Savanna Communities Research Articles

Ophidiophobia, myth generation, and human perceptions: Implications for snake conservation in a typical savanna community of northern Ghana

ABSTRACT Snakes have fascinated and terrified humans throughout history. Worldwide, innate fear (ophidiophobia), culturally-founded superstition, and myths have caused pervasive snake persecution, snakebite mismanagement, human injuries, and fatalities, particularly in the tropics. We analyzed 20 common snake myths narrated by 934 respondents inhabiting a typical rural savanna community of northern Ghana. The myths summarized perceived, self-assessed knowledge about snakes and were evaluated in their zoo-ecological contexts versus their folkloristic explanatory origins. Only eight snake myths (~40%) had any justifiable scientific basis, partially representing misinterpretations among predominantly male, less-educated respondents. Contrastingly, 70% of the myths were largely rooted in ophidiophobia, representing a major driver of human-wildlife conflict and indiscriminate snake persecution. To promote wildlife-friendly perceptions and behavior toward snakes and their conservation, we recommend innovative gap-bridging conservation education and public awareness that reconciles myths and realities about snakes, thus reducing snakebite incidences, mortality, and widespread persecution and killing of snakes.

Short-term impact of fire on the total soil microbial and nitrifier communities in a wet savanna.

Savannas are characterized by the coexistence of grasses and trees. Fires are critical for their coexistence, because they decrease the survival of tree seedlings and saplings and their recruitment to the adult stage. In some humid savannas, perennial grasses inhibit nitrification and trees stimulate nitrification, which likely favors coexistence between trees and grasses. However, fires may influence plant capacity to control nitrogen cycling, which could subsequently influence tree–grass coexistence and savanna nitrogen budget. Therefore, we sampled soil in a humid savanna of Ivory Coast under the dominant nitrification‐inhibiting grass species and the dominant nitrification‐stimulating tree species and under bare soil before and after (i.e., 5 days) fire during the long dry season. We quantified the total microbial and nitrifier abundances and transcriptional activities and the nitrification enzyme activity. Fire decreased soil water content, probably by increasing evaporation and, maybe, by triggering the growth of grasses, and increased soil ammonium availability likely due to ash deposition and increased mineralization. Fire did not impact the total archaeal, bacterial, or fungal abundances, or that of the nitrifiers. Fire did not impact archaeal transcriptional activity and increased bacterial and fungal total transcriptional activities. In contrast, fire decreased the archaeal nitrifier transcriptional activities and the nitrification enzymatic activity, likely due to the often reported resumption of the growth of nitrification‐inhibiting grasses quickly after the fire (and the subsequent increase in root exudation). These results pave the way for a better understanding of the short‐term effects of fire on nitrogen cycling and tree–grass competition for nitrogen.

Intraspecific trait variation of woody species reduced in a savanna community, southwest China

Plants deploy various ecological strategies in response to environmental heterogeneity. In many forest ecosystems, plants have been reported to have notable inter- and intra-specific trait variation, as well as clear phylogenetic signals, indicating that these species possess a degree of phenotypic plasticity to cope with habitat variation in the community. Savanna communities, however, grow in an open canopy structure and exhibit little species diversification, likely as a result of strong environmental stress. In this study, we hypothesized that the phylogenetic signals of savanna species would be weak, the intraspecific trait variation (ITV) would be low, and the contribution of intraspecific variation to total trait variance would be reduced, owing to low species richness, multiple stresses and relatively homogenous community structure. To test these hypotheses, we sampled dominant woody species in a dry-hot savanna in southwestern China, focusing on leaf traits related to adaptability of plants to harsh conditions (year-round intense radiation, low soil fertility and seasonal droughts). We found weak phylogenetic signals in leaf traits and low ITV (at both individual and canopy-layer levels). Intraspecific variation (including leaf-, layer- and individual-scales) contributed little to the total trait variance, whereas interspecific variation and variation in leaf phenology explained substantial variance. Our study suggests that intraspecific trait variation is reduced in savanna community. Furthermore, our findings indicate that classifying species by leaf phenology may help better understand how species coexist under similar habitats with strong stresses.

