Open Grassland Habitats Research Articles

Species Richness Responses to Structural or Compositional Habitat Diversity between and within Grassland Patches: A Multi-Taxon Approach.

Habitat diversity (spatial heterogeneity within and between habitat patches in a landscape, HD) is often invoked as a driver of species diversity at small spatial scales. However, the effect of HD on species richness (SR) of multiple taxa is not well understood. We quantified HD and SR in a wet-dry gradient of open grassland habitats in Hortobágy National Park (E-Hungary) and tested the effect of compositional and structural factors of HD on SR of flowering plants, orthopterans, true bugs, spiders, ground beetles and birds. Our dataset on 434 grassland species (170 plants, 264 animals) showed that the wet-dry gradient (compositional HD at the between-patch scale) was primarily related to SR in orthopterans, ground-dwelling arthropods, and all animals combined. The patchiness, or plant association richness, of the vegetation (compositional HD at the within-patch scale) was related to SR of vegetation-dwelling arthropods, whereas vegetation height (structural HD at the within-patch scale) was related to SR of ground-dwelling arthropods and birds. Patch area was related to SR only in birds, whereas management (grazing, mowing, none) was related to SR of plants and true bugs. All relationships between HD and SR were positive, indicating increasing SR with increasing HD. However, total SR was not related to HD because different taxa showed similar positive responses to different HD variables. Our findings, therefore, show that even though HD positively influences SR in a wide range of grassland taxa, each taxon responds to different compositional or structural measures of HD, resulting in the lack of a consistent relationship between HD and SR when taxon responses are pooled. The idiosyncratic responses shown here exemplify the difficulties in detecting general HD-SR relationships over multiple taxa. Our results also suggest that management and restoration aimed specifically to sustain or increase the diversity of habitats are required to conserve biodiversity in complex landscapes.

Influence of Habitat and Intrinsic Characteristics on Survival of Neonatal Pronghorn.

Increased understanding of the influence of habitat (e.g., composition, patch size) and intrinsic (e.g., age, birth mass) factors on survival of neonatal pronghorn (Antilocapra americana) is a prerequisite to successful management programs, particularly as they relate to population dynamics and the role of population models in adaptive species management. Nevertheless, few studies have presented empirical data quantifying the influence of habitat variables on survival of neonatal pronghorn. During 2002–2005, we captured and radiocollared 116 neonates across two sites in western South Dakota. We documented 31 deaths during our study, of which coyote (Canis latrans) predation (n = 15) was the leading cause of mortality. We used known fate analysis in Program MARK to investigate the influence of intrinsic and habitat variables on neonatal survival. We generated a priori models that we grouped into habitat and intrinsic effects. The highest-ranking model indicated that neonate mortality was best explained by site, percent grassland, and open water habitat; 90-day survival (0.80; 90% CI = 0.71–0.88) declined 23% when grassland and water increased from 80.1 to 92.3% and 0.36 to 0.40%, respectively, across 50% natal home ranges. Further, our results indicated that grassland patch size and shrub density were important predictors of neonate survival; neonate survival declined 17% when shrub density declined from 5.0 to 2.5 patches per 100 ha. Excluding the site covariates, intrinsic factors (i.e., sex, age, birth mass, year, parturition date) were not important predictors of survival of neonatal pronghorns. Further, neonatal survival may depend on available land cover and interspersion of habitats. We have demonstrated that maintaining minimum and maximum thresholds for habitat factors (e.g., percentages of grassland and open water patches, density of shrub patches) throughout natal home ranges will in turn, ensure relatively high (>0.50) neonatal survival rates, especially as they relate to coyote predation. Thus, landscape level variables (particularly percentages of open water, grassland habitats, and shrub density) should be incorporated into the development or implementation of pronghorn management plans across sagebrush steppe communities of the western Dakotas, and potentially elsewhere within the geographic range of pronghorn.

