Wet Forest Research Articles

A new leaf inhabiting ascomycete from the Jurassic (ca 170 Mya) of Yorkshire, UK, and insights into the appearance and diversification of filamentous Ascomycota

Leaf-associated fungi, the fungi that depend on leaves to sporulate, have a rich Cenozoic record, however their earlier diversity is poorly characterized. Here we describe Harristroma eboracense gen. et sp. nov., a Middle Jurassic leaf-associated fungus colonizing the leaf cuticle of Nilssonia tenuicaulis (cycadophyte). To place our newly described species into a picture of the diversification of Mesozoic fungi, we reassess fossils with leaf-associated stromata in the context of fungal molecular phylogeny. Being melanized, with radiate stromata, and on leaves, H. eboracense and other fossils from the Jurassic and earlier periods are probably related to filamentous Ascomycota in the superclass Leotiomyceta. Characters needed for further resolution of leaf-associated fungal biology and classification, such as the presence of an ostiole for spore discharge and appressoria for entry into leaf tissue first appear in the Mesozoic fossil record. Among Early Cretaceous fossils, Spataporthe taylorii represents the oldest unambiguous evidence of perithecial Sordariomycetes while Protographum luttrellii and Bleximothyrium ostiolatum are the oldest Dothideomycetes thyriothecia. Environmental observations show that broad leaved gymnosperms (especially cycadophytes) growing in warm temperate wet forests might have been the first environment for the radiation of Leotiomyceta.

Aridity and forest age mediate landscape scale patterns of tropical forest resistance to cyclonic storms

Abstract Cyclonic storms, or hurricanes, are expected to intensify as ocean heat energy rises due to climate change. Ecological theory suggests that tropical forest resistance to hurricanes should increase with forest age and wood density. However, most data on hurricane effects on tropical forests come from a limited number of well‐studied long‐term monitoring sites, restricting our capacity to evaluate the resistance of tropical forests to hurricanes across broad environmental gradients. In this study, we assessed whether forest age and aridity mediate the effects of hurricanes Irma and Maria in Puerto Rico, Vieques and Culebra islands. We leveraged functional trait data for 410 tree species, remotely sensed measurements of canopy height and cover, along with data on forest stand characteristics of 180 of 338 forest monitoring plots, each covering an area of 0.067 ha. The plots represent a broad mean annual precipitation (MAP) gradient from 701 to 4598 mm and a complex mosaic of forest age from 5 to around 85 years since deforestation. Hurricanes resulted in a 25% increase in basal area mortality rates, a 45% decrease in canopy height and a 21% reduction in canopy cover. These effects intensified with forest age, even after considering proximity to the hurricane path. The links between forest age and hurricane disturbances were likely due the prevalence of tall canopies. Tall forest canopies were strongly linked with low community‐weighted wood density (WD). These characteristics were on average more common in moist and wet forests (MAP >1250 mm). Conversely, dry forests were dominated by short species with high wood density (WD > 0.6 g cm−3) and did not show significant increases in basal area mortality rates after the hurricanes. Synthesis. Our findings show that selection towards drought‐tolerant traits across aridity gradients, such as short stature and dense wood, enhances resistance to hurricanes. However, forest age modulated responses to hurricanes, with older forests being less resistant across the islands. This evidence highlights the importance of considering the intricate links between ecological succession and plant function when forecasting tropical forests’ responses to increasingly strong hurricanes.

