Dry Forest Species Research Articles

Above and belowground functional trait response to biochar addition in seedlings of six tropical dry forest tree species

Above and belowground functional trait response to biochar addition in seedlings of six tropical dry forest tree species

Revealing suitable habitats for Juniperus procera and Olea europaea tree species in the remnant dry Afromontane forests of Ethiopia: Insights from ensemble species distribution modeling approach.

Human activities and climate change pose a significant threat to the dry Afromontane forests in Ethiopia, which are essential for millions of people both economically and ecologically. In Ethiopia, trees are planted elsewhere even if they are not likely to be well suited to the area. This study aims to identify the suitable habitat for the most exploited Juniperus procera (J. procera) and Olea europaea (O. europaea) tree species in northern Ethiopia. As inputs, least correlated temperature, moisture, soil, and topographic variables were selected through a stepwise procedure. The study evaluated five individual and ensemble models using the area under the curve (AUC) and true skill statistic (TSS) values. The ensemble model outperformed with mean AUC of 0.95 and TSS of 0.78 for J. procera, while securing the second position for O. europaea with an AUC of 0.88 and TSS of 0.71. Climatic factors emerged as the most influential, followed by soil and topography. Suitable areas for both species were found when Isothermality (Bio3) values range from 52% to 62%, temperature seasonality (Bio4) of 16-29°C. Moreover, well drained soils with soil texture not heavier than sandy clay, and soil organic carbon ranging from 5 to 42 g kg-1 were found suitable. The optimal suitable altitude for J. procera and O. europaea was determined to be 2200-2600 and 2100-2500 m.a.s.l., respectively. The suitable areas for J. procera and O. europaea were estimated to be 3130 and 3946 km2, respectively. Furthermore, potential plantation areas were identified beyond Desa'a and Hugumbirda Grat-Kahsu protected forests, covering 2721 km2 (86.9%) for J. procera and 3576 km2 (90.6%) for O. europaea. These findings hold significance for the conservation and sustainable management of these valuable tree species in northern Ethiopia. We recommend implementing a similar approach for other locally restricted dry Afromontane tree species with wider potential distribution.

Vegetation Structure, Composition and Plant Community types in Tropical Dry Deciduous Forests of Jaipur, Rajasthan, India

The research was carried out in the Aravalli Forests of Nahargarh (NWLS) and Jamwa Ramgarh Wildlife Sanctuaries (JRWLS) of Jaipur, Rajasthan, India. The vegetation structure, composition, biodiversity and plant community types were assessed across the five forest stands viz Nahargarh biological park (S1), Nahargarh Sanctuary (S2) in NWLS and Ramgarh (S3), Raisar (S4), and Digota (S5) of JRWLS, respectively. A total of 164 qaudrats of 20*20 m2 were laid to assess the vegetation data including frequency, basal area, density, importance value index (IVI), biodiversity indices (Shannon-weiner, Simpson, Pielou and Margalef’s) and plant community types. The tree basal area ranged between 18.56 -34.36 m2/ha while stand density was 923-1433 tree/ha. Our study indicated the dominance of family Fabaceae with 20 species and 11 genera with Anogeissus pendula showing the maximum frequency, density, mean basal area and IVI. Further, the agglomerative hierarchal clustering showed five types of plant communities with Anogeissus-Adhatoda as the most widely spread community in these forests. Among the two sanctuaries, species diversity was higher for JRWLS (2.83) than NWLS (2.80). The current study provides important baseline data for forthcoming research on monitoring and preserving these forest’s biological diversity. The significance of present study will provide insight into the structure and variety of tree species in tropical dry deciduous forests.

