Does post-fire abiotic habitat filtering create divergent plant communities in black spruce forests of eastern Canada?

We investigated the role of post-fire residual organic matter (ROM) thickness as a driver of community assembly in eastern Newfoundland. We hypothesized that if post-fire community assembly is predominantly controlled by ROM thickness (an abiotic habitat filter), then post-fire species composition and functional traits should correspond to the depth and distribution of ROM. However, if species interactions (biotic filter) are the primary constraints on community assembly, then post-fire species composition and their functional traits should be independent of the depth and distribution of ROM. We tested these predictions in three relatively mature plant communities, Kalmia angustifolia heath, black spruce (Picea mariana)-Kalmia shrub savannah and black spruce forest. Through pre-fire stand reconstruction, we found evidence that the three communities originated from black spruce forest. ROM thickness in heath was almost twice that of shrub savannah and six times more than forest, suggesting a gradient in fire severity. Distribution of ROM corresponded to patterns in vegetation dominance, where thick ROM (>2 cm) filtered out black spruce in favour of Kalmia. ROM thickness was a strong predictor of vegetation composition and function between heath and forest, but this was not found between the shrub savannah and forest. We attribute this to species interactions and allelopathy, which may have become important when ROM thickness was suitable for both seed (black spruce) and vegetative (Kalmia) regenerating species. Thus, priority effects or “who came first” may have lead to shrub savannah formation when ROM thickness was ~2 cm. We conclude that abiotic habitat filtering of thick ROM (>2 cm) on (primarily) species’ regeneration traits was the primary driver of community divergence from forest to heath and shrub savannah.     

Phylogeography of Mus (Nannomys) minutoides (Rodentia,Muridae) in West Central African savannahs: singular vicariance in neighbouring populations

We studied the phylogeography of the strict savannah pygmy mice Mus (Nannomys) minutoides in West Central Africa. A total of 846 base pairs of the cytochrome b sequence were obtained for 66 individuals collected in Gabon, Cameroon, Republic of Congo and Central African Republic. These sequences were compared to those of M. minutoides from other African countries and to eight other species of the genus Mus. We performed maximum likelihood, Bayesian and nested clade analyses, as well as neutrality tests and time estimates. We show that M. minutoides is a well‐differentiated monophyletic species that separated from other pygmy mice 1.17 Myr ago. A distinct West Central African M. minutoides clade diverged early from the other African populations of the species, with a more recent common ancestor dating 0.14 Myr. West Central African populations are globally homogeneous, despite the present fragmentation of savannahs by the rain forest. However, our analyses show an unexpected vicariance between geographically close savannahs, embedded in the rain forest in Central Gabon. One of these populations is genetically more similar to very distant peripheral populations than to three closely neighbouring populations situated on both sides of the Ogooué River. A non‐river geographical barrier probably persisted in this area, durably isolating these local populations. This hypothesis about the history of the savannah landscape should be testable through the biogeographical analysis of other strict savannah small mammal species.     

Diets of Frugivorous Bats in Montane Rain Forest and Coffee Plantations in Southeastern Chiapas,Mexico

Frugivorous are one of the main diaspore dispersers in tropical ecosystems, particularly in open areas and sites in the early stages of ecological succession. Frugivorous bat species respond differentially to habitat modification, and in the context of their diaspore dispersal functions it is important to understand species' ecological requirements. We compared the diversity of diaspores, obtained from fecal samples and from fruits carried by frugivorous bats, among five shaded coffee plantations under different management regimes and a montane rain forest in southeastern Chiapas, Mexico. At each site, bats were captured every 2 mo from March 2004 to July 2005, using six mist‐nets, during two consecutive nights. We captured 2589 individuals from 18 frugivorous species, from which we collected 969 fecal samples, containing 42 diaspore species associated with early and late successional plants. Although, we captured more frugivorous bat species in montane rain forest, the number of diaspore species in this site (N=14) was not significantly different from the coffee plantations under different management regimes (16–24). In montane rain forest, Sturnira ludovici fed mainly on Piper auritum, but in coffee plantations ate Peperomia sp., Saurauia madrensis, Solanum chrysotrichum and Solanum diphyllum. Artibeus jamaicensis and Artibeus intermedius feed mostly Cecropia obtusifolia and Ficus cookii in all coffee plantations. We suggest that the presence of frugivorous bats in shaded coffee plantations is favored by trees and shrubs associated with secondary and introduced vegetation that farmers have allowed to grow within or around the plantations.     

