Pristine Forest Research Articles

Year-round monitoring of antibiotic-resistant bacteria in pristine uppermost stream and estimation of pollution sources

Studies on the conditions and pollution routes of antibiotic-resistant bacteria (ARB) in rivers can help provide countermeasures against the spread of ARB. This study focused on the pristine uppermost stream of a river, where Escherichia coli (E. coli) and enterococci were detected, although the stream flows through a pristine forest catchment. Antibiotic resistance of E. coli and enterococci isolated from the river water, riverbed sediment, and feces of waterside animals, such as birds and Mustelidae, were investigated throughout the year in the pristine uppermost sites. Antibiotic resistance was present in 1.4% (7/494) of the E. coli strains and 3.0% (24/812) of the enterococcal strains, and was low throughout the year. Although antibiotic resistance of bacteria isolated from feces was not detected in this watershed, the prevalence of multidrug-resistant E. coli was 0.4% (1/246) and 0.6% (1/172) in river water and riverbed sediment samples, respectively were observed. The presence of extended-spectrum β-lactamase (ESBL)-producing E. coli was confirmed in river water samples, and genomic analysis revealed that the samples possessed the CTX-M-15 group. Multidrug-resistant strains and ESBL-producing strains were classified as phylogroups B1 and A, respectively, which are E. coli phenotypes isolated from wild animals. Pulsed-field gel electrophoresis revealed analysis targeting enterococci that strains isolated from river water and bird feces were in the same cluster with 100% similarity. Therefore, bird feces are a source of enterococci in the uppermost stream of the river. Because multidrug-resistant bacteria and ESBL-producing bacteria were present in the pristine uppermost stream of the pristine river, urgent elucidation of the spreading routes of ARB is important.

Impact of deforestation on the hydrogen, oxygen and iron isotope compositions of Amazonian streams

We examined the consequences of deforestation and pasture establishment on H, O and Fe isotope cycling in the hydrosphere, with focus on small watersheds from the central and eastern part of Brazilian Amazonia. The δ18O- δD relationships in stream water samples show that the evaporation effect is greater in pasture than in forest, thereby highlighting the impact of deforestation on atmospheric water circulation and rainfall.A clear effect of deforestation was also found on the dissolved load of these streams. Water temperature, pH, conductivity, major cations and dissolved carbon organic content are lower in forest streams compared to those from deforested areas. Dissolved (i.e., filtrate <0.45 μm) iron concentrations are typically higher in these tropical forest streams. They also show δ57Fe signatures commonly higher than that of the continental crust (i.e., > 0.1‰). In these black waters enriched in organic matter, the heavier iron isotope composition in the forested areas is related to the oxidized Fe strongly bound to colloidal organic matter. On the other hand, dissolved iron from streams draining older deforested areas shows isotopic compositions usually lighter than the continental crust (δ57Fe < 0.1‰). The negative δ57Fe signatures of these areas are likely caused by deforestation involving erosion and rejuvenation of soils in valleys, which leads to the occurrence of a partial iron reduction in the soils. These modifications increased the proportion of isotopically light, dissolved and more reduced Fe in the streams.Those effects are less obvious on more recent pastures since they display more chemical and isotopic scatter along the sampling months. In a stream flowing through an area undergoing slash and burned deforestation within the year, dissolved iron concentrations and isotopic compositions are much more scattered, with δ57Fe values varying by >10 ‰ as a result of fire or heavy rain events. This likely depicts the disruption of the iron cycling in the water-soil-plant system with strong changes in the soil mineralogy, organic matter characteristics and biomass activity resulting from the forest fire. Our results suggest that more than a decade is needed to reach a new dynamic steady state of the Fe biogeochemical cycle in pastures.Hence, the contrasted Fe isotopic compositions between the streams draining pristine tropical forests and those from deforested areas indicate that, like H and O isotopes, Fe isotopes are a sensitive indicator of the transformations affecting the biogeochemical cycling of tropical environment in response to deforestation. However, in contrast to hydrogen and oxygen isotopes that reveal the exchanges between surface waters and atmosphere, iron isotopes rather highlight the physical-chemical reactions occurring between surface waters and the soils, but with the biomass mediation for all three isotopic tracers.

