Deciduous Research Articles

Comparative Assessment of Different Architectures of Convolutional Neural Network for Semantic Segmentation of Forest Disturbances from Multi-Temporal Satellite Images

Algorithms based on convolutional neural networks are the most efficient for semantic segmentation of images, including segmentation of forest cover disturbances from satellite images. In this study, we consider the applicability of various modifications of the U-net architecture of convolutional neural network for recognizing logged, burnt and windthrow areas in forests from multi-temporal and multi-seasonal Sentinel-2 satellite images. The assessment was carried out on three test sites that differ significantly in the characteristics of forest stands and forest management. The highest accuracy (average F-measure of 0.59) was obtained from the U-net model, while the models that showed the best results during training (Attention U-Net and MobilNetv2 U-Net) did not improve segmentation of independent data. The resulting accuracy estimates are close to those previously published for forests with a substantial proportion of selective logged areas. Characteristics of logged areas and windthrows, namely their area and type are the main factor determining the accuracy of semantic segmentation. Substantial differences were also revealed between the images taken in different seasons of the year, with the maximum segmentation accuracy based on winter pairs of images. According to summertime and different-season pairs of images, the area of forest disturbances is substantially underestimated. Forest species composition has a less significant effect, although for two of the three test sites, the maximum accuracy was observed in dark coniferous forests, and the minimum in deciduous forests. There was no statistically significant effect of slope lighting factor calculated from digital elevation model on segmentation accuracy based for winter pairs of images. The accuracy of segmentation of burnt areas, which was assessed using the example of 14 large forest fires in 2021-2022, is unsatisfactory, which is probably due to the varying degrees of damage to the forest cover in the burnt areas.

Light conditions have a greater impact on leaf quality as food for emperor moth (Saturnia japonica) larvae than tree size

ABSTRACT Emperor moth (Saturnia japonica) outbreaks in Hokkaido’s deciduous forests have been happening since 2006. The susceptibility of monarch birch (Betula maximowicziana) leaves differs, with the specific mechanisms affecting their defensibility at the ontogenetic level remaining unknown. In this study, the first instar emperor moth larvae were fed monarch birch leaves from 32 individual trees (saplings to mature trees), and their body weights were compared. Various leaf characteristics (water content, toughness, leaf mass per area, total phenolics, condensed tannin, nitrogen content, carbon content, and carbon to nitrogen [C/N] ratio) were measured concurrently to identify the factors affecting larval growth. Structural equation model analysis indicated that the C/N ratio was the most important factor affecting larval weight and that light conditions have a greater effect on the C/N ratio. In conclusion, light conditions had a strong effect on the foliar C/N ratio which in turn had a significant impact on the weight of emperor moth larvae. This study provides insights into monarch birch management and proposes that maintaining a lighter canopy is important to reduce herbivore damage.

Interpopulation and seasonal variations in habitat and microhabitat use of Vipera ammodytes (Linnaeus, 1758)

Despite the abundant data on habitat use of Vipera ammodytes, most studies are purely descriptive, merely listing the habitats in which the species is most often found. More complete studies evaluating the habitat preference of the species are lacking. The intraspecific variation (i.e., interpopulation or seasonal) in habitat and microhabitat utilization of the species also remains a poorly studied topic. In the current study, we assessed the general patterns of habitat and microhabitat use of V. ammodytes and their interpopulation and seasonal variations, based on habitat/microhabitat availability. To achieve that, we studied five different populations along a latitudinal gradient in western Bulgaria. In all of the studied areas, V. ammodytes showed a clear preference for various stony and rocky habitats and microhabitats, overgrown with herbaceous and shrub vegetation, while it avoided bare habitats, dark deciduous forests as well as cultivated agricultural lands. There were clear interpopulation and seasonal variations in habitat and microhabitat preference and spatial niche utilization. Our results suggest that habitat and microhabitat use of V. ammodytes depends on a combination of many factors such as season, locally specific characteristics like habitat structure and availability, population dynamics, food availability, physical and microclimatic conditions, and possibly on the extent of the interspecific competition

Characteristics of soil organic carbon fractions and influencing factors in different understory mosses in karst urban parks.