Ant assemblage structure on cocoa trees in smallholder farms in the Centre Region of Cameroon

We investigated the ant community structure in cocoa farms in the Centre Region of Cameroon. Ants were collected on the cocoa trees during the years 2006 and 2007 using chemical knock‐down. We tested the hypothesis of the existence of deterministic factor in the structuration of ant mosaic using C‐Score; we assessed the relationship between the numerical dominant and subdominant ant species using Spearman correlation test and discussed on the influence of vegetation structure and farm management on the ant community structure. A total of 53 ant species belonging to 20 genera and five subfamilies were identified from a set of 51,525 workers collected. C‐score analysis supported the hypothesis that ant community were structured by competition. Negative relationships were found between dominant ant species. Farming practices which were mainly pruning, chemical treatment and habitat structure appeared to influence the ecological status and distribution of dominant ant species.     

Seasonal variation in food availability and relative importance of dietary items in the Gambian epauletted fruit bat (Epomophorus gambianus)

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Diversity of rodent and shrew assemblages in different vegetation types of the savannah biome in South Africa: no evidence for nested subsets or competition

Identifying nonrandom species composition patterns predicted by assembly rules has been a central theme in community ecology. Few studies have investigated the prevalence of multiple drivers on species composition patterns in small mammal assemblages in the Old World. This study investigated seasonal changes in rodent and shrew diversity in eleven savannah vegetation types in South Africa. We tested whether species composition patterns are nonrandom with respect to predictions from Diamond's assembly rules, niche limitation hypothesis and nestedness hypothesis. Species richness estimators indicated that inventories for the rodents (80%) and shrews (100%) were relatively complete. Rodent (n = 11 species) diversity and shrew (n = 5 species) diversity were highest in summer and lowest in autumn. Rodent richness was highest in the Terminalia sericea bushveld and woodlands and lowest in the Drypetes arguta sand forest, whilst shrew richness was highest in the T. sericea bushveld and woodlands and lowest in the Acacia nilotica/Dichrostachys cinerea open shrub savannah. We found no support for the predictions of competition and nestedness hypotheses and suggest that this was probably due to the high seasonal and annual variability in rodent and shrew diversity.     

Bat species diversity and distribution in a disturbed regime at the Lake Bogoria National Reserve,Kenya

Human population growth drives intrusion and progressive conversion of natural habitats for agriculture. We evaluated human impacts on bat species diversity and distribution among four vegetation types in and around Lake Bogoria National Reserve between November 2012 and July 2013. Plants were surveyed using the Braun–Blanquet cover/abundance method, whereas bats were sampled using standard mist nets erected on poles at ground level. Floristic similarity analysis revealed three broad vegetation assemblages, namely riverine vegetation, farmland and Acacia woodland/Acacia–Commiphora woodland. Two hundred and 33 bats representing eleven species in eleven genera and seven families were recorded. These were Epomophorus minimus, Rhinolophus landeri, Hipposideros caffer, Cardioderma cor, Lavia frons, Nycteris hispida, Chaerephon pumilus, Mops condylurus, Neoromicia capensis, Scotoecus hirundo and Scotophilus dinganii. Species richness estimators indicated that sampling for bats at ground level was exhaustive. Bat species richness and diversity were highest in the more structurally complex Acacia woodland compared to more homogenous farmlands where we recorded only common and generalist species that often occur in open habitats. The higher bat species richness and diversity in the Acacia woodland as compared to farmland underscore the importance of remnant natural savannah woodlands in the conservation of bats and other elements of biodiversity .     