Leaf spectrum analysis of three tropical timber species: Diomate (Astronium graveolens), Choibá (Dipteryx oleifera), and Algarrobo (Hymenaea courbaril)

This study analyzed the leaf spectral response of three native timber forest species in the tropical dry forest: Diomate (Astronium graveolens Jacq.), Choibá (Dipteryx oleifera Benth.), and Algarrobo (Hymenaea courbaril L.). The study was conducted at the León Morales Soto Arboretum and Palmetum, at the Universidad Nacional de Colombia in Medellín, Antioquia, Colombia. Spectral data from the leaves were collected in situ using the portable spectroradiometer ASD FieldSpec HandHeld-2, which operates with a spectral resolution of 1 nm (resampled to 10 nm) and covers a spectral range between 325 and 1,075 nm (limited to 400-900 nm). Based on the measurements, the behavior and spectral variability of the species were evaluated. One-factor Analysis of Variance and Mann Whitney-Wilcoxon U-test were implemented in reflectance spectra to select the optimal narrow bands for species discrimination. The classification capacity of the selected narrow bands was assessed using the K-nearest neighbors’ algorithm. It was found that A. graveolens and H. courbaril exhibited spectral signatures typical of healthy vegetation, while D. oleifera showed spectral changes during the early stages of senescence. Regarding spectral separability, 23 narrow bands in the visible region and near-infrared region were identified as optimal for distinguishing the plant species. The supervised classification algorithm applied to these 23 narrow bands achieved an overall accuracy of 95.8%. In conclusion, these findings provide valuable insights into the spectral response of important tropical species and contribute to their conservation efforts by enhancing understanding of their unique spectral characteristics in diverse and heterogeneous ecosystems like tropical forests.

Differences in germination traits of time-separated seed collections of dry forest species from Central Zambia and the potential role of climate

Abstract Time-separated seed collections with a separation period of 12–18 years were used to study recent changes in germination traits and the role of climate factors in seven tropical dry forest (TDF) woody species in Zambia, southern Africa. In all the species, peak and final germination were lower in recent (2016–2021) seed collections than in historic (1998–2005) seed collections during the first germination season. However, in species with seed dormancy, both peak and final germination after one year burial were higher in recent seed collections than in historic seed collections. Three monthly climate factors had significant effects on final germination in the different species and the timing of most of these factors was during seed development and ripening that suggest that these factors operated through mother plants. In species with seed dormancy, post-first-year germination of buried seeds responded to climate factors in the regeneration niche. Climate factors that significantly affected germination included those that changed over the separation period between historic and recent seed collections. This indicates that short-time climatic changes may have the potential to impact germination in TDF woody species of southern Africa. The germination responses to climate factors were both positive and negative and it is not clear whether these are adaptations or not. Further research is required to assess the adaptive significance of these changes in germination traits in TDF species of southern Africa.

Crown cover of a dominant pioneer legume affects tree species regeneration in a secondary tropical dry forest

Background: Individual pioneer tree species often dominate early tropical dry forest succession and thereby affect possible successional pathways. Mimosa acantholoba var. eurycarpa is a highly dominant species in the tropical dry forest in Mexico.
 Hypothesis: Mimosa acantholoba var. eurycarpa exerts an inhibitory effect on the germination, establishment, survival, and early growth of light-demanding pioneers, while facilitating these processes for shade-tolerant old-growth forests species.
 Studied species: Lonchocarpus torresiorum, Lysiloma divaricatum, Mimosa acantholoba var. eurycarpa and Vachellia farnesiana.
 Study site and dates: Nizanda, Oaxaca, Mexico, 2020-2021.
 Methods: In 12 early successional plots, we applied three levels of crown cover removal (100, 50, and 0 %) of established trees of the dominant pioneer legume (M. acantholoba var. eurycarpa). We sowed seeds of the four study species in each experimental plot and recorded their germination, establishment, survival, and early growth over a 2-mo period.
 Results: The removal of crown cover of established M. acantholoba var. eurycarpa trees did not significantly affect germination. Lysiloma divaricatum had the highest germination probability, the fastest germination, and the highest establishment probability regardless of treatment. Lonchocarpus torresiorum had the highest establishment probability in plots where the crown cover of established M. acantholoba var. eurycarpa trees was removed The survival probability of both shade-tolerant species was highest in the 100 % removal treatment.
 Conclusions: Despite successful germination of shade-tolerant species, their survival is inhibited under the dense canopy of the dominant legume. Therefore, interventions to reduce the crown cover area of this dominant legume may stimulate forest recovery.

