Search

Understanding the impact of herbivores on croplands is critical to developing sustainable agricultural landscapes. Here, we test the hypothesis that field size and landscape structure modulate the levels of herbivory in cowpea and maize subsistence croplands in Brazilian drylands. We conducted the study in nine small-scale farms with varying levels of landscape structure and field sizes (0.10–1.67 ha). In each farm, we haphazardly sampled 20 plants of maize and cowpea. The frequency of foliar herbivory was high for both crops (0.45–0.72), but the average magnitude of damage was low (<3% of leaf surface in both crops), indicating that herbivory is not an ecosystem disservice. Nonetheless, the field size and level of human impact on the landscape matrix were positively related to the frequency and magnitude of damage on maize foliage and cowpea foliage and pods. Landscape composition (proportion of woodland/forest surrounding the field) and configuration (number of surrounding woodland/forest patches) had weaker effects on herbivory levels, mixing positive and negative effects on both crops. Our findings indicate that herbivory attack is not concerning in the agricultural fields studied, but suggest that maize and cowpea should be preferably grown in small fields surrounded by an environmental-friendly matrix and patches of conserved ecosystems. [ABSTRACT FROM AUTHOR]

Tropical forests are incredibly diverse in structure and function. Despite, or perhaps because of, this diversity, tropical biologists often conduct research exclusively in one or perhaps a few forest types. Rarely do we study the ecotone—the interstitial region between forest types. Ecotones are hyper-diverse, dynamic systems that control the flow of energy and organisms between adjacent ecosystems, with their locations determined by species' physiological limits. In this review, we describe how studying ecotones can provide key indicators for monitoring the state of Neotropical forests from organisms to ecosystems. We first describe how ecotones have been studied in the past and summarize our current understanding of tropical ecotones. Next, we provide three example lines of research focusing on the ecological and evolutionary dynamics of the ecotone between tropical dry forests and desert; between tropical dry and rainforests; and between Cerrado and Atlantic rainforests, with the latter being a particularly well-studied ecotone. Lastly, we outline methods and tools for studying ecotones that combine remote sensing, new statistical techniques, and field-based forest dynamics plot data, among others, for understanding these important systems. [ABSTRACT FROM AUTHOR]

Previous studies of overwintering migratory birds in neotropical environments have found that species co-occur in the same habitats despite high diet overlap. Hence, discovering subtle diet differences within habitats can help explain patterns in bird species diversity. The Yucatan Peninsula in Mexico is an important region for overwintering migratory birds, but little is known about how habitat differences in food resources contribute to bird diversity. To address the knowledge gap, we compared the degree of overlap in the diet of all terrestrial migratory birds within and between mangrove and tropical dry forests on the Yucatan Peninsula's northern coast. We collected data on the consumption of food items through direct observation of birds feeding on four transects in each habitat every week (12 weeks) during the non-breeding season (i.e., overwinter, December-February). We recorded 19 species, 15 species in mangrove and 15 species in forest, with 11 of those found in both habitats. In both habitats, diet overlap was high. However, species present only in the tropical dry forest had less overlap than species occurring in both habitats, indicating that diet specialization might restrict the range of habitats that a species can occupy. On the other hand, species present only in the mangrove had similar diet overlap to species present in both habitats. The diet variation that did exist was greater within than between habitats possibly due to intraspecific diet differences among different geographic locations. Although small, within-habitat diet differences might be key to allowing species to coexist locally in the Yucatan, thus supporting studies demonstrating a similar mechanism in other neotropical regions. More generally, the information we provide on bird diet can be used to discover whether threats like anthropogenic development precipitate species loss via altering the resource base upon which birds rely. [ABSTRACT FROM AUTHOR]

Key message: Species interactions should be considered during the design of restoration plans for tropical dry forests. Legume trees dominate old-growth and regenerating tropical dry forests with some pioneers becoming temporarily monodominant during secondary succession. Yet, the mechanisms promoting legume coexistence in this ecosystem are poorly understood but essential to develop restoration strategies for degraded forests. We studied plant–plant interactions in the regeneration niche of an early and a late successional legume tree species, increasingly co-occurring in northwestern Mexico due to persistent climatic and anthropogenic disturbance that is altering forest dynamics. Our experiment comprised two species (Acacia cochliacantha, typical early successional and monodominant, and Lysiloma watsonii, typical late successional) × two habitats (direct light and shade) × three plant interaction treatments (control, intraspecific and interspecific). Each of the 12 experimental units contained 20 pots, totaling 240 replicates. We examined germination, seedling survival, and growth dynamics and determined seedling dry mass (total and root: shoot) at the end of the experiment. Our results suggest that legume monodominance in regenerating tropical dry forests starts early during germination and may be temporarily maintained through the interplay between interspecific facilitation and intraspecific competition. In contrast, late successional species may avoid negative heterospecific interactions by recruiting later (benefiting from neighbors' shade) and maintaining neutral associations with conspecifics since early ontogenetic stages. Therefore, a cautious selection of early and late successional species and their spatial arrangement should be considered during the planning stage of restoration programs for tropical dry forests. Advancing our understanding of plant interactions in tropical dry forests should lead us to develop better tools for restoring this highly degraded ecosystem. [ABSTRACT FROM AUTHOR]

We report a new breeding site of Ara militaris mexicanus (Ridway, 1915), Military Macaw, in the state of Puebla in the Alto Balsas river basin, Mexico. The breeding site is in the Cañón Grande area along the Nexapa River. Observed temporality and breeding behaviors agree with the recorded breeding season of this species in Central Mexico. Notably, the region has no current designation as a protected natural area for conservation. We recommend collaboration with the local community to initiate efforts towards designate the Alto Balsas river basin as a protected natural area.

Global climate crisis and severe water scarcity worldwide demand alternative genotypes that allow an adequate balance between production and water use while ensuring benefits for foresters. The genetic improvement of water use efficiency (WUE) in forest plantations could reduce water use without compromising yield. Above-ground biomass (AGB), saw-wood volume up to small-end diameter of 15 cm (V15), wood density (WD) and intrinsic WUE (WUEi) from wood carbon isotopic discrimination was evaluated in forty open-pollinated families of G. arborea grown in a tropical dry forest known as a water-limited environment, to select superior genotypes considering a balance in wood production and water use. Heritability of open-pollinated family means were moderate with values of h2f = 0.554 for AGB, h2f = 0.541 for V15, h2f = 0.608 for WD and h2f = 0.495 for WUEi. Significant genetic correlations between both WD and WUEi and production traits (p < 0.05) and a nonsignificant genetic correlation between WD and WUEi were found. Although production traits and WUEi showed moderate narrow-sense and family means heritabilities, considerable responses to selection of up to 13.7% in AGB, 15.5% in V15, 2.5% in WD and 3.0% in WUEi could be achieved from intensive selection of superior families. Our results showed that it may be possible balancing wood production and WUE by selecting open-pollinated families of G. arborea with higher V15 and WUEi. The deployment of these superior families can be used as a forest management strategy to adapt the species to future drought scenarios associated with global climate change. [ABSTRACT FROM AUTHOR]

