Forest Habitat (forest + habitat)

Distribution by Scientific Domains
Distribution within Life Sciences

Selected Abstracts

Foraging of lynxes in a managed boreal-alpine environment

ECOGRAPHY, Issue 3 2000
Peter Sunde
Foraging of Eurasian lynxes Lynx lynx was studied with telemetry and snow tracking in central Norway. In all habitats and at all seasons, medium-sized ungulates (roe deer Capreolus capreolus, reindeer Rangifer tarandus and domestic sheep Ovis aries) dominated the diet (81% of ingested biomass estimated from faeces). Mountain hares Lepus timidus and galliform birds comprised the remainder of the diet (15% and 3%, respectively). Lynxes with different life history status did not differ in prey choice, but adult males utilised carcasses of ungulate prey considerably less (16% of the edible parts) than did females with offspring (80%) and subadults (58%.). Forest habitats in lowlands and adjacent to cultivated fields were the most favourable foraging habitats (indexed as the prey encounter rate per km lynx track) primarily owing to the presence of roe deer. Two family groups tracked in winter killed 0.2 ungulate per day. The importance of agricultural land as a foraging habitat and the dominance of livestock in the diet in remoter areas indicate that the lynx has responded to agriculture and reindeer husbandry during the past century by switching from smaff game to ungulates. [source]

Patch Occupancy and Potential Metapopulation Dynamics of Three Forest Mammals in Fragmented Afromontane Forest in South Africa

Michael J. Lawes
We recorded patch occupancy of blue duiker ( Philantomba monticola), tree hyrax ( Dendrohyrax arboreus), and samango monkey (Cercopithecus mitis labiatus) in 199 forest patches. Their rarity is ascribed to the fragmentation and destruction of their forest habitat. Incidence functions, derived from presence and absence data, were formulated as generalized linear models, and environmental effects were included in the fitted logistic models. The small and mostly solitary hyrax and duiker persisted in smaller patches than the large and social monkey. Although this result follows expectations based on relative home-range sizes of each species, the incidence probability of the samango monkey was invariant with increasing isolation, whereas a gradual decrease with increasing isolation was observed for the hyrax and duiker. Group dynamics may inhibit dispersal and increase the isolation effect in social species such as samango monkeys. A mainland-island metapopulation model adequately describes patterns of patch occupancy by the hyrax and duiker, but the monkeys' poor dispersal ability and obvious area-dependent extirpation suggest that they exist in transient, nonequilibrium (declining) metapopulations. Through identification of large forest patches for careful protection and management, the survival of all three species,especially the monkey,could be prolonged. Because no functional metapopulation may exist for the monkey, however, this is an emergency measure. For the duiker and hyrax, larger patches should form part of a network of smaller and closer patches in a natural matrix. Resumen: Investigamos la persistencia de tres mamíferos forestales raros de tamaño mediano (2,9 kg) en los bosques fragmentados de cinturón de niebla Podocarpus en la región central de la provincia KwaZulu-Natal, Sudáfrica. Registramos la ocupación del duiker azul ( Philantomba monticola), el hyrax arborícola ( Dendrohyrax arboreus) y el mono samango (Cercopithecus mitis labiatus) en 199 parches forestales. Su rareza se atribuye a la fragmentación y destrucción de su hábitat forestal. Las funciones de incidencia, derivadas de datos de presencia y ausencia, fueron formuladas como modelos lineales generalizados, y los efectos ambientales fueron incluidos en los modelos logísticos ajustados. Los pequeños y mayormente solitarios hyrax y duiker persistieron en parches más pequeños que los monos, que son más grandes y más sociables. A pesar de que este resultado obedece a expectativas basadas en tamaños de rango de hogar relativos de cada especie, la probabilidad de incidencia del mono samango no cambió con un incremento en el aislamiento, mientras que una disminución gradual al crecer el aislamiento se observó en hyrax y duiker. Las dinámicas de grupos podrían inhibir la dispersión e incrementar el efecto de aislamiento en especies sociables como lo es el mono samango. Un modelo de metapoblación continente-isla describe adecuadamente los patrones de la ocupación de parches por hyrax y duiker; sin embargo, la pobre capacidad de dispersión de los monos y la obvia extirpación área-dependente sugiere que estos existen en metapoblaciones transitorias, desequilibradas (en disminución). Mediante la identificación de parches forestales grandes para la protección y manejo cuidadosos, la supervivencia de las tres especies ( pero especialmente la de los monos) podría ser prolongada. Sin embargo, debido a que no existen metapoblaciones funcionales de monos, esta es una medida de emergencia. Para el duiker y el hyrax, los parches grandes deberán formar parte de una red de parches más pequeños y más cercanos en una matriz natural. [source]

Extinction debt on oceanic islands

ECOGRAPHY, Issue 2 2010
Kostas A. Triantis
Habitat destruction is the leading cause of species extinctions. However, there is typically a time-lag between the reduction in habitat area and the eventual disappearance of the remnant populations. These "surviving but ultimately doomed" species represent an extinction debt. Calculating the magnitude of such future extinction events has been hampered by potentially inaccurate assumptions about the slope of species,area relationships, which are habitat- and taxon-specific. We overcome this challenge by applying a method that uses the historical sequence of deforestation in the Azorean Islands, to calculate realistic and ecologically-adjusted species,area relationships. The results reveal dramatic and hitherto unrecognized levels of extinction debt, as a result of the extensive destruction of the native forest:>95%, in<600,yr. Our estimations suggest that more than half of the extant forest arthropod species, which have evolved in and are dependent on the native forest, might eventually be driven to extinction. Data on species abundances from Graciosa Island, where only a very small patch of secondary native vegetation still exists, as well as the number of species that have not been found in the last 45,yr, despite the extensive sampling effort, offer support to the predictions made. We argue that immediate action to restore and expand native forest habitat is required to avert the loss of numerous endemic species in the near future. [source]

Patch occupancy, population density and dynamics in a fragmented red squirrel Sciurusvulgaris population