Terrestrial small mammal diversity and abundance in central Benin: comparison between habitats,with conservation implications

We performed a terrestrial small mammal species inventory in the Agoua and Wari‐Maro forest reserves (Benin). Four localities were sampled, and in each locality, three habitats were surveyed: dense forest, open forest or woodland savannah and shrub savannah. This is the first comprehensive inventory for small mammals in central Benin. We captured 794 small mammals representing twenty species (six shrew species, fourteen rodent species). Three new species that need to be described were recorded. We observed a mixture of both true forest species and of species adapted to a wider range of habitats ranging from savannah to forest clearings. Species with either Sudanian or Guinea–Congolian affinities were recorded, as well as a new species endemic to Togo and Benin. This rich biodiversity underlines the urgent need for an effective protection of these forests. The Sudanian species Crocidura cf. foxi was more abundant in Wari‐Maro than in Agoua forest, while the Guineo–Congolian species Praomys misonnei and Hylomyscus sp were only captured in Agoua forest. These results are in agreement with the fact that these two forests belong to two distinct chorological zones.     

Species turnover regulates leaf‐cutter ant densities in environmental gradients across the Brazilian Cerrado

Environmental changes resulting from Atta leaf‐cutter ant activities characterize them as ecosystem engineers of ecological and economic importance in multiple habitats. Although Atta effects depend strongly on colony density, there has been limited and inconsistent information available on their abundance and interspecific dominance in natural areas and across environmental gradients in the Brazilian Cerrado. Our study bridges this gap by testing the hypothesis that Atta nest density at genus level is high and relatively constant across locations regardless of vegetation type due to strong effects of dominant species turnover. To do so, we conducted a natural experiment surveying Atta nest abundance in five different vegetation types representing the environmental gradient from forest to savannah habitats found in the Cerrado. Our linear transect surveys covered 48.9 km in four well‐preserved areas across two Brazilian states in which we recorded 124 colonies. Of these, 84 nests belonged to A. laevigata and 40 to A. sexdens, the two dominant Atta species in the region. We also found no nests in 30% of the sampled area, which when combined with strong variation in density measured per transect indicates colonies tend to be aggregated in the landscape. Furthermore, we observed a strong dominant species turnover from forest habitats where 90% of nests belonged to A. sexdens to savannah habitats where 92% of nests were A. laevigata. Turnover effect was reflected in the absence of a significant difference in density between locations and vegetation types, indicating that density at genus level remains high and relatively constant regardless of nest aggregation. Our findings allow larger scale inferences about Atta effects and reveal new insights of their dynamics into natural areas that could affect plant species distribution and contribute to spatial heterogeneity of vegetation, having important implications for Cerrado conservation.     

Congruent phylogeographical patterns of eight tree species in Atlantic Central Africa provide insights into the past dynamics of forest cover

Cycles of Quaternary climatic change are assumed to be major drivers of African rainforest dynamics and evolution. However, most hypotheses on past vegetation dynamics relied on palaeobotanical records, an approach lacking spatial resolution, and on current patterns of species diversity and endemism, an approach confounding history and environmental determinism. In this context, a comparative phylogeographical study of rainforest species represents a complementary approach because Pleistocene climatic fluctuations may have left interpretable signatures in the patterns of genetic diversity within species. Using 1274 plastid DNA sequences from eight tree species (Afrostyrax kamerunensis, A. lepidophyllus, Erythrophleum suaveolens, Greenwayodendron suaveolens, Milicia excelsa, Santiria trimera, Scorodophloeus zenkeri and Symphonia globulifera) sampled in 50 populations of Atlantic Central Africa (ACA), we averaged divergence across species to produce the first map of the region synthesizing genetic distinctiveness and standardized divergence within and among localities. Significant congruence in divergence was detected mostly among five of the eight species and was stronger in the northern ACA. This pattern is compatible with a scenario of past forest fragmentation and recolonization whereby forests from eastern Cameroon and northeastern Gabon would have been more affected by past climatic change than those of western Cameroon (where one or more refugia would have occurred). By contrast, southern ACA (Gabon) displayed low congruence among species that may reflect less drastic past forest fragmentation or a more complex history of vegetation changes. Finally, we also highlight the potential impact of current environmental barriers on spatial genetic structures.     