The impact of different vegetation types on soil organic carbon (SOC) is a key focus in global warming research. Bryophytes, commonly found in karst urban forests, significantly contribute to carbon accumulation in surface soil. However, the changes in soil organic carbon fractions under moss and the influencing factors remain unclear. To address this knowledge gap, the study examined the organic carbon content, soil physicochemical properties, and associated environmental factors in both moss-covered soil and bare soil under six different forest species within an urban park. The results showed that the SOC contents under moss cover in evergreen coniferous forest (127.28g/kg), bamboo forest (144.70g/kg), deciduous broad-leaved forest (87.63g/kg), and evergreen shrub (109.28g/kg) were significantly higher compared to bare soil. Moss cover also had a significant impact on soil readily oxidizable carbon (ROC), particulate organic carbon (POC), mineral-associated organic carbon (MOC), and heavy fraction organic carbon (HFOC) (P < 0.01). The soil under moss had a higher content of stable organic carbon fraction, which is conducive to the stability of the soil organic carbon pool. The interaction between moss cover and stand type had the most significant effect on soil organic carbon, especially in bamboo forests. Canopy density, moss biomass, and soil moisture were the main environmental factors affecting the content of soil organic carbon and its fractions, while soil organic carbon content was mainly affected by soil nitrogen and phosphorus. This study establishes a theoretical framework for investigating the carbon cycle in karst urban underforest ecosystems, offering a scientific basis for the management and preservation of urban green space ecosystems. Future studies should include bryophytes in the assessment of dynamic factors affecting the soil carbon pool under forest cover and further explore the function and ecological significance of bryophytes in understory ecosystems.

Understory Environmental Conditions Drive Leaf Level-Lipid Biosynthesis in a Deciduous and Evergreen Tree Species.

Plants in the understory experience climatic conditions affected by the overstory canopy that influence physiological and biochemical processes. Here, we investigate the relationships of leaf lipid molecular abundances to leaf water content, transmitted irradiance, and free-air temperature (Tair) from deciduous angiosperm (Quercus buckleyi) and evergreen gymnosperm (Juniperus ashei) understory trees across an elevation gradient in a central Texas (USA) woodland. Monthly sampling from 04/2019 to 01/2020 revealed that long-chain leaf waxes (≥ C27) accumulated with leaf water deficit over the growing season for both tree species. Higher transmitted light during the hottest, driest months was due to a decreased leaf area index (LAI) in the canopy as leaf shedding is a common drought response. Isoprenoids (sesqui-, di-terpenoids, phytosterols) in leaves changed by month with changing LAI and transmittance associated with monthly Tair changes. The chain length of n-alkanols in Q. buckleyi shifted with seasonal LAI at different topographic positions. The unsaturation of fatty acids in both tree species decreased with increased seasonal Tair but showed topography sensitivity. Leaf-level metabolites responded to understory microclimatic variables that were influenced by seasonality and topography.

Correlation between Woody Species and Environmental Variables in a Tropical Forest in Central Laos

The tropical forest biome serves as a significant focal point for conservation endeavors. However, understanding the variations in woody plant composition and the underlying driving factors remains limited. The vegetation gradient within Phou Khao Khouay (PKK) National Park in central Laos presents an intriguing environmental model for investigating these patterns. This study, conducted within PKK National Park, aims to classify woody plant communities of three different forest types: mixed deciduous forest (MDF), dry evergreen forest (DEF), and mixed coniferous forest (MCF), utilizing both the phytosociology approach and multivariate analysis. Data from 32 permanent plots (each measuring 50 m × 50 m) were analyzed, revealing 5,477 tree individuals with a diameter at breast height (DBH) ≥ 5 cm, representing 194 woody species from 64 families and 133 genera. The results indicate significant diversity at the family and genus levels, identifying four distinct plant communities and 44 indicator species based on Tichy and Chytry's phi coefficient method. Stability characterizes the MCF forest type, while the stands of DEF and MDF exhibit differentiation into three communities each. Notably, high heterogeneity in species composition and environmental conditions is evident, with elevation and soil nutrient levels (specifically total phosphorus and total potassium) emerging as primary influencers on species coexistence. The study also highlights correlations between woody plant species composition and topographic and soil variables. These findings underscore the importance of identifying microhabitats conducive to growing and conserving woody plant species within PKK National Park for future research and conservation efforts.