ECOGRAPHY, Issue 1 2003
Goedele Verbeylen
We studied population dynamics of red squirrels in a group of small forest fragments, that cover only 6.5% of the total study area (4664 ha) and where distances to the nearest source population were up to 2.2 km. We tested effects of patch size, quality and isolation and supplementary feeding on patch occupation during 1995,99. Larger patches and patches with supplementary feeding had a higher probability of being occupied. No patch <3.5 ha was ever occupied. No effects of isolation were found, suggesting that the forest habitat in the study area is not sufficiently fragmented to influence red squirrel distribution across patches. For medium sized patches (3.7,21 ha), that were occupied some years, there was an increase in patch occupation over the years, even though overall population size tended to decrease. These patches had a high turnover, especially of males. Patches in which the squirrel population went extinct were recolonized within a year. For patches that were at least some years occupied, squirrel density depended on patch quality only. No effects of patch size, isolation and winter temperature on population density were found. These data suggest that in our study area habitat fragmentation has no effect on local squirrel density and that the random sample hypothesis explains the distribution pattern across patches. [source]

Avifauna response to hurricanes: regional changes in community similarity

Abstract Global climate models predict increases in the frequency and intensity of extreme climatic events such as hurricanes, which may abruptly alter ecological processes in forests and thus affect avian diversity. Developing appropriate conservation measures necessitates identifying patterns of avifauna response to hurricanes. We sought to answer two questions: (1) does avian diversity, measured as community similarity, abundance, and species richness, change in areas affected by hurricane compared with unaffected areas, and (2) what factors are associated with the change(s) in avian diversity? We used North American Breeding Bird Survey data, hurricane track information, and a time series of Landsat images in a repeated measures framework to answer these questions. Our results show a decrease in community similarity in the first posthurricane breeding season for all species as a group, and for species that nest in the midstory and canopy. We also found significant effects of hurricanes on abundance for species that breed in urban and woodland habitats, but not on the richness of any guild. In total, hurricanes produced regional changes in community similarity largely without significant loss of richness or overall avian abundance. We identified several potential mechanisms for these changes in avian diversity, including hurricane-induced changes in forest habitat and the use of refugia by birds displaced from hurricane-damaged forests. The prospect of increasing frequency and intensity of hurricanes is not likely to invoke a conservation crisis for birds provided we maintain sufficient forest habitat so that avifauna can respond to hurricanes by shifting to areas of suitable habitat. [source]

Exploration correlates with settlement: red squirrel dispersal in contrasting habitats

Summary 1Dispersers in heterogeneous habitat theoretically should target the habitat(s) where reproduction and survival (i.e. fitness) will be highest. However, the cues that dispersing animals respond to are not well understood: differences in habitat quality ultimately may be important, but whether animals respond to these differences may be influenced by their own familiarity with different habitats. 2To determine if dispersers reacted to differences in habitat, we documented the exploratory movements, dispersal, and settlement patterns of juvenile North American red squirrels (Tamiasciurus hudsonicus) originating in adjacent patches of different habitats. 3Dispersers originating in mature, closed-canopy forest (linked to higher female reproductive success and smaller territories) did not explore contrasting open forest with lower tree densities, and the magnitude of the dispersers' explorations was relatively similar. In contrast, dispersers from the open forest habitat made explorations that carried them into contrasting, mature forest habitat, and their explorations were more variable across individuals. 4When settlement occurred, it was strongly philopatric in all groups of dispersers, although the distances and directions favoured during the exploratory phase of dispersal remained strong predictors of where settlement occurred. Overall, processes favouring philopatry (i.e. maternal influences, competitive advantages, etc.) appeared to dominate the dispersal of our study animals, even those that were exposed to higher quality habitat during their explorations. 5Secondarily, annual stochasticity (or some correlate) affected the scale of exploration and timing of settlement more than the relative quality of habitat in which dispersers were born. 6Studies such as this that seek to understand the relative importance of individual experience, habitat familiarity, and habitat quality are important to ultimately understanding how individual animals and populations react to habitat heterogeneity. [source]

Historical and contemporary distributions of carnivores in forests of the Sierra Nevada, California, USA

William J. Zielinski
Abstract Aim, Mammalian carnivores are considered particularly sensitive indicators of environmental change. Information on the distribution of carnivores from the early 1900s provides a unique opportunity to evaluate changes in their distributions over a 75-year period during which the influence of human uses of forest resources in California greatly increased. We present information on the distributions of forest carnivores in the context of two of the most significant changes in the Sierra Nevada during this period: the expansion of human settlement and the reduction in mature forests by timber harvest. Methods, We compare the historical and contemporary distributions of 10 taxa of mesocarnivores in the conifer forests of the Sierra Nevada and southern Cascade Range by contrasting the distribution of museum and fur harvest records from the early 1900s with the distribution of detections from baited track-plate and camera surveys conducted from 1996 to 2002. A total of 344 sample units (6 track plates and 1 camera each) were distributed systematically across c. 3,000,000 ha area over a 7-year period. Results, Two species, the wolverine (Gulo gulo) and the red fox (Vulpes vulpes), present in the historical record for our survey area, were not detected during the contemporary surveys. The distributions of 3 species (fisher [Martespennanti], American marten [M. americana], and Virginia opossum [Didelphisvirginiana]) have substantially changed since the early 1900s. The distributions of fishers and martens, mature-forest specialists, appeared to have decreased in the northern Sierra Nevada and southern Cascade region. A reputed gap in the current distribution of fishers was confirmed. We report for the first time evidence that the distribution of martens has become fragmented in the southern Cascades and northern Sierra Nevada. The opossum, an introduced marsupial, expanded its distribution in the Sierra Nevada significantly since it was introduced to the south-central coast region of California in the 1930s. There did not appear to be any changes in the distributions of the species that were considered habitat generalists: gray fox (Urocyon cinereoargenteus), striped skunk (Mephitis mephitis), western spotted skunk (Spilogale gracilis), or black bear (Ursus americanus). Detections of raccoons (Procyon lotor) and badgers (Taxidea taxus) were too rare to evaluate. Contemporary surveys indicated that weasels (M. frenata and M. erminea) were distributed throughout the study area, but historical data were not available for comparison. Main conclusions, Two species, the wolverine and Sierra Nevada red fox, were not detected in contemporary surveys and may be extirpated or in extremely low densities in the regions sampled. The distributions of the mature forest specialists (marten and fisher) appear to have changed more than the distributions of the forest generalists. This is most likely due to a combination of loss of mature forest habitat, residential development and the latent effects of commercial trapping. Biological characteristics of individual species, in combination with the effect of human activities, appear to have combined to affect the current distributions of carnivores in the Sierra Nevada. Periodic resampling of the distributions of carnivores in California, via remote detection methods, is an efficient means for monitoring the status of their populations. [source]