Hurricanes are extreme climatic events frequently affecting tropical regions such as the tropical dry forests (TDFs) in Mexico, where its frequency/intensity is expected to increase toward the year 2100. To answer how resistant is a Mexican tropical dry forest to a high-intensity hurricane, and if its degree of resistance was mediated by its conservation degree, we evaluated the effect of a category 4 hurricane over the tree community, soil nutrients, and soil enzymatic activity in two contrasting TDF ecosystems: Old-Growth Forest (OGF) and Secondary Forest (SF). In general, vegetation richness and diversity showed very high resistance one year after the hurricane, but several structural attributes did not, especially in the OGF where the tree mortality related to vegetation structure and spatial distribution of individuals was higher. Then, in the short term, SF vegetation appeared to be more resistant, whereas the OGF, with more biomass to lose, appeared to be more vulnerable. Conversely, most soil attributes showed low resistance in both stages, but especially in SF which could face more severe nutrient limitations. The response of TDF to high-intensity hurricanes, in terms of above- and belowground processes, was in part dependent on its disturbance level. Moreover, an increase in the intensity/frequency of hurricanes could lead this TDF toward a high nutrient limitation (especially by phosphorus) for the plants and consequently toward a loss of soil functioning, especially in the SF. This eventually could produce a severe degradation in fundamental attributes and functions of the ecosystem. [ABSTRACT FROM AUTHOR]

Axial parenchyma proliferation (non-lignified parenchyma) in wood has been characterized for only a few species. In the present study, we characterized the proliferation, ontogeny, and seasonal variation of wood axial parenchyma in Cochlospermum vitifolium (Bixaceae). This study included material from natural populations from different sites in Mexico. We analyzed the wood anatomy and development in stems of different ages, and monthly sampling of the main stem during the growing season. The results show that the wood anatomy of C. vitifolium is characterized by features associated with efficient water transport, such as wide vessels and low vessel frequency. The wood has a high storage and radial transport capacity. Axial parenchyma is abundant and constitutes the main cell type of the wood. Rays are wide and tall with a high starch content. Ontogenetic development of the wood showed that non-lignified axial parenchyma differentiates after secondary growth has been established. Parenchyma proliferation does not occur in an axially orderly fashion and the results suggest that there is a relationship between maximum proliferation and precipitation. We found high variation in wood parenchymatization between trees. The maximum parenchymatization and succulence was found in trees with larger stem diameter. The ecological and ontogenetic implications of wood parenchymatization are discussed. [ABSTRACT FROM AUTHOR]

Copyright of Caldasia is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The association between cacti and nurse plants has been reviewed by different authors. These reviews however were qualitative because only evaluated aspects such as species identity of cacti and nurse plants, probable explanatory causes of their association, and location of study sites. To our knowledge, there are no quantitative reviews that have evaluated the association between cacti and nurse plants for different subfamilies, tribes, and growth forms of cacti and nurse plants, and different plant communities and soil properties. To address these issues, we performed a quantitative review of the studies on the association between cacti and nurse plants. The studies were searched in the ISI Web of Knowledge from 1986 to 2021. Data obtained from studies were analyzed with the relative risk ratio and ratio of medians. Most studies on the association between cacti and nurse plants were performed mainly in Mexico and the USA. Globose, cylindrical, and columnar cacti of the subfamily Cactoideae, and tribes Cacteae, Cereeae, and Echinocereeae were associated to nurse plants of Asteraceae, Euphorbiaceae, and Fabaceae. However, other subfamilies (Opuntioideae) and tribes (Notocacteae) of cacti, and families (Asparagaceae) of nurse plants were not associated. Nurse plants ameliorated temperature, moisture, and nitrogen of soil. The association between cacti and nurse plants occurred in desert shrubland and tropical dry forest. Further studies are needed on the association between cacti and nurse plants that consider more cactus subfamilies and tribes in countries with high cactus diversity in Central and South America.

Canopy greenness is an indicator of ecosystem primary productivity, which is often limited by temperature and precipitation. Changes in vegetation greening have been reported mostly at global scales. However, we still have a poor understanding of vegetation greening patterns and drivers for major vegetation types, such as the tropical dry forest, one of the most extensive vegetation types in Mexico. Here, we analyze two decades of interannual variation in greenness and its relationship to temperature and precipitation in the northmost neotropical dry forest occurring in Northwestern Mexico. We constructed time-series linear regression models using standardized anomalies with z-scores (i.e., standard deviations away from the long-term mean) for the Normalized Difference Vegetation Index (NDVI) and the climate data from 2001 to 2021. Our best models indicate both temperature and precipitation exert positive effects on vegetation greenness, particularly from a lagged effect perspective, as retained predictors were the accumulated precipitation of two monsoon (summer) seasons and previous year mean temperature. The lowest levels of landscape greenness seem connected to prolonged droughts and extreme frost events. In fact, a switch from negative to positive NDVI anomalies was observed in the years following the February 2011 extreme frost that affected much of North America, including northern Mexico. Notable, under the stricter statistical criterion of −1.7 ≥ z score ≥ 1.7, only climatic variables presented very-extreme anomalies and these were not necessarily linked to a very-extreme response in landscape greenness. However, considering the criterion of −1.3 ≥ z score ≥ 1.3, we identified several extreme NDVI anomalies and their corresponding climatic anomaly. Therefore, more flexible statistical criteria might reveal climate extremes of ecological and social relevance. Our overall findings have implications for forest and climate risk management, particularly as extreme climatic anomalies are expected to continue increasing in light of climate change.

Tropical dry forests are among the most threatened ecosystems worldwide, with severe deforestation and regeneration problems compounded by an increasing climate change threat. Lomas de Atiquipa in the Peruvian–Chilean Coastal Desert (Atacama Desert) comprises one of these formations, mainly dominated by the Tara tree (Tara spinosa), which is a Neotropical legume tree with high ecological and commercial value. However, approximately 80% of the original area has been reduced mainly by deforestation. An ecological restoration experience was demonstrated in this study by investigating the use of thorny shrubs as nurse plants to promote forest regeneration. This approach is based on the idea of facilitation between plants and can be a suitable “nature-based solution” to decrease reforestation costs. Accordingly, 170 seedlings and 128 seeds of Tara were installed in two contrasting environments: 1) under the cover of the nurse plant and 2) outside the vegetation cover. Survival rates of the seedlings and germinated seeds were periodically monitored from August to December. We also measured microclimatic conditions outside and under the canopy of the nurse plant, including temperature (°C), relative humidity (%), soil moisture (v:v), and illumination (lux), to assess the recruitment niche. Our results showed the highest seedling survival rates at the end of the experiment under the canopy of the nurse plant (22.4%) vs. outside (8.2%). This could be linked to the better performance of juvenile plants owing to the nursing effect of shrubs, as we detected a significant reduction in the extreme environmental conditions under the canopy of the nurse plant, with the lowest temperatures and highest humidity, as well as a significant reduction in light incidence. Our findings suggest that using local shrubs as nurse plants is a promising method for restoring Tara in the Lomas ecosystem because it reduces the stress of direct insolation and high temperatures and reduces the cost and effort of hand watering the seedlings after planting.