Vegetation response to Early Holocene cooling events in the Moervaart region (northwestern Belgium)

A high‐resolution palynological record from northwest Belgium is presented. The record encompasses the second part of the Younger Dryas and the Early Holocene. The basal part of the pollen record reflects a relatively open landscape, characteristic for the Younger Dryas. The transition to the Holocene is marked by an expansion of birch woodland, followed by an expansion of pine in the Late Preboreal (~11.2–10.7 cal. ka BP). Subsequently, the record shows an expansion of mixed deciduous forest with hazel, elm and oak, characteristic for the Boreal (~10.7–8.6 cal. ka BP). Early Holocene forest expansion was interrupted by a number of short‐lived fluctuations, presumably driven by climatic changes. The most distinct event is the Rammelbeek phase (~11.4–11.2 cal. ka BP), during which forest development was temporarily interrupted in favour of grasses, while wildfires increased. Following this climatic event, hunter‐gatherers returned to the area after a period of almost 1.5 millennia of low population density. They most likely were attracted by the increased temperatures and abundance of edible plants present in the birch‐pine forests and on the banks of the river Kale/Durme. A temporary expansion of pine during the Boreal (~10.7–8.6 cal. ka BP) may correspond with the 9.3‐ka event. At this time, superimposed on a trend of gradual infilling of the channel, a temporary change to drier conditions is observed. The significant drop in the number of prehistoric sites in the Moervaart region clearly cannot be attributed to this short‐term climatic event alone but was most likely caused by a combination of environmental changes, such as the decreasing availability of hazelnuts as well as freshwater and edible (semi‐)aquatic plants as the Kale/Durme river gradually turned dry. The study provides insight into, partly climate‐driven, Early Holocene environmental changes and the effect this may have had on human occupation.

Internal physiological drivers of leaf development in trees: Understanding the relationship between non‐structural carbohydrates and leaf phenology

Abstract Plant phenology is crucial for understanding plant growth and climate feedback. It affects canopy structure, surface albedo, and carbon and water fluxes. While the influence of environmental factors on phenology is well‐documented, the role of plant intrinsic factors, particularly internal physiological processes and their interaction with external conditions, has received less attention. Non‐structural carbohydrates (NSC), which include sugars and starch essential for growth, metabolism and osmotic regulation, serve as indicators of carbon availability in plants. NSC levels reflect the carbon balance between photosynthesis (source activity) and the demands of growth and respiration (sink activity), making them key physiological traits that potentially influence phenology during critical periods such as spring leaf‐out and autumn leaf senescence. However, the connections between NSC concentrations in various organs and phenological events are poorly understood. This review synthesizes current research on the relationship between leaf phenology and NSC dynamics. We qualitatively delineate seasonal NSC variations in deciduous and evergreen trees and propose testable hypotheses about how NSC may interact with phenological stages such as bud break and leaf senescence. We also discuss how seasonal variations in NSC levels, align with existing conceptual models of carbon allocation. Accurate characterization and simulation of NSC dynamics are crucial and should be incorporated into carbon allocation models. By comparing and reviewing the development of carbon allocation models, we highlight the shortcomings in current methodologies and recommend directions to address these gaps in future research. Understanding the relationship between NSC, source–sink relationships, and leaf phenology poses challenges due to the difficulty of characterizing NSC dynamics with high temporal resolution. We advocate for a multi‐scale approach that combines various methods, which include deepening our mechanistic understanding through manipulative experiments, integrating carbon sink and source data from multiple observational networks with carbon allocation models to better characterize the NSC dynamics, and quantifying the spatial pattern and temporal trends of the NSC‐phenology relationship using remote sensing and modelling. This will enhance our comprehension of how NSC dynamics impact leaf phenology across different scales and environments. Read the free Plain Language Summary for this article on the Journal blog.