Seasonal diets of insectivorous birds using canopy gaps in a bottomland forest

Christopher E. Moorman
ABSTRACT Little is known about how insectivorous bird diets are influenced by arthropod availability and about how these relationships vary seasonally. We captured birds in forest-canopy gaps and adjacent mature forest during 2001 and 2002 at the Savannah River Site in Barnwell County, South Carolina, and flushed their crops to gather information about arthropods eaten during four periods: spring migration, breeding, postbreeding, and fall migration. Arthropod availability for foliage- and ground-gleaning birds was examined by leaf clipping and pitfall trapping. Coleopterans and Hemipterans were used by foliage- and ground-gleaners more than expected during all periods, whereas arthropods in the orders Araneae and Hymenoptera were used as, or less than, expected based on availability during all periods. Ground-gleaning birds used Homopterans and Lepidopterans in proportions higher than availability during all periods. Arthropod use by birds was consistent from spring through fall migration, with no apparent seasonal shift in diet. Based on concurrent studies, heavily used orders of arthropods were equally abundant or slightly less abundant in canopy gaps than in the surrounding mature forest, but bird species were most frequently detected in gaps. Such results suggest that preferential feeding on arthropods by foliage-gleaning birds in gap habitats reduced arthropod densities or, alternatively, that bird use of gap and forest habitat was not determined by food resources. The abundance of arthropods across the stand may have allowed birds to remain in the densely vegetated gaps where thick cover provides protection from predators. SINOPSIS Se conoce poco de como la dieta de insectívoros está influenciada por la disponibilidad de artrópodos y de como estas interacciones varían estacionalmente. Capturamos aves en huecos o aberturas del docel de un bosque, adyacente a un bosque maduro durante el 2001 y el 2002 en Savannah River Site, Condado Garnwell, Carolina del Sur. A las aves le lavamos el buche para obtener información sobre los artrópodos utilizados como alimento durante la migración primaveral, durante la época reproductiva, post-reproductiva y durante la migración otoñal. Para determinar la disponibilidad de artrópodos en el follaje y en el suelo, usamos la técnica de cortar hojas con artrópodos y la de trampas de envases en el suelo. Los coleópteros y los hemípteros fueron utilizados como fuente de alimento, más de lo esperado tanto por aves que se alimentaron en el follaje como en los suelos, durante todos los periodos. Por su parte, los arácnidos y los himenópteros, fueron utilizados menos de lo esperado, basándose en la disponibilidad de estos durante todos los periodos de estudio. Las aves que se alimentaron en los suelos utilizaron homópteros y lepidópteros en mayor proporción que lo esperado, dada su disponibilidad, durante todos los periodos. Los artrópodos utilizados por las aves fueron consistentes desde la primavera hasta la migración otoñal, sin que hubiera desplazamiento o cambios estacionales en la dieta. Basado en estudios concurrentes, los ordenes de artrópodos más utilizados como alimento, estuvieron en similar o un poco más bajo en abundancia en los huecos del docel que en los alrededores de bosque maduro, pero las especies de aves se detectaron con mayor frecuencia en los huecos. Estos resultados sugieren que la alimentación preferencial de artrópodos por aves que se alimentan buscando insectos entre el follaje en habitats con huecos, reducen la densidad de artrópodos, o que el uso de los huecos o de bosque maduro no esta determinado por los recursos alimentarios. La abundancia de artrópodos a lo largo del rodal puede haber permitido que la aves permanecieran en los huecos o aperturas con alta densidad de plantas, en donde el follaje provee de protección contra los depredadores. [source]

55 Ice age kelp forests: climate-driven changes in kelp forest distribution since the last glacial maximum

M. H. Graham
Kelp forest distributions are constrained by the availability of rocky substrate within the depth range tolerable for growth and reproduction, which can vary over relatively short geological timescales (millennia) due to interactions between coastal bathymetry and climate-driven changes in eustatic sea level. Using GIS, a digital bathymetric map, sea level curves, and published kelp depth tolerances, I reconstructed changes in the size and distribution of giant kelp (Macrocystis pyrifera) forests in the Southern California Bight since the last glacial maximum. Reconstructions predicted that the total area of available kelp forest habitat for the California Channel Islands during the last glacial maximum (18.5 kyr BP; 628 square km) was greater than at present (382 square km) but less than at 16.5 kyr BP (1130 square km). Available kelp forest habitat along the southern California mainland also increased rapidly from 18.5 to 16.5 kyr BP but continued to increase with sea level rise. Differences in the effects of sea level rise on coastal geomorphology between the islands and mainland further constrained the extent of rocky substrate available to kelps. Given biomass and productivity estimates from present-day kelp forests, these reconstructions suggest more productive and spatially extensive island kelp forests near the last glacial maximum than at present, but the opposite pattern for the mainland. These climate-driven changes in kelp forest distribution and productivity likely had important historical impacts on the ecology and evolution of the present-day kelp ecosystem including kelp forest exploitation by early human inhabitants of southern California. [source]

The role of tropical dry forest as a long-term barrier to dispersal: a comparative phylogeographical analysis of dry forest tolerant and intolerant frogs

Abstract We used a comparative phylogeographical approach to investigate the origins of the disjunct wet forest biota of the Golfo Dulce region along the Pacific slope of Costa Rica. This region is isolated by Pacific dry forests north and south and isolated from Caribbean wet forests by mountains. We studied three sympatric lowland frog species in the Craugastor fitzingeri species group that prefer wet forest but differ in their response to dry habitats. In dry forest, C. fitzingeri can survive along streams while C. crassidigitus and C. talamancae are entirely absent. We collected samples from across the ranges of all three species, and obtained mitochondrial DNA sequence data from the COI and cytochrome b genes. We observed significant phylogeographical structure in C. crassidigitus and C. talamancae, but much less in C. fitzingeri, demonstrating that mountain barriers and dry forest habitat have reduced mitochondrial gene flow in the strictly wet-forest species. Additionally, we discovered that the Golfo Dulce and Central Panama populations of C. crassidigitus appear to have diverged in the Pliocene or earlier, suggesting that the dry forest separating these populations is old. Our phylogenetic analysis of 12 of approximately 16 species of the C. fitzingeri species group suggests that the three lowland species are each other's closest relatives. Because of this shared phylogenetic history, we attribute the striking differences in phylogeographical structure to the different ecologies of the frogs. In summary, we find that what appear to be minor differences in the natural history of these three closely related species may profoundly impact the potential for dispersal, range size, and cladogenesis. [source]