Composition of Woody Species in a Dynamicforest–woodland–savannah Mosaic in Uganda: Implications for Conservation and Management

Forest–woodland–savannah mosaics are a common feature in the East African landscape. For the conservation of the woody species that occur in such landscapes, the species patterns and the factors that maintain it need to be understood. We studied the woody species distribution in a forest–woodland–savannah mosaic in Budongo Forest Reserve, Uganda. The existing vegetation gradients were analyzed using data from a total of 591 plots of 400 or 500 m² each. Remotely sensed data was used to explore current vegetation cover and the gradients there in for the whole area. A clear species gradient exists in the study area ranging from forest, where there is least disturbance, to wooded grassland, where frequent fire disturbance occurs. Most species are not limited to a specific part of the gradient although many show a maximum abundance at some point along the gradient. Fire and accessibility to the protected area were closely related to variation in species composition along the ordination axis with species like Cynometra alexandri and Uvariopsis congensis occurring at one end of the gradient and Combretum guenzi and Lonchocarpus laxiflorus at the other. The vegetation cover classes identified in the area differed in diversity, density and, especially, basal area. All vegetation cover classes, except open woodland, had indicator species. Diospyros abyssinica, Uvariopsis congensis, Holoptelea grandis and all Celtis species were the indicator species for the forest class, Terminalia velutina and Albizia grandbracteata for closed woodland, Grewia mollis and Combretum mole for very open woodland and Lonchocarpus laxiflorus, Grewia bicolor and Combretum guenzi for the wooded grassland class. Eleven of the species occurred in all cover classes and most of the species that occurred in more than one vegetation cover class showed peak abundance in a specific cover class. Species composition in the study area changes gradually from forest to savannah. Along the gradient, the cover classes are distinguishable in terms of species composition and vegetation structure. These classes are, however, interrelated in species composition. For conservation of the full range of the species within this East African landscape, the mosaic has to be managed as an integrated whole. Burning should be varied over the area with the forest not being burnt at all and the wooded grassland burnt regularly. The different vegetation types that occur between these two extremes should be maintained using a varied fire regime.     

Male Seminole Bat Winter Roost-Site Selection in a Managed Forest

Abstract: Understanding year-round roost-site selection is essential for managing forest bat populations. From January to March, 2004 to 2006, we used radiotelemetry to investigate winter roost-site selection by Seminole bats (Lasiurus seminolus) on an intensively managed landscape with forested corridors in southeastern South Carolina, USA. We modeled roost-site selection with logistic regression and used Akaike's Information Criterion for small samples (AIC_c) and Akaike weights to select models relating roost-site selection to plot- and landscape-level variables. We tracked 20 adult male bats to 71 individual roosts. Bats used a variety of roosting structures, including the canopy of overstory trees, understory vegetation, pine (Pinus spp.) needle clusters, and leaf litter. Roost height, structure type, and habitat type were influenced by changes in minimum nightly temperature. On warmer nights, bats selected taller trees in mature forest stands, but when minimum nightly temperatures were <4° C, bats typically were found roosting on or near the forest floor in mid-rotation stands. We recommend avoiding prescribed burning in mid-rotation stands on days when the previous night's temperature is <4 °C to minimize potential disturbance and direct mortality of bats roosting on or near the forest floor. We encourage forest managers to incorporate seasonal changes in roost-site selection to create year-round management strategies for forest bats in managed landscapes.     

Bat Response to Woodland Restoration within Urban Forest Fragments

In urban environments, woodland areas are typically fragmented and subject to invasive species encroachment, woody overgrowth, and natural succession. In response to negative impacts, conservationists and land managers have implemented restoration strategies to enhance the integrity of woodlands. Because woodland habitat is important for bats (Order Chiroptera), alterations to forest structures may affect how bats utilize forest fragments in urban environments. We evaluated relationships among restoration efforts, microhabitat characteristics and overall bat activity, and interspecific variation among bats in response to woodland characteristics. We monitored bats in nine woodland forest preserves representing various stages of restoration within the Chicago metropolitan area in 2004 and 2005. Overall bat activity was positively related to prescribed burning, invasive species removal, and small tree density (7.7‐20 cm dbh) and inversely related to shrub density and clutter at 0‐6 m heights. There was interspecific variation in response to alterations in woodland structure, with Lasiurus borealis (L. borealis) positively associated with small and medium (20.1‐33 cm) tree densities and inversely related to clutter at 0‐9 m; Myotis spp. positively associated with canopy cover, clutter at 6‐9 m, and small and medium tree densities; and Lasionycteris noctivagans (L. noctivagans) positively associated with more open forests. Eptesicus fuscus (E. fuscus) activity was not strongly associated with any measured vegetation variable. Our results demonstrate bats positively respond to some forms of woodland restoration in urban landscapes. However, species‐specific responses to vegetation differed and should be taken into consideration when developing management plans.     