The Impact of Bamboo (Phyllostachys edulis) Expansion on the Water Use Patterns of Broadleaf Trees

The expansion of bamboo (Phyllostachys edulis) affects the growth status of trees in colonized forests, but there has been insufficient research on changes in tree water physiology. In this study, we used stable δ2H, δ18O, and 13C isotope ratios to analyze the water sources and water use efficiency (WUE) of bamboo, deciduous broadleaf trees (Alniphyllum fortunei), and evergreen broadleaf trees (Machilus pauhoi and Castanopsis eyrei) in a bamboo-expended broadleaf forest (BEBF), a bamboo-absent broadleaf forest (BABF), and a bamboo forest (BF). We found that the expansion of bamboo had no significant effect on the water sources and WUE of deciduous broadleaf trees, but altered the water sources of evergreen broadleaf trees. During the growing season, evergreen broadleaf trees decrease their uptake fractions of surface soil water by 7.1% to 9.6% and increased their uptake fractions of middle soil water by 5.8%~9.4%. Conversely, during the non-growing season, they increased their uptake fractions of surface soil water by 11.9% and decreased their uptake fractions of deeper soil water by 5.6%~12.9%. Additionally, after expanding into broadleaf forests, bamboo increased its uptake proportion of surface and shallow soil water by 20.0% and 9.4% during the growing season. Its WUE also improved, increasing by 20.0 μmol/mol and 13.0 μmol/mol during the growing and non-growing seasons, respectively. These results indicate that as bamboo expands into broadleaf forests, it enhances its competitiveness for water resources by changing its water use strategy. Compared to deciduous broadleaf trees, evergreen broadleaf trees exhibit more flexible water use strategies under the conditions of bamboo expansion. Our research reveals, for the first time, how broadleaf trees adjust their water use strategies in response to bamboo expansion, and uncovers the mechanisms behind bamboo expansion into evergreen broadleaf forests from the perspective of water use strategies. This will aid future forest management under the conditions of bamboo expansion.

Reaching new heights: Arboreal ant diversity in a North American temperate forest ecosystem

Abstract Most canopy insect research takes place in tropical forests, where communities are highly vertically stratified. However, temperate forest canopies also provide critical resources to many species and are under intense pressure from global change drivers. The relative lack of knowledge regarding temperate canopy insect ecology impedes our forest management and conservation decisions such that we may be losing temperate canopy biodiversity before we know it exists. We directly compared ant diversity and community composition on the ground and in the tree canopy of North American temperate deciduous forests for the first time. We also evaluated two canopy sampling methods—baits and hand collections. We collected 34 ant species from 102 trees across seven sites. Ant diversity was greater on the ground than in the canopy, and species turnover created distinct communities across vertical strata. Only 12% of species were exclusively arboreal, but 47% were collected in both strata, indicating the canopy is an important resource for temperate ants, even if they are not restricted there. Baiting and hand‐collecting recovered similar species richness, but whether baits captured a subset of hand‐collected species or a unique assemblage was site‐dependent. Nevertheless, we suggest that these methods are most effective in conjunction. Hand collection allowed us to document arboreal nests of 10 species, including the invasive needle ant, Brachyponera chinensis, which was previously thought to be strictly terrestrial. Our results emphasise the importance of including the canopy in temperate forest ecology and conservation assessments.

Thermal Comfort and Green Spaces: The Role of Temperature-Regulating Elements in Neighborhood Parks

According to current studies, the thermal effects of global warming will affect urban areas more intensely. In the face of this situation, strategies for the improvement and management of urban green spaces are becoming increasingly important in sustainable landscape design. These strategies promote social sustainability by positively affecting individuals’ physical and psychological well-being, taking into consideration ecological sustainability. Projections regarding global warming emphasize that the density of hardscapes and green spaces, the selection of plant species, and the distribution of plants considered within the scope of this study should be taken into account. This research was conducted in the Görükle neighborhood of Bursa, focusing on the role of temperature-regulating elements in 14 neighborhood parks. Systematic temperature measurements were carried out in the research area on the 10th, 20th, and 30th of July and August, specifically between 12:00 and 13:00, during peak temperature hours. The presence of parks that are close to each other and relatively far away from each other in the study area was seen as advantageous to filter the effects of plant differences in similar conditions. Furthermore, evaluating these various factors together highlights the multifaceted nature of thermal comfort. Designated temperature measurement points included three points (hard surfaces and hard surfaces surrounded by vegetation and planted green spaces) in each park. An analysis utilizing SPSS and the RayMan program revealed that parks with a softscape to hardscape ratio of approximately two to one experienced temperature reductions of 2.5 to 3 °C. Furthermore, the findings indicate that coniferous trees have a more significant impact on thermal comfort compared to deciduous trees. The significant differences identified in this study underscore essential considerations for urban design processes aimed at achieving sustainability.

Influence of trap type on the captures of Lymantria dispar L. (Lepidoptera: Erebidae): trials from different European countries.