Comparative phylogeography of eastern chipmunks and white-footed mice in relation to the individualistic nature of species

Abstract Palaeoecological studies have demonstrated that ecological communities as a whole did not remain stable throughout the climatic fluctuations of the Quaternary. The result is that long-term associations of species cannot be inferred by contemporary associations in ecological communities. Therefore, the evolutionary significance of any contemporary ecological interactions among species and of the biotic community within which species have evolved also cannot be assumed from contemporary conditions. Comparative phylogeographic data provide a method to identify species within ecological communities that have shared biogeographic histories. We present an example of a long-term association between populations of two mammalian species, eastern chipmunks (Tamias striatus) and white-footed mice (Peromyscus leucopus), which are commonly associated with deciduous forest habitats. The distribution of mitochondrial DNA variation in T. striatus and P. leucopus from previously glaciated regions of the eastern United States support the hypothesis that, in at least part of their range, genetic lineages of the two species have expanded from similar population sources since the Last Glacial Maximum. In addition, the spatial concordance of genetic lineages of T. striatus and P. leucopus with the oak-savannah forest formations of Wisconsin and Illinois, suggest that populations associated with this community colonized the area in association with a set of arboreal species that comprise their deciduous forest habitat. [source]

Partitioning nuclear and chloroplast variation at multiple spatial scales in the neotropical epiphytic orchid, Laelia rubescens

Abstract Insights into processes that lead to the distribution of genetic variation within plant species require recognition of the importance of both pollen and seed movement. Here we investigate the contributions of pollen and seed movement to overall gene flow in the Central American epiphytic orchid, Laelia rubescens. Genetic diversity and structure were examined at multiple spatial scales in the tropical dry forest of Costa Rica using nuclear (allozymes) and chloroplast restriction fragment length polymorphism (RFLP) markers, which were found to be diverse (allozymes, P = 73.3%; HE = 0.174; cpDNA, HE = 0.741). Nuclear genetic structure (FSTn) was low at every spatial scale (0.005,0.091). Chloroplast markers displayed more structure (0.073,0.254) but relatively similar patterns. Neither genome displayed significant isolation-by-distance. Pollen and seed dispersal rates did not differ significantly from one another (mp/ms = 1.40) at the broadest geographical scale, among sites throughout Costa Rica. However, relative contributions of pollen and seeds to gene flow were scale-dependent, with different mechanisms determining the dominant mode of gene flow at different spatial scales. Much seed dispersal is highly localized within the maternal population, while some seeds enter the air column and are dispersed over considerable distances. At the intermediate scale (10s to 100s of metres) pollinators are responsible for substantial pollen flow. This species appears capable of distributing its genes across the anthropogenically altered landscape that now characterizes its Costa Rican dry forest habitat. [source]

Mitochondrial DNA control region diversity in the endangered blue chaffinch, Fringilla teydea

J. Pestano
Abstract The blue chaffinch (Fringilla teydea) is found only on the two central Canary Islands of Gran Canaria and Tenerife, where it is restricted to pine forest habitat. It is reasonably abundant on the latter island but endangered on the former. Here, sequence variation was studied in a fragment spanning domains I and II of the mitochondrial DNA (mtDNA) control region. Phylogenetic analysis of all haplotypes with a F. coelebs outgroup indicated the two island populations were reciprocally monophyletic, supporting their individual conservation. Unlike in other species, most within-island haplotype diversity was due to mutations in the domain II region. Surprisingly, genetic diversity was greater in the smaller Gran Canarian population. We suggest that this is unlikely to be maintained under current population sizes although it may be mitigated by incorporating genetic information into the captive breeding programme. [source]

Electrophysiological identification of antennal pH receptors in the ground beetle Pterostichus oblongopunctatus

Enno Merivee
Abstract., Electrophysiological responses of antennal taste bristles to 100 mm acetate and phosphate buffers were tested at pH 3,11 in the ground beetle Pterostichus oblongopunctatus (F.) (Coleoptera, Carabidae). Additionally, responses of these sensilla to 10 and 100 mm phosphate buffers were compared with each other. Generally, in response to these stimulating solutions, two sensory cells, classified as a salt cell (cation cell) and a pH cell, respectively, showed action potentials distinguished by differences in their amplitudes and polarity of spikes. The firing rate of the cation cell increased with increasing buffer concentration, and was influenced by buffer pH in a complicated way. The best stimulus for the second cell (pH cell) was pH of the stimulating buffer solution. As the pH of the stimulus solution increased, higher rates of firing were produced by the pH cell. For example, the number of action potentials elicited by 100 mm phosphate buffer at pH 11.1 was approximately 16-fold higher compared with that at pH 8.1, and firing rates during the first second of the response were 27.9 and 1.7 imp/s, respectively. The pH cell did not fire or fired at very low frequency (first second response below 5 imp/s) at pH 3,6. This level of acidity probably represents the pH preferences of this ground beetle in its forest habitat and hibernating sites. By contrast to the cation cell, the pH cell responded to increases in buffer concentration by decreasing its firing rate. [source]

Impacts of Restored Patch Density and Distance from Natural Forests on Colonization Success

Hans Jacquemyn
Abstract The reduction and fragmentation of forest habitats is expected to have profound effects on plant species diversity as a consequence of the decreased area and increased isolation of the remnant patches. To stop the ongoing process of forest fragmentation, much attention has been given recently to the restoration of forest habitat. The present study investigates restoration possibilities of recently established patches with respect to their geographical isolation. Because seed dispersal events over 100 m are considered to be of long distance, a threshold value of 100 m between recent and old woodland was chosen to define isolation. Total species richness, individual patch species richness, frequency distributions in species occurrences, and patch occupancy patterns of individual species were significantly different among isolated and nonisolated stands. In the short term no high species richness is to be expected in isolated stands. Establishing new forests adjacent to existing woodland ensures higher survival probabilities of existing populations. In the long term, however, the importance of long-distance seed dispersal should not be underestimated because most species showed occasional long-distance seed dispersal. A clear distinction should be made between populations colonizing adjacent patches and patches isolated from old woodland. The colonization of isolated stands may have important effects on the dynamics and diversity of forest networks, and more attention should be directed toward the genetic traits and viability of founding populations in isolated stands. [source]