Effect of intraspecific seed trait variation on the germination of eight tropical dry forest species

Functional traits can have intraspecific and interspecific variations essential in the structure and dynamics of natural communities. These traits may have implications in the germination and seedling establishment phases in seeds. The objective of this study was to evaluate the effect of variations in mass, volume, and nutrient content (C, N, and P) on the germination of eight species representative of the tropical dry forest (TDF). Our results showed that seed size, both in terms of mass and volume, did not predict germination rates or percentages, nor were they related to nutrient content. In contrast, N content was the most important trait in the germination phase. Larger seeds did not germinate more or faster, but they could offer better resistance against desiccation, since they had higher C/N ratios in their tissues, a characteristic of orthodox seeds. The species A. guachapele, B. arborea, H. crepitans, and V. tortuosa presented a high biological potential in terms of their regeneration capacity, particularly, because the characteristics of their seeds, as well as the nutrient content, revealed consistent implications in their reproductive success, promoting high germination percentages in less time. In general, the results obtained in this study provide basic knowledge for future research, offering starting points for further exploration of species-specific adaptations and how they may be affected by the environment.

Influence of anthropic disturbance in structure of plant populations along an elevation gradient in caatinga region

Elevation gradients are useful models for testing how the variation of abiotic factors and anthropogenic disturbance modulate the population structure of plant species. Despite the small range of elevation, mountains in the semi-arid region of Brazil are subject to different levels of anthropic pressure. We investigated whether structural parameters of two species (Croton blanchetianus Baill. and Cenostigma pyramidale (Tul.) Gagnon & G.P. Lewis) with wide distribution in Caatinga, vary along an elevation gradient. We established 45 plots on three elevation levels. Next, we calculated abundance, percentage of tiller individuals, number of tillers, average diameter, average height, basal area, and above-ground biomass in each plot. Additionally, we recorded six metrics of chronic anthropogenic disturbance (CAD) in each plot. We tested whether species parameters differed between elevation levels and evaluated the influence of CAD on the structural parameters of each species. Abundance, percentage of tiller individuals, and number of tillers were higher at the gradient base for the two species. The metrics of CAD significantly influenced abundance and number of tillers, showing that there is an increase in these parameters in the most disturbing areas. The high capacity for regrowth of dry forest species provides resilience; however, it can contribute to proliferating populations of generalist species tolerant to environments with high rates of CAD. The study highlights relevant observations related to the ecology and distribution of plant populations in the Caatinga, mainly related to elevation gradient recognized as important refuges of biodiversity in this region of Brazil.

Comparative phylogeography shows congruent co‐divergence in Neotropical seasonally dry forest and savanna tree species

AbstractAimThe response of South American seasonally dry tropical forest (SDTF) and savanna species to the Quaternary climate changes is still poorly understood. Here we use multi‐model inference approach to compare the phylogeography and demographic history of five trumpet tree species (also known as pau‐d'arco) and draw general biogeographical patterns: Handroanthus impetiginosus, H. ochraceus, H. serratifolius, Tabebuia aurea and T. roseoalba.LocationAmazonia, Atlantic Forest, Cerrado and Caatinga ecoregions, South America and Brazil.TaxaBignoniaceae, Tabebuia Alliance, trees.MethodsWe compiled genetic data, occurrence records and ecological niche modelling (ENM) from published articles. We used coalescent modelling to test patterns of co‐divergence, and analysed niche breadth and overlap and spatial patterns in genetic diversity using quantile regressions.ResultsSpecies showed concordant lineage divergence times in the Pleistocene. Lineage diversification and phylogeographical patterns are more related to species niche breadth than to biome (savanna or SDTF). Differences in genetic diversity among species matches the expected for the demographic scenarios obtained with coalescent simulations and ENMs: species with wider range expansion during the Last Glacial Maximum had higher diversity than species with range retraction or multiple refugia.Main ConclusionsDiversification burst in the Pliocene, and major diversification of lineages during the Pleistocene seems to be a general pattern in SDTF and savannas in the South America. The high number of haplotypes at the Central Brazil, corresponding to the Cerrado ecoregion, highlights the importance of Protected Areas for SDTFs and savannas, highly threatened biomes in Brazil.