Defaunation and changes in climate and fire frequency have synergistic effects on aboveground biomass loss in the brazilian savanna

As a result of anthropogenic pressure, three drives are expected to affect Brazilian savannas: an increase in the dry season, more frequent fire events, and defaunation. These drivers are a trigger for biodiversity loss and undermine the ecosystems services like carbon storage. Here our goal was to analyze how these drivers can affect the structure and dynamics of the savanna's tree species and how they impact the savanna's total estimating aboveground biomass (AGB). We analysed eight sites that comprise a physiognomic gradient from open savanna to savanna woodland. The species were classified by three traits: phenological strategies (deciduous or evergreen), fire resistance (resprouting or non-resprouting), and dispersal syndrome (animal or non-animal). Then, we modelled AGB loss in a dry season in the austral winter, a 2 °C increase in daily temperature, five fire events by decadal-series, and a defaunation scenario. Although climate change, change in fire frequency, and defaunation effects impact AGB separately, they also have a synergistic effect. This effect was observed in functional strategies and also in the total AGB of the community. In some cases, the total AGB loss exceeded 70%. The negative effects on performance were highest in species which were decidual, non-resprouting, and which employed animal dispersal for their seed. If different types of disturbances are not controlled in the near future, savanna communities will be dominated by evergreen, resprouters, and non-animal dispersed species, representing a steeply decline in the diversity of species and ecosystem functions.

Bachman's Sparrow survival and nest predation response to a hardwood canopy reduction experiment

AbstractWhere historical fire regimes have been disrupted, reduction in woody vegetation is often used to maintain or restore habitat for grassland and early successional birds. In pine savanna ecosystems of the southeastern USA, mechanical hardwood canopy reduction can restore pine savanna communities and is often employed on privately owned lands to improve habitat for the Northern Bobwhite (Colinus virginianus), although scant empirical evidence exists of its effects on target or non‐target species. We measured the response of a pine savanna specialist, the Bachman's Sparrow (Peucaea aestivalis), to large‐scale hardwood reduction in a before–after–control–impact design on two properties where two‐year fire‐return intervals were established and the Bachman's Sparrow population was stable. We investigated the effects of mechanical hardwood reduction on Bachman's Sparrow daily nest survival, cause‐specific nest mortality and adult male annual survival. During the four‐year study, we monitored 107 Bachman's Sparrow nests, recorded 49 nest predation events, and banded 113 adult male Bachman's Sparrows. We found Bachman's Sparrow nest and adult survival were resilient to changes in the hardwood canopy and did not differ significantly between treatment and control sites. Average annual adult male survival was 0.41 (0.32–0.52) and daily survival rate of nests with surveillance declined annually from 0.94 (0.92–0.96) to 0.88 (0.83–0.92). The identity of predators at nests was dominated by two snake species, black racer (Coluber constrictor) and corn snake (Pantherophis guttata). We found evidence for opposing treatment effects on the frequency of nest depredations by the dominant species; racers responded positively and corn snakes responded negatively. Our results suggest a moderate midstory canopy does not limit Bachman's Sparrow vital rates when management includes frequent prescribed fire. Our results also suggest hardwood reduction to mitigate nest predation may be complicated with a diverse predator suite.