Bats in a changing landscape: Linking occupancy and traits of a diverse montane bat community to fire regime

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EFFECT OF HABITAT AND FORAGING HEIGHT ON BAT ACTIVITY IN THE COASTAL PLAIN OF SOUTH CAROLINA

Abstract: We compared bat activity levels in the Coastal Plain of South Carolina among 5 habitat types: forested riparian areas, clearcuts, young pine plantations, mature pine plantations, and pine savannas. We used time-expansion radio-microphones and integrated detectors to simultaneously monitor bat activity at 3 heights (30, 10, 2 m) in each habitat type. Variation in vegetative clutter among sampling heights and among habitat types allowed us to examine the differential effect of forest vegetation on the spatial activity patterns of clutter-adapted and open-adapted bat species. Moreover, monitoring activity at 30, 10, and 2 m permitted us to also compare bat activity above and below the forest canopy. We detected calls of 5 species or species groups: eastern red/Seminole bats (Lasiurus borealis/L. seminolus), eastern pipistrelles (Pipistrellus subflavus), evening bats (Nycticeius humeralis), big brown bats (Eptesicus fuscus), and hoary bats (Lasiurus cinerius). At 2 and 10 m, bat activity was concentrated in riparian areas, whereas we detected relatively low levels of bat activity in upland habitats at those heights. Activity was more evenly distributed across the landscape at 30 m. Bat activity levels above the forest canopy were almost 3 times greater than within or below the canopy. We detected significantly greater activity levels of 2 open-adapted species (hoary and big brown bats) above rather than within or below the forest canopy. However, activity levels of 2 clutter-adapted species (eastern red/Seminole bats and eastern pipistrelles) did not differ above, within, or below the forest canopy. Despite classification as a clutter-adapted species, evening bat activity was greater above rather than within or below the forest canopy. We believe our results highlight the importance of riparian areas as foraging habitat for bats in pine-dominated landscapes in the southeastern United States. Although acoustical surveys conducted below forest canopies can provide useful information about species composition and relative activity levels of bats that forage in cluttered environments, our results showing activity above canopy suggest that such data may not accurately reflect relative activity of bats adapted to forage in more open conditions, and therefore may provide an inaccurate picture of bat community assemblage and foraging habitat use.     

Taxonomy of the African giant pouched rats (Nesomyidae: Cricetomys): molecular and craniometric evidence support an unexpected high species diversity

Our study combined a mitochondrial cytochrome b phylogeny with cranial measurements from giant pouched rats collected across sub‐Saharan Africa. The mitochondrial phylogeny resolves two West African clades and a clade with east and central Africa representatives. This last clade can be further divided into four subclades. Altogether they represent six species (Cricetomys gambianus, Cricetomys ansorgei, Cricetomys emini, and three undescribed taxa) that can be distinguished on the basis of their mitochondrial DNA sequences and craniometry. In the absence of adequate craniometric data the existence of Cricetomys kivuensis cannot be confirmed by our data. Our combined molecular and craniometric data allowed us to broadly delineate the distribution ranges of the detected species. Cricetomys gambianus occurs in the savannah and forest clearings of West Africa. Cricetomys ansorgei is distributed in the savannah of East and southern Africa. Cricetomys emini, as currently recognized across the Guineo‐Congolian forest of Africa, is shown to be diphyletic. Cricetomys sp. 1, a separate operational taxonomic unit closely resembling C. emini, occurs in the forest zone of West Africa. An undescribed sister‐species of C. ansorgei, Cricetomys sp. 2, occurs in the forest of Central Africa along the left bank of the Congo River. Cricetomys sp. 3 occurs on the right bank of the Congo River from Cameroon to the Republic of Congo, whereas the true C. emini also occurs on the right bank of the Congo River but appears to be restricted to the Democratic Republic of Congo. Cranial phenotype within the genus tends to conform to ecological zonation (either forest or savannah) rather than to phylogenetic affiliation of the species concerned, suggesting that diversifying selection across environmental gradients could be responsible for biological diversification within the genus.     