Foliar disease incidence in a tropical seedling community is density dependent and varies along a regional precipitation gradient

Abstract Many studies identify fungal and oomycete phytopathogens as natural enemies capable of influencing plant species composition and promoting diversity in plant communities. However, little is known about how plant‐pathogen interactions vary along regional abiotic gradients or with tree species characteristics, which limits our understanding of the causes of variation in tree species richness. We surveyed 10,756 seedlings from 272 tree species for disease symptoms along a mean annual precipitation gradient in the tropical wet forests of Central Panama for 3 months in the early wet season (June–August) and 2 months in the following dry season (March–April). Over 99% of observed disease symptoms were caused by necrotrophic foliar pathogens, while less than 1% of symptoms were attributed to soilborne pathogens. Foliar disease incidence was inversely related to mean annual precipitation, a pattern which may be due to greater disease susceptibility among dry forest species. Foliar disease incidence increased with conspecific seedling density but did not respond to the proximity of conspecific adults. Although foliar disease incidence decreased as mean annual precipitation increased, the strength of conspecific density‐ or distance‐dependence was independent of the precipitation gradient. Seedlings of common tree species and species dispersed by non‐flying mammals had a higher risk of foliar pathogen incidence. Increased disease in common species may help reduce their dominance. Synthesis. The increases in foliar pathogen incidence with conspecific seedling density, species abundance, and dispersal mechanism indicate that foliar disease incidence is non‐random and may contribute to the regulation of tropical plant communities and species coexistence. Furthermore, the relationships between foliar disease incidence, dispersal mechanism and precipitation suggest plant‐pathogen interactions could shift as a response to climate change and disruption of the disperser community.

Vertical root development of seedlings grown in deep containers: Comparison of five tropical dry forest species in Myanmar

Vertical root development of seedlings grown in deep containers: Comparison of five tropical dry forest species in Myanmar

Canopy-mediated microclimate refugia do not match narrow regeneration niches in a managed dry conifer forest

Structurally heterogeneous forest conditions provide diverse microclimates which can support juvenile tree regeneration, survival, and growth. However, the extent to which juvenile trees depend on moderated microclimates depends on their physical maturity and species-specific tolerances for environmental stresses related to variables like soil moisture, heat, and shade. Linking juvenile responses to microclimates for different life-stages and species facilitates more nuanced understanding of regeneration niches and is especially important in dry conifer forests where structurally heterogeneous conditions are a frequent objective of forest restoration treatments. In this study, we sampled microclimate conditions and planted seeds and greenhouse-grown seedlings across a range of overstory structure and microclimate conditions in a heterogeneous forest restoration treatment in Colorado, USA. We assessed how fine-scale (∼1–20 m) spatial variation in overstory structure and topography related to variability in microclimate conditions and, collectively, how these biophysical conditions influenced survival and growth of ponderosa pine (Pinus ponderosa var. scopulorum) and Douglas-fir (Pseudotsuga menziesii var. glauca) over 3 years. We found evidence of strong canopy buffering of mean daily vapor pressure deficit (VPD), but buffering of daily maximum VPD was moderate, and buffering of soil moisture was weak except in the hottest and driest month of our 3-year study. Although canopy cover provided refuge from hot and dry conditions, survival and growth of juvenile trees across life-stages and species were greatest in above-average canopy openness, with warm and dry microclimate conditions in May. The spatial patterns of seedling establishment relative to canopy cover, driven by early-season microclimate conditions, did not match canopy-mediated, moderate microclimates later in growing seasons when weather conditions were most limiting. Importantly, our results reflect a specific regeneration trajectory initiated by favorable early-growing season conditions in the first year of study, which promoted survival and growth resilience through subsequent limiting conditions, most notably a hot and dry second year of study. The patterns observed in this study are consistent with drivers of landscape-scale regeneration previously identified for dry conifer forests and show that overstory structure and microclimate variation can mediate these patterns at very fine spatial scales. The narrow spatial and temporal ranges of conditions which supported survival and growth in this study highlight opportunities for restoration treatment planning in similar forests, but also underscore the susceptibility of these dominant dry forest species to potential future changes in the timing and intensity of abiotic conditions which limit regeneration success.