Use, perception, and local management of Copernicia prunifera (Miller) H. E. Moore in rural communities in the Brazilian Savanna

BackgroundCopernicia prunifera belongs to the Arecaceae family, and its production chain includes a set of economic activities based on the use of the stipe, petiole, fiber, fruits, roots, and leaves from which carnaúba wax is extracted, an economically valuable resource in the region. This study aimed to evaluate the uses, management, and perception of the species by local extractors.MethodsTwo communities were studied, Bem Quer, where 15 extractors of carnaúba leaves were interviewed, and Cana, where 21 extractors considered specialists were interviewed, totaling a sample of 36 interviewees. Interviewees were asked questions about uses, ways of handling, and perception of morphological variation in the carnaúba leaves. The number of leaves extracted and the income obtained from the sale of leaves were estimated from interviews and notes that each leader of extractors held during the year of the research and previous years, as well as direct observations made by researchers in the communities which recollection area of straw hold about 80 thousand individuals of C. prunifera. A regression analysis was used to explore the relationships between social variables (age, time in extractive activity, and income obtained from extraction) with the number of leaves exploited.ResultsThe leaf was indicated as the most used part, from which an important powder is extracted for the production of wax. In addition, the leaf was also indicated to be used for fertilization and construction. The relationship between the socioeconomic variables, income from extraction, and the number of leaves extracted (in thousands) was significant (R2 = 0.73 and p < 0.001). However, the other variables analyzed in this study, such as the time spent extracting leaves and the years of residence in the community (R2 = 0.03 and p > 0.05); the number of leaves extracted and interviewee age (R2= 0.05 and p > 0.05); and the number of leaves extracted and extraction time (R2 = 0.04 and p > 0.05) did not indicate a relationship.ConclusionLocal extractors observed that new leaves have the highest sales value, as they have the highest production of powder. In addition, economic factor is the preponderant force that directs the management strategies of native species. For this species, however, morphological and genetic studies are needed for further clarification.

Low-cost drones help measure tree characteristics in the Sahelian savanna

Savanna is one of the main African ecosystems. The tree community in the savanna is a key element and provides many ecosystem services. Unmanned aerial vehicles (UAVs) combined with photogrammetric analysis are useful tools to produce accurate 3D maps, which, in turn, help describe the structure of the tree populations. The purpose of this study was to evaluate the use of commercial economical UAVs to assess tree characteristics in the savanna. A Dji Spark UAV was used to map 24 1-ha plots in northern Senegal. The images were processed using Pix4D software to produce a high-resolution canopy height model (CHM). A total of 239 trees were selected and their heights and crown areas were manually measured in the field. A strong correlation was found between UAV and field measurements with R2 = 0.84 for height and R2 = 0.93 for crown area. Based on tree canopy colours and tree morphologies measured by UAV, it was possible to predict tree species with an error rate of 20%, using a random forest classification. This study thus confirms the possibility of using low-cost UAVs to assess tree structures in the savanna not only for research on tree communities in savanna, but also by forestry agencies to inform stakeholders.

Plant and invertebrate macrofossils from the Pipe Creek Sinkhole (Late Neogene), Grant County, Indiana

ABSTRACT Examination of macrofossils from the late Neogene Pipe Creek Sinkhole in Indiana, USA, yielded 15 distinct plant taxa, one fungal taxon, and six invertebrate taxa. The plant assemblage was dominated by terrestrial taxa both in richness and abundance. Of the 12 terrestrial plant taxa, eight were trees or shrubs including two Carya spp., Corylus sp., Fraxinus sp., aff. Pinaceae, Quercus sp., aff. Rosaceae, and an unknown gymnosperm, possibly Ginkgophyta or Cycadophyta. Fossil nuts of a new species, Carya pipecreekensis Swinehart and Farlow sp. nov., are described. Other terrestrial plant macrofossils include a species of Asteraceae, Vitis sp., Xanthium sp., and Poaceae indet. Charcoalified remains of wood, Asteraceae achenes, and Poaceae crowns suggest fires were an important factor in ecosystem structure. Condition of some of the macrofossils suggests high-energy, post-depositional transport. Aquatic species include the plants Chara sp. and two Potamogeton spp. as well as the animals Helisoma sp., Physa sp., Sphaeriidae, and ostracoda. The terrestrial flora suggests a temperate woodland savanna community with a canopy that includes Carya, Fraxinus, Quercus, Corylus, and Pinaceae, a sub-canopy with Vitis, and a ground flora with a species of Asteraceae and abundant Poaceae. The assemblage shares elements and characteristics with the similarly-aged Gray Fossil Site in Tennessee.