The spongy moth, Lymantria dispar L. (Lepidoptera: Eribidae), is a serious pest of deciduous forests and causes widespread defoliation. Despite this, few studies have evaluated the wide-ranging surveillance of adult male L. dispar using different types of pheromone-baited traps. We evaluated the effect of trap type on captures of adult male L. dispar at 18 sites in Europe; two in Slovenia, two in Spain, 12 in Greece, one in Hungary, and one in Croatia. Seven different trap types, G trap and eGymer 1-6, were evaluated June-September 2022 and 2023. Generally, captures of L. dispar started in late June and lasted until mid-August. Trap type affected captures. The G trap (consisting of a dark brown plastic rectangular parallel-piped body) caught significantly more L. dispar than other trap types in many instances, particularly when the peak of the flight period occurred. Captures of L. dispar in pairs of different trap types showed a significant correlation in trap catch in most investigations, suggesting that most detected comparable fluctuations in L. dispar abundance. We recommend that the G trap be used for wide-ranging surveillance of L. dispar in Europe.

Availability of alternative prey rather than intraguild interactions determines the local abundance of two understudied and threatened small carnivore species.

Intraguild interactions influence the structure and local dynamics of carnivore mammals' assemblages. The potential effects of these interactions are often determined by the body size of competing members and may result in negative relationships in their abundance and, ultimately, lead to species exclusion or coexistence. The relative importance of interspecific interactions along with landscape characteristics in determining population patterns of understudied and threatened sympatric small carnivores, such as skunks, remains poorly documented. Therefore, we assessed the spatiotemporal variation in the abundance of American hog-nosed skunks Conepatus leuconotus and pygmy spotted skunks Spilogale pygmaea and the effect of interspecific interactions, resource availability, and habitat complexity on their local abundance in areas with the deciduous tropical forest south of the Mexican Pacific slope. We used presence-absence data for skunk species from three camera-trapping surveys between 2018 and 2020 in combination with Royle-Nichols occupancy models fitted in a Bayesian framework to estimate abundance, incorporating the effects of covariates related to the factors evaluated. We analyzed the relationship between the abundances of skunks using Bayesian Generalized Linear Models. Both skunk species showed significant differences in their abundances between seasons and between study sites. Overall, pygmy skunks were more abundant than hog-nosed skunks. We found negative relationships among the relative abundances of skunks during the dry seasons, but no evidence that local abundance is governed by the competitive dominance of the larger species. Patterns of skunk abundance were better explained by prey availability and other predictors related to habitat complexity, rather than interspecific interactions, since these models showed the highest predictive accuracies and strong positive and negative relationships. Our study highlights the underlying factors that determine the local abundance of these understudied and threatened small carnivores, allowing us to better understand the mechanisms that govern their coexistence for effective management and conservation of species in seasonal environments.

First records of moss-feeding aphids (Hemiptera: Sternorrhyncha: Aphididae) from Hungary

Four species of moss-feeding aphids were captured by Berlese samples collected in Heves county, NE Hungary. These data are establishing the first Hungarian records of moss-dwelling aphids, all the four species and three genera are reported from the country for the first time. Muscaphis (Aspidaphium) eschirichi (Börner, 1939) was yielded from a colony of Palustriella commutata (Hedw.) Ochyra collected from rock in a karst spring outlet, Muscaphis (Muscaphis) musci Börner, 1933 was yielded from colonies of Hypnum cupressiforme Hedw. collected from bark of Quercus pubescens Wild. in an open karst forest, Pseudacaudella rubida (Börner, 1939) was yielded from both of the above mosses, while a Myzodium sp. was yielded from a colony of Hypnum cupressiforme mixed with a single stem of Brachythecium salebrosum (Hoffm. ex F.Weber &amp; D.Mohr) Schimp., collected from bark of dead trunk of Quercus cerris L. in a mixed deciduous forest. All moss species are new host records for the corresponding species. Myzodium sp. explain some distinctive characters different from the only European species of its genus and probably belong to an undescribed species, but we are avoiding of describing it on the basis of the single adult captured. Distinctive morphological and biological characteristics of the Hungarian specimens of the four aphid species are discussed and illustrated. A list of the accompanying taxa yielded from the Berlese samples are listed in a table.