Foliar non-structural carbohydrates and resprouting ability of woody species in a tropical dry forest

Diverse disturbances contribute to biomass loss in tropical dry forests (TDF), of which slash-and-burn agriculture (SBA) may be the most severe; it is practiced by large populations of residents. Plant species capable of resprouting in response to such disturbances often possess above-ground structures that survive and mobilize resources for resprouting, in addition to below-ground structures. In Brazilian TDF, woody species regenerating from stem pieces that persist after SBA events are common. In this study, we evaluated the foliar concentrations of non-structural carbohydrates (NSC) and mineral nutrients during the first six months after an SBA event in all species that resprouted within the experimental area. Almost all the species resprouted exclusively from the stems. The measured nutrient concentrations did not change drastically after an SBA event. Two patterns were observed with respect to NSC concentrations among the species. Half of the studied species exhibited high concentrations of NSC before the SBA event, which gradually decreased three and six months after the disturbance. In contrast, the remaining species maintained consistent NSC concentrations throughout the study period. The cost of building new leaf tissue was similar for all species before the SBA event. However, after disturbance, the species invested different amounts of carbon into the new leaves. Those species that decreased NSC leaf concentration after SBA showed the highest regrowth intensity through the number of new tillers. Our results suggest that the intense translocation of NSC from the leaves before SBA may support the increased activity of the buds present in the remaining stem piece.

Herbaceous species and dry forest species have more acquisitive leaf traits than woody species and wet forest species

Abstract Life forms are key to understand the changes in species composition and vegetation types in space and with succession over time. We asked how life forms from dry and wet regions differ in their leaf traits and trait hyperspace (i.e. trait variation) in early tropical forest succession on abandoned agricultural fields. We compared 324 early successional species from six life forms (herbs, grasses, vines, lianas, shrubs and trees) that occur in the first 5 years of succession on abandoned fields in Ghanaian wet and drought deciduous tropical forests. We measured 12 leaf traits that are important for carbon, water and nutrient use. A principal component analysis showed that 46% of trait variation is captured by a two‐dimensional spectrum of plant form and function: a leaf economics spectrum underpinning fast‐slow growth strategies, and a leaf size spectrum related to plant size and heat balance, which underlie species sorting along environmental gradients in space and time (during succession). Herbaceous and woody life forms had different leaf economics strategies: herbaceous species had more acquisitive trait values (e.g. higher leaf nutrient concentrations) that increase resource capture and use efficiency whereas woody species had more conservative trait values (e.g. higher leaf mass per area) that increase resource conservation. Regardless of life forms, dry forest species and deciduous species had more acquisitive trait values than wet forest species and evergreen species as they maximize their growth during the shorter growing season. The trait hyperspace was larger for woody life forms especially in wet forests. Synthesis. Herbaceous species had ‘faster’ leaf economics trait values and, hence, rapid carbon gain, explaining their success earlier in succession. In contrast, woody species had ‘slower’ resource conservation trait values that increase persistence, thus explaining their success later in succession. Deciduous species especially in a dry region had higher leaf nitrogen and phosphorus concentration to attain faster carbon gain to cope with a seasonally harsh environment. The trait hyperspace was generally smaller in the dry forest, as there are more deciduous species, and as a result, there is less variation in leaf lifespan and associated traits. Read the free Plain Language Summary for this article on the Journal blog.

The influence of seed functional traits and anthropogenic disturbances on persistence and size of the soil seed bank from dry subtropical forest species