Environmental filtering and spatial processes shape the beta diversity of liana communities in a valley savanna in southwest China

AbstractQuestionsLianas contribute substantially to the diversity and function of ecosystems. What is the relative importance of environmental filtering and spatial processes on structuring liana beta diversity at taxonomic, functional and phylogenetic levels? Is there any synergy between these drivers (environmental factors and spatial distance) on shaping these three dimensions of beta diversity in a savanna liana community?LocationA dry‐hot valley savanna in Yunnan Province, southwest China.MethodsWe established 30 20 m × 20 m plots in the savanna to collect data on the distribution of 22 liana species, 19 functional traits, and plot‐level soil nutrients, elevation, and slope. The relative contributions of these environmental factors and spatial distance to liana taxonomic, functional and phylogenetic dissimilarity were analyzed using multiple regression on distance matrices. We also tested which environmental factors influence the beta diversity of liana community using permutational multivariate analysis of variance.ResultsBoth environmental and spatial distances were significantly correlated with taxonomic, functional and phylogenetic dissimilarity. Spatial distance explained more variation in taxonomic beta diversity than environmental factors. But for both nearest‐neighbour functional and phylogenetic distance Dnn’, environment explained relatively more variation than space did. Moreover, the proportion explained by environmental variables was ranked in decreasing order as follows: functional Dnn’, phylogenetic Dnn’, and taxonomic beta diversity. We found soil pH had the highest contribution to taxonomic and functional beta diversity, while soil total nitrogen contributed most to phylogenetic beta diversity.ConclusionsThis study revealed that liana taxonomic, functional and phylogenetic beta diversity in the studied hot‐dry savanna ecosystem is affected and maintained by both environmental filtering and spatial processes. Moreover, the functional and phylogenetic diversities were more strongly subject to environmental filtering. Our study provides information on the mechanisms underlying liana diversity maintenance in savanna, which is necessary to inform conservation management in this vulnerable ecosystem.

Influence of Climate on Oak Savanna Tree Species in the Midwestern United States

Aims: The previously abundant high quality and open canopy oak savanna communities in the Midwest have been reduced by more than 98% of their pre-settlement (pre-1840) area because of changing land use and represent some of the most threatened ecosystems in North America. Prior knowledge of oak savanna communities’ climatic resilience to potential impact of climate change and competition is critical to restoration success. This study examined sensitivity to climatic stress, and effects of competition, which are important considerations during oak savanna restoration.&#x0D; Methodology: Dendrochronological methods were used to sample oak savanna communities located in MacCready Reserve (MR) situated in southern Michigan, U.S.A. The influence of climate (mainly temperature and precipitation) on white oak (Quercus alba L.), red maple (Acer rubrum L), and black cherry (Prunus serotina Ehrh) were correlated using dendroclimatic techniques. The effect of competitor species (A. rubrum and P. serotina) on Q. alba were examined using competitor ratio chronologies and examining correlations with climatic variables.&#x0D; Results: Findings indicate that precipitation in winter, spring, and summer is beneficial for radial growth of white oak. White oak is more resilient to drought stress than red maple and black cherry due to its ecophysiological adaptations but tends to grow rather slower when in competition with shade tolerant and fire sensitive competitor species.&#x0D; Conclusion: Overall, this study has shown that temperature and precipitation play key roles in tree productivity and thus climatic sensitivity should be incorporated in the restoration of oak savanna ecosystems.

Dynamics of malaria vector indices in two vegetation zones within North Eastern Adamawa State, Nigeria.

