 % reduction in crown die-back. This size-dependent process is also species-specific. Among the 12 species with significant (p < 0.05) linear relationship between height and die-back, 9 species demonstrated negative correlations and 3 species showed positive relationships. Species tolerant to drought or cavitation (e.g., trees with diffuse porous xylem, 21 species) had significantly lower crown dieback. For example, with a 1-point-scale increase in drought tolerance crown die-back declined 14.35 %. Trees that experienced high canopy surface temperature and grew with high tree density and species diversity (Shannon's diversity) had more crown die-back. However, high structural diversity (Gini coefficient) was related to lower crown die-back. Our results suggested that future research should focus more on tree species-specific hydraulic and thermal traits and tree density and structure management to improve tree health and species selection in peri-urban forests under future climate change.

Characteristics of urban park recreation and health during early COVID-19 by on-site survey in Beijing.

The positive health effects of green space have received increasing attention, however, on-site surveys and city-level research to reveal the relationship between urban park recreation and urbanite health in metropolitan areas during a post-pandemic period are lacking. We conducted an on-site survey using a questionnaire with 225 respondents from 22 urban parks distributed across the metropolitan area of Beijing during the early COVID-19 eased period with another 1346 respondents in 2021 to make verification. We identified factors that could influence public perceptions of park quality and human health (i.e., physical, mental, and social health) and revealed gender differences in perceptions of park characteristics. The correspondence pattern of perceived urban park quality with social health is distinct from that of physical and mental health. Due to the strict social distancing policy in early COVID-19 period, urban parks in different levels of urbanization environment could exert varied health effects.

Jasmonate signaling controls negative and positive effectors of salt stress tolerance in rice.

Plant responses to salt exposure involve large reconfigurations of hormonal pathways that orchestrate physiological changes towards tolerance. Jasmonate (JA) hormones are essential to withstand biotic and abiotic assaults, but their roles in salt tolerance remain unclear. Here we describe the dynamics of JA metabolism and signaling in root and leaf tissue of rice, a plant species that is highly exposed and sensitive to salt. Roots activate the JA pathway in an early pulse, while the second leaf displays a biphasic JA response with peaks at 1 h and 3 d post-exposure. Based on higher salt tolerance of a rice JA-deficient mutant (aoc), we examined, through kinetic transcriptome and physiological analysis, the salt-triggered processes that are under JA control. Profound genotype-differential features emerged that could underlie the observed phenotypes. Abscisic acid (ABA) content and ABA-dependent water deprivation responses were impaired in aoc shoots. Moreover, aoc accumulated more Na+ in roots, and less in leaves, with reduced ion translocation correlating with root derepression of the HAK4 Na+ transporter gene. Distinct reactive oxygen species scavengers were also stronger in aoc leaves, along with reduced senescence and chlorophyll catabolism markers. Collectively, our results identify contrasted contributions of JA signaling to different sectors of the salt stress response in rice.

Climate change adaptation measures conflicted with the recreational demands on city forests during COVID-19 pandemic.

Recurrent droughts in southwest Germany threaten the city and community-owned forests (CCF). At the same time, the COVID-19 pandemic has increased the demand for recreation in CCF of southwest Germany. We interviewed stakeholders from different interest groups to critically analyze their opinion on how the high recreation demand on CCF due to the pandemic can be ensured along with implementing climate change adaptation measures in CCF in Karlsruhe, Germany. We found that stakeholders particularly highlighted the importance of the recreational function of the CCF during the pandemic. However, the behavior of visitors was criticized by the stakeholders. We showed that demand for the recreational use of CCF conflicted with climate change adaptation measures such as sanitary and forest restoration actions, creating a dilemma among stakeholders. Therefore, enhancing citizens' knowledge of forests' recreation functions and the need for climate change adaptation through communication and education should be prioritized.

Native pedunculate oaks support more biodiversity than non-native oaks, but non-native oaks are healthier than native oaks: A study on street and park trees of a city.