Genetic structure and origin of Busseola fusca populations in Cameroon

The cereal stem borer Busseola fusca Fuller (Lepidoptera: Noctuidae) is a species endemic to sub‐Saharan Africa. It is a major pest of maize and cultivated sorghum, the main cereal crops on the African mainland. Previous studies using mitochondrial markers revealed the presence of three clades of haplotypes (W, KI, KII) among B. fusca populations. Previous preliminary studies based on a few B. fusca individuals collected from three localities within the Guineo‐Congolian rain forest in Cameroon demonstrated a matching with clade KII, a fairly surprising result because the putative centre of origin of that clade is located 3 000 km away in East Africa. To check this finding, 120 individuals of B. fusca covering several Cameroonian sites belonging to both Guineo‐Congolian rain forest and Afromontane vegetation mosaics were collected. Comparison of cytochrome b sequences using the same marker revealed low mitochondrial diversity (h = 0.483 ± 0.054, π = 0.073 ± 0.061%). Moreover, molecular diversity in the Guineo‐Congolian rain forest zone was lower than that in Afromontane vegetation, which is therefore thought to be the likely starting point for the colonization of other zones in Cameroon. The study showed a moderate but significant structuring between populations (Φ_ST = 0.034, P<0.001) as well as within and among the two Cameroonian phytogeographical groups considered (Φ_SC = 0.000 and Φ_CT = 0.051, respectively, both P<0.001). Nested clade phylogeographic analysis indicated that all Cameroonian clades with significant geographical associations were interpreted as a phenomenon of contiguous range expansion. All results suggest that the Cameroonian population of B. fusca is relatively recent and originates from the recent geographical expansion of clade KII.     

Phyllostomid Bat Assemblage Structure in Amazonian Flooded and Unflooded Forests

In Amazonia, the assemblages of several taxa differ significantly between upland terra firme and white‐water flooded várzea forests, but little is known about the diversity and distribution of bats in these two forest types. We compare the spatio‐temporal patterns of bat assemblage composition and structure in adjacent terra firme and várzea forests in the lower Purus River region of central Brazilian Amazonia. Bats were sampled using mist nets at five sites in each forest type during 40 nights (2400 net‐hours). We captured 1069 bats representing 42 species and Phyllostomidae bats comprised 99.3 percent of all captures. The bat assemblages in várzea and terra firme forests were significantly different, mainly due to a marked dissimilarity in species composition and in the number of captures during high‐water season. In addition, bat assemblages within forest types differed significantly between seasons for both terra firme and várzea. Frugivores dominated the bat assemblages in both forest types. Overall guild structure did not change between várzea and terra firme or between seasons, but frugivore and animalivore abundance increased significantly in várzea forest during the inundation. The difference in assemblage structure observed in the high‐water season is probably caused by the annual várzea flooding, which provides an effective barrier to the persistence of many understory bats. We also hypothesize that some bat species may undertake seasonal movements between forest types in response to fruit abundance, and our results further underline the importance of floodplain habitats for the conservation of species in the Amazon.     

Importance of traditional protected areas for the collection of medicinal plants,Kongo‐Central (DRC)

The Mbanza‐Ngungu region (Kongo‐Central province, DRC) currently faces continued forest deterioration. Many of these forests were traditionally protected areas of which to date, only traces are left. The aim of this study was to evaluate and compare the importance of forest remnants and other components of the landscape for the collection of medicinal plants in the Mbanza‐Ngungu Region, DRC. Between February 2009 and May 2012, semi‐structured interviews and participatory observations were conducted in this region with 51 traditional healers selected by means of the ‘snowball method’. Local importance of medicinal plants was determined by the medicinal Use Value parameter. Statistical analyses were carried out with SPSS 20.0 and based on chi‐square test, analysis of variance and post hoc comparison of means. Our results show that the forest remnants remain the main medicinal species provider: 68 species against 62 for agro‐ecosystems. However, the total number of citations for medicinal species uses is higher for agro‐ecosystems (293) than for forest remnants (233), and this difference is significant (P < 0·05). This could be explained, among others, by the fact that some forest remnants are respected or protected by the villagers for religious and ritual purposes (Sangi). This also points to the importance of agro‐ecosystems and secondary vegetation as provider of medicinal plants around rural villages, as seen elsewhere in the tropics.