Studies profiling community and zonal malaria entomological risk indices are required to identify high risk areas where targeted control resources are most needed or likely to have the greatest impact on reducing risk of malaria infection. This study presents a first report on malaria vector risk indices in two vegetation zones within Adamawa state, Nigeria. Endophilic mosquitoes were collected for one year in selected communities in the Guinea and Sudan savanna zones within the State. Plasmodium falciparum Sporozoite and human blood meal ELISA assays were carried out on the female Anopheles mosquitoes collected. Sibling species composition of the An. gambiae complex were determined using PCR assays. Mean numbers of mosquitoes in the Guinea savanna communities were significantly (t = 7.73, DF = 11, p < 0.001) higher than the Sudan. Man-biting rates (F = 2.76, p = 0.13) of Anopheles mosquitoes were higher in the Guinea but not significantly different from Sudan savanna. Sporozoite rates of mosquitoes within the Guinea savanna were 2.7 times higher than the Sudan. The predominant Anopheles coluzzii species encountered in the state had higher overall human blood indices (0.63) and sporozoite rates (6.9%) compared to An. gambiae (0.39, 1.9%) and An. arabiensis (0.58, 2.3%) respectively. Overall annual human blood indices (0.59) of mosquitoes in Adamawa were lower compared to reports from other States. Prevalence and higher transmission risks indices of endophilic An. coluzzii mosquitoes reveal the need for LLIN and management of relatively permanent An. coluzzii breeding sites in the State. Widespread cattle rearing lifestyle and lower human blood indices of mosquitoes in the study area suggest the need to investigate cattle blood indices of the mosquitoes in the state. Higher entomological risk indices in the Guinea Savanna zone provide baseline information for prioritization of malaria vector control supplies within the State.

Spatial patterning of soil microbial communities created by fungus‐farming termites

Spatially overdispersed mounds of fungus-farming termites (Macrotermitinae) are hotspots of nutrient availability and primary productivity in tropical savannas, creating spatial heterogeneity in communities and ecosystem functions. These termites influence the local availability of nutrients in part by redistributing nutrients across the landscape, but the links between termite ecosystem engineering and the soil microbes that are the metabolic agents of nutrient cycling are little understood. We used DNA metabarcoding of soils from Odontotermes montanus mounds to examine the influence of termites on soil microbial communities in a semi-arid Kenyan savanna. We found that bacterial and fungal communities were compositionally distinct in termite-mound topsoils relative to the surrounding savanna, and that bacterial communities were more diverse on mounds. The higher microbial alpha and beta diversity associated with mounds created striking spatial patterning in microbial community composition, and boosted landscape-scale microbial richness and diversity. Selected enzyme assays revealed consistent differences in potential enzymatic activity, suggesting links between termite-induced heterogeneity in microbial community composition and the spatial distribution of ecosystem functions. We conducted a large-scale field experiment in which we attempted to simulate termites' effects on microbes by fertilizing mound-sized patches; this altered both bacterial and fungal communities, but in a different way than natural mounds. Elevated levels of inorganic nitrogen, phosphorus and potassium may help to explain the distinctive fungal communities in termite-mound soils, but cannot account for the distinctive bacterial communities associated with mounds.

Urbanization alters the composition, but not the diversity and structure, of Neotropical savanna woody plant communities

Urbanization is one of the main drivers of environmental change and can result in drastic changes to the biodiversity and composition of plant communities. The objective of the present work was to investigate whether the structure, diversity and composition of Neotropical savanna woody plant communities differ among fragments immersed in urban, peri-urban and rural environments. The study was carried out in nine Neotropical savannas with distinct levels of urbanization in the municipality of Montes Claros, state of Minas Gerais, Brazil. A total of 469 woody individuals belonging to 76 species and 30 families of plants were sampled. The most specious families were the Fabaceae with seventeen species and the Vochysiaceae with eight. The most abundant species were Myracrodruon urundeuva in urban areas, Byrsonima pachyphyla in peri-urban areas and Hymenaea stigonocarpa in rural areas. The diversity (species richness, estimated species richness and Simpson diversity index) and structure (abundance, cover and height) of the plant communities under study did not vary in response to urbanization, although species composition experienced notable changes. The urban plant communities were very distinct from the rural plant communities. Furthermore, the dominant species were very different among the urban, peri-urban and rural areas. These findings demonstrate that urbanization affects Neotropical savanna species that are susceptible to anthropization. Furthermore, among the anthropogenic pressures related to urbanization, fragmentation and isolation seem to be the most influential determinants of the composition of Neotropical savanna communities.