Spatial variation in density and total size estimates in fragmented primate populations: the golden-crowned sifaka (Propithecus tattersalli)

Erwan Quéméré
Abstract The golden-crowned sifaka (Propithecus tattersalli) is an endangered lemur species found only in the Daraina region, a very restricted area in north-eastern Madagascar. Its forest habitat is highly fragmented and expected to suffer from significant changes in the near future. The species is poorly known and only one census study, carried out in 2000, has ever been published. It is thus crucial to update the conservation status of the golden-crowned sifaka before major anthropogenic environmental changes take place. Using the line-transect approach, we estimated the species density in the main forest fragments located in both the peripheral and central parts of the distribution range, including both protected and unprotected areas. In parallel, we tried to determine whether an edge effect could be detected by comparing densities at different distances from the forest edges. We found important variation of sifaka densities among forest fragments. The total species abundance is thus difficult to determine, but we estimated that it is likely to be over 18,000, two to three times higher than previously thought. However, our data also suggested that most P. tattersalli live in forests located in the central part of the distribution range and that the estimated densities in the central part were high (>80 individuals/km2). Two forest fragments, found to host a large part of the total population, are currently outside the managed area and their incorporation to the managed area is strongly recommended. Lastly, as expected for a folivorous and not heavily hunted species, our results are consistent with the hypothesis that this species does not experience a clear edge effect, at least during the first half of the dry season. This could be due to a high resiliency to habitat fragmentation or to the fact that fragmentation has been going on for some time. Am. J. Primatol. 72:72,80, 2010. © 2009 Wiley-Liss, Inc. [source]

Intra-community coalitionary lethal attack of an adult male southern muriqui (Brachyteles arachnoides)

M.G. Talebi
Abstract We report on the first evidence of intra-community coalitionary lethal aggression in muriquis (Brachyteles). The event occurred in southern muriquis (Brachyteles arachnoides) during a long-term study (>15 years) of two social groups inhabiting mostly pristine Atlantic forest habitat in the Parque Estadual Carlos Botelho, southern São Paulo State, Brazil. The attack took place deep in the core area of the Group Caetê home range. Tense agonistic behaviors and vocalizations preceded the lethal coalitionary attack, and the tension increased over a 36,48,hr period. One adult female and two unidentified individuals also took part in a coalition led by six adult males. The members of the coalition collectively approached, embraced, immobilized and repeatedly bit the entire body of an adult male, resulting in severe bleeding injuries and the victim's death in less than 1,hr after the attack commenced. Combined ecological, behavioral and spatial data related to the event indicate that this was an intra-community attack and suggest social tensions related to mating competition as the proximate trigger of the coalitionary killing. The attack resembled those reported for chimpanzees, with clear numeric superiority and a low risk of injury to aggressors, resulting in the death of a lone conspecific victim. This observation (n=1) is suggestive of a capacity for escalated aggression in muriquis and reinforces arguments for the potential adaptive significance of intra-community aggression in male philopatric societies, as reported for spider monkeys and chimpanzees. These characteristics challenge the view of the muriquis as a peaceful primate and support the general hypothesis that imbalances of power contribute to intra-specific killing in primates, such as chimpanzees and humans. Am. J. Primatol. 71:860,867, 2009. © 2009 Wiley-Liss, Inc. [source]

The Delphi process , an expert-based approach to ecological modelling in data-poor environments

D. C. MacMillan
Abstract Resource managers are involved in difficult decisions that affect rare species and habitats but often lack relevant ecological knowledge and experience. Ecological models are increasingly being looked to as a means of assisting the decision-making process, but very often the data are missing or are unsuited to empirical modelling. This paper describes the development and application of the Delphi approach to develop a decision support tool for wildlife conservation and management. The Delphi process is an expert-based approach to decision support that can be used as a means for predicting outcomes in situations where ,absolute' or ,objective' models are unavailable or compromised by lack of appropriate data. The method aims to develop consensus between experts over several rounds of deliberation on the assumption that combining the expertise of several individuals will provide more reliable results than consulting one or two individuals. In this paper the approach is used to engineer soft knowledge on the conservation requirements of capercaillie Tetrao urogallus, an endangered woodland grouse, into a model that can be used by forests managers to improve the quality of forest habitat for capercaillie over extensive commercial forest areas. This paper concludes with a discussion of the potential advantages and disadvantages of Delphi and other soft knowledge approaches to ecological modelling and conservation management. [source]

Applying a continua landscape approach to evaluate plant response to fragmentation: Primula vulgaris in the Cantabrian mountains

Alicia Valdés
Abstract Question: Continua landscape approaches conceptualize the effects of habitat fragmentation on the biota by considering fragmented landscapes as continuous gradients, departing from the view of habitat as either suitable (fragment) or unsuitable (matrix). They also consider the ecological gradients or the ,Umwelt' (species-specific perception of the landscape) to represent the processes that ultimately limit organisms' ability to colonize and persist within habitat remnants. Are these approaches suitable for evaluating the response of plant species to fragmentation? Location: Fragmented mid-elevation temperate forests, Cantabrian range, Spain. Methods: The presence, abundance and demographic structure of populations of the perennial herb Primula vulgaris were sampled across a continuous extent of 100 ha, subdivided into 400 50 m × 50 m sampling units. These variables were related to forest availability, forest subdivision and edge density, topography and the spatial clumpiness of populations (a measure of plant dispersal constraints and, hence, a major surrogate of plant Umwelt). Results: Fragmentation processes, especially habitat loss, negatively affect P. vulgaris, with a stronger effect on presence than on abundance and demography. Despite the importance of habitat availability, P. vulgaris does not occupy all potentially suitable forest habitat, mostly owing to dispersal constraints. A positive effect of slope on plant presence also suggests some effect of habitat quality in determining establishment and occupancy of forest landscape. Conclusions: Within-habitat dispersal constraints are as important as forest fragmentation in determining the landscape-scale distribution of P. vulgaris. By assessing the relative role of the diverse fragmentation processes, and of the species' landscape perception, a continua landscape approach proves to be a valuable tool for predicting plant response to landscape change. [source]

