Tropical Forest Regions Research Articles

Advancing Forest Degradation and Regeneration Assessment Through Light Detection and Ranging and Hyperspectral Imaging Integration

Integrating Light Detection And Ranging (LiDAR) and Hyperspectral Imaging (HSI) enhances the assessment of tropical forest degradation and regeneration, which is crucial for conservation and climate mitigation strategies. This study optimized procedures using combined airborne LiDAR, HSI data, and machine learning algorithms across 12 sites in the Brazilian Amazon, covering various environmental and anthropogenic conditions. Four forest classes (undisturbed, degraded, and two stages of second-growth) were identified using Landsat time series (1984–2017) and auxiliary data. Metrics from 600 samples were analyzed with three classifiers: Random Forest, Stochastic Gradient Boosting, and Support Vector Machine. The combination of LiDAR and HSI data improved classification accuracy by up to 12% compared with single data sources. The most decisive metrics were LiDAR-based upper canopy cover and HSI-based absorption bands in the near-infrared and shortwave infrared. LiDAR produced significantly fewer errors for discriminating second-growth from old-growth forests, while HSI had better performance to discriminate degraded from undisturbed forests. HSI-only models performed similarly to LiDAR-only models (mean F1 of about 75% for both data sources). The results highlight the potential of integrating LiDAR and HSI data to improve our understanding of forest dynamics in the context of nature-based solutions to mitigate climate change impacts.

To improve estimates of neotropical forest carbon stocks more direct measurements are needed: An example from the Southwestern Amazon

Tropical forests play a critical role in the global carbon cycle, storing 40–55 % of terrestrial plant carbon and significantly contributing to primary productivity. However, uncertainties persist in estimating carbon stocks and fluxes, exhibiting variation across the Neotropics, Africa, and Asia tropical forest regions. Despite hosting some of the most densely sampled forests, significant uncertainties persist in biomass and forest carbon stock estimates in the Neotropics. Although the Southwestern Amazon (SWA) forests span over 20 million hectares, no specific biomass or above- and below-ground carbon model has been calibrated for this region thus far. In our study, we conducted direct forest inventories in the SWA to address the following question: Do the allometric patterns, biomass, and carbon stocks observed in the Southwestern Amazon differ from those found in other regions of the Amazon or Pantropical? Our research reveals substantial differences in water and carbon content, biomass stocks, above- and below-ground oven-dry biomass ratios, and allometric patterns between SWA forests and other Amazonian and Pantropical forests. We have demonstrated that these differences result in overestimations of forest biomass when applying allometric equations developed for other Amazonian and Pantropical regions to the open forests of Southwestern Amazonia. This overestimation can reach up to 37 % when using equations from the eastern Amazon, and between 26 % and 46 % depending on the applied Pantropical equation. The use of an inappropriate factor for the root-to-shoot ratio in the Southwestern Amazon (SWA) can lead to overestimates of belowground oven-dry biomass by up to 20 %. To reduce uncertainties related to estimates of forest carbon stock and flux in Neotropical forests, it is necessary to enhance the density of direct biomass measurements, particularly in southwestern Amazonia.

Diversity and Distribution of Monocot Understory Herbs during Tropical Forest Succession in Northeastern Costa Rica

Broad-leaved monocot herbs form one of the most common and diverse growth forms of Neotropical plants. Their significance and frequency of occurrence is particularly notable in the understories of tropical rainforests, where they form a dominant element. We assessed and quantified changes in the cover and diversity of understory herb communities in a chronosequence of 1 ha permanent plots established as part of a multidisciplinary study on tropical forest regeneration in the Atlantic lowlands of northeastern Costa Rica. Sampled were two young stands cleared 12 years ago, two secondary forests with 21 and 39 of years of recovery since clearance, and two stands in old-growth primary forest. Changes in species composition during succession were assessed using Chao’s Jaccard similarity index. Observed species richness ranged from 15 to 26 species in individual plots, with the greatest number of species in the 21-year intermediate-age and fewest in the young 12-year plots. Herb species sampled represented 6 families, 15 genera, and 39 species, with the Araceae contributing the largest number of species. Ten species were sampled in all six stands, while fourteen species were found exclusively in one plot. Herb density (ramets m−2) showed a hump-shade trend, with peak density in the intermediate stands and a lower level in mature and young secondary forests. Mean herb cover in 25 m2 quadrats ranged from 2.0% (young stand) to 22.7% (intermediate-age stand) and differed significantly both among stand types and among sites. Both observed and estimated species richness increased along the chronosequence as a whole, with the highest number of species in primary forest, although only slightly higher than in intermediate-age stands. Over half of the species exhibited some degree of clonal growth, with the extent of clonal spread varying among species and forest stands. Although we did not find a clear pattern between clonality and forest age, we observed a greater number of clonal patches in secondary over primary forest stands.