Tropical dry forests are highly threatened at a global scale. Long-term monitoring of remaining stands is needed to assess forest health, efficacy of management practices, and potential impacts of climate change. Using a multi-seasonal Landsat time series, we examined Normalized Difference Vegetation Index (NDVI) patterns in native dry forest, non-native vegetation types, and dry forest restoration sites from 1999 to 2022 in the Hawaiian Islands. We calculated trends in median NDVI and robust coefficient of variation of NDVI for dry and wet seasons, and used Breaks for Additive Seasonal and Trend analysis to detect trend departures. To assess the impact of regional drying trends, NDVI trends were compared to the seasonal long-term precipitation anomaly and cumulative precipitation anomaly. We found that native dry forest was less green than non-native forest, particularly during the dry season, and that median NDVI increased in both native and non-native dry forests over the study period despite negative precipitation anomaly trends. This result differs from coarser-scale studies in Hawaii, but is supported by trends in other dry forest regions. Greening was also observed in restoration study sites, especially larger sites where native species establishment and recruitment has been reported. Non-native grassland NDVI exhibited a strong positive link to precipitation anomalies, suggesting that drier climate scenarios may exacerbate the invasive grass-wildfire cycle that threatens native dry forest. These results demonstrate that Landsat time series may be used to detect seasonal variation in dry forest plots and to support restoration site monitoring in a highly fragmented ecosystem.

The fruits of some Anacardiaceae tree species are important sources of food and water for vertebrate species in seasonal tropical forest. During a monitoring study using camera-traps in a tropical dry forest of the Tehuacán-Cuicatlán Biosphere Reserve, Mexico, we documented tree visitation and fruit consumption in the 'Chupandillo' Cyrtocarpa procera by medium to large-sized terrestrial mammals species. From 2012 to 2017, we established cameras-traps in front of six adult chupandillo trees during 385–499 days. A total of 4,831 photographs were obtained during a total of 2,706 days. The camera-traps recorded 12 mammals species visiting, passing in front the tree, or consuming its fruits. The white-tailed deer, cotton rabbit, collared peccary and gray fox were the species that presented the highest number of visit events, with the two ungulate species recorded visiting all of the sampled trees. These species, as well as coati, consumed fruits of this tree species from September to October. The white-tailed deer visited during the day, while the collared peccary mainly visited during the twilight-night time period. We propose that fruits of C. procera are an important resource for mammals in this region, in particular for white-tailed deer and collared peccary. [ABSTRACT FROM AUTHOR]

Genetic diversity is a key component of evolution, and unraveling factors that promote genetic differentiation in space and time is a central question in evolutionary biology. One of the most diverse and ecologically important tree genera in tropical forests worldwide is Ficus (Moraceae). It has been suggested that, given the great dispersal capacity of pollinating fig wasps (Chalcidoidea; Agaonidae), the spatial genetic structure, particularly in monoecious fig species, should be weak. However, no studies have addressed the factors that determine the genetic structure of Ficus species in regions of high geological, geographic, and climatic complexity, such as the Mexican Transition Zone. Using nuclear single nucleotide polymorphisms (5311 SNPs) derived from low‐coverage whole genomes and 17 populations, we analyzed the population genomics of Ficus pringlei to characterize neutral and adaptive genetic variation and structure and its association with geographic barriers such as the Trans‐Mexican Volcanic Belt, environmental heterogeneity, and wind connectivity. From genomic data of 71 individuals, high genetic diversity, and the identification of three genomic lineages were recorded (North, South, and Churumuco). The results suggest that genetic variation is primarily determined by climatic heterogeneity. Ficus pringlei populations from the north and south of the Trans‐Mexican Volcanic Belt also exhibited minimal genetic differentiation (FST = 0.021), indicating that this mountain range may not act as an insurmountable barrier to gene flow. Wind connectivity is also highlighted in structuring putative adaptive genetic variation, underscoring the intricate complexity of the various factors influencing genetic variation in the species. This study provides information on the possible mechanisms underlying the genetic variation of endemic species of the tropical dry forest of Western Mexico, such as F. pringlei. [ABSTRACT FROM AUTHOR]

Abiotic and biotic factors have considerable impact on the plasticity of plant functional traits, which influences forest structure and productivity; however, their inter-relationships have not been quantified for fragmented tropical dry forest (TDF) ecosystems. We asked the following questions: (1) what are the variations in the plasticity of functional traits due to soil moisture availability in TDF fragments? (2) what are the roles of soil nutrients and forest disturbances in influencing variations in the plasticity of functional traits in the TDF fragments? and (3) how do the variations in the plasticity of functional traits influence the structure and productivity of TDF fragments? Based on linear mixed-effects results, we observed significant variations among tree species for soil moisture content (SMC) under the canopy and selected functional traits across forest fragments. We categorized tree species across fragments by principal component analysis (PCA) and hierarchical clustering on principal components (HCPC) analyses into three functional types, viz., low wood density high deciduous (LWHD), high wood density medium deciduous (HWMD), and high wood density low deciduous (HWLD). Assemblage of functional traits suggested that the LWHD functional type exhibits a drought-avoiding strategy, whereas HWMD and HWLD adopt a drought-tolerant strategy. Our study showed that the variations in functional trait plasticity and the structural attributes of trees in the three functional types exhibit contrasting affinity with SMC, soil nutrients, and disturbances, although the LWHD functional type was comparatively more influenced by soil resources and disturbances compared to HWMD and HWLD along the declining SMC and edge distance gradients. Plasticity in functional traits for the LWHD functional type exhibited greater variations in traits associated with the conservation of water and resources, whereas for HWMD and HWLD, the traits exhibiting greater plasticity were linked with higher productivity and water transport. The cumulative influence of SMC, disturbances, and functional trait variations was also visible in the relative abundance of functional types in large and small sized fragments. Our analysis further revealed the critical differences in the responses of functional trait plasticity of the coexisting tree species in TDF, which suggests that important deciduous endemic species with droughtavoiding strategies might be prone to strategic exclusion under expected rises in anthropogenic disturbances, habitat fragmentation, and resource limitations. [ABSTRACT FROM AUTHOR]