English

Abstract. Surface mining transforms landscapes and ecosystem functions through the removal of vegetation and soil. Losses of vegetation correlate with declines, displacement, and transformations of songbird communities. Mine reclamation is a legislative requirement that can influence wildlife communities. The purpose of this study was to examine the avian community responses to mine reclamation practices and, as a proxy, assess the potential benefits and limitations of current reclamation approaches. Avian point counts were carried out at 202 plots on mined and surrounding non-mined areas throughout the Shale Hills Region of Alabama. These mines were reclaimed across a 26 year time-frame and using a variety of reclamation techniques. Six of the thirty-six bird species observed in high enough densities for detailed analysis showed differences of interest between reclaimed and random non-mined sites. Two species showed negative density responses: Carolina Chickadees (Poecile carolinensis), Hooded Warblers (Setophaga citrina). Conversely, densities of Field Sparrows (Spizella pusilla), Gray Catbirds (Dumetella carolinensis), Pine Warblers (Setophaga pinus), and Prairie Warblers (Setophaga discolor) responded positively to mine reclamation. We found that most mine reclamation in the Shale Hills Region of Alabama tended to shift habitat towards open canopy, edge, and grassland habitats. Though our study area tended to have fairly open forest structures (average basal areas around 13 m 2 /ha and average canopy closures around 50%), species that responded negatively were often associated with older sites with more closed canopies. Reclamation techniques should incorporate diverse canopy vegetation and thick mid-story cover to promote more complex vertical forest structure.

The energy balance of utilising meadow grass in Danish biogas production

This paper presents a study of the energy balance of utilising nature conservation biomass from meadow habitats in Danish biogas production. Utilisation of nature conservation grass in biogas production in Denmark represents an interesting perspective for enhancing nature conservation of the open grassland habitats, while introducing an alternative to the use of intensively cultivated energy crops as co-substrates in manure based biogas plants. The energy balance of utilising nature conservation grass was investigated by using: data collected from previous investigations on the productivity of meadow areas, different relevant geo-datasets, spatial analyses, and various statistical analyses. The results show that values for the energy return on energy invested (EROEI) ranging from 1.7 to 3.3 can be obtained when utilising meadow grasses in local biogas production. The total national net energy gain (NEG) was estimated to more than 600,000GJ corresponding to ≈15% of the total Danish biogas production in 2012.

Influence of topography on tropical African vegetation coverage

Hominid evolution in the late Miocene has long been hypothesized to be linked to the retreat of the tropical rainforest in Africa. One cause for the climatic and vegetation change often considered was uplift of Africa, but also uplift of the Himalaya and the Tibetan Plateau was suggested to have impacted rainfall distribution over Africa. Recent proxy data suggest that in East Africa open grassland habitats were available to the common ancestors of hominins and apes long before their divergence and do not find evidence for a closed rainforest in the late Miocene. We used the coupled global general circulation model CCSM3 including an interactively coupled dynamic vegetation module to investigate the impact of topography on African hydro-climate and vegetation. We performed sensitivity experiments altering elevations of the Himalaya and the Tibetan Plateau as well as of East and Southern Africa. The simulations confirm the dominant impact of African topography for climate and vegetation development of the African tropics. Only a weak influence of prescribed Asian uplift on African climate could be detected. The model simulations show that rainforest coverage of Central Africa is strongly determined by the presence of elevated African topography. In East Africa, despite wetter conditions with lowered African topography, the conditions were not favorable enough to maintain a closed rainforest. A discussion of the results with respect to other model studies indicates a minor importance of vegetation–atmosphere or ocean–atmosphere feedbacks and a large dependence of the simulated vegetation response on the land surface/vegetation model.

Provisioning nest material for Rooks; a potential tool for conservation management

Abstract Active conservation measures often entail supplementing scarce resources, such as food or nesting site to high conservation value species. We hypothesized that adequate nest material in reasonable distance is a scarce resource for Rooks breeding in open grassland habitats of Hungary. Here we show that Rooks willingly utilize large quantities of provided excess nesting material, and that this procedure may alter nest composition, and increase the number of successful pairs. Our results show that while nest height remains constant, twig diameter is significantly larger, the number of twigs used per nest is presumably smaller, and that the ratio of nests with fledglings is higher in a rookery where supplementary twigs were present. Providing twigs and branches in the vicinity of rookeries may serve as an active conservation measure to increase the number of nests in a rookery, and thus the potential number of nesting possibilities for Red-footed Falcons.