Girrimarring wiirrilgal bulany ngayanbading (bat nest-type fur sun-like): blending traditional knowledge and western science to create roosting habitat for the threatened golden-tipped bat Phoniscus papuensis

Context Despite being widely distributed along eastern Australia, the golden-tipped bat (Phoniscus papuensis) is listed as Vulnerable in New South Wales (NSW). The 2019–2020 wildfires affected an estimated 40% of foraging and roosting habitat, causing further conservation concern. The species roosts in suspended birds’ nests located along watercourses in rainforest or wet sclerophyll forests. Habitat augmentation is a key recovery action for the species; however, effective techniques are unknown. Aims We integrated western scientific and Indigenous cultural knowledge and practice to deliver an artificial roosting structure for golden-tipped bats, and designed and implemented a collaborative model for habitat restoration, with genuine opportunity for cultural practice and two-way knowledge sharing. Methods In partnership, members of Indigenous groups, western scientific organisations and volunteers shared learnings about bats, culture and caring for Country. Weaving materials were collected from local forests, roosts were woven and hung in rainforest gullies and monitored using remote cameras and direct visual inspection. Key results Golden-tipped bats used woven roosts, suggesting that roosting-habitat augmentation could support recovery of the species. Strong partnerships were established between government conservation programs and local Indigenous communities, engaging younger generations in cultural practice and learning. Delivery models were demonstrated for further collaborative, two-way threatened species projects. Conclusions Golden-tipped bats will use woven structures for roosting. Integrating Indigenous knowledge into threatened species programs can deliver effective conservation outcomes for specialist and cryptic species. Implications Should further broadscale fire, or other impact causing loss of roosting structures occur, community, Indigenous groups or government agencies can utilise this model to implement effective conservation actions together.

The biogeography of the Amazonian tree flora

We describe the geographical variation in tree species composition across Amazonian forests and show how environmental conditions are associated with species turnover. Our analyses are based on 2023 forest inventory plots (1 ha) that provide abundance data for a total of 5188 tree species. Within-plot species composition reflected both local environmental conditions (especially soil nutrients and hydrology) and geographical regions. A broader-scale view of species turnover was obtained by interpolating the relative tree species abundances over Amazonia into 47,441 0.1-degree grid cells. Two main dimensions of spatial change in tree species composition were identified. The first was a gradient between western Amazonia at the Andean forelands (with young geology and relatively nutrient-rich soils) and central–eastern Amazonia associated with the Guiana and Brazilian Shields (with more ancient geology and poor soils). The second gradient was between the wet forests of the northwest and the drier forests in southern Amazonia. Isolines linking cells of similar composition crossed major Amazonian rivers, suggesting that tree species distributions are not limited by rivers. Even though some areas of relatively sharp species turnover were identified, mostly the tree species composition changed gradually over large extents, which does not support delimiting clear discrete biogeographic regions within Amazonia.

Light quality and spatial variability influences on seedling regeneration in Hawaiian lowland wet forests

Abstract Tropical forest understories tend to be light‐limited. The red‐to‐far‐red ratio (R:FR) is a useful and reliable index of light quality and its spatial variability can influence competition between native and non‐native seedlings. While per cent light transmittance has been quantified in some Hawaiian lowland wet forests (HLWF), no information exists on how the spatial distribution of understorey light varies in relation to species invasion, or if patterns of seedling regeneration and light are linked. We measured the R:FR of light in the understorey to assess light quality in three HLWF forest types: native‐dominated, partially invaded and Psidium cattleyanum‐ (strawberry guava) dominated to quantify light quality in the understorey (0–50 cm height). We also identified relationships between light quality and native and non‐native seedling presence, diversity and abundance. Together, these data can help to determine the restoration potential of HLWF. Linear mixed‐effect modelling showed that native‐dominated forests had significantly greater R:FR than P. cattleyanum‐dominated forests, demonstrating a transformation in the light environment with increased invasion. Heterogeneity in R:FR varied more across sites than among forest types. In both native‐dominated and partially invaded forests, there were more native seedlings in the low‐quality R:FR (0.0–0.40) category and fewer in the medium‐ (0.41–0.70), and high‐quality (≥0.71) light categories than would be expected by chance, and there were no native seedlings in the P. cattleyanum‐dominated forests. Native‐dominated forests had greater species richness and abundance of native seedlings than the partially invaded forests, likely due to propagule availability. However, the spatial clustering of seedlings, the mismatch of native seedlings in light environments less suitable, and a considerable proportion of open high‐quality microsites, highlights that conditions are not optimal for native species in HLWF in the long term. Synthesis and applications. The native‐dominated and partially invaded forests still hold conservation value, despite variation among sites. Seedling additions could be targeted to different R:FR environments and at different spatial scales, but the lack of a strong relationship between R:FR and seedling number suggests that other factors besides light quality should be considered in seedling enrichment or other management activities.