Evidence of thermophilization in Afromontane forests

Thermophilization is the directional change in species community composition towards greater relative abundances of species associated with warmer environments. This process is well-documented in temperate and Neotropical plant communities, but it is uncertain whether this phenomenon occurs elsewhere in the tropics. Here we extend the search for thermophilization to equatorial Africa, where lower tree diversity compared to other tropical forest regions and different biogeographic history could affect community responses to climate change. Using re-census data from 17 forest plots in three mountain regions of Africa, we find a consistent pattern of thermophilization in tree communities. Mean rates of thermophilization were +0.0086 °C·y−1 in the Kigezi Highlands (Uganda), +0.0032 °C·y−1 in the Virunga Mountains (Rwanda-Uganda-Democratic Republic of the Congo) and +0.0023 °C·y−1 in the Udzungwa Mountains (Tanzania). Distinct from other forests, both recruitment and mortality were important drivers of thermophilzation in the African plots. The forests studied currently act as a carbon sink, but the consequences of further thermophilization are unclear.

GC-MS analysis of three Diospyros species and evaluation of its in vitro rat intestinal a-glucosidase and FRAP activity

Abstract. Hariyanto NA, Ramadhan R, Raharjo Y, Firdaus YFH, Kurnia IT, Lestari DA, Suwandari S, Mahmuda NF, Nathanael J, Phontree K, Phuwapraisirisan P, Riyadi L, Rahman A, Abdulgani N. 2024. GC-MS analysis of three Diospyros species and evaluation of its in vitro rat intestinal a-glucosidase and FRAP activity. Biodiversitas 25: 2442-2453. The vast diversity of natural products has long been recognized as a potentially valuable source of bioactive compounds derived from nature. The Diospyros species, belonging to the Ebenaceae family, thrive in tropical forest regions and have been traditionally used for treating various disorders such as ischemic stroke, hypertension, and infectious diseases. This research aims to assess the phytochemical constituents, rat intestinal a-glucosidase, and Ferric-Reducing Antioxidant Power (FRAP) of non-polar (n-hexane) and semi-polar (dichloromethane) extracts from three Diospyros species, i.e., Diospyros buxifolia (Blume) Hiern; Diospyros celebica Bakh.; Diospyros confertiflora (Hiern) Bakh). Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified numerous bioactive secondary metabolites in the extracts. The study revealed that the semi-polar extracts of D. buxifolia exhibited potent rat intestinal a-glucosidase inhibitory activities, with an IC50 value of 33.31±3.23 ug/mL. The IC50 of acarbose as a positive control was 6.31±0.31 ug/mL. The FRAP test demonstrated that the non-polar and semi-polar leaf extracts of the three Diospyros species from East Kalimantan are potential sources of natural antioxidants, with the IC50 in the range of 6.48±0.38 umol Fe/g - 11.35±0.16 umol Fe/g. The results of this study confirm the therapeutic properties of leaf extracts derived from 3 Diospyros species, which align with their traditional medicinal use.

Impacts of Deforestation on Soil Quality and Water Resources in Tropical Forest Areas of Sumatra

Deforestation poses a significant threat to the tropical forest regions of Sumatra, impacting soil quality and water resources crucial for ecosystem health and human well-being. This paper synthesizes the multifaceted impacts of deforestation on soil and water in Sumatra and proposes strategies for sustainable land management. Deforestation leads to a decline in soil organic matter, nutrient levels, and microbial diversity, affecting soil fertility and erosion susceptibility. Additionally, the loss of forest cover disrupts the hydrological cycle, altering water availability, quality, and distribution. Increased surface runoff and sedimentation degrade water bodies, threatening aquatic biodiversity and community water supplies. Integrated analysis highlights the interdependencies between land cover change, soil degradation, and hydrological processes, emphasizing the need for holistic management approaches. Reforestation, agroforestry, and community engagement are proposed as essential strategies for mitigating deforestation impacts and promoting ecosystem resilience in Sumatra.