Flower colours in temperate forest and grassland habitats: a comparative study

Flower colours are important cues shaping the interaction between plants and pollinators. Plants flowering in distinct habitats like grasslands and forests present their flowers in very different light environments and against different backgrounds. Since most Angiosperms depend on or profit from pollination by animals, plants may exhibit flower colours that are most conspicuous when seen in the predominant illumination or against the predominant background colour of their environment. To compare flower colours of different habitats, we collected flower reflectance spectra of 239 herbs from forest and grassland sites in three German regions. We compared chromatic and achromatic components of flower colours from the honeybee’s point of view as well as in principal component analysis (PCA) to exclude the bias of particular visual systems. Our results show that flower colours do not differ between closed forest and open grassland habitats in any chromatic or achromatic aspect both from the bee’s perspective and without any model bias (PCA). Thus, although the colours of lights and backgrounds are different between both types of habitats, we find no evidence of an adaptation of flower colours to the visual system of bees. The finding that flower colours look similar for bees in different environments may be related to a mechanism called colour constancy which allows bees and other pollinator species to compensate for varying illumination conditions.

Calidad térmica a través de un gradiente altitudinal para una comunidad de lagartijas en la sierra del Ajusco y el Pedregal de San Ángel, México

We evaluated and compared the thermal quality for a lizard community (9 species) in Sierra del Ajusco and Pedregal de San Ángel (central Mexico) along an altitudinal gradient (2 320-3 530 m) to determine whether different thermal environments may be influencing species distribution and thermoregulatory behavior. Six areas that differ in elevation and vegetation type are chosen to survey environmental operative temperatures. Habitat thermal quality is estimated from the mean deviation of operative temperatures from lizards’ selected thermal range. Results indicate 3 key findings: 1) operative temperature and thermal quality are higher at lower elevations (2 320 and 2 540 m), where xeric scrub vegetation was abundant; 2) thermal quality is lowest in closed-canopy pine forest (2 870 and 3 220 m); and 3) intermediate values of operative temperature and thermal quality are observed in open grassland habitat (3 000 and 3 530 m). These results support our hypothesis that elevation and vegetation type affect thermal quality and we conclude that thermal ecology studies should be conducted at multiple spatial scales to gain a better understanding of factors influencing the thermal niche and thermoregulatory profiles.

Does habitat heterogeneity in a multi-use landscape influence survival rates and density of a native mesocarnivore?

The relationships between predators, prey, and habitat have long been of interest to applied and basic ecologists. As a native Great Plains mesocarnivore of North America, swift foxes (Vulpes velox) depended on the historic disturbance regime to maintain open grassland habitat. With a decline in native grasslands and subsequent impacts to prairie specialists, notably the swift fox, understanding the influence of habitat on native predators is paramount to future management efforts. From 2001 to 2004, we investigated the influence of vegetation structure on swift fox population ecology (survival and density) on and around the Piñon Canyon Maneuver Site, southeastern Colorado, USA. We monitored 109 foxes on 6 study sites exposed to 3 different disturbance regimes (military training, grazing, unused). On each site we evaluated vegetation structure based on shrub density, basal coverage, vegetation height, and litter. Across all sites, annual fox survival rates ranged from 0.50 to 0.92 for adults and 0.27 to 0.78 for juveniles. Among sites, population estimates ranged from 1 to 7 foxes per 10 km transect. Fox density or survival was not related to the relative abundance of prey. A robust model estimating fox population size and incorporating both shrub density and percent basal cover as explanatory variables far outperformed all other models. Our results supported the idea that, in our region, swift foxes were shortgrass prairie specialists and also indicated a relationship between habitat quality and landscape heterogeneity. We suggest the regulation of swift fox populations may be based on habitat quality through landscape-mediated survival, and managers may effectively use disturbance regimes to create or maintain habitat for this native mesocarnivore.