Soil seed banks (SSB) are reservoirs of viable mature seeds that play a crucial role in the dynamics and recovery of vegetation following disturbances. Despite its importance, there is still limited understanding of their characteristics of SSB in semiarid subtropical ecosystems. Our objective was to evaluate the effects of wildfire and roller-chopping on the size and persistence of the SSB of six native woody species, considering the influence of seed functional traits (FT). This study was conducted in dry subtropical forests of the western Argentine Chaco region. We evaluated SSB of six woody species: Aspidosperma quebracho-blanco (Aqb); Schinopsis lorentzii (Sl); Sarcomphalus mistol (Sm); Senegalia gilliesii (Sg) and Vachellia aroma (Va) in experimental plots located in two sites (forest plots of ca. 5 ha): forests without disturbance within the last four decades (conserved forest - CF) and forests subjected to fires and mechanical treatments for the partial removal of the shrub layer (roller-chopping and burned forest -RBF). Samples of the SSB were taken under the canopy of six focal individuals of each species in two reproductive seasons between 2016 and 2018. Seeds from ten mature trees of each species were collected to characterize their functional traits (shape and seed mass) related to their aptitude to form the SSB. Three groups of species were identified based on FT analysis: I-large, compressed seeds (Sl, Aqb and Sg); II- medium-size subspherical seeds (Va and Nn); and III- large spherical seeds (Sm). Aqb, Sl, Nn, and Va presented significant differences in the size of their SSB when comparing between sites and sampling years (p = 0.0013; p = 0.0006; p = 0.0020; p = 0.0151, respectively), but no clear patterns emerged among them. The SSB from Aqb and Va were greater in RBF than in CF, only during the second sampling season (105.3 ± 35.2; 352.6 ± 133.4 seeds.m−2, respectively). Sl also exhibited the highest SSB (97.7 ± 30.5) in the second year of sampling, while Nn showed the largest SSB in the first year, (1569.0 ± 847.0 seeds.m−2), both within CF. Finally, Sm and Sg did not present significant differences in their SBB between sites and years. We concluded that all studied species form transient SSB and that the shape index type II favors seed burial, so increasing SSB size and viability. Forest disturbances differentially affect the SSB of woody species in the dry subtropical Chaco because some species decreased, increased or showed no effects during different reproductive seasons. Thus, the potential long-term influence on the dynamics and resilience of dry forests in the subtropics needs to be monitored in the long term.

Rare plant species occurrence patterns are associated not with soil properties, but with frequent fire in a southeast Australian dry sclerophyll forest

AbstractQuestionSoil properties can play a crucial role in influencing the abundance and distribution of plant species. Fire regimes can also have substantial impacts on plant community composition. However, few studies have examined the effects of both fire regimes and soil properties on the occurrence of rare plant species. Here, we asked if rare species have specific soil and fire regime associations relative to common species, and if soil properties may explain potential fire effects.LocationBooderee National Park, southeastern Australia.MethodsWe collected soil cores and completed vegetation surveys on 42 sites in Sydney Coastal Dry Sclerophyll Forest vegetation. We tested for associations between the number of rare species and common species present in relation to three soil chemical properties (available phosphorus, ammonium and organic carbon), fire frequency, and time since fire.ResultsWe found that rare and common species were not associated with any of the examined soil properties. However, rare species were associated with sites with a high fire frequency, while common species were negatively associated with time since fire.ConclusionsOur results indicate that rare species’ occurrence patterns may be influenced by the direct effects of fire or mediated by multiple factors, rather than shaped solely by soil properties in our study area. Future work to understand the factors that underpin rare species’ occurrence patterns in response to fire is critical to develop fire management protocols that effectively conserve rare species in dry sclerophyll forests.

The Barrens Flora of Wisconsin’s Northwest Sands Ecological Landscape

The barrens of Wisconsin’s Northwest Sands Ecological Landscape are a dynamic mosaic shifting between dry forests and woodlands to open, prairie-like communities depending on the frequency of disturbance. We examined the floristics of eight sites within the barrens that were selected to represent the full latitudinal gradient of the ecological landscape. In the course of this study, we collected 2,213 voucher specimens representing 71 plant families, 217 genera, and 404 taxa. We compared the sites to one another using floristic quality assessments, the Sørensen–Dice similarity index, and various qualitative comparisons. The barrens flora becomes less diverse as you move from the southwest to the northeast. Prairie species are more common and dominant in the southwestern sites, and northern dry forest species are more common and dominant in the northeastern sites.

The breeding systems and floral visitors of two widespread African dry forest species of ethnobotanical significance.