Land cover change homogenizes functional and phylogenetic diversity within and among African savanna bird assemblages

Conversion of natural ecosystems into anthropogenic landscapes can result in biotic homogenization, whereby differences in species composition among sites are diminished through colonization or local extinction. This may reduce the resilience of assemblages to further perturbation and the range or quality of ecosystem services they offer. We investigate how land cover change has altered patterns of compositional, functional and phylogenetic diversity of avian communities in a typical African savanna. We investigate if there has been selection for closely-related or functionally similar species with increasing land use intensity and how this has affected alpha and beta components of diversity. We conducted point counts over 2 years in four distinct land cover types (urban, rural, protected and a transitional matrix), representing a gradient of land cover change. We compared alpha and beta phylogenetic, compositional and functional diversity between sites to assess whether land cover change has homogenized avian communities. While alpha diversity tended to be higher in transformed land cover types (urban, rural and matrix), measures of beta diversity among sites within these types were significantly lower than beta diversity within the protected area. Furthermore, assemblages in transformed areas were functionally and phylogenetically more similar than expectation based on a null model, particularly in the urban area. While transformed areas may support higher diversity than natural habitats inside the protected area, human impacts are filtering for species with specific traits and thus homogenizing functional and phylogenetic diversity within and between sites in our study system.

Thinking Like a Grassland: Challenges and Opportunities for Biodiversity Conservation in the Great Plains of North America

Fauna of North America’s Great Plains evolved strategies to contend with the region’s extreme spatiotemporal variability in weather and low annual primary productivity. The capacity for large-scale movement (migration and/or nomadism) enables many species, from bison to lark buntings, to track pulses of productivity at broad spatial scales (> 1 000 km2). Furthermore, even sedentary species often rely on metapopulation dynamics over extensive landscapes for long-term population viability. The current complex pattern of land ownership and use of Great Plains grasslands challenges native species conservation. Approaches to managing both public and private grasslands, frequently focused at the scale of individual pastures or ranches, limit opportunities to conserve landscape-scale processes such as fire, animal movement, and metapopulation dynamics. Using the US National Land Cover Database and Cropland Data Layers for 2011−2017, we analyzed land cover patterns for 12 historical grassland and savanna communities (regions) within the US Great Plains. On the basis of the results of these analyses, we highlight the critical contribution of restored grasslands to the future conservation of Great Plains biodiversity, such as those enrolled in the Conservation Reserve Program. Managing disturbance regimes at larger spatial scales will require acknowledging that, where native large herbivores are absent, domestic livestock grazing can function as a central component of Great Plains disturbance regimes if they are able move at large spatial scales and coexist with a diverse array of native flora and fauna. Opportunities to increase the scale of grassland management include 1) spatial prioritization of grassland restoration and reintroduction of grazing and fire, 2) finding creative approaches to increase the spatial scale at which fire and grazing can be applied to address watershed to landscape-scale objectives, and 3) developing partnerships among government agencies, landowners, businesses, and conservation organizations that enhance cross-jurisdiction management and address biodiversity conservation in grassland landscapes, rather than pastures.

Epidemiology, ecology and human perceptions of snakebites in a savanna community of northern Ghana.