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.

Anatomical traits explain drought response of seedlings from wet tropical forests.

Water availability regulates plant community dynamics but the drought response of seedlings remains poorly known, despite their vulnerability, especially for the Asian tropics. In particular, discerning how functional traits of seedlings mediate drought response can aid generalizable predictions of tree responses to global environmental change. We assessed interspecific variation in drought response explained by above- and below-ground seedling traits. We conducted a dry-down experiment in the greenhouse using 16 tree species from the humid forests of Western Ghats in southern India, chosen to represent differences in affinity to conditions of high and low seasonal drought (seasonality affiliation). We compared survival, growth, and photosynthetic performance under drought and well-watered conditions and assessed the extent to which species' responses were explained by seasonality affiliation and 12 traits of root, stem and leaf. We found that the species from seasonally dry forest reduced photosynthetic rate in drought compared with well-watered conditions, but seasonality affiliation did not explain differences in growth and survival. Performance in drought vs well-watered conditions were best explained by anatomical traits of xylem, veins and stomata. Species with larger xylem reduced their growth and photosynthesis to tolerate desiccation. In drought, species with smaller stomata correlated with lower survival even though photosynthetic activity decreased by a larger extent with larger stomata. Overall, anatomical traits of xylem and stomata, directly related to water transport and gas-exchange, played a more prominent role than commonly used traits (e.g., specific leaf area, leaf dry matter content) in explaining species response to drought, and may offer a good proxy for physiological traits related to drought tolerance of seedlings.

Management lessons from a long‐term captive‐breeding program for a critically endangered species, Leadbeater's possum, Gymnobelideus leadbeateri

AbstractLeadbeater's possums (Gymnobelideus leadbeateri) are a critically endangered marsupial found in a restricted area of cold, wet forest in South‐Eastern Australia. The majority of Leadbeater's possums inhabit highland forest, with one outlying lowland population. In 2012, a breeding program was established for the lowland Leadbeater's possums when this genetically distinct population faced imminent extinction. Successful reproduction by highland Leadbeater's possums in the international zoo‐based population between 1970 and 2010 led to the widespread belief that the species bred readily in captivity. Lowland possums have not bred in the 2012–2021 contemporary captive conservation breeding program. This study reviewed the historic captive‐breeding data and found that of the 84% (162/194) that reached reproductive maturity; 37% of males (n = 30) and 39.5% of females (n = 32) bred, and this success was highly skewed towards a subset of highly fecund individuals (14% of females and 15% of males produced 75% and 80% of all offspring). Although lack of reproductive output in the captive lowland animals could be explained if age at mortality was lower than that of highlands possums, comparison of the longevity of highland and lowland animals had no significant difference. Conservation objectives that specify how captive breeding may support in situ recovery of wild populations are integral to the success of captive programs. A lack of reflective analysis of past husbandry records allowed misconceptions of success and approaches implemented in the management of the breeding program, reducing the benefits for the conservation of this high profile threatened species. This case study provides a lesson for the management of conservation breeding programs and illustrates the importance of well‐defined conservation objectives, integration of in situ and ex situ strategies, and the importance of objective, systematic and timely analysis of available evidence to inform management objectives and improve conservation outcomes in real time.

Moderating effects of past wildfire on reburn severity depend on climate and initial severity in Western US forests.