Understanding why animals avoid some locations is needed to improve the theory of habitat selection. This is key in semi‐sedentary organisms, such as antlion larvae, because once established they rarely move, and their performance largely depends on local environmental conditions.Antlion larvae are sit‐and‐wait predators that build conical pitfall traps in sandy soils to capture passing prey. They clean constantly their traps, expelling soil, prey carcasses and debris out of the pit to maintain their trapping success. Therefore, we propose that they avoid soils with leaf litter because leaves hinder the maintenance of their pits; a hypothesis that has not yet been tested.We first demonstrated that antlion larvae (Myrmeleon inmaculatus) are rare from soils with leaf litter in a tropical semi‐deciduous forest in Mexico. We then experimentally tested the effect of leaf litter on pit maintenance by adding debris in 90 antlion traps, 45 of which were covered with a leaf, and 45 remained uncovered. Two hours after adding the debris, we recorded its location and quantified the variation in depth and diameter of the pits.Larvae in uncovered traps were twice as effective at cleaning up the debris than larvae in covered traps. Furthermore, in just 2 h, covered traps were on average 21% shallower than control traps, probably because unsuccessful attempts to clean debris caused sand slides to fill the pit partially.Leaf litter seems to hinder the proper maintenance of antlion traps, explaining at least partially, why these animals are rare under leaf litter. [ABSTRACT FROM AUTHOR]

Background: The patterns of richness, diversity, and abundance of an odonate assemblage from San Buenaventura, Jalisco are presented here. A total of 1087 specimens from seven families, 35 genera and 66 species were obtained through monthly samplings of five days each during a period of one year. Libellulidae was the most diverse family (28 species), followed by Coenagrionidae (21), Gomphidae (7), Aeshnidae (6), Calopterygidae (2), Lestidae (1) and Platystictidae (1). Argia was the most speciose genus. The highest species richness and Shannon diversity were found during August and September, whereas the highest abundance was observed in June and the highest Simpson diversity was recorded in September -- all of which were associated with the rainy season. The highest values of phylogenetic diversity were found from June to October. The different diversity facets of this assemblage were positively correlated with precipitation and minimum temperature, whereas maximum temperature showed no influence. In addition, we found that this odonate diversity was higher than most Mexican localities with tropical dry forest (TDF) studied. New information: We continue our efforts to describe the patterns of richness, diversity and abundance of some insect groups associated with the tropical dry forest ecosystem in Mexico, following a latitudinal gradient of the distribution of this ecosystem in the country. Our emphasis here was to evaluate the spatial and temporal patterns of richness and diversity of an Odonata assemblage from Jalisco, Mexico. [ABSTRACT FROM AUTHOR]

ABSTRACTClimatic seasons have been shown to determine the temporal fluctuations in species communities of different ecosystems. Here, we assessed the diversity of spider assemblages in dry, transition and rainy seasons in the “Guillermo Piñeres” Botanical Garden (GPBG), Turbaco, Colombia. We collected spider assemblages between June 2018 and April 2019 through standardized day and night sampling methods for tropical ecosystems: looking up, looking down, beating and leaf litter sieving. In total, we collected 1585 individuals, belonging to 28 families and 112 (morpho) species. We calculated the effective species richness (Hill numbers) to evaluate the changes in diversity across seasons and used clustering and ordination methods (Jaccard index-based nMDS) to identify differences in the composition of the assemblages. Also, we compared the abundance and species richness of predatory guilds of the three seasons. The transition season showed the highest diversity with 94 morphospecies, an effective number of species of 48.7 and a dominance of 32.4 effective species. The clustering and ordination methods grouped the sampling events into three groups, each corresponding to a climatic season. The most abundant guild was the orb web weavers, with the highest value in the rainy season, while “other hunters” were the most species rich. Our results indicate that the spider assemblages in GPBG present a seasonal variation in diversity, probably influenced by climatic conditions. Understanding how these seasonal changes occur is necessary to develop forest management strategies for monitoring and management projects on the conservation of species assemblages according to the Convention on Biological Diversity.

Tropical forests are incredibly diverse in structure and function. Despite, or perhaps because of, this diversity, tropical biologists often conduct research exclusively in one or perhaps a few forest types. Rarely do we study the ecotone—the interstitial region between forest types. Ecotones are hyper-diverse, dynamic systems that control the flow of energy and organisms between adjacent ecosystems, with their locations determined by species’ physiological limits. In this review, we describe how studying ecotones can provide key indicators for monitoring the state of Neotropical forests from organisms to ecosystems. We first describe how ecotones have been studied in the past and summarize our current understanding of tropical ecotones. Next, we provide three example lines of research focusing on the ecological and evolutionary dynamics of the ecotone between tropical dry forests and desert; between tropical dry and rainforests; and between Cerrado and Atlantic rainforests, with the latter being a particularly well-studied ecotone. Lastly, we outline methods and tools for studying ecotones that combine remote sensing, new statistical techniques, and field-based forest dynamics plot data, among others, for understanding these important systems.

The Military Macaw (Ara militaris) is not considered within the avifauna of Morelos due to a lack of solid evidence confirming the presence of the species in the state. We conducted systematic surveys from elevated viewpoints in the tropical dry forest of the Sierra de Huautla Biosphere Reserve from August to December 2017 and 2020-2022 to confirm the presence of the Military Macaw in the reserve. We obtained 36 records of the Military Macaw, with photographic evidence, and observed a mean of 10.0 ± 11.2 macaws per record, registering flocks of 32-39 individuals on three occasions. We identified sites within the reserve that Military Macaws recurrently used for resting, foraging, and roosting. We also observed macaws foraging in three tree species, with another six plant species reported in the diet by local people. We could not confirm nesting by macaws in the reserve as observations were conducted outside the breeding season. Some sightings occurred outside the biosphere reserve, in an area of the Mixteca Baja Poblana (Puebla) proposed as a new protected area. Our findings provide the first systematic and photographic evidence of the presence of the Military Macaw in Morelos state, confirm the relevance and effectivity of the Sierra de Huautla Biosphere Reserve for regional conservation of the species and the tropical dry forest, and provide additional support for the proposal to create a new protected area and conservation corridor in the Balsas Basin that could benefit the conservation of this endangered bird species. [ABSTRACT FROM AUTHOR]