Implementing ITS1 metabarcoding for the analysis of soil microeukariotic diversity in the Mountain Cloud Forest

PurposeIn threatened diversity hotspots, such as mountain cloud forests, microbiome studies have focused essentially on bacteria. Unlike prokaryotic microbiomes, the study of the microeukaryotes has largely been restricted to the visual identification of specific groups. Herein, microeukaryotic edaphic diversity from a pristine mountain cloud forest (MCF) of Mexico was analyzed via the metabarcoding of the ITS1 region of ribosomal DNA.Materials and methodsAn exploratory triangular sampling was conducted in the mountain cloud forest located in El Relámpago Mount, Santiago Comaltepec, Oaxaca, Mexico. Each vertex was located adjacent to a dominant plant species in the ecosystem (Oreomunnea mexicana and Alsophila salvinii). After DNA extraction the ITS1 region (rDNA) was amplified. Microeukaryotic sequences were filtered by computational subtraction against the ITS2 Database. Next, alpha and beta diversity indexes were calculated, and the relationship between abiotic variables and diversity patterns were inferred by means of a Canonical Correspondence Analysis.ResultsOverall, 138 inferred sequence variants were identified, including 87 protists, 35 animals (microfauna), and 16 algae. Within the animals, the nematodes were the dominant group, chlorophytes dominated algae, and in Protista, no dominance patterns were observed given the high diversity and equitability of this group. Soil available carbon, carbon degrading enzymes and the pH play a key role in modeling the community structure. Remarkably, high beta diversity levels were obtained, evidencing a strong spatial heterogeneity at the small scale.ConclusionsThe ITS metabarcoding proved to be a useful tool to conduct multi-taxa diversity assessments for microeukaryotes, allowing the identification of alpha and beta diversity patterns and overcoming limitations of sampling and the direct observation of individuals. The results presented in this work evidenced high microeukaryotic diversity levels in the soil of MCF and encourage future studies aiming to explore the taxonomic diversity of individual taxa.

Notes on the ecology, activity patterns and behavior of the kinkajou (Potos flavus)

Abstract Kinkajous are one of the most widely distributed Neotropical mammals, nonetheless, their nocturnal habits have posed challenges on the study of their ecology and behavior. Here, we used arboreal camera trapping in a pristine Amazonian forest in Ecuador, and ad libitum data from direct encounters in a lowland and a highland forest in Colombia to describe their activity patterns and describe anecdotal data on their diet and reproductive behaviors. As expected, kinkajous are strictly nocturnal and seem to be active throughout the entire night, although in our study there was less activity towards the beginning and the end of the night. Kinkajous were observed to be mostly solitary, rarely in groups of two to three adult individuals. Although their diet has not been described in detail, fruits from Moraceae and Urticaceae appear to be important components of their diet. Their reproductive behavior involves an isolated pair of kinkajous, and may be interrupted by other males. Pairs seem to meet for reproductive purposes and range together for several hours, during which courtship may take place, ending in copulation, which lasts for approximately 3 min. After copulation, the male and female appear to separate and return to their solitary habits. The results of this study complement the scarce information on the elusive kinkajous in the Neotropical forests.

Ideas and perspectives: Sensing energy and matter fluxes in a biota-dominated Patagonian landscape through environmental seismology – introducing the Pumalín Critical Zone Observatory