BackgroundWorldwide, snakebite envenomations total ~2.7 million reported cases annually with ~100,000 fatalities. Since 2009, snakebite envenomation has intermittently been classified as a very important ‘neglected tropical disease’ by the World Health Organisation. Despite this emerging awareness, limited efforts have been geared towards addressing the serious public health implications of snakebites, particularly in sub-Saharan Africa, where baseline epidemiological and ecological data remain incomplete. Due to poverty as well as limited infrastructure and public health facilities, people in rural Africa, including Ghana, often have no other choice than to seek treatment from traditional medical practitioners (TMPs). The African ‘snakebite crisis’ is highlighted here using regionally representative complementary data from a community-based epidemiological and ecological study in the savanna zone of northern Ghana.Methodology and findingsOur baseline study involved two data collection methods in the Savelugu-Nanton District (in 2019 the district was separated into Savelugu and Nanton districts) in northern Ghana, comprising a cross-sectional study of 1,000 residents and 24 TMPs between December 2008 and May 2009. Semi-structured interviews, as well as collection of retrospective snakebite and concurrent rainfall records from the Savelugu-Nanton District Hospital and Ghana Meteorological Authority respectively over 10-years (1999–2008) were used in the study. Variables tested included demography, human activity patterns, seasonality, snake ecology and clinical reports. Complementary data showed higher snakebite prevalence during the rainy season, and a hump-shaped correlation between rainfall intensity and snakebite incidences. Almost 6% of respondents had experienced a personal snakebite, whereas ~60% of respondents had witnessed a total of 799 snakebite cases. Out of a total of 857 reported snakebite cases, 24 (~2.8%) died. The highest snakebite prevalence was recorded for males in the age group 15–44 years during farming activities, with most bites occurring in the leg/foot region. The highest snakebite rate was within farmlands, most severe bites frequently caused by the Carpet viper (Echis ocellatus).ConclusionThe relatively high community-based prevalence of ~6%, and case fatality ratio of ~3%, indicate that snakebites represent an important public health risk in northern Ghana. Based on the high number of respondents and long recording period, we believe these data truly reflect the general situation in the rural northern savanna zone of Ghana and West Africa at large. We recommend increased efforts from both local and international health authorities to address the current snakebite health crisis generally compromising livelihoods and productivity of rural farming communities in West Africa.

Characterization of Native American vegetation disturbance in the forests of central New York State, USA during the late 18th century ce

Historic land survey records (LSRs) offer important details on local- and landscape-scale vegetation patterns related to Native American land-use practices prior to widespread Euro-American settlement. This study’s use of an expanded range of vegetation-related variables derived from LSR sources, combined with archaeological site distribution data, and analysed using complementary multivariate statistical methods, has provided new insights on the spatial and compositional dynamics of the vegetation of central New York State, USA, an area historically occupied by the Cayuga and Onondaga nations. The upland vegetation of the study area was modulated primarily by fire, followed by soil fertility, and canopy disturbance. Clear signals of Native American agriculture and silviculture were associated with a number of fire-tolerant vegetation communities that were geographically concentrated within an area most conducive to maize cultivation. Numerical classification partitioned the LSR vegetation data into distinct community types: mesophytic upland forest and xerophytic upland forest. This latter type was secondarily differentiated into an unequivocally anthropogenic landscape (Iroquoian agricultural mosaic) and a series of fire-tolerant forest and savanna communities with possible connections to silvicultural land-use practices. Distance analysis of ordination scores indicated statistically-significant spatial trends associated with the distribution of archaeological sites, with disturbance most heavily concentrated within 6 km of most sites. Given the success of this methodology, we recommend that this integrated approach become the standard for LSR-based research of Native American vegetation disturbance.

Forb ecology research in dry African savannas: Knowledge, gaps, and future perspectives.