Improving airborne laser scanning-based species-specific forest volume estimation using sentinel-2 time series

ABSTRACT Species-specific timber volume estimates are required to support forest planning and conservation. We evaluated whether additional predictors from a Sentinel-2 time series can improve airborne laser scanning (ALS)-based estimation of species-specific timber volumes. Furthermore, we determined the satellite image dates that provided the greatest improvement in accuracy. The Sentinel-2 time series was constructed to cover 1 March–30 November time-period, with a focus on late spring and early summer. The estimation was done using the k Most Similar Neighbor method and predictors extracted from the ALS data and Sentinel-2 images. Our best model included both ALS and Sentinel-2 time-series predictors, and the relative root mean square error (RMSE) values for pine, spruce and deciduous timber volumes were 40.8%, 57.0% and 51.3%, respectively (mean 49.7%). All deciduous trees were treated as one species. When bands from an individual image were used instead of the time series, the best result was obtained with an image from September where the respective relative RMSE values were 42.2% (deciduous), 58.4% (pine) and 60.6% (spruce) with a mean value of 53.7%. A fusion of a Sentinel-2 time-series and ALS data can improve species-specific estimation results compared to the use of individual Sentinel-2 images or ALS only.

Local environment perceived in daily life and urban green and blue space visits: Uncovering key factors for different age groups to access ecosystem services

Inequality in access to green and blue spaces is a major issue in the field of environmental justice. Various factors significantly influence visitations to these spaces, including residential, commuting, and shopping areas. However, studies have mainly focused on residential environments. Analyzing the coupling of environmental and socioeconomic factors, including age, income, and childhood experience, and examining the direct and indirect effects of these factors for different age groups are needed to better understand the detailed context of inequalities in access to ecosystem services. We conducted a questionnaire survey and analysis to address these needs in an urban setting. The results demonstrate that several land use categories (i.e., agricultural lands in residential areas, grasslands near shopping areas, and deciduous forests near commuting destinations) positively correlated with visitation frequency, suggesting the lack thereof may be the cause of access inequalities. In particular, the perimeter per unit area of some land cover types, which shows the complexity of the form of each land cover category, was found to be a significant factor. We identified inequality in nature experience to be the key factor correlated with inequality in nature visits among the young age group. For the middle-aged and old age groups, nature-relatedness was positively correlated with visitation frequency. Proper design of the local environment, such as through land use planning, can be an effective measure for all age groups. For instance, long-bordered green areas in the Monsoon Asian region are an attractive traditional landscape, with high accessibility and a comfortable thermal environment. The key factors for each age group should be considered in spatial design and inclusive information-sharing to reduce inequality in access to ecosystem services.

Non-native palm affects arthropod communities and litter decomposition in an ongoing biome shift

The emergence of novel ecosystems, characterized by shifts in species composition and interactions, abiotic conditions and altered ecosystem functioning, is a major and inevitable challenge to contemporary ecosystem management. This study examines the ecological implications of Trachycarpus fortunei, a non-native evergreen palm, currently involved in a biome shift from deciduous temperate forest to evergreen laurophyllous forest in the Southern European Alps. Specifically, we investigated the effects of T. fortunei encroachment in peri-urban forests on flying and ground-dwelling arthropod communities as well as on leaf-litter decomposition. We found that the presence of T. fortunei altered arthropod community composition, mostly by reducing the number of herbivore species. This effect was likely driven by the lower quality of palm leaves as a food source compared to deciduous, dicotyledonous tree leaves and by a lower plant richness in the herb and shrub layer. Furthermore, we observed higher rates of leaf-litter decomposition associated with increasing abundance of young palm trees, which was not explained by predictors commonly associated with litter decomposition (i.e., detritivore abundance, litter depth and air temperature). Hence, the slow decay of palm leaves appears to be counterbalanced by the favourable conditions for litter decomposition within dense palm stands. Overall, our findings indicate that high densities of the non-native palm species (T. fortunei) impacts herbivore arthropod communities in the Southern European Alps, providing first evidence of possible effects on ecosystem functioning of this ongoing biome shift. These outcomes are integral components of the broader process of laurophyllisation in the study region, a phenomenon linked to climate warming and land use change, encompassing both native and non-native species.