Abstract. The coastal temperate rainforests (CTRs) of Chilean Patagonia are a valuable forest biome on Earth given their prominent role in biogeochemical cycling and the ecological value and dynamics of surface processes. The Patagonian CTRs are amongst the most carbon-rich biomes on Earth. Together with frequent landscape disturbances, these forests potentially allow for episodic and massive release or sequestration of carbon into and from the atmosphere. We argue that, despite their particular biogeographic, geochemical, and ecological roles, the Patagonian CTRs in particular and the global CTRs in general are not adequately represented in the current catalog listing critical zone observatories (CZOs). Here, we present the Pumalín CZO as the first of its kind, located in Pumalín National Park in northern Chilean Patagonia. We consider our CZO a representative end-member of undisturbed ecosystem functioning of the Patagonian CTRs. We have identified four core research themes for the Pumalín CZO around which our activities circle in an integrative, quantitative, and generic approach using a range of emerging techniques. Our methodological blend includes an environmental seismology that also fills a critical spatiotemporal scale in terms of monitoring critical zone and surface processes with a minimum intervention in those pristine forests. We aim to gain quantitative understanding of these topics: (1) carbon sink functioning; (2) biota-driven landscape evolution; (3) water, biogeological, and energy fluxes; and (4) disturbance regime understanding. Our findings highlight the multitude of active functions that trees in particular and forests in general may have on the entire cascade of surface processes and the concomitant carbon cycling. This highlights the importance of an integrated approach, i.e., “one physical system”, as proposed by Richter and Billings (2015), and accounts for the recent advances in pushing nature conservation along the Chilean coast.

Non fire-adapted dry forest of Northwestern Madagascar: Escalating and devastating trends revealed by Landsat timeseries and GEDI lidar data.

Ankarafantsika National Park (ANP), the last significant remnant of Northwestern Madagascar's tropical dry forests, is facing rapid degradation due to increased incidences of fire. This poses severe threats to biodiversity, local livelihoods, and vital ecosystem services. Our study, conducted on 3,052-ha of ANP's pristine forests, employed advanced remote-sensing techniques to assess fire impacts during the past 37 years. Our aims were to understand historical fire patterns and evaluate forest recovery and susceptibility to repeated fires following initial burns. Using data from multiple Landsat satellite sensors, we constructed a time series of fire events since 1985, which revealed no fire activity before 2014. The Global Ecosystem Dynamics Investigation (GEDI) lidar sensor data were used to observe forest structure in both post-fire areas and undisturbed zones for comparison. We recorded six fire incidents from 2014-2021, during which the fire-affected area exponentially grew. A significant fire incident in October 2021 impacted 1,052 hectares, 59% of which had experienced at least one fire in two-to-four years prior, with 60% experiencing two preceding incidents: one in 2017 and another in 2019. The initial fire drastically reduced plant cover and tree height, with subsequent fires causing minor additional loss. Post-fire recovery was negligible within the initial four years, even in patches without recurrent fires. The likelihood for an initial burn to trigger subsequent fires within a few years was high, leading to larger, more severe fires. We conclude that ANP's dry forests exhibit high vulnerability and low resilience to anthropogenic fires. Prompt preventive measures are essential to halt further fire spread and conserve the park's unique and invaluable biodiversity.

Storm Surges and Sea Level Rise Cluster Hydrological Variables Across a Coastal Forest Bordering a Salt Marsh

AbstractSea level rise and storm surges drive coastal forest retreat and salt marsh expansion. Both salinization and flooding control ecological zonation and ecosystem transition in coastal areas. Hydrological variables, if coupled with ecological surveys, can explain the different stages of coastal forest retreat and marsh encroachment. In this research, long‐term data of a host of hydrological variables collected along transects from marsh to inner forest were analyzed. Linear discriminant analysis (LDA) was used to identify the primary hydrological variables responsible for the forest‐marsh gradient and their seasonal patterns. Water content (WC) in the soil (WC) and groundwater electrical conductivity (EC) were found to be the main variables responsible for the hydrological differences among the sites. Higher values of WC and EC were found in the low‐forest area near the salt marsh, with hydrological differences between forest levels reflected in ecological community structure. In particular, some sites were characterized by high EC while others by high WC values, suggesting significant spatial variations within hundreds of meters. The forested area, relatively flat in elevation, was characterized by limited hydraulic gradients and consequently lateral discharges. These characteristics made the role of groundwater level negligible in driving the hydrological clustering. Seasonal LDA data suggest that the sites are hydrologically different during winter (higher distance among clusters of variables) and similar during summer (low distance among clusters). In the study area, higher rainfall occurs during summer, decreasing groundwater EC in areas characterized by low canopy cover (dying forest). Rainfall moved low forest sites closer to the pristine high forest in the LDA analysis. During storm surge events, the distance between clusters decreased, indicating uniform salinization and flooding across the forest. Therefore, we conclude that ecological zonation in a coastal forest is reflected in seasonal hydrological differences in the absence of storm surges. Storm surges do not produce contrasting hydrological conditions and might not be responsible for ecological differences in the short‐term. On the contrary, differences in hydrological recovery are responsible for forest zonation. An additional analysis carried out using a binary Marsh‐Healthy forest LDA classifier indicates when each site switches from a forest hydrological state to a salt‐marsh hydrological state. Our results are useful for long‐term predictions of the ecological evolution of the forest–salt marsh ecotone.