Rising global fire activity is increasing the prevalence of repeated short-interval burning (reburning) in forests worldwide. In forests that historically experienced frequent-fire regimes, high-severity fire exacerbates the severity of subsequent fires by increasing prevalence of shrubs and/or by creating drier understory conditions. Low- to moderate-severity fire, in contrast, can moderate future fire behavior by reducing fuel loads. The extent to which previous fires moderate future fire severity will powerfully affect fire-prone forest ecosystem trajectories over the next century. Further, knowing where and when a wildfire may act as a landscape-scale fuel treatment can help direct pre- and post-fire management efforts. We leverage satellite imagery and fire progression mapping to model reburn dynamics within forests that initially burned at low/moderate severity in 726 unique fire pair events over a 36-year period across four large fire-prone Western US ecoregions. We ask (1) how strong are the moderating effects of low- to moderate-severity fire on future fire severity, (2) how long do moderating effects last, and (3) how does the time between fires (a proxy for fuel accumulation) interact with initial fire severity, day-of-burning weather conditions, and climate to influence reburn severity. Short-interval reburns primarily occurred in dry- and moist-mixed conifer forests with historically frequent-fire regimes. Previous fire moderated reburn severity in all ecoregions with the strongest effects occurring in the California Coast and Western Mountains and the average duration of moderating effects ranging from 13 years in the Western Mountains to >36 years in the California Coast. The strength and duration of moderating effects depended on climate and initial fire severity in some regions, reflecting differences in post-fire fuel accumulation. In the California Coast, moderating effects lasted longer in cooler and wetter forests. In the Western Mountains, moderating effects were stronger and longer lasting in forests that initially burned at higher severity. Moderating effects were largely robust to fire weather, suggesting that previous fire can mediate future fire severity even under extreme conditions. Our findings demonstrate that low- to moderate-severity fire buffers future fire severity in historically frequent-fire forests, underlining the importance of wildfire as a restoration tool for adapting to global change.

Anatomy of a post-wildfire recovery: Responses of mammals to a Black Summer wildfire in a fox-free landscape

Wildfires are predicted to increase in frequency and severity with climate change. Devising effective strategies to ensure wildfires do not hasten a decline in wildlife populations hinges on developing a deeper understanding of how species are affected by recent wildfires. I investigated the response of eight species of medium-sized mammals over a 4-year period (2020–2023) following a wildfire in the Australian Black Summer fire season. Pre-wildfire population levels were not known. These species differed in their ability to survive the passage of fire; from being able to flee the fire front, to remaining in protective shelters, to favouring unburnt forest types, to none of these strategies. Camera trapping was conducted from 5 months to 4 years after the fire across 62 sites in wet and dry sclerophyll forest (burnt and unburnt) and rainforest (unburnt) to characterise both initial survival and subsequent reproduction-led post-fire occupancy. There was consistency in the response of species in year 1. Those assumed to be able to flee the fires showed medium-high post-fire occupancy regardless of whether a site was burnt. Those that use protective shelters and unburnt forest also showed high occupancy. One species without these options showed greatly reduced occupancy in year 1 relative to years 3 and 4. Most species showed evidence of increased detection across years, which is inferred to reflect increased abundance, and was expected given substantially above average rainfall for three years following the fire. The feral cat was the only predator sufficiently widespread to be of concern in species’ recovery but was rarely detected in years 1 and 2, relative to years 3 and 4. This study provides evidence that many species, including three threatened species, have the ability to survive the passage of fire, and show high post-fire occupancy. The study landscape contained abundant habitat elements (unburnt rainforest, boulder fields) that promote survival through a wildfire and post-fire recovery, providing insights to guide future conservation actions.