Modeling carbon dynamics from a heterogeneous watershed in the mid-Atlantic USA: A distributed-calibration and independent verification (DCIV) approach

The terrestrial ecosystem plays a vital role in regulating regional and global carbon budgets. Ecosystem models are extensively employed to estimate carbon fluxes across different spatial scales. However, there remains a need to reduce the uncertainties associated with model parameterization and input data. To address these limitations, we assessed a distributed-calibration and independent-verification (DCIV) approach that uses (1) remotely sensed net primary production (NPP) and evapotranspiration (ET) data from the Moderate Resolution Imaging Spectroradiometer (MODIS), (2) multi-site eddy covariance net ecosystem exchange (NEE) data; and (3) field sampling of soil organic carbon (SOC) and aboveground biomass (ABG) data to improve the overall predictability of carbon fluxes for the different land use and land cover (LULC) types at a watershed scale. The DCIV approach was applied to an advanced version of the Soil and Water Assessment Tool (SWAT)-Carbon (or SWAT-C), equipped with Century-based SOC algorithms to simulate carbon dynamics for watersheds with heterogeneous vegetation. The objective of the modeling effort was to assess carbon stocks and fluxes under different land management scenarios for a 3000-acre experimental farm and forest preserve in the northeastern United States. Our study showed that a large SOC stock of at least 100 tons ha−1 is stored under mixed forest, deciduous, shrubland, and floodplain (grass). Our study also showed that converting floodplain (grass) to deciduous forest has the potential to increase CO2 uptake (-NEE) by an order of three magnitude and ABG by 77 %, leading to an increased SOC stock of 23 % after twenty years. Similarly, we found that converting ungrazed grassland to grazed pasture leads to a non-statistically decreasing trend of SOC, especially in the 0–30 cm soil layer. Thus, the methodology used in this study can be applied to improve carbon dynamic prediction from a heterogeneous watershed at a regional scale.

Green Turtle Feeding on Terrestrial Leaves Reveals Energy Pathway From Land to Sea.

We report on an adult male green turtle (Chelonia mydas) feeding on fallen leaves from a terrestrial tree, frangipani (Plumeria rubra), in the waters in front of Cabuyal-a known sea turtle nesting beach-on thenorth Pacific coast ofCosta Rica. This observation, in conjunction with similar reports worldwide, corroborates that terrestrial leaves may be a common food item for green turtles in areas near mangrove forests or coastal deciduous trees. Our observation also indicatesthat male turtles may feed during reproductive periods if food is available.

Regional Variability of Chestnut (Castanea sativa) Tolerance Toward Blight Disease.

Since its introduction into Europe in the first half of the 20th century, Cryphonectria parasitica has been gradually spreading across the natural range of the sweet chestnut (Castanea sativa Mill.), infecting the trees and causing lethal bark cankers. Serendipitously, a hyperparasitic Cryphonectria hypovirus 1 (CHV1), which attenuates C. parasitica virulence in combination with more tolerant European chestnut species, was able to ward off the worst effect of the disease. In North America, unfortunately, the native Castanea dentata is now functionally extinct since it occurs only as root sprouts in eastern deciduous forests where it was once dominant. In our work, we investigated changes in C. parasitica populations over time and the regional variability in chestnut populations' tolerance toward the blight disease. While vegetative compatibility (vc) type diversity and prevalence of hypovirulence remained similar as in previous studies, in the Buje population, unlike in previous studies, we were unable to find any hypovirulent fungal strains. The most common vegetative compatibility types (vc types) were EU-1, EU-2 and EU-12. However, several rare EU-types were found, including one previously unreported: EU-46. By inoculating several C. parasitica strains on tree stems from several chestnut populations, we observed that the induced lesion size was affected by the type of inoculum (CHV1-free or CHV1-infected), genotype-related individual chestnut stem and chestnut stem population of origin-related variability. The largest lesions were induced by CHV1-free fungal isolate DOB-G: 20.13 cm2 (95% C.I. 18.10-22.15) and the smallest by CHV1-infected L14/EP713: 2.49 cm2 (95% C.I. 1.59-3.39). Surprisingly, the size of the lesions induced by other CHV1-infected strains fell somewhere in between these extremes. The size of induced lesions was dependent on the population of origin as well and ranged from 11.60 cm2 (95% C.I. 9.87-13.33) for stems from the Moslavačka gora population to 17.75 cm2 (95% C.I. 15.63-19.87) for stems from Ozalj.