Tiger Habitat Quality Modelling in Malaysia with Sentinel-2 and InVEST

Deforestation is a threat to habitat quality and biodiversity. In intact forests, even small levels of deforestation can have profound consequences for vertebrate biodiversity. The risk hotspots are Borneo, the Central Amazon, and the Congo Basin. Earth observation (EO) now provides regular, high-resolution satellite images from the Copernicus Sentinel missions and other platforms. To assess the impact of forest conversion and forest loss on biodiversity and habitat quality, forest loss in a tiger conservation landscape in Malaysia is analysed using Sentinel-2 imagery and the InVEST habitat quality model. Forest losses are identified from satellites using the random forest classification and validated with PlanetScope imagery at 3–5 m resolution for a test area. Two scenarios are simulated using InVEST, one with and one without the forest loss maps. The outputs of the InVEST model are maps of tiger habitat quality and habitat degradation in northeast Peninsular Malaysia. In addition to forest loss, OpenStreetMap road vectors and the GLC2000 land-cover map are used to model habitat sensitivity to threats from roads, railways, water bodies, and urban areas. The landscape biodiversity score simulation results fall sharply from ~0.8 to ~0.2 for tree-covered land cover when forest loss is included in the habitat quality model. InVEST makes a reasonable assumption that species richness is higher in pristine tropical forests than in agricultural landscapes. The landscape biodiversity score is used to compare habitat quality between administrative areas. The coupled EO/InVEST modelling framework presented here can support decision makers in reaching the targets of the Kunming-Montreal Global Biodiversity Framework. Forest loss information is essential for the quantification of habitat quality and biodiversity in tropical forests. Next generation ecosystem service models should be co-developed alongside EO products to ensure interoperability.

Forest management affects ecosystem functioning (predation and herbivory) but not ecosystem constancy: A comparative study across four forest ecosystems around the world

Forest management can affect both the functioning and stability of ecosystems. Constancy and persistence are key factors that contribute to the overall stability of an ecosystem. These factors can be highly variable and change across forest ecosystems. We studied the effects of forest management on the strength of resource–consumer interactions (bird predation and insect herbivory) as important measures of ecosystem functioning, as well as on their constancy in time in four different forested regions globally. Within each region, we selected (i) three heavily managed or plantation forests, and (ii) three urban/peri-urban forests or urban plantings, and paired each of them with pristine/semi-natural forests. Bird predation was estimated using plasticine caterpillars of different colors. Chewer, galler, and miner herbivory on leaves were estimated for 15 plants (shrubs and trees) per study site. Constancy was quantified as the invariability of both predation and herbivory during a period of three (exceptionally two) years. We found no consistent responses of either predation or herbivory to forest management practices across study regions. Bird predation was higher in urban/peri-urban forests than in pristine/semi-natural forests in Patagonian and boreal forest, with intermediate levels of predation in managed or plantation forests. These differences might be explained by the increase of resource availability during the winters and by the higher abundances of generalist predators due to increase of temperatures (i.e., urban heat effect), for those regions where winter temperatures could be a limiting factor. Chewing insect herbivory was lower in urban/peri-urban forests, probably due to the exclusion of certain herbivores in response to warming and the higher predation pressure relative to pristine forests. No differences were found in other types of herbivory, indicating that effects of urbanization are guild-specific. In addition, we consistently found no effects of forest management practices on predation invariability and herbivory, thereby demonstrating the high constancy of ecosystem functioning to different forest management practices across regions. These findings advance our knowledge of the generalized effects of forest management on ecosystem functions and stability by establishing a connection between the ecology and management and conservation of plantations and natural forests.