Land use history and landscape forest cover determine tropical forest recovery

Abstract To conserve biodiversity and combat climate change it is vital to restore forest ecosystems. Natural forest regrowth is a nature‐based solution to restore forests, but it has rarely been evaluated how this is affected by the combination of previous land use intensity and surrounding forest cover, and how this varies between the two main tropical forest types; dry and wet forests. Thirty‐three plots were established on abandoned agricultural fields in a dry (13 plots) and wet (20 plots) tropical forest in Mexico and monitored 3 years for the following tree community attributes: structure, diversity, regeneration mode, potential symbioses with N fixing bacteria and mycorrhizal fungi. Previous land use intensity was described using interviews, and landscape forest cover and fragmentation within a 1000 m radius surrounding the plots were quantified using satellite images. Variable importance analyses indicated that land use intensity was more important than forest cover and fragmentation for the state of the tree community attributes after 3 years. This suggests that previous land use impacts the start of succession and leaves important legacies on the vegetation. Land use intensity, forest cover and fragmentation were equally important in determining the change in tree community attributes over time, indicating that both management practices and dispersal shape subsequently community assembly. A higher land use intensity decreases tree richness recovery, while size of the largest forest patch decreases tree density and connectivity of these patches increases tree density. The dry forest had a faster increase in tree density recovery compared to the wet forest through a high initial resprouting capacity and abiotically dispersed trees. Synthesis and applications: Both a higher land use intensity and fragmented forest landscape decreases the speed of forest recovery, indicating that human actions and landscape transformation shape the course of succession. Restoration in fragmented forest landscapes through natural regeneration is more suitable in areas with low previous land use intensity, higher forest connectivity and abiotically dispersed species. Effective restoration should therefore consider both land use history and landscape forest cover and be tailored to local socio‐ecological conditions.

Quantifying habitat and biodiversity services and hotspots of Indian forests: A GIS-Based assessment

The present study attempted to quantify and value of supporting services of India's forest ecosystem. The supporting services comprises by habitat and biodiversity services across India's sixteen forest types was estimated using data for various factors through Remote Sensing and secondary sources as per the proposed model. Indicators were combined using an Analytical Hierarchical Process, and various class of each service was also estimated using the equal interval method in QGIS. Hotspot analysis was used to identify key areas for forest conservation. The results suggest that littoral and swamp forest had maximum habitat services and tropical semi-evergreen forest had maximum biodiversity service and tropical wet evergreen forest had maximum supporting services. Out of total forest of country, 11.52%, 17.48% and 10.34% forest area was having high value for habitat, biodiversity and supporting service, respectively. Hotspot analysis revealed that 22.93%, 23.61% and 26.44% Indian forest had high habitat, biodiversity and supporting service, respectively. The annual per hectare economic value using Benefit Transfer method for habitat, biodiversity and supporting services of forests was US$ 4330.71, US$ 5987.38 and US$ 10,624.23, respectively. The annual economic value of habitat, biodiversity and supporting services from Indian forests was US$ 303,506.09 million, US$ 419,609.45 million and US$ 744,570.85 million, respectively. In totality, tropical dry deciduous forest, tropical moist deciduous and tropical semi-deciduous forest had high economic value for supporting service. Monetary valuation of forest ecosystem services assists to determine the net present value and costs for conservation interventions. Biodiversity hotspots as the Western Ghats, Indo-Burma region, and Eastern Himalayas offer high ecosystem service and thus attach prime importance for conservation, while the Western Himalayas, with lower ecosystem service, requires customized ecosystem management strategies.

Future climate doubles the risk of hydraulic failure in a wet tropical forest.

Future climate presents conflicting implications for forest biomass. We evaluate how plant hydraulic traits, elevated CO2 levels, warming, and changes in precipitation affect forest primary productivity, evapotranspiration, and the risk of hydraulic failure. We used a dynamic vegetation model with plant hydrodynamics (FATES-HYDRO) to simulate the stand-level responses to future climate changes in a wet tropical forest in Barro Colorado Island, Panama. We calibrated the model by selecting plant trait assemblages that performed well against observations. These assemblages were run with temperature and precipitation changes for two greenhouse gas emission scenarios (2086-2100: SSP2-45, SSP5-85) and two CO2 levels (contemporary, anticipated). The risk of hydraulic failure is projected to increase from a contemporary rate of 5.7% to 10.1-11.3% under future climate scenarios, and, crucially, elevated CO2 provided only slight amelioration. By contrast, elevated CO2 mitigated GPP reductions. We attribute a greater variation in hydraulic failure risk to trait assemblages than to either CO2 or climate. Our results project forests with both faster growth (through productivity increases) and higher mortality rates (through increasing rates of hydraulic failure) in the neo-tropics accompanied by certain trait plant assemblages becoming nonviable.