Forest products derived from woody trees, such as fruits, seeds, honey, wood and others, are important resources for supporting rural livelihoods. However, little is known about the breeding systems or floral visitors of trees that provide these resources, often due to the difficulty of accessing tree canopies. This study addresses key knowledge gaps from a data poor region, providing information on the breeding systems and contribution of biotic pollination to two trees abundant in south-central Africa, that provide forest product supports for rural livelihoods: Julbernardia paniculata (Benth.) Troupin and Syzygium guineense (Willd.) subsp. barotsense F. White (Fabaceae and Myrtaceae respectively). The breeding systems of these species were assessed by conducting controlled pollination experiments, and then measuring the effects on reproductive success to determine the degree of self-compatibility and pollen limitation. Floral visitors and their behaviour were observed to provide preliminary information on possible pollinator groups. S. guineense appeared to be self-compatible, while J. paniculata showed signs of both self-incompatibility and pollen limitation. Floral visitors of both species were dominated by bees, with native honeybees (Apis mellifera) providing the highest visitation rates. These insights provide the first steps for understanding the reproductive ecology of these key tree species and can help to inform sustained management and conservation aimed at protecting forests and supporting rural livelihoods, as well as broaden the understanding of the floral visitors, and contribution of biotic pollination to forest tree reproductive success.

Leech‐derived iDNA complements traditional surveying methods, enhancing species detections for rapid biodiversity sampling in the tropics

AbstractDeforestation, exploitation, and other drivers of biodiversity loss in Madagascar leave its highly endangered and predominantly endemic wildlife at risk of extinction. Decreasing biodiversity threatens to compromise ecosystem functions and vital services provided to people. New, economical, and diverse methods of biodiversity monitoring can help to establish reliable baseline and long‐term records of species richness. Metabarcoding with invertebrate‐derived DNA (iDNA) has emerged as a promising new biosurveillance tool. An unexpected wet forest fragment tucked in the dry cliffs of Madagascar's southcentral plateau, the Ivohibory Protected Area (IPA), hosts a unique mosaic of species diversity, featuring both dry and wet forest species. Recently elevated to protected status, the IPA has been surveyed for flora and fauna with a range of inventory methods over the course of three years and six expeditions (2016, 2017, & 2019). We collected 1451 leeches over 12 days from the IPA to supplement known species richness and to compare results against current records. With iDNA, we pooled tissues, isolated, and amplified bloodmeal DNA with five sets of primers. We detected 20 species of which four are species of frogs previously undetected and three of which are previously unknown to exist in this region. iDNA surveys have the capacity to provide complementary data to traditional surveying methods like camera traps, line transects, and bioacoustic methods.

Spatially explicit models of seed availability improve predictions of conifer regeneration following the 2018 Carr Fire in northern California

For many conifer species in dry conifer forests of North America, seeds must be present for postfire regeneration to occur, suggesting that seed dispersal from surviving trees plays a critical role in postfire forest recovery. However, the application of tree fecundity and spatial arrangement to postfire conifer recovery predictions have only recently become more common, and is often included at relatively coarse scales (i.e., 30 meters). In this study, we mapped surviving trees using lidar and created a spatially explicit estimate of seed density (seed shadows) with 10 m, 50 m, and 100 m median dispersal distances. We estimated the number of seeds produced by each tree using allometric relationships between tree size and fecundity. Along with the seed shadows, we used a suite of topographic variables as inputs to negative binomial hurdle models to predict conifer seedling abundance in 131 plots following the 2018 Carr Fire in northern California, USA. We compared models using each of the seed shadows to each other as well as to a model using the distance to the nearest surviving tree, which served as a baseline. All model formulations indicated that estimated seed availability was positively associated with conifer regeneration. Despite the importance of seed availability plays in regeneration and the substantial differences in seed availability represented by the different seed shadows in our analysis, we found surprisingly little difference in model performance regardless of which seed shadow was used. However, the models employing seed shadows outperformed the models with distance to the nearest live tree. Although we have demonstrated a modest improvement in predicting postfire conifer regeneration, the uncertainty in our results highlights the importance of tree detection and classification in future studies of this kind. Future studies may find it useful to consider other factors such as predation, site suitability, and seed mortality as potential drivers of discrepancies between total and realized dispersal kernels.