Hysterium madraspatanum (Hysteriaceae), a new species from Tropical Dry Evergreen Forest of Tamil Nadu, India

A new species of Hysterium, is described from tropical dry evergreen forest region of Chennai, Tamil Nadu, India, based on both morphological characteristics and molecular phylogenetic analysis using the Internal Transcribed Spacers (ITS) region of nuclear ribosomal DNA. The key morphological characters of the ascomata include the presence of a longitudinal slit remaining closed even at maturity. The ascospores biseriate having three septa with all the cells evenly pigmented including the terminal cells. The ascus measuring 115–122 × 20–22 μm. Ascospores initially two celled and finally become four celled, hyaline first, later changing to yellow and then dark brown, oblong to ellipsoid, 28–39 × 7–12 μm. The nrITS-based phylogenetic tree inferred from the Bayesian posterior probabilities indicate that H. madraspatanum is closely related to Hysterium pulicare, H. angustatum and H. rhizophorae. However, H. madraspatanum is morphologically distinct from them by having relatively larger spore size, shallow groove in the ascomata, spores with concolorous terminal cells. Therefore, is a novel species under the genus Hysterium. Azadirachta indica is reported in the study as a new host for the genus Hysterium.

Normalized Difference Vegetation Index (NDVI) marked reliable value of Ulu Muda Forest Reserve

Water resources must be preserved because they are vital for agricultural, industrial, and domestic use, especially in tropical forest regions. Given the importance of the Ulu Muda Forest Reserve to the Kedah state in sustaining paddy cultivation for the country, this study aimed to provide reliable forest classification method and produce Normalized Difference Vegetation Index-Maximum Likelihood Classification of forest density map for Ulu Muda Forest Reserve. Here, the study reports measurements of the satellite remote sensing index for the forest based the image date. The forest recorded NDVI index of 0.72 to 0.98 for high density, NDVI index of 0.61 to 0.71 for moderate and NDVI index of 0.26 to 0.60 for low density area. The index showed higher value, which is comparable with reports of other tropical forest elsewhere. The results were influenced using satellite remote sensing pre-processing, processing, and classification. As a result, based on the satellite image indices approach, upper threshold of the higher density, the forest can exhibit higher capability for sustaining its ecological and hydrological functions. Given that most of the tropical forest biome has sustained this threshold, forest management should be sustained at this state, and more measures should be taken for example increase of protection forest classification in Rancangan Pengurusan Hutan (RPH) that is one of yearly planning report in states of Peninsular Malaysia. In the meantime, Geographical Information System (GIS) capacity should be mandate looking forwards for more utilisation in mapping for planning and projection of forest resource management activities.

Progress and challenges in remotely sensed terrestrial carbon fluxes

ABSTRACT Accurate evaluation of terrestrial carbon balance is essential for designing climate change mitigation policies, and capabilities of remote sensing techniques in monitoring carbon fluxes are widely recognized for their great contributions to regional and global carbon budget accounting. In this review, we synthesized satellite-based data and methodologies to estimate the main flux components of terrestrial carbon balance and their uncertainties over the past two decades. The global gross primary production (GPP) during the period 2001–2022 is 134 ± 14 PgC yr−1, and nearly half of them occurs in tropical forest regions such as South America and Africa. Less than 2% of global GPP is converted into a net carbon sink of 2.28 ± 1.12 PgC yr−1 using satellite-based atmospheric inversion during 2015–2020, and this sink is comparable to the stock change-based estimate (2.49 PgC yr−1) but twice as large as model-based estimate (1.08 ± 0.78 PgC yr−1). By decomposing satellite-derived net carbon balance into different terms including satellite-derived carbon emissions from land-use change and wildfires (3.55 PgC yr−1), we inferred that ~ 43% of global GPP would be respired through soil microbes (57.1 PgC yr−1), but which is higher than the previous bottom-up estimate (39–46 PgC yr−1). We then propose that an accurate remote sensing of terrestrial carbon balance requires to enhance representations of photosynthetic responses to rising CO2 and disturbances, develop satellite-constrained belowground carbon dynamics and separate natural fluxes from anthropogenic CO2 emissions, by integrating multi-source satellite sensors in orbit, revolutionized remote sensing capabilities with focused field campaigns in data-scarce regions.