Worldview, Conflicting Spiritualities and Religious Ecology in Nigeria

Abstract This article contributes to the religion and environment field by analyzing the environmental impact of two divergent ethical responses within Nigerian Christianity. Based on different interpretations of a specific aspect of African spiritual cosmologies, African Indigenous churches (AIC s) and African independent Pentecostals (AIP s) in Nigeria have formulated conflicting spiritualities that shape their ecotheologies. Based on this same cosmology, the ecotheology of the AIC s shows continuity with the indigenous notion of sacred space which also encourages the preservation of the ecosystem especially trees and wet forests. The AIP s, on the other hand, interpret the same notion differently by segregating the public space into holy and evil ecologies. To rid these habitats of perceived evil spirits in the ecosystem, some AIP s have constructed a theology of evangelism and spiritual warfare to expel these spirits by destroying their habitats and converting such habitats into holy use such as building churches and prayer camps. Based on data obtained through observation and literature, the proliferation of prayer camps along the Lagos-Ibadan Expressway is analysed as a product of these notions of holy and evil ecologies.

Photographic monitoring of glowworm Arachnocampa luminosa (Diptera: Keroplatidae) bioluminescence in a tourist cave reveals diurnal and annual cycles

AbstractGlowworms are the bioluminescent larvae of a group of dipteran insects related to fungus gnats. They require sheltered, consistently moist conditions and are found in aggregations on the walls and ceilings of caves and near streams in wet forests where they attract flying insects as prey. The Waitomo Glowworm Cave in New Zealand receives many thousands of visitors each year to see the colony of the glowworm, Arachnocampa luminosa. The cave climate is managed to ensure the glowworms are not harmed by influxes of dry air, as happened in the 1970s. To monitor the population and warn of catastrophic population declines, time‐lapse photographic monitoring of the glowworm population began in 2011 using a permanent, fixed camera. Photographs are taken 30 min apart. The population exhibits synchronised diurnal cycles of bioluminescence intensity. The time of the acrophase (the peak) of the diurnal cycle varied seasonally between 5 pm in early southern spring and 8 pm in summer. Cross‐correlation analyses with cave and water temperatures incorporating time lags suggest that this annual cycle could be related to changes in the composition or density of prey insects. Annual cycles also occur in the number of glowing larvae and their overall intensity. In most years, the numbers are lowest in winter and increase in spring to produce the brightest display through summer. The summer peak is not seen every year and autocorrelation of the 13‐year time series of count shows signs of a 3‐ to 4‐year cycle beyond the annual periodicity. The availability of prey in the cave chamber could influence the annual cycles in glowworm density, underscoring the need for a deeper knowledge of the bionomics of prey species, mainly Chironomidae (non‐biting midges). The photographic monitoring has proven to be a useful component of the management of the glowworm population.

Identifying biodiversity surrogates and management indicator species for tall, WET Forests: A case study of australian arboreal marsupials