Система мониторинга природной динамики лесного массива заповедника «Костомукшский»

The concept and current results of setting up the forest monitoring network at the Kostomukshska Strict Nature Reserve (Zapovednik) are presented. It has been demonstrated that pine forests predominate in the reserve’s forest cover (80.4 % of the forested area), followed by spruce (19.1 %) and birch (0.5 %). The ecological spectrum of the reserve’s forests comprises 7 groups of forest types, with the bilberry group prevailing (67 %) both among pine and among spruce stands. In terms of age structure, coniferous stands in the reserve are even-aged, multi-aged and all-aged, representing stages of the post-catastrophic regeneration succession and phases of subclimax and climax community cycles. Analysis of spatial patterns in the distribution of pristine and secondary forests has shown that anthropogenically altered forests are mainly situated in the western part of the reserve, at the border with Finland. The eastern part is a concentration of pristine north-taiga forests with a distinct mosaic of natural age dynamics phases. It was suggested that the forest monitoring network should be based on the landscape typological and spatial-temporal approaches taking into account the sublandscape-level structure of the reserve’s natural territorial complex and the distribution of forests in the study area by the rate of anthropogenic influence, prevalent species, forest types, and age structure types. Permanent sample plots will be established within 3 model areas (sites). For each of the 5 forest types of pine and 2 types of spruce stands, such plots should represent all age groups of even-aged stands (4 sample plots at maximum), and at least one sample plot should be allocated for each type (subtype) of the uneven-aged structure. The preliminary estimate is that, in total, there should be at least 98 permanent sample plots in the forest monitoring network of the Kostomukshskiy Zapovednik. So many units are needed to work out the algorithm for correcting the existing forest compartment characteristics given by the forest inventory in what concerns the age structure and the succession phase of stands. It is foreseen that all the factual material thus amassed will serve as the basis for modeling the scenarios of the natural dynamics of this forest massif and, perhaps, of other objects with similar structure. For citation: Raevsky B.V., Ilinov A.A., Medvedeva M.V., Rudkovskaya O.V. The Natural Dynamics Monitoring System of the Forests in the Kostomukshsky Reserve. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 6, pp. 81–101. (In Russ.). https://doi.org/10.37482/0536-1036-2023-6-81-101

Biological Integrity of Azorean Native Forests Is Better Measured in Cold Season

The Azorean archipelago, recognized as one of the world’s biodiversity hotspots, is home to a diverse and unique community of arthropod species, highlighting a notable degree of endemism. However, the native forests that support these species are facing significant degradation due to habitat loss and fragmentation. In this study, we aimed to determine the ideal season for measuring the biological integrity of forest sites using a biological integrity index (IBI) based on arthropod communities captured with Sea, Land, and Air Malaise (SLAM) traps. Drawing on more than thirty years of research experience in the Azorean forests, we selected twelve reference sites, six representing preserved native forest and six representing disturbed native forest, and compared how IBI values vary between seasons. IBI values exhibited consistent variations between seasons in disturbed sites, indicating that measuring the biological integrity in these areas can be conducted at any time of the year without a specific seasonal preference. In contrast, significant differences were observed in pristine forest sites, with the winter season and the combination of winter and spring data (cold semester) showing notably higher values compared to other seasons and semesters. This finding suggests that measuring the biological integrity of preserved sites is best optimized in the cold seasons, while the detection of exotic species impact is most effective in summer and autumn. Consequently, if resources are limited, monitoring efforts should be concentrated in the winter and summer seasons to obtain the maximum and minimum values of IBI, respectively. Additionally, our study suggests that the summer season is the optimal time to detect potentially invasive exotic species.