Sexual reproduction in the phyllodioicous bryophyte Homalothecium lutescens (Hedw.) H.Rob. in relation to habitat age, growth conditions and genetic variation

Sporophyte production and female fertility were investigated in seventeen calcareous grassland demes of the moss Homalothecium lutescens (Hedw.) H.Rob. on the Baltic island of Öland, with the aim of understanding the relationships between sexual reproduction, habitat age, genetic variation and factors related to growth conditions. The overall proportion of fertile female shoots (with perichaetia) was 35%. Fertility status at the level of individual shoots was positively associated with shoot length and density, while within deme fertility was positively associated with bush cover. There was no association between female fertility and habitat age, genetic diversity (HS) or allelic richness. Out of 1344 investigated shoots, only two were normal-sized fertile males. Dwarf males were also extremely rare, and found almost exclusively on shoots with sporophytes. Few sporophytes were observed (in the two demes with highest fertility and bush cover). No relationship between genetic variation and the frequency of sporophytes and males was found. The lack of a relationship between sexual reproduction and genetic variation suggests that sexual reproduction may not occur in the same grassland fragments as the recruitment of new clones (from spores or vegetative fragments). The majority of the dry, open grassland habitats, where H. lutescens is typically found in the study area, appear to be suboptimal for both dwarf males and fertilization. Sexual reproduction is more likely to occur in shaded (although grazed) grassland patches, where moisture levels are likely to be higher and the moss colonies are generally more vigorous.

Phenotypic and transgenerational plasticity promote local adaptation to sun and shade environments

Adaptive plasticity is expected to be important when the grain of environmental variation is encompassed in offspring dispersal distance. We investigated patterns of local adaptation, selection and plasticity in an association of plant morphology with fine-scale habitat shifts from oak canopy understory to adjacent grassland habitat in Claytonia perfoliata. Populations from beneath the canopy of oak trees were >90 % broad leaved and large seeded, while plants from adjacent grassland habitat were >90 % linear-leaved and small seeded. In a 2-year study, we used reciprocal transplants and phenotypic selection analysis to investigate local adaptation, selection, plasticity and maternal effects in this trait-environment association. Transgenerational effects were studied by planting offspring of inbred maternal families grown in both environments across the same environments in the second year. Reciprocal transplants revealed local adaptation to habitat type: broad-leaved forms had higher fitness in oak understory and linear-leaved plants had higher fitness in open grassland habitat. Phenotypic selection analyses indicated selection for narrower leaves and lower SLA in open habitat, and selection for broad leaves and intermediate values of SLA in understory. Both plant morphs exhibited plastic responses in traits in the same direction as selection on traits (narrower leaves and lower SLA in open habitat) suggesting that plasticity is adaptive. We detected an adaptive transgenerational effect in which maternal environment influenced offspring fitness; offspring of grassland-reared plants had higher fitness than understory-reared plants when grown in grassland. We did not detect costs of plasticity, but did find a positive association between leaf shape plasticity and fitness in linear-leaved plants in grassland habitat. Together, these findings indicate that fixed differences in trait values corresponding to selection across habitat contribute to local adaptation, but that plasticity and maternal environmental effects may be favored through promotion of survival across heterogeneous environments.

Collembolan response to red mud pollution in Western Hungary

Effects of red mud pollution on the community structure of Collembola were studied in soils from open grassland and forest habitats following the red mud disaster in Western Hungary. Nearby unpolluted control plots of each habitat types were selected for comparative purposes. Analyses revealed that soil became strongly alkaline and, even nine months after the disaster, pH exceeded a value of 9.0 in the polluted forests. Water soluble Na content found to be 50–160 times greater in the polluted area, and total content of metals (e.g. Fe, Al, Mn, Zn, As, Cr, Cu, Ni, Pb, Zn) also increased considerably. Nevertheless, owing to the high alkalinity and red mud's adsorption capacity, bioavailable forms of heavy metals were lower in comparison to the acid control soils. Collembola species richness was about the same in the polluted and control forests (31 and 32, respectively), but lower in the polluted meadows compared to the control plots (21 and 27, respectively). Total community abundance changed differently in the open habitat and in the forest. Its value dropped by 45% in the polluted meadows, while almost tripled in the polluted forests. Changes in the abundance of individual species involved both decrease/elimination of sensitive species (e.g. Isotomiella minor, Sminthurinus aureus) and displacement of species tolerant to pollution (e.g. Micranurida pygmaea) into higher abundance classes. Certain species (e.g. Folsomia manolachei, Sphaeridia pumilis), following the pollution, showed a reverse pattern of abundance in the two habitat types; increasing in the forest while decreasing in the meadow. This study has suggested that soil alkalinity and salt (Na) toxicity were presumably the two most important factors determining the structure of Collembola communities in the area affected by red mud pollution. Despite the high toxicity risk associated with this accident, no adverse effect has been observed in Collembola abundance. Nevertheless, as a consequence of soil re-acidification, re-mobilisation of fixed metals may occur in the long term, constituting to a potential risk to soil Collembola.