Halting the loss of biodiversity is a major challenge for humanity given the number of species at risk, the limited resources dedicated to conservation relative to levels of investment that are needed, and the impossibility of monitoring all threatened species, even in wealthy nations. Some of these challenges might be possibly addressed, in part, if conservation shortcuts could be found. These include the use of surrogates, proxies, and indicators in which easy to measure entities can accurately reflect the remainder of, for example, a particular assemblage of species.In the work reported here, we explored the indicator potential of particular species of arboreal marsupials in the tall, wet forests of south-eastern Australia. We did this through an empirical exploration of co-occurrence patterns using an analysis of a long-term dataset on arboreal marsupials that we gathered between 1997 and 2022 at 178 permanent field sites.Our analyses contained evidence of positive co-occurrence relationships between some pairs of species, but negative ones between others. In addition, relatively high levels of overall species richness in the arboreal marsupial assemblage were associated with four of the six species we analysed. We then tested the idea that these co-occurrence patterns were context-dependent. Although context dependence is a familiar issue in ecology, its importance for recognizing and understanding the limitations of surrogates like indicator species is often not well recognised. Indeed, we present evidence that some co-occurrence patterns varied across time and in response to key aspects of forest condition including the availability of nest sites in hollow-bearing trees, forest type, and stand age. We discuss these findings in relation to how context dependence can help us understand the applicability and limitations of ecological indicators. Our findings, based on long-term data, suggest that focused management efforts for a particular species as a “management indicator species” will not necessarily ensure positive outcomes for other species across all contexts. Therefore, targeted conservation efforts may be required for individual species, particularly species of conservation concern.

Stream chemical response is mediated by hydrologic connectivity and fire severity in a Pacific Northwest forest

AbstractLarge‐scale wildfires are becoming increasingly common in the wet forests of the Pacific Northwest (USA), with predicted increases in fire prevalence under future climate scenarios. Wildfires can alter streamflow response to precipitation and mobilize water quality constituents, which pose a risk to aquatic ecosystems and downstream drinking water treatment. Research often focuses on the impacts of high‐severity wildfires, with stream biogeochemical responses to low‐ and mixed‐severity fires often understudied, particularly during seasonal shifts in hydrologic connectivity between hillslopes and streams. We studied the impacts of the 2020 Holiday Farm Fire at the HJ Andrews Experimental Forest where rare pre‐fire stream discharge and chemistry data allowed us to evaluate the influence of mixed‐severity fire on stream water quantity and quality. Our research design focused on two well‐studied watersheds with low and low‐moderate burn severity where we examined long‐term data (pre‐ and post‐fire), and instantaneous grab samples collected during four rain events occurring immediately following wildfire and a prolonged dry summer. We analysed the impact of these rain events, which represent the transition from low‐to‐high hydrologic connectivity of the subsurface to the stream, on stream discharge and chemistry behaviour. Long‐term data revealed total annual flows and mean flows remained fairly consistent post‐fire, while small increases in baseflow were observed in the low‐moderately burned watershed. Stream water concentrations of nitrate, phosphate and sulfate significantly increased following fire, with variance in concentration increasing with fire severity. Our end member mixing models suggested that during rain events, the watershed with low‐moderate severity fire had greater streamflow inputs from soil water and groundwater during times of low connectivity compared to the watershed with low severity fire. Finally, differences in fire severity impacts on concentration‐discharge relationships of biogenic solutes were most expressed under low catchment connectivity conditions. Our study provides insights into post‐wildfire impacts to stream water quality, with the goal of informing future research on stream chemistry responses to low, moderate and mixed severity wildfire.

Modern pollen and non-pollen palynomorphs from sub-tropical central India: discerning anthropogenic signal in surface pollen assemblages

Interpretation of past vegetation using pollen analysis depends on our understanding about the relationship between the modern vegetation and surface pollen assemblages. In the present study, we sampled the modern pollen-rain in a mixed environment of cultivated land and dry and wet tropical forests in central India. We established to which extent modern vegetation types are reflected in the pollen-rain and explained biases in the modern pollen spectra. Our study revealed that the modern pollen assemblages do not fully represent the extant regional vegetation, as many of the forest components, especially trees and shrubs, are either under-represented or remained palynologically silent in the pollen records. Low pollen productivity of most of the tropical deciduous taxa, owing to entomophily, as well as low preservation potential of some tree pollen are primarily responsible for this irregularity in their representation in the pollen spectra. Moreover, Shorea robusta and Tectona grandis pollen, despite being high pollen producers, are not encountered in any sample, which could be further attributed to their poor preservation in surface soil samples, as well as to their low (pollen) dispersal efficiency. Cerealia, Amaranthaceae, Caryophyllaceae, Brassicaceae, Cannabis sativa, Artemisia spp. and Alternanthera spp. indicate agricultural practices and other human activities around the respective study areas. Moreover, the consistent presence of Asteroideae pollen indicates pastoral activities, whereas Sporormiella spp., Sordaria spp., Podosora spp., Delitschia spp., and Cercophora spp. indicate local grazing and herbivory.