Loquat (Eriobotrya japonica) fruit consumption and preference by cloud forest birds: Implications for woody native species regeneration

Secondary forests from abandoned shade coffee plantations are commonly found close to Neotropical cities. These peri-urban forests provide important environmental services; however, their abandonment and proximity to the city can promote an increase of exotic species that could potentially change the structure and function of the system by creating novel ecosystems. The loquat (Eriobotrya japonica) is a tree native to Asia and is recognized as a potentially invasive species in the tropical montane cloud forest region of Central Veracruz, Mexico. We analyzed the consumption of and preference for loquat fruits in cloud forest frugivorous birds. In November 2020, we established six feeding stations with camera traps in a peri-urban cloud forest fragment in Xalapa, Mexico. To determine which bird species could consume and disperse E. japonica, fruits of this and another four native species (Psychotria nervosa, Hoffmannia excelsa, Picramnia antidesma, and Xylosma flexuosa) were exposed separately. After 444 camera-days, we recorded eight frugivorous bird species, seven of which consumed E. japonica fruits. Chlorospingus flavopectus was the only species to present a level of loquat fruit consumption greater than that expected by chance. We conducted experiments to assess whether the birds preferred to consume E. japonica fruits compared to those from three native species (Cestrum miradorense, P. nervosa, and X. flexuosa) that were offered simultaneously. All bird species exclusively consumed E. japonica fruits when contrasted against P. nervosa or X. flexuosa. The only native species fruits that were consumed were those of C. miradorense, although the birds also preferred to consume loquat fruits rather than this native species. The loquat therefore represents an important food resource and could act to influence the consumption and dispersal of native cloud forest plant species. The implications for cloud forest management are discussed.

Land use legacies affect early tropical forest succession in Mexico

AbstractQuestionsAgricultural expansion is one of the dominant drivers of forest and biodiversity loss, and shifting cultivation is the most widely used form of agriculture in many tropical forest regions. Where forests have been cleared, they have the potential to recover once the land is abandoned. However, legacies of land use are often overlooked in successional studies, and a deeper understanding of this legacy effect is needed to define efficient restoration practices using natural or assisted regeneration. Here, we analysed how land‐use history affects soil properties and early succession on abandoned agricultural fields in two contrasting Mexican socio‐ecological systems.LocationMexico, Oaxaca and Chiapas.MethodsWe sampled soil and monitored vegetation for 2 years after agricultural abandonment, and interviewed landowners about their land‐use practices.ResultsLand‐use practices were clearly influenced by landowners’ social context (residence time, rural or urban origin), and topography and soil type also constrained or facilitated land‐use practices. Soil characteristics were strongly affected by three land‐use practices: mechanical tillage decreased soil N and K; frequent herbicide and pesticide use increased N and K; and for pasture systems, stocking density increased soil bulk density and decreased pH and N. High‐intensity land management practices, specifically use of machinery, had the highest impact on early forest succession. When machinery was not used, the frequency of land‐use practices, particularly weeding frequency, is the main factor influencing tree cover and sapling diversity.ConclusionsTo facilitate post‐agricultural forest recovery, we recommend restoration efforts using natural regeneration in areas with low previous land‐use intensity and frequency.

Utilizing Multi-Temporal ALOS/PALSAR Backscatter Data to Detect Deforestation in the Indonesian Tropical Forest

Deforestation detection mapping has been analyzed using Synthetic Aperture Radar (SAR) data from the ALOS PALSAR satellite. SAR is a promising tool for deforestation mapping in tropical forest regions because microwave energy can penetrate clouds. This study examined the effect of SAR polarization on the accuracy of deforestation mapping and the seasonal variation of radar backscattering values in Riau Province, Indonesia. Image differencing was used to determine the threshold value for distinguishing between forest and non-forest areas. The difference between HV (horizontal transmit-vertical receive) and HH (horizontal transmit-horizontal receive) polarization was used as the discriminant variable. The correlation between radar backscattering value and accumulated rainfall was also analyzed to assess the effect of seasonal change. The findings demonstrated that the accuracy of deforestation detection mapping using HV polarization outperforms that achieved with HH polarization. Moreover, seasonal variations in rainfall were observed to influence radar backscatter signatures in bare soil, acacia, and oil palm, though no such influence was detected in forested areas. The accuracy of deforestation detection mapping, employing the thresholding method, reached a rate of 92.21%. During the period from November 2007 to July 2009, forested areas in Riau experienced a reduction, decreasing to 6.77%, and further decreasing to 6.08% by October 2010.