Palynological response deduced through spatially distinct surface samples to reconstruct palaeoecology and palaeoclimate of the Barak Valley, Assam (Indo-Burma region), northeast India

Establishing modern pollen analogues under various vegetation types in a location is necessary without which it is difficult to accurately interpret fossil pollen assemblages in any region in terms of the past environment and palaeoclimate. We have analysed the modern pollen dataset of 30 surface soil and sediment samples from the forested, cropland, wetland and river sites of the Karimganj District in south Assam, to comprehend the connection between the recent pollen assemblage and the vegetation patterns in the Barak Valley. The overall pollen data reflect the tropical moist deciduous and semi-evergreen forest comprising Syzygium, Schleichera, Terminalia, Lagerstroemia, Duabanga, Sapotaceae, Ilex, Mesua and Schima under a warm and humid climate in response to rainfall variations in the region. The presence of Euphorbiaceae and Convolvulaceae inferred high monsoonal activity in and around the region. A robust relationship between local herbaceous vegetation and pollen was observed. The steady occurrence of cereal pollen (average 18.67%) along with other cultural pollen taxa like Brassicaceae, Coriandrum and Solanaceae illustrate intense agricultural activity around the valley areas. Multivariate principal component analysis (PCA) and box plot were applied to the quantified data obtained from pollen frequency analyses of the surface samples which clearly revealed a significant variation and similarity in vegetation types. Thus, an attempt has been commenced to precisely observe the behavioural pattern of modern pollen deposition in a varied depositional setting, which could, in turn, help in assessing the expanse of agricultural practices and the depth of deterioration of pristine forests and surrounding areas. This modern training dataset could also help in the precise reconstruction of past climate and vegetation shifts in the Barak Valley region. A correlation of regional palynodata with other regions of the Indian subcontinent and Indo-Burma will also be assessed for better interpretation.

Emission characteristics of biogenic volatile organic compounds in a subtropical pristine forest of southern China

Emission characteristics of biogenic volatile organic compounds (BVOCs) from dominant tree species in the subtropical pristine forests of China are extremely limited. Here we conducted in situ field measurements of BVOCs emissions from representative mature evergreen trees by using dynamic branch enclosures at four altitude gradients (600–1690 m a.s.l.) in the Nanling Mountains of southern China. Composition characteristics as well as seasonal and altitudinal variations were analyzed. Standardized emission rates and canopy-scale emission factors were then calculated. Results showed that BVOCs emission intensities in the wet season were generally higher than those in the dry season. Monoterpenes were the dominant BVOCs emitted from most broad-leaved trees, accounting for over 70% of the total. Schima superba, Yushania basihirsuta and Altingia chinensis had relatively high emission intensities and secondary pollutant formation potentials. The localized emission factors of isoprene were comparable to the defaults in the Model of Emissions of Gases and Aerosols from Nature (MEGAN), while emission factors of monoterpenes and sesquiterpenes were 2 to 58 times of those in the model. Our results can be used to update the current BVOCs emission inventory in MEGAN, thereby reducing the uncertainties of BVOCs emission estimations in forested regions of southern China.

Distribution and characterization of nematodes in above-ground microhabitats in a natural pristine cedar forest in Yakushima Island, Japan

Nematode communities in natural pristine forests composed of trees aged over 1000 years have not been thoroughly studied. Old-growth forests can provide diverse microhabitats for nematodes such as fallen trees with mossy conditions. This study aimed to characterize the community and trophic compositions of nematodes in relation to different microhabitats in old-growth Japanese cedar ( Cryptomeria japonica (L. f.) D. Don) forests in Yakushima Island, Japan. To this aim, nematodes retrieved from four different types of microhabitats were morphologically identified at the family/genus level and divided into five trophic groups. A nonmetric multidimensional scaling scatterplot showed that nematode communities clustered significantly in each microhabitat and their community compositions were significantly affected by C/N ratio. With respect to nematode trophic composition, bacterivorous nematodes dominated decaying barks of fallen trees, with a relative abundance of 45%, while fungivorous nematodes were dominant in living barks of cedar trunks (61%). Predatory–omnivorous nematodes predominated in mosses of fallen trees (51%). These results showed that nematode community and trophic composition were different among microhabitats characterized by nutrient conditions. The predatory–omnivorous nematodes were abundant in mosses with N-rich conditions. In contrast, fungivorous nematodes were abundant in cedar trunks with high C/N conditions. Thus, old-growth natural forests can provide diverse microhabitats where various nematode taxa coexist due to the presence of fallen trees and mosses.