Habitat niches of bird species along a recovery gradient in the Chocó tropical forest

Conservation programs need improved tools to measure the recovery of animal diversity across restoration gradients. We used soundscapes and expert identifications of bird species to calculate niche position (i.e., mean of environmental conditions across all areas a species occupies) and niche breadth (i.e., the standard deviation of the species distribution) along a recovery gradient; from agriculture to early (up to 20 yrs) and late (up to 38 yrs) recovery, to old-growth forests. Our survey included 323 bird species and was conducted in 66 plots in the lowland Chocoan tropical rainforest in Ecuador where less than 11% of the forest remains intact, and large areas are currently undergoing regeneration post-abandonment. First, we validated our niche metrics by contrasting them against independent global categories of forest density dependency. We then explained the niche metrics of the bird species with different ecological traits, gathered from the literature, reflecting species-specific primary diet, morphology and distribution, and accounting for the phylogenetic relatedness of species. Finally, we explored the phylogenetic signal present in bird species’ ecological traits and recovery niche metrics. Niche position and breadth across the recovery gradient closely followed global categories of forest density dependency. However, our approach provided a more fine-scaled sorting of bird species in forest plots categorized as late recovery and old-growth. Granivorous birds occupied niche positions in active cacao and pasture plots and were replaced by frugivorous birds in older regeneration plots. Along the recovery gradient, tail length and handwing index decreased with niche position, supporting previous observations that birds in old-growth forests are less mobile. Birds in old-growth forests had smaller global distribution ranges than birds in agricultural plots. Finally, the latitudinal distribution of birds in the study area averaged south of the equator, with birds in old-growth plots averaging latitudinal centroids in wet forests north of the equator, whereas birds in agriculture plots averaged latitudinal centroids further south of the country, towards the dry and open Tumbesian forest. Frugivores, invertivores and vertivores had broader niche breadths, but these decreased (marginally) with tail length. We suggest these recovery niche metrics as a potentially powerful tool for the rapid assessment of the recovery process, which might support conservation strategies such as biodiversity credits, compensation payments, and strategic land purchases. With the increasing availability of information-intensive models for bird species identification, such as deep learning artificial intelligence, our new niche metrics open the avenue for rapid assessment of tropical biodiversity and new conservation areas at larger scales.

Linkages among forests, food security and livelihoods: A comparative analysis of tropical dry forests and tropical wet evergreen forests in Sri Lanka

Forests are increasingly recognised as an important contributor to food security and nutrition, especially for the poorest people, in various ways. Their roles and impacts including the degree of access to forest-based nutrition to the poorer segments however vary depending on the specific geographic and socio-political contexts and forest types. This study examines the nature of forest dependence for food security and nutrition in two dominant forest types in Sri Lanka, namely dry humid forest and wet evergreen forests. Proportionate to the forest cover area in either forest system, this study enumerated 500 households in the dry forest ecology and 190 households in the wet evergreen forest ecology. The findings provide a first quantitative benchmarking of the nature of forest food collection and modelling of the socio-demographic factors determining the forest food collection in the Sri Lankan context. The results show that food produce collection in terms of quantity and value are significantly higher in the wet evergreen forest system and the factors driving the dependence on forests are tied to agricultural involvement of the households. Other factors such as economic status, education, accessibility of the forest emerge statistically insignificant. On the other hand, in dry humid forests, economic status and access to forest become significant factors. Evidence confirms the location specific nature of forest food connection and make the case for context-relevant interventions to foster forest-food interface.