English

A study on the distribution, abundance and population status of Burchell’s zebra (Equus quagga, Gray 1824) was carried out in the Yabello Wildlife Sanctuary, Southern Ethiopia from October, 2009 to March, 2010 including wet and dry seasons. Distance sampling line-transect counting method was used to estimate the population status. A total of 5151 individuals were estimated with a population density of 6.5 km2. The population was female biased. The sex ratio of adult male to adult female was 1.0:1.27 and adult to young ratio was 2.9:0.6. Age composition of Burchell’s zebra comprised 78.2% adult, 13.0% sub-adult, 5.3% juvenile and 3.5% foal. Group size changed seasonally and the mean group size was 12.5. The average herd sizes of one male harem and bachelor stallion herds were 7.8 and 5.3, respectively. Distribution and vegetation utilization of the animal showed a marked preference for open grassland habitat. However, there was a seasonal change in the preference of habitat. Increase in human and livestock population was observed in the study area. Overgrazing by cattle and encroachment are the primary factors that affect the population status of Burchell’s zebra by reducing the grass quality in the Sanctuary. The study recommends an effective and realistic management policy to control illegal human settlement and encroachment in the sanctuary.   Key words: Abundance, distribution, Equus quagga, Oromia, population size, Yabello sanctuary.

The Diet of Ryukyu Scops OwlOtus Elegans InterpositusOwlets on Minami-Daito Island

Abstract We identified the diet of owlets of the Daito subspecies of the Ryukyu Scops Owl Otus elegans interpositus on Minami-daito Island during late May and early June 2009, by means of high-resolution color photography. Cockroaches were provided by parents to their young at all eight nests studied, and contributed the largest single component of the diet (33%). Orthoptera species, which inhabited open grassland habitats, constituted >20% of the total occurrences in the diet of owlets. It is suggested that Ryukyu Scops Owls depend heavily on food items obtained from habitats that have been modified by human activity on Minami-daito Island. Diets for owlets differed widely among nests, and the differences were considered to result from individual differences among parents and/or the environments surrounding each nest.

Dental remains of immature individuals of Rhynchotherium blicki (Frick 1933) of San Gerardo de Limoncito, Coto Brus, Costa Rica

Remains of juvenile individuals of Rhynchotherium blicki (Frick 1933) mastodon have been collected from sediments of the Upper Miocene (Late Hemphillian) locality of San Gerardo de Limoncito, corresponding with the top of Curré Formation. The recovered material, includes two second left upper deciduous molars and three frag- ments of tusks that were associated to the false gavial Gavialosuchus americanus (Sellards, 1915), remains of a soft shelled turtle Apalone sp., teeth of selachians (sharks and rays) and other icthyolites. The ecological requirements of the taxa suggest the existence of different environmental conditions from open grassland habitats to more closed marine environments like estuaries.

A new genus and species of Euptychiina (Lepidoptera: Nymphalidae: Satyrinae) from southern Brazil

This paper describes a new genus and a new species of Euptychiina from open grassland habitats (campos de cima da serra) in southern Brazil. The systematic position of this new taxon is discussed based on morphological and molecular data, and it is considered sister to Taydebis Freitas. Since the campos vegetation is considered endangered due to anthropogenic activities, this butterfly species deserves attention and should be included in future conservation plans for this biome.

Resource partitioning between sympatric columbian white‐tailed and black‐tailed deer in western Oregon