Savannas are commonly described as a vegetation type with a grass layer interspersed with a discontinuous tree or shrub layer. On the contrary, forbs, a plant life form that can include any nongraminoid herbaceous vascular plant, are poorly represented in definitions of savannas worldwide. While forbs have been acknowledged as a diverse component of the herbaceous layer in savanna ecosystems and valued for the ecosystem services and functions they provide, they have not been the primary focus in most savanna vegetation studies. We performed a systematic review of scientific literature to establish the extent to which forbs are implicitly or explicitly considered as a discrete vegetation component in savanna research. The overall aims were to summarize knowledge on forb ecology, identify knowledge gaps, and derive new perspectives for savanna research and management with a special focus on arid and semiarid ecosystems in Africa. We synthesize and discuss our findings in the context of different overarching research themes: (a) functional organization and spatial patterning, (b) land degradation and range management, (c) conservation and reserve management, (d) resource use and forage patterning, and (e) germination and recruitment. Our results revealed biases in published research with respect to study origin (country coverage in Africa), climate (more semiarid than arid systems), spatial scale (more local than landscape scale), the level at which responses or resource potential was analyzed (primarily plant functional groups rather than species), and the focus on interactions between life forms (rather seldom between forbs and grasses and/or trees). We conclude that the understanding of African savanna community responses to drivers of global environmental change requires knowledge beyond interactions between trees and grasses only and beyond the plant functional group level. Despite multifaceted evidence of our current understanding of forbs in dry savannas, there appear to be knowledge gaps, specifically in linking drivers of environmental change to forb community responses. We therefore propose that more attention be given to forbs as an additional ecologically important plant life form in the conventional tree–grass paradigm of savannas.

Differential effects of soil waterlogging on herbaceous and woody plant communities in a Neotropical savanna.

The impacts of soil properties and fire regime on Neotropical savannas are well-known, but the importance of hydrological regime for plant species assembly has received less attention. Here, we assessed changes in diversity patterns of herbaceous and woody communities along a water table gradient in a fire-excluded Neotropical savanna. We found that increased waterlogging of soils was associated with declines in both herbaceous and woody species richness. Woody species richness decreased once the water table depth is less than 4m and no woody species occurred once water table depth was less than 23cm. Herbaceous communities remained species rich until the shallowest water table depth, where there is flooding at some point in the year, and even there, over a dozen species occurred. Woody species that occurred in areas with shallower water tables were a nested subset of those in areas with deeper water tables. In contrast, herbaceous communities showed turnover over the hydrological gradient, with distinct species specialized for different water table levels. However, we found that those specialists are restricted to few evolutionary lineages, evidenced by increased phylogenetic clustering over the water table gradient in herbaceous communities. We suggest that evolutionarily conserved hydrological niches define the herbaceous layer over the hydrological gradient, whereas only generalist woody species persist under high water tables. Our findings show that the effect of soil waterlogging differs between the herbaceous and woody layer of savannas, indicating that these communities will respond differently to shifts in the hydrological regime under future environmental change.

Satellite image texture for the assessment of tropical anuran communities

AbstractThe relationship between environmental heterogeneity and biodiversity represents a cornerstone of ecological research. While environmental descriptors over large extents usually have medium‐to‐low spatial resolution, in situ measures provide accurate information for limited areas, and a gap remains in providing remote descriptors that represent local environmental structure. Texture from satellite images can represent fine‐scale heterogeneity over wide spatial coverage, but to date, it has mostly been used to predict general aspects of species diversity, such as richness. Here, we assess the utility of image textures from high‐resolution satellite images (RapidEye 3A) and in situ variables to predict differences in the composition of anuran communities in a tropical savanna (Cerrado) of Brazil. While in situ measures accounted for compositional differences in the whole community, two measures of image textures were associated only with the variation of species within the Hylidae family (adj. R² = 0.16 and 0.14). Comparatively, image textures predicted ~2/3 of the variation explained by in situ measures (adj. R² = 0.23). When both approaches were combined, a greater compositional variation was achieved (adj. R² = 0.28), with 1/5 of it shared by both in situ and textures, and 1/5 attributed solely to texture. Our findings suggest that image texture can complement the assessment of environmental heterogeneity acting on the assembly of local anuran communities. This approach can be valuable for explicitly including spatial heterogeneity in biological assessments over broad spatial extents, especially for biological groups strongly filtered by environmental conditions.Abstract in Portuguese is available with online material.