Human-driven degradation impacts on mangroves in southern Sierra Leone

Mangrove ecosystems remove carbon from the atmosphere and store it predominantly in soils constituting an important carbon sink. Additionally, they foster biodiversity and provide ecosystem services supporting local livelihoods and enhancing coastal protection. However, mangroves are declining in extent and experiencing degradation due to human activities as well as climate change impacts like sea-level rise and increasing frequency of extreme events. This study investigated how different levels of human-driven degradation affect forest structure, above- and belowground carbon stocks, tree species composition, and the population structures of dominant tree species. We investigated 19 transects of different degradation levels (pristine, moderately degraded, heavily degraded) in various locations (oceanic, riverine, interior) in the Sherbro river estuary in Sierra Leone.Results showed that total carbon stocks of pristine mangroves amounted to 707 Mg C ha−1 including soils to 1 m depth, which is higher than carbon stocks reported from many other regions in Africa.Degradation resulted in declining basal area, decreasing density of large trees (≥ 30 cm diameter) but increasing stem density of small trees (5–10 cm diameter). All carbon pools declined with increasing degradation across all locations. While above- and belowground carbon decreased by 96 %, soil carbon (up to 1 m depth) decreased by 44 %. Heavy degradation resulted in a change in the dominating species from Rhizophora racemosa to Rhizophora mangle across all locations. Overall, we found major effects of degradation on mangrove characteristics and minor effects of location. We urge conservation of pristine forests, restoration of degraded mangroves, and the establishment of management systems that are ecologically informed and based on a comprehensive understanding of human-driven degradation impacts.

Profile of tree-related microhabitats in the primeval Białowieża Forest: A benchmark for temperate woodlands

Tree-related Microhabitats (TreMs) are a key structural element having a significant impact on the biodiversity and functioning of forest ecosystems. Although forests enjoying long-term protection host richer and more abundant TreMs compared to managed stands, the quantity and quality of such microstructures in primeval temperate forests are unknown. This study investigates for the first time the assemblage of TreMs in the Białowieża Forest (BF), which is regarded as the last surviving fragment of pristine lowland forests in the temperate zone of Europe. Relatively undisturbed by human activity since the last glacial period, the BF ecosystem has remained remarkably intact, which may have given rise to its unique TreM assemblage. Here, we show that a primeval forest is characterized by an exceptionally high richness and density of TreMs compared to previously studied natural forests, and that the richness, density and diversity of TreMs are spatially heterogeneous at the micro-scale but homogeneous at the macro-scale. This indicates that adjacent small fragments of habitat (0.05 ha) may have different TreM profiles, but large patches of forest (several ha) host similar assemblages of TreMs. Our profile of TreMs depends on the basal area and density of living trees, the basal area of dead standing trees and the dominance of specific TreM-hosting tree species in a stand. Our study suggests that both the ecological continuity and complexity of a forest supporting many different tree species and the diversity of TreM-forming biota that typically occurs in primeval temperate forests are factors that appear to contribute to the observed profile of TreMs. The results of our study set a benchmark for the quantity and quality of TreMs in broadleaved temperate forests and indicate that the long-term spontaneous natural processes occurring in primeval forests lead to the emergence of ultra-rich, complex assemblages of TreMs.