Climate Seasonality of Tropical Evergreen Forest Region

Climatic seasonality has lacked research attention in terms of global tropical forests, where it impacts vegetation productivity, biodiversity, and hydrological cycles. This study employs two methods—climatological anomalous accumulation (CAA) and potential evapotranspiration (PET) threshold—to detect the climatic seasonality of global tropical forests, including the onset and duration of wet seasons. Spatial clustering based on the length of the wet season is used to delineate smaller regions within the tropical forest areas to observe their precipitation patterns. The results show that these methods effectively reveal more homogeneous regions and their respective rainfall patterns. In particular, we found that the wet season in Amazon forests detected by the CAA method is more uniform in space than the PET threshold, but the global tropical forest regions divided by the CAA method on average contain more complex climates than the PET threshold. Moreover, the year-round abundant precipitation in Southeast Asia, which is strongly influenced by monsoons, presents challenges for wet season detection. Overall, this work provides an objective perspective for understanding the climatic seasonality changes in tropical forests and lays a scientific foundation for future forest management and the development of adaptation strategies to global climate change.

Regional-Scale Assessment of Burn Scar Mapping in Southwestern Amazonia Using Burned Area Products and CBERS/WFI Data Cubes

Fires are one of the main sources of disturbance in fire-sensitive ecosystems such as the Amazon. Any attempt to characterize their impacts and establish actions aimed at combating these events presupposes the correct identification of the affected areas. However, accurate mapping of burned areas in humid tropical forest regions remains a challenging task. In this paper, we evaluate the performance of four operational BA products (MCD64A1, Fire_cci, GABAM and MapBiomas Fogo) on a regional scale in the southwestern Amazon and propose a new approach to BA mapping using fraction images extracted from data cubes of the Brazilian orbital sensors CBERS-4/WFI and CBERS-4A/WFI. The methodology for detecting burned areas consisted of applying the Linear Spectral Mixture Model to the images from the CBERS-4/WFI and CBERS-4A/WFI data cubes to generate shadow fraction images, which were then segmented and classified using the ISOSEG non-supervised algorithm. Regression and similarity analyses based on regular grid cells were carried out to compare the BA mappings. The results showed large discrepancies between the mappings in terms of total area burned, land use and land cover affected (forest and non-forest) and spatial location of the burned area. The global products MCD64A1, GABAM and Fire_cci tended to underestimate the area burned in the region, with Fire_cci underestimating BA by 88%, while the regional product MapBiomas Fogo was the closest to the reference, underestimating by only 7%. The burned area estimated by the method proposed in this work (337.5 km2) was 12% higher than the reference and showed a small difference in relation to the MapBiomas Fogo product (18% more BA). These differences can be explained by the different datasets and methods used to detect burned areas. The adoption of global products in regional studies can be critical in underestimating the total area burned in sensitive regions. Our study highlights the need to develop approaches aimed at improving the accuracy of current global products, and the development of regional burned area products may be more suitable for this purpose. Our proposed approach based on WFI data cubes has shown high potential for generating more accurate regional burned area maps, which can refine BA estimates in the Amazon.

Co‐production of agroecological innovations to improve sustainability in South American fruit farms

Abstract Agricultural intensification and expansion are the main drivers of biodiversity loss that continue to increase this century, especially in South America. International markets and global policy provide incentives and frameworks to address this, but these are unlikely to be effective unless farmers on the ground are enabled and motivated to respond to them by developing long‐term solutions that fit their production systems and local contexts. Here, we use a multi‐actor transdisciplinary approach to co‐design and test agroecological innovations suitable for intensive, exporting South American fruit farms. We focus on highly biodiverse regions experiencing habitat loss in the Mediterranean and dry tropical forest regions of Chile and Brazil, respectively. The innovations were designed to support local biodiversity without compromising productivity or quality. Fourteen farmers participated throughout the project, covering a total of 4178 ha of intensive table grape, mango and cherry production. All were under pressure from buyers to report action on biodiversity. Farmers worked with researchers and industry representatives through an iterative process of dialogues and workshops to select, co‐design and implement three agroecological innovations: perches for birds of prey, cover crops and native hedgerows. Farmers became engaged in monitoring their effectiveness and redesigning them to suit local contexts. We develop an extensive set of resources for ongoing dissemination, including an online sustainability metric to report the practices carried out. Eight farms continued to implement at least one agroecological innovation beyond the end of the project, motivated by its fit to their management system and their ability to report positive actions in their supply chains. Policy implications. Our model of knowledge co‐production demonstrates how transdisciplinary research in agriculture, fully localised in a particular food‐producing context, can enable farmers in the global South to engage with biodiversity conservation in response to top‐down market signals incentivising sustainability. We argue that many top‐down efforts to enhance the sustainability of food supply chains, whether through market incentives, voluntary codes or trade regulations, require locally based knowledge co‐production, in which multiple stakeholders from agriculture and the food industry can benefit from working with locally based researchers. Read the free Plain Language Summary for this article on the Journal blog.