Spatiotemporal changes of beetle communities across a tree diversity gradient

Stephanie Sobek
Abstract Aim, Plant and arthropod diversity are often related, but data on the role of mature tree diversity on canopy insect communities are fragmentary. We compare species richness of canopy beetles across a tree diversity gradient ranging from mono-dominant beech to mixed stands within a deciduous forest, and analyse community composition changes across space and time. Location, Germany's largest exclusively deciduous forest, the Hainich National Park (Thuringia). Methods, We used flight interception traps to assess the beetle fauna of various tree species, and applied additive partitioning to examine spatiotemporal patterns of diversity. Results, Species richness of beetle communities increased across the tree diversity gradient from 99 to 181 species per forest stand. Intra- and interspecific spatial turnover among trees contributed more than temporal turnover among months to the total ,-beetle diversity of the sampled stands. However, due to parallel increases in the number of habitat generalists and the number of species in each feeding guild (herbivores, predators and fungivores), no proportional changes in community composition could be observed. If only beech trees were analysed across the gradient, patterns were similar but temporal (monthly) species turnover was higher compared to spatial turnover among trees and not related to tree diversity. Main conclusions, The changes in species richness and community composition across the gradient can be explained by habitat heterogeneity, which increased with the mix of tree species. We conclude that understanding temporal and spatial species turnover is the key to understanding biodiversity patterns. Mono-dominant beech stands are insufficient to conserve fully the regional species richness of the remaining semi-natural deciduous forest habitats in Central Europe, and analysing beech alone would have resulted in the misleading conclusion that temporal (monthly) turnover contributes more to beetle diversity than spatial turnover among different tree species or tree individuals. [source]

Trophic level modulates carabid beetle responses to habitat and landscape structure: a pan-European study

1. Anthropogenic pressures have produced heterogeneous landscapes expected to influence diversity differently across trophic levels and spatial scales. 2. We tested how activity density and species richness of carabid trophic groups responded to local habitat and landscape structure (forest percentage cover and habitat richness) in 48 landscape parcels (1 km2) across eight European countries. 3. Local habitat affected activity density, but not species richness, of both trophic groups. Activity densities were greater in rotational cropping compared with other habitats; phytophage densities were also greater in grassland than forest habitats. 4. Controlling for country and habitat effects, we found general trophic group responses to landscape structure. Activity densities of phytophages were positively correlated, and zoophages uncorrelated, with increasing habitat richness. This differential functional group response to landscape structure was consistent across Europe, indicated by a lack of a country × habitat richness interaction. Species richness was unaffected by landscape structure. 5. Phytophage sensitivity to landscape structure may arise from relative dependency on seed from ruderal plants. This trophic adaptation, rare in Carabidae, leads to lower phytophage numbers, increasing vulnerability to demographic and stochastic processes that the greater abundance, species richness, and broader diet of the zoophage group may insure against. [source]

Possible effects of habitat fragmentation and climate change on the range of forest plant species

Olivier Honnay
Global circulation models predict an increase in mean annual temperature between 2.1 and 4.6 °C by 2080 in the northern temperate zone. The associated changes in the ratio of extinctions and colonizations at the boundaries of species ranges are expected to result in northward range shifts for a lot of species. However, net species colonization at northern boundary ranges, necessary for a northward shift and for range conservation, may be hampered because of habitat fragmentation. We report the results of two forest plant colonization studies in two fragmented landscapes in central Belgium. Almost all forest plant species (85%) had an extremely low success of colonizing spatially segregated new suitable forest habitats after c. 40 years. In a landscape with higher forest connectivity, colonization success was higher but still insufficient to ensure large-scale colonization. Under the hypothesis of net extinction at southern range boundaries, forest plant species dispersal limitation will prevent net colonization at northern range boundaries required for range conservation. [source]

Seasonal distribution and species composition of daytime biting mosquitoes

Waseem AKRAM
Abstract Adults and immatures of Aedes mosquito populations were collected at temperatures between 40 and 44°C (summer), while larvae were collected at 0°C (winter). Major mosquito activities were observed from February to mid-December at various collection sites that yielded high populations of Aedes spp. from May to September, and high populations of Culex spp. and Anopheles spp. from March to September. In June to July, mosquito activity was suspended because the relative humidity was high (70%); a result of the monsoon rains. In August, with temperature ranging from 38 to 42°C, the populations of Culex, Anopheles and Aedes began to increase (36.8, 32.1 and 26.3%, respectively). Population estimates (through standard prototype Centers for Disease Control (CDC) and Biogents (BG)-sentinel) and species composition of Aedes in forest habitats indicated a rapid increase in the populations of Ae. albopictus (52.3%), Ae. aegypti (19.1%) and Ae. vittatus (28.5%) following the rainy season in July. Areas positive for Ae. albopictus had identical population levels and distribution ranges of Ae. vittatus, however, there were no Ae. aegypti in Ae. albopictus areas from August to September. The population level, seasonal distribution, habitat and areas of adult activity marked by global positioning system (GPS) coordinates are being used for reference and for species composition data of Anopheles spp. (2), Culex spp. (10) and Aedes spp. (5) in addition to associated temperature, relative humidity and physico-chemical factors of larval habitat. Global meteorological changes have caused an expansion of the active period, leading to the mosquito's possibility of being a vector of disease increasing, resulting in the spread of dengue fever. [source]

Diversity and species composition of West African ungulate assemblages: effects of fire, climate and soil