Mosses in pristine and young lowland rain forests in north-eastern French Guiana

Mosses in pristine and young lowland rain forests in north-eastern French Guiana

Litter dynamics of forest ecosystem in an urban and pristine area of West Bengal, India

Aim: A comparative assessment of forest litterfall dynamics was carried out between the Garadaha forest (GF or urban) and the Pratappur forest (PF or pristine), located in Burdwan districts of West Bengal, and the litterfall components were correlated with the environmental factors that govern the dynamics. Methodology: Nets of dimension 1m × 1m were placed below the tress of both forests and litter was collected at regular intervals per month and brought to the laboratory for separation into the categories like leaf litter, woody litter (bark), miscellaneous (mixed) and twig. Two types of litterfall such as specific litterfall and standing litterfall were calculated. Environmental factors such as maximum and minimum temperature, rainfall, relative humidity, wind speed, solar irradiance, and photosynthetically active radiation (PAR) were studied simultaneously followed by correlation and Principal Component Analysis. Results: Pre-monsoon showed the highest total litterfall (specific litterfall and standing litterfall) in both types of forests. The decomposition quotient was higher in the pristine forest than in the urban forest. The correlation between litterfall components and environmental factors showed that solar irradiance was positively correlated with litterfall dynamics. Interpretation: The work emphasizes the forest management of urban areas impacted by industrialization and urbanization. The anthropogenic causes influence the plant growth and litterfall pattern thereby affecting the decomposition process and soil health. The selection of proper tree species should be given priority for social forestry in industrialized zones of India. Key words: Litter decomposition, Seasonal pattern, Solar irradiance, Standing litter, Temperature

Methanogens limited to lower rhizosphere and to an atypical salt marsh niche along a pristine intertidal mangrove continuum

AbstractMangroves are valuable ecosystems that facilitate primary production, carbon sequestration, and regulation of greenhouse gas (GHG) cycles in coastal sediments, with microorganisms playing key roles. Specialized bacteria and archaea compete for energy and resources in mangrove sediments to inhabit optimal ecological niches and can produce or consume methane (CH4)—a potent GHG—in the process. CH4 cycling in mangroves has gained growing attention, yet uncertainties regarding functional and spatial distributions of microorganisms remain. Here, we demonstrate that in a pristine mangrove forest, CH4 concentrations and methanogen communities are concentrated within lower or below rhizosphere depths. We also reveal atypical niches for methanogens in the upper tidal salt marsh zone where vegetation is sparse and highest methanogens abundances were detected at deepest depths (4715 reads g−1) despite relatively high redox potentials (&gt; 250 mV). Pore water CH4 concentrations were highest at the deepest depth within the mangrove forest (max. 3.40 ± 0.21 μM) and coincided with the highest sediment CH4 fluxes (276.4 ± 54.2 μmol m−2d−1) and methanotroph abundances at the surface (1309 reads g−1). Sediment CH4 oxidation fractions between the deepest (60 cm) and shallowest (5 cm) depths were estimated between 18.8% and 64.9%. Positive correlation between crab burrows and CH4 fluxes suggests that CH4 from deeper sediment and salt marsh niches can be transported via conduits to the atmosphere. The spatial data from this study highlights the importance of investigating CH4 dynamics across estuarine ecosystem gradients to better understand the complex roles of vital coastal vegetation zones in the face of a changing climate.

Effect of logged forests on diet of small characids from Neotropical streams

AbstractStudies relating to fish trophic ecology provide important insights regarding their life history. However, there is a lack of information linking fish diet composition with riparian cover in small streams. To investigate whether diet composition varied between streams with pristine and logged forests, I compared the food items consumed by four characid species: Bryconops melanurus, Moenkhausia collettii, Moenkhausia dichroura, and Moenkhausia oligolepis. I sampled 18 first‐order streams in the eastern Amazon: six with pristine forest, six with conventional logging, and six with selective logging. All fish species were classified as omnivorous, with diverse food categories recorded in their diets: mainly terrestrial insects for Moenkhausia species and aquatic insect nymphs for B. melanurus. However, the relative importance of each category varied only in streams with conventional logged forests. In these streams, all fish species consumed mainly autochthonous items, especially aquatic insect nymphs. In addition, terrestrial insects and seeds were absent in these streams with reduced riparian cover. In summary, this study highlighted that fish diet in conventional logged forests strongly differed from areas with pristine and selective logged forests. This finding states that managed forests may support a diverse diet for fish community, similar to that found in pristine forests. Therefore, management and conservation strategies of riparian vegetation in Amazonian streams are important to maintain habitat and food quality, which may be associated with a diverse diet for fish species.