Calling for the future of conservation: a protocol for passive acoustic monitoring of small arboreal primates

Biodiversity conservation faces challenges due to a lack of accurate information on species occurrence. Various techniques have been used to survey species diversity and estimate population density, but monitoring species over large spatial and temporal scales remains challenging. Passive acoustic monitoring (PAM) has emerged as a cost-effective and non-invasive method for monitoring biodiversity. PAM utilizes autonomous recording units (ARUs) installed in different areas and is particularly relevant for monitoring threatened species in tropical forest regions. In the case of non-human primates, PAM has proven effective in detecting endangered species, monitoring populations, studying vocal behavior, and evaluating territory use. The black lion tamarin (Leontopithecus chrysopygus), an endangered species of the Atlantic Forest, relies on acoustic signals for communication. This study proposes a PAM protocol for monitoring arboreal primates using the black lion tamarin as a model. It reviews PAM's use in primate research and emphasizes defining target vocalizations. We recommend optimal recording conditions, including distance, height, and equipment. Recordings should be positioned high above the ground, considering the arboreal nature of primates. The choice of spatial distribution, including random placement, transects, and grids, depends on the research question and objectives. Lastly, the study addresses the recording schedule, considering periods of greater species activity, such as from sunrise to sunset. In summary, this study highlights PAM's potential for monitoring arboreal primates providing recommendations for vocalizations, recording conditions, equipment, spatial distribution, and schedules, contributing to effective monitoring, and supporting conservation efforts in tropical forests.

Diversity patterns along ecological succession in tropical dry forests: a multi‐taxonomic approach

Evaluating the diversity of multiple taxa is fundamental to understand community assembly and to assess the integrity and functionality of tropical secondary forests. In this study, we analyzed the natural regeneration of tropical dry forests (TDFs) in three regions of Brazil using Hill–Simpson diversity, abundance and β‐diversity of trees and five groups of insects (herbivores, fruit‐feeding butterflies, ants, culicid mosquitoes and dung beetles). Sampling was conducted in 39 0.1 ha plots using a chronosequence approach (13 plots in early, intermediate and old‐growth forests). We evaluated the contribution of three different levels to γ‐diversity: α (within plots), β1 (among plots) and β2 (among successional stages), and further determined the relative importance of turnover (species replacement) and nestedness (differences in species number among sites) to β2. Our results showed that, unexpectedly, the Hill–Simpson diversity was consistently higher in early than old‐growth stages for all regions, but varied more widely in the intermediate stages. For each group separately, the same trend was observed for butterflies, ants, dung beetles and herbivores and did not differ among stages for mosquitoes. Successional differences in abundance were only detected for trees (increasing along the gradient) and for mosquitoes (decreasing). According to our expectations, the additive partitioning analysis showed that β2‐diversity contributed more to γ‐diversity than β1‐diversity, when all taxa were considered together and for most of them separately (except for butterflies and dung beetles). Most of the β2‐diversity was due to species turnover, but this contribution varied among groups and regions, with the highest turnover for herbivores and the lowest for dung beetles. Our results suggest that the Hill–Simpson diversity and changes in species composition (as given by β2‐diversity) are better indicators of forest natural regeneration than raw species richness, corroborating previous studies with plants and animals.