GLOBAL ECOLOGY, Issue 6 2008
Erik Klop
ABSTRACT Aim, Anthropogenic fires are a major component of the ecology of rangelands throughout the world. To assess the effects of these fires on the diversity patterns of herbivores, we related gradients in fire occurrence, climate and soil fertility to patterns in alpha and beta diversity of African ungulates. Location, West Africa. Methods, We used a survey-based approach for ungulates in 37 protected areas in desert, savanna and rain forest habitats throughout West Africa, combined with satellite images of fire occurrence and digital maps of actual evapotranspiration and soil fertility. Alpha diversity was related to the environmental variables using conventional and spatial regression models. We investigated beta diversity using partial Mantel tests and ordination techniques, and by partitioning the variance in assemblage composition into environmental and spatial components. Results, The species richness of grazers showed a quadratic relationship with actual evapotranspiration, whereas that of browsers and frugivores showed a linear relationship. However, in the multiple regression models fire occurrence was the only variable that significantly correlated with the species richness of grazers. Soil fertility was weakly related to overall beta diversity and the species richness of browsers, but was non-significant in the multiple regression models. Fire occurrence was the most important variable explaining species composition of the overall species set and of grazers, whereas the assemblage composition of browsers and frugivores was explained mostly by actual evapotranspiration. Main conclusions, In contrast to previous studies, our analyses show that moisture and nutrients alone fail to adequately predict the diversity patterns of grazing ungulates. Rather, the species richness and assemblage composition of grazers are largely governed by anthropogenic fires that modify the quality and structure of the grass sward. Diversity patterns of browsers and frugivores are markedly different from grazers and depend mainly on the availability of moisture, which is positively correlated with the availability of foliage and fruits. Our study highlights the importance of incorporating major human-induced disturbances or habitat alterations into analyses of diversity patterns. [source]

Bergmann's rule does not apply to geometrid moths along an elevational gradient in an Andean montane rain forest

GLOBAL ECOLOGY, Issue 1 2004
Gunnar Brehm
ABSTRACT Aim, Bergmann's rule generally predicts larger animal body sizes with colder climates. We tested whether Bergmann's rule at the interspecific level applies to moths (Lepidoptera: Geometridae) along an extended elevational gradient in the Ecuadorian Andes. Location, Moths were sampled at 22 sites in the province Zamora-Chinchipe in southern Ecuador in forest habitats ranging from 1040 m to 2677 m above sea level. Methods, Wingspans of 2282 male geometrid moths representing 953 species were measured and analysed at the level of the family Geometridae, as well as for the subfamily Ennominae with the tribes Boarmiini and Ourapterygini, and the subfamily Larentiinae with the genera Eois, Eupithecia and Psaliodes. Results, Bergmann's rule was not supported since the average wingspan of geometrid moths was negatively correlated with altitude (r = ,0.59, P < 0.005). The relationship between body size and altitude in Geometridae appears to be spurious because species of the subfamily Larentiinae are significantly smaller than species of the subfamily Ennominae and simultaneously increase in their proportion along the gradient. A significant decrease of wingspan was also found in the ennomine tribe Ourapterygini, but no consistent body size patterns were found in the other six taxa studied. In most taxa, body size variation increases with altitude, suggesting that factors acting to constrain body size might be weaker at high elevations. Main conclusions, The results are in accordance with previous studies that could not detect consistent body size patterns in insects at the interspecific level along climatic gradients. [source]

Avian distribution in treefall gaps and understorey of terra firme forest in the lowland Amazon

IBIS, Issue 1 2005
We compared the bird distributions in the understorey of treefall gaps and sites with intact canopy in Amazonian terra firme forest in Brazil. We compiled 2216 mist-net captures (116 species) in 32 gap and 32 forest sites over 22.3 months. Gap habitats differed from forest habitats in having higher capture rates, total captures, species richness and diversity. Seventeen species showed a significantly different distribution of captures between the two habitats (13 higher in gap and four higher in forest). Gap habitats had higher capture rates for nectarivores, frugivores and insectivores. Among insectivores, capture rates for solitary insectivores and army ant followers did not differ between the two habitats. In contrast, capture rates were higher in gaps for members of mixed-species insectivore flocks and mixed-species insectivore,frugivore flocks. Insectivores, especially members of mixed-species flocks, were the predominant species in gap habitats, where frugivores and nectarivores were relatively uncommon. Although few canopy species were captured in gap or forest habitats, visitors from forest mid-storey constituted 42% of the gap specialist species (0% forest) and 46% of rare gap species (38% forest). Insectivore, and total, captures increased over time, but did so more rapidly in gap than in forest habitats, possibly as a response to gap succession. However, an influx of birds displaced by nearby timber harvest also may have caused these increases. Avian gap-use in Amazonian terra firme forests differs from gap-use elsewhere, partly because of differences in forest characteristics such as stature and soil fertility, indicating that the avian response to gaps is context dependent. [source]

Phylogenetic relationships, diversification and biogeography in Neotropical Brotogeris parakeets

Camila C. Ribas
Abstract Aim, We present a molecular phylogenetic analysis of Brotogeris (Psittacidae) using several distinct and complementary approaches: we test the monophyly of the genus, delineate the basal taxa within it, uncover their phylogenetic relationships, and finally, based on these results, we perform temporal and spatial comparative analyses to help elucidate the historical biogeography of the Neotropical region. Location, Neotropical lowlands, including dry and humid forests. Methods, Phylogenetic relationships within Brotogeris were investigated using the complete sequences of the mitochondrial genes cyt b and ND2, and partial sequences of the nuclear intron 7 of the gene for Beta Fibrinogen for all eight species and 12 of the 17 taxa recognized within the genus (total of 63 individuals). In order to delinetae the basal taxa within the genus we used both molecular and plumage variation, the latter being based on the examination of 597 skin specimens. Dates of divergence and confidence intervals were estimated using penalized likelihood. Spatial and temporal comparative analyses were performed including several closely related parrot genera. Results,Brotogeris was found to be a monophyletic genus, sister to Myiopsitta. The phylogenetic analyses recovered eight well-supported clades representing the recognized biological species. Although some described subspecies are diagnosably distinct based on morphology, there was generally little intraspecific mtDNA variation. The Amazonian species had different phylogenetic affinities and did not group in a monophyletic clade. Brotogeris diversification took place during the last 6 Myr, the same time-frame as previously found for Pionus and Pyrilia. Main conclusions, The biogeographical history of Brotogeris implies a dynamic history for South American biomes since the Pliocene. It corroborates the idea that the geological evolution of Amazonia has been important in shaping its biodiversity, argues against the idea that the region has been environmentally stable during the Quaternary, and suggests dynamic interactions between wet and dry forest habitats in South America, with representatives of the Amazonian biota having several independent close relationships with taxa endemic to other biomes. [source]

Patterns of density, diversity, and the distribution of migratory strategies in the Russian boreal forest avifauna