AbstractWe studied resource partitioning between sympatric populations of Columbian white‐tailed (CWTD; Odocoileus virginianus leucurus) and black‐tailed (BWTD) deer (O. odocoileus hemionus columbianus) in western Oregon to understand potential mechanisms of coexistence. We used horseback transects to describe spatial distributions, population overlap, and habitat use for both species, and we studied diets with microhistological analysis of fecal samples. Distribution patterns indicated that white‐tailed and black‐tailed deer maintained spatial separation during most seasons with spatial overlap ranging from 5%–40% seasonally. Coefficients of species association were negative, suggesting a pattern of mutual avoidance. White‐tailed deer were more concentrated in the southern portions of the study area, which was characterized by lower elevations, more gradual slopes, and close proximity to streams. Black‐tailed deer were more wide ranging and tended to occur in the northern portions of the study area, which had higher elevations and greater topographical variation. Habitat use of different vegetative assemblages was similar between white‐tailed and black‐tailed deer with overlap ranging from 89%–96% seasonally. White‐tailed deer used nearly all habitats available on the study area except those associated with conifers. White‐tailed deer used oak‐hardwood savanna shrub, open grassland, oak‐hardwood savanna, and riparian habitats the most. Black‐tailed deer exhibited high use for open grassland and oak‐hardwood savanna shrub habitats and lower use of all others. The 2 subspecies also exhibited strong seasonal similarities in diets with overlap ranging from 89% to 95%. White‐tailed deer diets were dominated by forbs, shrubs, grasses, and other food sources (e.g., nuts and lichens). Columbian black‐tailed deer diets were dominated mostly by forbs and other food sources. Seasonal diet diversity followed similar patterns for both species with the most diverse diets occurring in fall and the least diverse diets in spring. High overlap in habitat use and diets resulted in high trophic overlap (81–85%) between white‐tailed and black‐tailed deer; however, the low spatial overlap reduced the potential for exploitative competition but may have been indicative of inference competition between the species. Diverse habitat and forage opportunities were available on the study area due to heterogeneous landscape characteristics, which allowed ecological separation between white‐tailed and black‐tailed deer despite similarities in diets and habitat use. We make several recommendations for management of CWTD, a previously threatened species, based on the results of our study. © 2011 The Wildlife Society.

Nesting status of African White-backed Vultures Gyps africanus in the Masai Mara National Reserve, Kenya

Vulture populations have declined globally as well as regionally within Africa. Little is known about the status of the African White-backed Vulture Gyps africanus in Kenya, but ongoing studies indicate that its population has declined over the last two decades. A total of 32 African White-backed Vulture nests were monitored in the Masai Mara National Reserve over a five-year period between 2003 and 2007. Mean nesting success was 59%, which is comparable to that of populations from southern Africa. Nearest neighbour distances were significantly closer in wooded habitats (‘trees and shrubs savanna’) than in more open grassland habitats (‘open low shrubs’). Based on nearest neighbour distances, the estimated total breeding population within the Masai Mara National Reserve is 1 106 pairs, a figure that may be an overestimate and requires ground-truthing. Collecting baseline data on numbers of breeding pairs and regular nest monitoring are essential in order to assess the impact of various threats to vultures in Kenya, which include growing threats (elephant-mediated habitat disturbance and fire) as well as emerging threats (such as poisoning with the carbamate-based pesticide Furadan™).

Reptilia, Squamata, Dipsadidae, Tomodon orestes Harvey and Muñoz, 2004: distribution extension, new country record

We report the first record of Tomodon orestes Harvey and Muñoz, 2004 for Argentina. An adult male was collected in November 2008 in an open grassland habitat in the locality of Vallecito, Santa Victoria department, Salta province, Argentina. This new record is the southernmost locality for the species extending its distribution range ca. 95 km straight-line south from type locality.

Explaining patterns in modern ruminant diversity: contingency or constraint?

Bovid species outnumber those of cervids by over two and half to one. The present study attempts to explain this difference using two principle concepts: contingency and constraint. The concept of contingency considers the role of biogeography and the distributions and timings of major dispersals seen in the two families. Although this historical context is considered vital for understanding the problem, cervids are also characterized by their global absence from open and arid grassland habitats. This is explained in terms of phylogenetic constraint. One proposal considers the deciduous antlers of cervids as constraining the group to higher quality forage that is not generally associated with open habitats. Alternatively and more generally applicable to all ruminants is the ‘cusp fusion hypothesis’, presented here for the first time. The hypothesis seeks to explain how the primitive ruminant molar state, as seen in modern cervids and giraffids, prevents the attainment of very high molar crowns and, with it, the ability to cope with high rates of dietary tooth wear. Conversely, the derived condition of precocial cusp fusion seen in the Bovidae and Antilocapridae has enabled higher tooth crowns, their expansion into open habitats, and an increased diversity potential. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 657–672.