Natural forest regeneration over a fallow age chronosequence in central African moist forests

AbstractA better understanding of the natural regeneration in tropical forests could help develop more effective restoration strategies. This study examined relationships in structural and diversity attributes of natural regeneration in five forest fallow ages after slash‐and‐burn agriculture (6 months, 2 years, 5 years, 10 years, and 15 years) in the Republic of Congo. For each fallow age, all stems with a diameter ≥1 cm and below 5 cm (height ≥ 130 cm), corresponding to natural forest regeneration, were identified to the species level, and measured (diameter and height) in 12 plots (10 m × 10 m). Three structural attributes (stem density, maximum diameter, and maximum height) and five diversity indices (species richness, Shannon diversity, Simpson diversity, Fisher's alpha and Pielou's evenness) were estimated at the plot level. Our results revealed an increase in structural and diversity attributes with fallow ages, except stem density. The young fallow (6 months, 2 years and 5 years) had greater stem density (61 ± 48 stems), while the old fallow (10 years and 15 years) had higher maximum height (5.39 ± 2.36 m) and Shannon's index (0.94 ± 0.18). These results provided new insights into natural regeneration between young and old secondary forests.

Biogeographic analysis of population density of white-tailed deer in Mexico: Importance of the Protected Natural Areas and Wildlife Management Units

The white-tailed deer Odocoileus virginianus is the wildlife species with the greatest geographic distribution and economic importance in Mexico. This article presents a biogeographic analysis of the population density of this deer species by federal states, vegetation types, biogeographic provinces, and field methods, based on 200 selected studies. Estimates are highly variable and potentially biased due to the different field designs and statistical analyses. The national average density was estimated at 6.9 deer/km2 (SD = 5.1); specifically, 75.5 % of the estimates were less than 10 deer/km2, and only 5.5 % were greater than 15 deer/km2. The highest densities were obtained in the northern region by applying the strip transect counts; while estimations using the fecal group count method were more variable and were the most used method in temperate and tropical dry forest regions. The states with the highest densities were Coahuila, Tamaulipas, Jalisco, Morelos, Michoacán, and Durango. The highest densities were estimated in the xerophilous scrublands of the northeast, intermediate for temperate, tropical dry, and sub-deciduous forests; and the lowest in the tropical wet forest. The highest densities were reported for the Tamaulipeca province followed by the Altiplano Chihuahuense, Sierra Madre Occidental, Costa Pacífica, and Depresión del Balsas. The results of this analysis could guide management strategies for the conservation and sustainable use of this species in extensive UMAs and ANPs, and also to test ecological hypotheses. However, applying more rigorous field design and statistical analysis is important to obtain confident estimates of population density and other demographic parameters to monitor population dynamics.

The distribution and conservation of areas with microendemic species in a biodiversity hotspot: a multi-taxa approach.

Microendemic species are species with very small geographic distributions (ranges). Their presence delimitates areas with microendemic species (AMs), denoting a spatial unit comprising at least one population of at least one microendemic species. AMs are assumed to be distributed distinctively and associated with specific ecological, historical, and anthropogenic attributes. However, the level of influence of these factors remains unclear. Thus, we studied the distribution patterns of microendemic species within the Brazilian Atlantic Forest to (a) identify the region's AMs; (b) evaluate whether ecological (latitude, altitude, distance from the coastline), historical (climate stability), and anthropogenic (ecological integrity) attributes distinguish AMs from non-AMs; and (c) assess the conservation status of the Atlantic Forest's AMs. We mapped the ranges of 1,362 microendemic species of angiosperms, freshwater fishes, and terrestrial vertebrates (snakes, passerine birds, and small mammals) to identify the region's AMs. Further, spatial autoregressive logit regression models were used to evaluate whether latitude, altitude, distance from the coastline, Climate Stability Index, and ecological integrity can be used to discern AMs from non-AMs. Moreover, the AMs' conservation status was assessed by evaluating the region's ecological integrity and conservation efforts (measured as the proportion of AMs in protected areas). We identified 261 AMs for angiosperm, 205 AMs for freshwater fishes, and 102 AMs for terrestrial vertebrates in the Brazilian Atlantic Forest, totaling 474 AMs covering 23.8% of the region. The Brazilian Atlantic Forest is a large and complex biogeographic mosaic where AMs represent islands or archipelagoes surrounded by transition areas with no microendemic species. All local attributes help to distinguish AMs from non-AMs, but their impacts vary across taxonomic groups. Around 69% of AMs have low ecological integrity and poor conservation efforts, indicating that most microendemic species are under threat. This study provides insights into the biogeography of one of the most important global biodiversity hotspots, creating a foundation for comparative studies using other tropical forest regions.