Russell Greenberg
Abstract Aim, Comparisons of the biotas in the Palaearctic and Nearctic have focused on limited portions of the two regions. The purpose of this study was to assess the geographic pattern in the abundance, species richness, and importance of different migration patterns of the boreal forest avifauna of Eurasia from Europe to East Asia as well as their relationship to climate and forest productivity. We further examine data from two widely separated sites in the New World to see how these conform to the patterns found in the Eurasian system. Location, Boreal forest sites in Russia and Canada. Methods, Point counts were conducted in two to four boreal forest habitats at each of 14 sites in the Russian boreal forest from near to the Finnish border to the Far East, as well as at two sites in boreal Canada. We examined the abundance and species richness of all birds, and specific migratory classes, against four gradients (climate, primary productivity, latitude, and longitude). We tested for spatial autocorrelation in both dependent and independent variables using Moran's I to develop spatial correlograms. For each migratory class we used maximum likelihood to fit models, first assuming uncorrelated residuals and then assuming spatially autocorrelated residuals. For models assuming unstructured residuals we again generated correlograms on model residuals to determine whether model fitting removed spatial autocorrelation. Models were compared using Akaike's information criterion, adjusted for small sample size. Results, Overall abundance was highest at the eastern and western extremes of the survey region and lowest at the continent centre, whereas the abundance of tropical and short-distance migrants displayed an east,west gradient, with tropical migrants increasing in abundance in the east (and south), and short-distance migrants in the west. Although overall species richness showed no geographic pattern, richness within migratory classes showed patterns weaker than, but similar to, their abundance patterns described above. Overall abundance was correlated with climate variables that relate to continentality. The abundances of birds within different migration strategies were correlated with a second climatic gradient , increasing precipitation from west to east. Models using descriptors of location generally had greater explanatory value for the abundance and species-richness response variables than did those based on climate data and the normalized difference vegetation index (NDVI). Main conclusions, The distribution patterns for migrant types were related to both climatic and locational variables, and thus the patterns could be explained by either climatic regime or the accessibility of winter habitats, both historically and currently. Non-boreal wintering habitat is more accessible from both the western and eastern ends than from the centre of the boreal forest belt, but the tropics are most accessible from the eastern end of the Palaearctic boreal zone, in terms of distance and the absence of geographical barriers. Based on comparisons with Canadian sites, we recommend that future comparative studies between Palaearctic and Nearctic faunas be focused more on Siberia and the Russian Far East, as well as on central and western Canada. [source]

Arctiid moth ensembles along a successional gradient in the Ecuadorian montane rain forest zone: how different are subfamilies and tribes?

Nadine Hilt
Abstract Aim, We examined changes in the species diversity and faunal composition of arctiid moths along a successional gradient at a fine spatial scale in one of the world's hot spots for moths, the Andean montane rain forest zone. We specifically aimed to discover whether moth groups with divergent life histories respond differentially to forest recovery. Location, Southern Ecuador (province Zamora-Chinchipe) along a gradient from early successional stages to mature forest understorey at elevations of 1800,2005 m a.s.l. Methods, Moths were sampled with weak light traps at 21 sites representing three habitat categories (early and late succession, mature forest understorey), and were analysed at species level. Relative proportions were calculated from species numbers as well as from specimen numbers. Fisher's , was used as a measure of local diversity, and for ordination analyses non-metric multidimensional scaling (NMDS) was carried out. Results, Proportions of higher arctiid taxa changed distinctly along the successional gradient. Ctenuchini (wasp moths) contributed more strongly to ensembles in natural forest, whereas Lithosiinae (lichen moths) decreased numerically with forest recovery. Arctiid species diversity (measured as Fisher's ,) was high in all habitats sampled. The three larger subordinated taxa contributed differentially to richness: Phaegopterini (tiger moths) were always the most diverse clade, followed by Ctenuchini and Lithosiinae. Local species diversity was higher in successional habitats than in forest understorey, and this was most pronounced for the Phaegopterini. Dominance of a few common species was higher, and the proportion of species represented as singletons was lower, than reported for many other tropical arthropod communities. NMDS revealed a significant segregation between ensembles from successional sites and from forest understorey for all larger subordinated taxa (Phaegopterini, Ctenuchini, Lithosiinae). Abandoned pastures held an impoverished, distinct fauna. Faunal segregation was more pronounced for rare species. Ordination axes reflected primarily the degree of habitat disturbance (openness of vegetation, distance of sites from mature forest) and, to a lesser extent, altitude, but not distance between sampling sites. Main conclusions, Despite the geographical proximity of the 21 sites and the pronounced dispersal abilities of adult arctiid moths, local ecological processes were strong enough to allow differentiation between ensembles from mature forest and disturbed sites, even at the level of subfamilies and tribes. Differences in morphology and life-history characteristics of higher arctiid taxa were reflected in their differential representation (proportions of species and individuals) at the sites, whereas patterns of alpha and beta diversity were concordant. However, concordance was too low to allow for reliable extrapolation, in terms of biodiversity indication, from one tribe or subfamily to the entire family Arctiidae. Phaegopterini (comprising more putative generalist feeders during the larval stages) benefited from habitat disturbance, whereas Ctenuchini (with host-specialist larvae) were more strongly affiliated with forest habitats. [source]

Comparative phylogeography of eastern chipmunks and white-footed mice in relation to the individualistic nature of species

Abstract Palaeoecological studies have demonstrated that ecological communities as a whole did not remain stable throughout the climatic fluctuations of the Quaternary. The result is that long-term associations of species cannot be inferred by contemporary associations in ecological communities. Therefore, the evolutionary significance of any contemporary ecological interactions among species and of the biotic community within which species have evolved also cannot be assumed from contemporary conditions. Comparative phylogeographic data provide a method to identify species within ecological communities that have shared biogeographic histories. We present an example of a long-term association between populations of two mammalian species, eastern chipmunks (Tamias striatus) and white-footed mice (Peromyscus leucopus), which are commonly associated with deciduous forest habitats. The distribution of mitochondrial DNA variation in T. striatus and P. leucopus from previously glaciated regions of the eastern United States support the hypothesis that, in at least part of their range, genetic lineages of the two species have expanded from similar population sources since the Last Glacial Maximum. In addition, the spatial concordance of genetic lineages of T. striatus and P. leucopus with the oak-savannah forest formations of Wisconsin and Illinois, suggest that populations associated with this community colonized the area in association with a set of arboreal species that comprise their deciduous forest habitat. [source]