We used pollen and charcoal analyses of sediments from two lakes at the southern end of Eleuthera Island, the Bahamas, to reconstruct vegetation and fire history over the past 5000 years. We obtained a 254-cm long sediment sequence from Shad Pond on the south end of Eleuthera near the coast. We obtained a 140-cm long sediment sequence from Duck Pond Blue Hole midway from either coast. Shad Pond sediment from 180 to 240 cm is fibrous peat dating from ~ 3800 to 4800 cal yr BP. The pollen spectrum in the peat is dominated by red mangrove (Rhizophora mangle) indicating the presence of a red mangrove swamp during this period. Duck Pond Blue Hole sediment from 100 to 140 cm is fine calcareous mud with only traces of pollen present. Palm pollen dominate the middle portion of both sediment sequences with pollen from rockland and coppice species also present. Palm pollen decline in both lakes ~ 1200 to 1300 cal yr BP, the start of Lucayan occupation. Palm pollen nearly disappear from Shad Pond sediments after ~ 1200 cal yr BP coincident with a spike in charcoal particles. Palm pollen drop by over one-half in Duck Pond Blue Hole after ~ 1200 cal yr BP, but there is only a small increase in charcoal particles. Palm pollen return in modest amounts toward the top of the Shad Pond sediments and there is a second, smaller peak in charcoal ~ 350 cal yr BP. This suggests a recovery of palms near the coast during the Plantation Period. Palm pollen gradually decline, charcoal increases, and pollen from disturbance species become very dominant toward the top of Duck Pond Blue Hole sediments after ~ 350 cal yr BP. The decline of palm pollen and increase in pollen from disturbance species in sediments from both sites ~ 1200 cal yr BP suggests heavy exploitation of palms by Lucayans, particularly near the coast. The later increase in charcoal and the significant increase in pollen from disturbance species in sediments from the inland Duck Pond Blue Hole site ~ 350 cal yr BP suggests inland land clearing during the Plantation Period. [ABSTRACT FROM AUTHOR]

Copyright of Jangwa Pana is the property of Revista Jangwa Pana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The reproductive phenology of plants has profound influence on ecosystem dynamics including plant–animal interactions. Broad phenological patterns, especially the timing of reproduction, may result from long‐term climate trends and co‐evolution between plants and their pollinators, dispersers, and predators. Yet, interannual climate variation and local abiotic conditions may also affect the timing and magnitude of plant reproduction. Understanding the patterns of and controls on plant reproduction are crucial for conservation efforts under a changing global climate and rapidly expanding human development. However, phenology studies from the Neotropics are sparse. Here, we examine the relative timing and magnitude of fleshy‐fruited plant reproduction during the winter dry season in subtropical dry forest on Eleuthera, The Bahamas over a nine‐year period. At least 47 species were observed with some dry season reproductive activity, but only 17% showed evidence of a fruiting peak or continuous reproduction. Overall fruit abundance generally declined through the dry season, but flower production increased between mid and late dry season. Variation in fruit and flower abundance among years was related to temperature and rainfall, but local site conditions—particularly successional stage and groundwater availability—explained more variability in reproductive activity than climate variation. Groundwater availability had a particularly strong positive influence on flower and fruit abundance at the end of the dry season, a critical time for migrant frugivores preparing to return to their breeding grounds. This emphasizes the importance of protecting sites with accessible groundwater to conserve biodiversity in the archipelago and elsewhere. [ABSTRACT FROM AUTHOR]

Copyright of Caldasia is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Climatic seasons have been shown to determine the temporal fluctuations in species communities of different ecosystems. Here, we assessed the diversity of spider assemblages in dry, transition and rainy seasons in the "Guillermo Piñeres" Botanical Garden (GPBG), Turbaco, Colombia. We collected spider assemblages between June 2018 and April 2019 through standardized day and night sampling methods for tropical ecosystems: looking up, looking down, beating and leaf litter sieving. In total, we collected 1585 individuals, belonging to 28 families and 112 (morpho) species. We calculated the effective species richness (Hill numbers) to evaluate the changes in diversity across seasons and used clustering and ordination methods (Jaccard index-based nMDS) to identify differences in the composition of the assemblages. Also, we compared the abundance and species richness of predatory guilds of the three seasons. The transition season showed the highest diversity with 94 morphospecies, an effective number of species of 48.7 and a dominance of 32.4 effective species. The clustering and ordination methods grouped the sampling events into three groups, each corresponding to a climatic season. The most abundant guild was the orb web weavers, with the highest value in the rainy season, while "other hunters" were the most species rich. Our results indicate that the spider assemblages in GPBG present a seasonal variation in diversity, probably influenced by climatic conditions. Understanding how these seasonal changes occur is necessary to develop forest management strategies for monitoring and management projects on the conservation of species assemblages according to the Convention on Biological Diversity. [ABSTRACT FROM AUTHOR]

Cyrtocarpa is a generic name that has been applied to members of a complex of dry-habitat Neotropical taxa, but recent investigations have revealed that in fact this group represents three distinct genera. Tumultivenia and Uniostium, two new genera of Anacardiaceae-Spondioideae, are described and illustrated, as is one new species, Cyrtocarpa caribaea. Both new genera are strongly supported as distinct in a published phylogeny. Uniostium velutinifolium was originally published in Bursera and subsequently combined in both Tapirira and Cyrtocarpa, while Tumultivenia caatingae was originally published in Cyrtocarpa. The number of locules and number and position of opercula in the pyrene provide the salient characters distinguishing these genera. The new species is a distinctive member of Cyrtocarpa sensu stricto but requires more collections (including flowering material) as well as material for molecular studies. [ABSTRACT FROM AUTHOR]

Copyright of People & Nature is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Tropical rainforest woody plants have been thought to have uniformly low resistance to hydraulic failure and to function near the edge of their hydraulic safety margin (HSM), making these ecosystems vulnerable to drought; however, this may not be the case. Using data collected at 30 tropical forest sites for three key traits associated with drought tolerance, we show that site‐level hydraulic diversity of leaf turgor loss point, resistance to embolism (P50), and HSMs is high across tropical forests and largely independent of water availability. Species with high HSMs (>1 MPa) and low P50 values (< −2 MPa) are common across the wet and dry tropics. This high site‐level hydraulic diversity, largely decoupled from water stress, could influence which species are favoured and become dominant under a drying climate. High hydraulic diversity could also make these ecosystems more resilient to variable rainfall regimes. [ABSTRACT FROM AUTHOR]

The common name of pampas cat includes a complex of small Neotropical felid species found in various habitats of South America. Recently several species of this complex were proposed, but there are few records in the northernmost distribution of the continent, and reports of the pampas cat's presence in Colombia have been ambiguous. Current northern limits of Leopardus garleppi are limited to the Andes of Ecuador. Here we present the northernmost record of the species, validating its presence in Colombia and review previous controversial records from the country. The new record is based on a road-killed specimen in a dry tropical forest ecosystem in the municipality of Mercaderes, Department of Cauca. Our morphological and genetic comparisons also shown that a previous record from Colombia supported by a single skin recently used to described a new species named Leopardus narinensis belong to Leopardus tigrinus. With the information compiled from new localities in Colombia and Ecuador, the known distribution range for L. garleppi is increased towards the northern part of South America into areas of Tropical Dry Forest. The distribution now includes 14 ecoregions from Colombia to Bolivia, and four in Colombia (Eastern Cordillera real montane forests, Northwestern Andean montane forests, Northern Andean paramo, and the Patía Valley dry forests), which correspond to similar ecosystems inhabited by the species in other Andean landscapes. The potential distribution hypothesis showed that the species has high suitability in large areas of southwestern Colombia (Nariño). With the recording of L. garleppi in Colombia, the number of extant felid species in the country has increased to seven. [ABSTRACT FROM AUTHOR]