Trees in cities provide multiple ecosystem services. However, simultaneously ensuring healthy trees with high habitat diversity can be challenging in a harsh urban environment. We compared health, microhabitats, and bat activities between native (Quercus robur L.) and non-native (Quercus rubra L.) oaks growing in different urban habitats (street vs. park) in Karlsruhe, southwestern Germany. We randomly selected 167 oak trees with a diameter at breast height (DBH) >20 cm across the city from Urban Tree Registrar. We performed tree health assessment, dendrometric, and microhabitat inventory. We recorded the four-day bat activities on 45 native and non-native oaks with acoustic loggers installed on the trees. We found that non-native oaks were healthier than native oaks but provided less abundance and richness of microhabitats. Tree size (positive effect) and pruning (negative effect) strongly influence microhabitat richness and abundance. In addition, park trees hosted significantly more microhabitats than street trees. We recorded the activities of 9 bat species from 4 genera. Pipistrellus bats were more active in park trees than street trees. Long-eared bats (Plecotus) were more active near the native than non-native oaks. Bats are likely favored by microhabitats such as fork split, lightning scar, and woodpecker "flute" that are more common in less healthy trees. We conclude that non-native red oak can be planted alongside streets, where the conditions are harsher than in parks to better adapt to climatic changes and stay healthy with less maintenance. The preservation of native pedunculate oak trees, especially within parks, is paramount for urban biodiversity conservation because of their potential to provide microhabitats and supporting bats.

First Report on the Ethnopharmacological Uses of Medicinal Plants by Monpa Tribe from the Zemithang Region of Arunachal Pradesh, Eastern Himalayas, India.

The Himalayas are well known for high diversity and ethnobotanical uses of the region's medicinal plants. However, not all areas of the Himalayan regions are well studied. Studies on ethnobotanical uses of plants from the Eastern Himalayas are still lacking for many tribes. Past studies have primarily focused on listing plants' vernacular names and their traditional medicinal uses. However, studies on traditional ethnopharmacological practices on medicine preparation by mixing multiple plant products of different species has not yet been reported in published literature from the state of Arunachal Pradesh, India, Eastern Himalayas. In this study, we are reporting for the first time the ethnopharmacological uses of 24 medicines and their procedures of preparation, as well as listing 53 plant species used for these medicines by the Monpa tribe. Such documentations are done first time in Arunachal Pradesh region of India as per our knowledge. Our research emphasizes the urgent need to document traditional medicine preparation procedures from local healers before traditional knowledge of tribal people living in remote locations are forgotten in a rapidly transforming country like India.

Decrease in Available Soil Water Storage Capacity Reduces Vitality of Young Understorey European Beeches (Fagus sylvatica L.)-A Case Study from the Black Forest, Germany.

Growth and survival of young European beech (Fagus sylvatica L.) is largely dependent on water availability. We quantified the influence of water stress (measured as Available Soil Water Storage Capacity or ASWSC) on vitality of young beech plants at a dry site. The study site was located in a semi-natural sessile oak (Quercus petraea (Mattuschka) Liebl.) stand adjacent to beech stands on a rocky gneiss outcrop in southwestern Germany. Plant vitality was measured as crown dieback and estimated by the percentage of dead above ground biomass. The magnitude of crown dieback was recorded in different vertical parts of the crown. Biomass was calculated from the harvested plants following allometric regression equations specifically developed for our study site. Stem discs from harvested plants were used for growth analysis. We found that soil depth up to bedrock and skeleton content significantly influenced ASWSC at the study site. A significant negative correlation between ASWSC and crown dieback was found. Highest rates of crown dieback were noticed in the middle and lower crown. The threshold of crown dieback as a function of drought stress for young beech plants was calculated for the first time in this study. This threshold of crown dieback was found to be 40% of above ground biomass. Beyond 40% crown dieback, plants eventually experienced complete mortality. In addition, we found that the extremely dry year of 2003 significantly hampered growth (basal area increment) of plants in dry plots (ASWSC < 61 mm) in the study area. Recovery in the plants' radial growth after that drought year was significantly higher in less dry plots (ASWSC > 61 mm) than in dry plots. We concluded that a decrease in ASWSC impeded the vitality of young beech causing partial up to complete crown dieback in the study site.