Conspecific plant density and heterospecific frequency are key drivers of herbivore damage. However, most studies have investigated their effects separately and for single (rather than multiple) focal plant species.We conducted an experiment involving three tree species, namely: Cordia dodecandra (Boraginaceae), Manilkara zapota (Zapotaceae), and Piscidia piscipula (Fabaceae). We manipulated understory densities of M. zapota and C. dodecandra (focal species) and their frequency relative to P. piscipula. Three months after planting, we surveyed insect leaf chewer and sucking damage on the former two. Because these species are attacked by different herbivores, we predicted a negative effect of heterospecific frequency on herbivory.Density and frequency varied in the direction and function of their effects on herbivory depending on the plant species and attacking herbivore. As expected, Piscidia piscipula frequency had a negative linear effect on M. zapota leaf‐chewer damage, whereas conspecific density did not affect chewer damage on this species. In contrast, density and frequency had non‐linear effects on C. dodecandra chewer damage, namely positive (hump‐shaped) and negative (U‐shaped) relationships, respectively. In addition, density and frequency had positive linear effects on C. dondecandra damage by leafhoppers.These findings call for more work jointly assessing plant inter‐specific variation in density‐ and frequency‐dependent variation in herbivory and its underlying drivers. [ABSTRACT FROM AUTHOR]

Abstract Genetic diversity is a key component of evolution, and unraveling factors that promote genetic differentiation in space and time is a central question in evolutionary biology. One of the most diverse and ecologically important tree genera in tropical forests worldwide is Ficus (Moraceae). It has been suggested that, given the great dispersal capacity of pollinating fig wasps (Chalcidoidea; Agaonidae), the spatial genetic structure, particularly in monoecious fig species, should be weak. However, no studies have addressed the factors that determine the genetic structure of Ficus species in regions of high geological, geographic, and climatic complexity, such as the Mexican Transition Zone. Using nuclear single nucleotide polymorphisms (5311 SNPs) derived from low‐coverage whole genomes and 17 populations, we analyzed the population genomics of Ficus pringlei to characterize neutral and adaptive genetic variation and structure and its association with geographic barriers such as the Trans‐Mexican Volcanic Belt, environmental heterogeneity, and wind connectivity. From genomic data of 71 individuals, high genetic diversity, and the identification of three genomic lineages were recorded (North, South, and Churumuco). The results suggest that genetic variation is primarily determined by climatic heterogeneity. Ficus pringlei populations from the north and south of the Trans‐Mexican Volcanic Belt also exhibited minimal genetic differentiation (FST = 0.021), indicating that this mountain range may not act as an insurmountable barrier to gene flow. Wind connectivity is also highlighted in structuring putative adaptive genetic variation, underscoring the intricate complexity of the various factors influencing genetic variation in the species. This study provides information on the possible mechanisms underlying the genetic variation of endemic species of the tropical dry forest of Western Mexico, such as F. pringlei.

The koinobiont endoparasitoid genus Triraphis Ruthe, 1855 (Rogadinae Foerster, 1863) is a group of braconid wasps that contains 74 species distributed along the Nearctic, Neotropical, Oriental and Palearctic regions. We amplified a fragment of the cytochrome oxidase subunit I (COI) for 19 specimens of Triraphis from the Chamela Biological Station (CBS), a region mainly composed of tropical dry forest near the Pacific coast of Jalisco, Mexico. Based on genetic distances among specimens of Triraphis from the CBS and all COI sequences of BINs assigned to Triraphis and Rogas Nees, 1819 available in the BOLDSYSTEMS database, we identified three clusters in the CBS that correspond with T. bradzlotnicki Sharkey, 2021, T. davidwahli Sharkey, 2021 and T. defectus Valerio, 2015, which were previously described from Costa Rica. Based on morphology, we identified individuals of T. fusciceps Cresson, 1869 and provided COI sequences of this species for the first time. Four genetic clusters of Triraphis correspond to four new species that are described here: T. kardia sp. nov., T. ocellatus sp. nov., T. divergens sp. nov. and T. luzabrilae sp. nov. Since T. bradzlotnicki and T. davidwahli were exclusively described with molecular data (COI), we morphologically described them based on Mexican specimens.

Abiotic and biotic factors have considerable impact on the plasticity of plant functional traits, which influences forest structure and productivity; however, their inter-relationships have not been quantified for fragmented tropical dry forest (TDF) ecosystems. We asked the following questions: (1) what are the variations in the plasticity of functional traits due to soil moisture availability in TDF fragments? (2) what are the roles of soil nutrients and forest disturbances in influencing variations in the plasticity of functional traits in the TDF fragments? and (3) how do the variations in the plasticity of functional traits influence the structure and productivity of TDF fragments? Based on linear mixed-effects results, we observed significant variations among tree species for soil moisture content (SMC) under the canopy and selected functional traits across forest fragments. We categorized tree species across fragments by principal component analysis (PCA) and hierarchical clustering on principal components (HCPC) analyses into three functional types, viz., low wood density high deciduous (LWHD), high wood density medium deciduous (HWMD), and high wood density low deciduous (HWLD). Assemblage of functional traits suggested that the LWHD functional type exhibits a drought-avoiding strategy, whereas HWMD and HWLD adopt a drought-tolerant strategy. Our study showed that the variations in functional trait plasticity and the structural attributes of trees in the three functional types exhibit contrasting affinity with SMC, soil nutrients, and disturbances, although the LWHD functional type was comparatively more influenced by soil resources and disturbances compared to HWMD and HWLD along the declining SMC and edge distance gradients. Plasticity in functional traits for the LWHD functional type exhibited greater variations in traits associated with the conservation of water and resources, whereas for HWMD and HWLD, the traits exhibiting greater plasticity were linked with higher productivity and water transport. The cumulative influence of SMC, disturbances, and functional trait variations was also visible in the relative abundance of functional types in large and small sized fragments. Our analysis further revealed the critical differences in the responses of functional trait plasticity of the coexisting tree species in TDF, which suggests that important deciduous endemic species with drought-avoiding strategies might be prone to strategic exclusion under expected rises in anthropogenic disturbances, habitat fragmentation, and resource limitations.

Abstract Species of Opuntia (prickly pears), widely propagated for human use, are present in many agroforestry systems. Like other perennials, they are subject to environmental pressures that influence their reproductive ecology and reproductive output. Here, we studied floral biology, breeding system, and flower-bee interactions of Opuntia atropes, which is subject to management, to better understand its reproductive ecology. We documented floral phenology, morphology, and mating system by observing live flowers, measuring fixed flowers, and performing pollination treatments. We recorded frequency, behavior, and floral visitors’ handling time to determine the most effective pollinator. Opuntia atropes has large, herkogamous flowers and high P/O ratios. These traits promote outcrossing, which was supported by the results of pollination treatments. Fruit weight and seed set exhibited moderate pollen limitation. Floral visitors comprised nine bee species. Diadasia sp. was the most effective pollinator according to frequency and behavior. Opuntia atropes shows preferential outcrossing through pollination by a specialist bee despite being in a modified habitat. Pollen limitation and variation in reproductive success may lead to mating system evolution in O. atropes. The observed bee diversity suggests that O. atropes is an important source of floral resources in the dry season in semi-arid environments under moderate human disturbance.

Soil respiration (CO2 emission to the atmosphere from soils) is an important component of the global carbon cycle. In highly seasonal ecosystems the magnitudes and the underlying mechanisms that control soil respiration (RS) are still poorly understood and measurements are underrepresented in the global flux community. In this dataset, systematic and monthly measurements of RS were conducted with an infrared gas analyzer coupled to a static chamber during 2015, 2016, 2017 and 2019 in a tropical dry forest with a land use history from Northwestern México. These data is useful to assess the intra-annual and seasonal variations of RS at a highly seasonal dry forests and serves as a base line to benchmark soil carbon models in regional and global contexts. The data presented supports the research manuscript: “Soil respiration is influenced by seasonality, forest succession and contrasting biophysical controls in a tropical dry forest in Northwestern Mexico” from Vargas-Terminel et al. [1].

The Military Macaw (Ara militaris) is not considered within the avifauna of Morelos due to a lack of solid evidence confirming the presence of the species in the state. We conducted systematic surveys from elevated viewpoints in the tropical dry forest of the Sierra de Huautla Biosphere Reserve from August to December 2017 and 2020-2022 to confirm the presence of the Military Macaw in the reserve. We obtained 36 records of the Military Macaw, with photographic evidence, and observed a mean of 10.0 ± 11.2 macaws per record, registering flocks of 32-39 individuals on three occasions. We identified sites within the reserve that Military Macaws recurrently used for resting, foraging, and roosting. We also observed macaws foraging in three tree species, with another six plant species reported in the diet by local people. We could not confirm nesting by macaws in the reserve as observations were conducted outside the breeding season. Some sightings occurred outside the biosphere reserve, in an area of the Mixteca Baja Poblana (Puebla) proposed as a new protected area. Our findings provide the first systematic and photographic evidence of the presence of the Military Macaw in Morelos state, confirm the relevance and effectivity of the Sierra de Huautla Biosphere Reserve for regional conservation of the species and the tropical dry forest, and provide additional support for the proposal to create a new protected area and conservation corridor in the Balsas Basin that could benefit the conservation of this endangered bird species.

Little is known of intra- and inter-specific territoriality in Neotropical raptors that may defend territories throughout the year, and face greater inter-specific competition for resources. We evaluated intra- and inter-specific territorial responses of four species of Neotropical raptors in the tropical dry forest of the Chamela-Cuixmala Biosphere Reserve, Mexico. We conducted broadcast calls in territories of the Collared Forest-Falcon (Micrastur semitorquatus), Crane Hawk (Geranospiza caerulescens), Gray Hawk (Buteo plagiatus), and Roadside Hawk (Rupornis magnirostris), and measured the latency, duration, and type of territorial response to broadcast calls of conspecifics and sympatric raptor species. We applied repeated measures analysis to determine differences in intra- and inter-specific territorial responses of raptors, and GLMMs to evaluate whether traits of body size, nest type, and hunting technique were associated with territorial response by focal raptors. Large-bodied focal raptor species showed high intra-specific territoriality, giving faster, prolonged responses of various types, including duets and combined responses, to broadcast calls of conspecifics compared to sympatric species. All focal raptors showed some inter-specific territorial response, but this was mainly as vocalizations or displacements towards sympatric species broadcast calls. Species traits of body size, nest type, and hunting technique were associated with latency and duration of territorial response by the larger raptor species that nest in the forest canopy. These traits may be more strongly associated with territorial response of forest raptors that defend limited resources in a structurally complex environment.

The Armadillidae are the most diverse family within the Oniscidea, widely distributed around the world. To date, only seven species of the family are known from Colombia. After the examination of a collection from the Colombian departments of Atlántico, Bolívar, Cesar, Magdalena, Risaralda, Santander, and Sucre, eight species were recognized as belonging to the genus Ctenorillo, of which six are considered to be new to Science: C. binomio n. sp., C. humboldti n. sp., C. mincaensis n. sp., C. orientalis n. sp., C. papagayoensis n. sp., and C. tayrona n. sp. Moreover, the distribution knowledge of C. dazai and C. tuberosus has expanded. Ctenorillo species in Colombia are predominantly distributed in Tropical Dry Forest areas, which is one of the most endangered ecosystems in the world. Considering the new taxa presented here, allied with other Oniscidea groups, there is an urgent need to raise the awareness level regarding the conservation status of this ecosystem in the country.

Tropical dry forests (TDFs) support endemic biodiversity, and the livelihoods of millions of people globally. Invasive species, such as Lantana camara, are a predominant cause of degradation of TDFs. We examined lesser-studied vocalizing fauna and social outcomes of TDF restoration through Lantana removal, focusing on a Central Indian TDF. We quantified biodiversity using acoustics in 55 locations in restored, unrestored, and Low Lantana Density (LLD) forest sites and surveyed 656 households across villages adjacent to these forest sites. Our ecological analysis showed that in comparison to unrestored and LLD sites, restoration was not significantly associated with a different acoustic space occupancy (ASO) in higher frequencies (9–24 kHz) during night time hours, meaning restoration does not impact nocturnal vocalising or stridulating species. However, restored and LLD sites had significantly lower ASO in the day time hours, potentially due to differences in the insect community when Lantana is absent. Through the household surveys, we found that the highest number of respondents across all the three types of sites valued the cash payment they received for participating in restoration efforts. Perceptions of lower amounts of crop raiding by wild ungulates were associated by villagers with a restored site. This perception was mediated by the total number of households in a village with a restored site. Focusing restoration efforts on forests surrounding villages, restoration planners could reduce potential negative human-wildlife interactions. Combining ecological and social outcomes, we found that there are immediate positive outcomes of restoration for people. However, in the short term (three years following restoration), there was no significant biodiversity ‘benefit’. Based on our results, we recommend that restoration planners (1) consult local people about their perception of forest degradation and restoration because people’s perceptions can accurately mirror the condition of the forest; (2) provide a cash income for participating in restoration activities and (3) anticipate potential changes in the faunal species community in the short term when large scale invasive species removal takes place.

Background and Research Aims: Historical geological events and climatic changes have played important roles in shaping population differentiation and distribution within species. Amazilia rutila (Trochilidae) is a widespread hummingbird species in the tropical dry forest along the Pacific slope and the Yucatán Peninsula in Mexico. Methods: We used mitochondrial DNA sequence, ecological niche modelling and niche divergence tests to determine the effects of major geographic barriers and environmental variability on genetic and niche divergence of A. rutila continental populations. Results: Our results revealed three genetic groups without haplotype sharing corresponding to the distribution of individuals/populations from the Pacific slope W of the Isthmus of Tehuantepec (PAC), in Oaxaca and Chiapas E of the Isthmus of Tehuantepec (CHIS_OAX) and those from the Yucatán Peninsula and Guatemala (YUC). Values of neutrality tests suggest past demographic expansion without effective population size changes over time, and the time since the demographic expansion ranged between 39.4 and 84.45 ka BP. Each genetic group differed in their position in environmental space, with low-to-very limited overlap in the fundamental climatic niche dimensions of all groups analyzed, particularly between YUC and PAC. Analysis of climate differentiation and ecological niche comparisons showed that the environmental space occupied by these mtDNA groups is similar but not identical. Conclusion: We conclude that the genetic differentiation of A. rutila is consistent with a model of population isolation by geographical barriers and environmental differences. Inferences about the consequences of past demographic expansion and isolation underlying intraspecific evolutionary relationships await further study. Implications for Conservation: Our findings highlight the importance of preserving evolutionary significant units of this widespread hummingbird species. Conservation actions must consider intrinsic requirements of evolutionarily distinct populations and the environmental drivers that shape their distributions, maximizing preservation of intraspecific genetic variability and monitoring changes in genetic diversity. [ABSTRACT FROM AUTHOR]

Chronosequence changes among Tropical Dry Forests (TDFs) are essential for understanding this unique ecosystem, which is characterized by its seasonality (wet and dry) and a high diversity of deciduous trees and shrubs. From 2005 to 2021, we used two different airborne LiDAR systems to quantify structural changes in the forest at Santa Rosa National Park. Line- and shape-based waveform metrics were used to record the overall changes in the TDF structure. Based on a 16-year growth analysis, notable variations in height-related profiles were observed, particularly for RH50, RH100, and waveform-produced canopy heights. The results showed that Cy and RG have increased since the forests have been growing, whereas Cx has decreased. The decrease in Cx is because ground returns are lower when the canopy density i and canopy height increase. A positive relationship was observed between Cy and CH, RG, and RH100, particularly for the wet season data collected in 2021. These findings provide important insights into the growth dynamics of TDFs in Santa Rosa National Park and could inform future conservation efforts. [ABSTRACT FROM AUTHOR]

Tropical drylands are among the most threatened ecosystems worldwide, and fewer than 10% of tropical dry forests in Hawai'i remain intact. Terrestrial arthropods comprise most of the endemic fauna on many islands, including Hawai'i, where they provide ecosystem services such as pollination, decomposition, and a reliable prey base for predators. The objective of our study was to measure understory arthropod diversity and relative abundances in two common habitat types within dryland Hawai'i—a non-native grassland, dominated by Cenchrus setaceus (fountain grass) with few native shrubs, and a native woodland, dominated by Metrosideros polymorpha ('ōhi'a). We used generalized additive models to examine patterns of understory arthropod dynamics measured monthly or bimonthly in relation to the two habitat types and local climatic variables. We found that temperature and habitat type were significant predictors of the abundance of certain arthropod families and orders. A greater abundance of spiders was in the woodland than grassland habitat, and more beetles and ants (particularly the Argentine ant, Linepithema humile) were in the grassland than woodland habitat. Temperature significantly predicted overall family-level richness and diversity of arthropods as well as Araneae, Heteroptera, Hymenoptera, and Lepidoptera abundance. Precipitation significantly predicted Heteroptera abundance. Significant positive associations were found among some arthropod groups, including several arachnid groups and families of Hemiptera. Documentation of insect and other arthropod community dynamics improves our understanding of ecological community function, supporting management of island communities comprised of both native and non-native species. [ABSTRACT FROM AUTHOR]

The influence of land use on the content and distribution of soil carbonates was assessed in representative sites from three basins on the Santa Elena Peninsula. Two samplings were conducted: one at the surface, at a depth of 0-30 cm (Río Verde: 100 points; El Chaparral: 50 points; PIDAASSE: 100 points; Manglaralto: 50 points), and another at depth (0-10, 10-20, 20-40, 40-60, and 60-100 cm) in areas preserved under tropical dry forest. The Bernard calcimeter method was employed to determine equivalent calcium carbonate (ECC). It is concluded that soils in the investigated sites from different basins are slightly calcareous and exhibit low levels of total carbonates, thus not posing a potential problem for crops at present. The depth-wise distribution of carbonates in soils with alluvial influence may respond to sedimentological dynamics associated with rainy periods and cyclic extreme events. The influence of land use on ECC contents was evident, with statistically significant differences found for soils with lower anthropogenic intervention in sites with varying humidity gradients. However, no differences were observed between sites with the most contrasting climatic conditions, Manglaralto (sub-humid) and Zapotal (arid), under agricultural uses for short and intermediate crop cycles, attributable to the influence of agricultural practices. These results may be indicative of advancing desertification in the more humid regions of the northern peninsula. [ABSTRACT FROM AUTHOR]

Summary: Nutrient allocation is central to understanding plant ecological strategies and forest roles in biogeochemical cycles. Thought to be mainly driven by environmental conditions, nutrient allocation to woody organs, especially to living tissues, is poorly understood.To examine the role of differences in living tissues (sapwood, SW, vs inner bark, IB), organs, ecological strategies, and environmental conditions in driving nutrient allocation and scaling in woody plants, we quantified nitrogen and phosphorus in main stems and coarse roots of 45 species from three tropical ecosystems with contrasting precipitation, fire regime, and soil nutrients.Nutrient concentration variation was mostly explained by differences between IB and SW, followed by differences between species and, in the case of phosphorus, soil nutrient availability. IB nutrient concentrations were four times those of SW, with root tissues having slightly higher concentrations than stem tissues. Scaling between IB and SW, and between stems and roots, was generally isometric. In cross‐sections, IB contributed half of total nutrients in roots and a third in stems.Our results highlight the important role of IB and SW for nutrient storage, the coordination in nutrient allocation across tissues and organs, and the need to differentiate between IB and SW to understand plant nutrient allocation. [ABSTRACT FROM AUTHOR]