The effects of human visits on the use of a waterhole by endangered ungulates

We report the impacts of human visits at a waterhole used by mountain gazelles, Gazella gazella, and Nubian ibex, Capra ibex nubiana, in the Ibex Reserve of Saudi Arabia. Our hypothesis was that the species that normally used the waterhole during the day, the typical period of human visits, would be negatively affected. The results did not support our hypothesis, as both the diurnal mountain gazelles and partly nocturnal Nubian ibex avoided the waterhole within 6 h after human visits. We found no significant difference of waterhole use by Nubian ibex and mountain gazelles within the period of 6–12 h or 12–24 h after human visits. Given the high conservation concern of these species and the rarity of waterholes, we suggest that human visits continue to be regulated by allowing visits on non-consecutive days to give the ungulates opportunities to drink, especially during the summer and droughts when heat stresses are higher, animals are less tolerant of water deprivation, and there are less alternative waterholes.     

Effects of interannual variations in environmental conditions on seasonal range selection by Mongolian gazelles

To examine the effects of interannual variations in environmental conditions on the seasonal range selection and movement pattern of Mongolian gazelles Procapra gutturosa, we compared the summer and winter ranges of satellite tracked gazelles among 3 years, and we analyzed the environmental conditions in the gazelles' seasonal ranges by using a satellite-derived normalized difference vegetation index (NDVI). The movement pattern of the tracked Mongolian gazelles was not regular migration between specific seasonal ranges. The locations of the summer ranges in 2003 and 2004 were similar for all gazelles, but in 2005, when the NDVI values were lower, the animals ranged about 30–70 km farther north, suggesting that the gazelles used areas of similar vegetation availability with former 2 years. The winter ranges were widely separated among years; the longest distance between winter ranges of the same individual in different years was about 340 km. During winter, the NDVI values of the winter ranges of tracked gazelles were almost always higher than or not significantly different from the mean of the 3-year range. Conservation strategies to allow access to wide ranges containing suitable areas in each year for gazelles, which location is changing interannually, are important.     

Habitat preference of reintroduced dorcas gazelles (Gazella dorcas neglecta) in North Ferlo,Senegal

In March 2009, 23 dorcas gazelles (9 males and 14 females) were reintroduced in the Katané enclosure, a 440 ha fenced-in area in the North Ferlo Fauna Reserve (Senegal). In the enclosure, the dorcas gazelle live with other reintroduced (the mohor gazelles and the scimitar-horned oryx) and native ungulate species (the Red-fronted gazelle), as well other native mammals. Seven habitat types were characterized in the enclosure. Habitat preference of dorcas gazelles was studied using presence and abundance of gazelle signs (tracks, latrines, fecal deposits) and direct observations. Seasonal data were collected along a 6-km long transect in the enclosure. The presence of dorcas gazelles is significantly dependent on the type of habitat in the Katané enclosure and they prefer open habitats (plateaus) to habitats with less visibility. This preference did not change according to season and the number of fecal deposits increased with proximity to the fence.     

Feeding ecology of the Asiatic cheetah Acinonyx jubatus venaticus in low prey habitats in northeastern Iran: Implications for effective conservation

Feeding ecology of the critically endangered Asiatic cheetah was investigated from 2004 to 2009 in northeastern Iran where prey population has been depleted due to poaching. The survey was mainly based on scat analysis, complemented by kill monitoring and local inquiries of direct observations. Results of the research revealed that the Asiatic cheetahs mainly rely on medium-sized ungulates. However, with respect to low density of gazelles, they catch a considerable proportion of their food demands based on livestock which brings the cheetahs in direct conflict with local people. Meanwhile, smaller mammals only meet a small proportion of cheetah's diet. Our data indicate high importance of enhancing conservation efforts in northeastern Iran as well as other cheetah habitats where normal prey ungulates have experienced severe decline.     

Demographic variation in a desert shrub, Larrea tridentate, in response to a thinning treatment

We performed a perturbation experiment to determine the relative importance of intra-specific competition on the demographic performance of a population of creosotebush, Larrea tridentata. From 1992 to 1995, we followed 1000 individuals, half of which were in plots subjected to a thinning treatment, and the other half were in unmanipulated plots. We found no significant response to the thinning treatment for any of the traits studied. The strict interpretation of these results is that intra-specific competition is not important in this Larrea population.     

Migration Drift

For perhaps the first time since the founding of the United States the net direction of interstate migration was to the east rather than the west for the period 1992–1993 through 1994–1995. This and other findings, such as a general slowdown in the southward tendency of U.S. population movement over the period 1980–1981 to 1994–1995, are highlighted using the concept of migration drift. I propose the migration drift measure to summarize the net directionality and distance moved by migrants in any country's population system. Like the concept of a center of population or a population centroid, migration drift is an intuitive one. Unlike the population centroid, however, migration drift summarizes the pure effects of population movement without confounding those influences with spatial variations in birth, death, and net foreign immigration rates.     

The recent expansion of an avian invasive species (the Cattle Egret Ardea ibis) in Algeria

This study identifies new information on the recent distribution of an invasive bird species, the Cattle Egret Ardea ibis, in Algeria. Breeding and wintering distributions as well as breeding numbers were obtained from large-scale surveys in 1999 and 2007, and from historical data. Between 1999 and 2007, the total number of colonies found increased from 51 to 87, and most were located in the northern part of the country. The breeding distribution area, confined to the coastal areas in the 1970s, has shifted further south, and reached the northern part of the Sahara since the 2000s. Most colonies were established during the period 1980-1995. The oldest colonies were generally larger than the recent ones. The number of colonies increased by 83% between 1999 and 2007 in the 12 administrative units (wilayas) surveyed. The number of breeding pairs increased from 7765 in 1999 to 28544 in 2007, corresponding to an annual population growth rate of 17.7%. The changes in distribution and population dynamics since the 1970s and the potential factors affecting these changes are discussed.     

Seed bank dynamics in a Great Basin salt playa

Salt playa are common in the Great Basin area with halophytes as the dominant flora. The relationship between the seed bank flora and existing vegetation was studied. The seed bank flora showed a high degree of similarity with that of perennial and annual halophytic vegetation. Both above and below ground components of the community are dominated by halophyte species like Allenrolfea occidentalis, Holosteum umbellatum, Salicornia rubra and Salicornia utahensis. Seasonal variation in the seed bank was also studied for the 1995–1996 and 1996–1997 growing seasons. The seeds of A. occidentalis persist in the soil of the upper zone in large densities. Salicornia utahensis was much higher in the upper zone throughout the study period. Most species demonstrated the persistent nature of the seed banks with their numbers increasing after seed dispersal and decreasing in subsequent months. The variation illustrates the transient nature of the seed bank. We concluded that A. occidentalis is more dependent on a large seed bank for maintaining its population than the two annual halophytes. The significance of the seed bank and their variation due to environmental conditions for perennial and annual species of the Great Basin salt playa community is discussed.     

基于生态足迹的区域生态适度人口研究——以新疆生产建设兵团为例

适度人口取决于生态、经济和土地等多要素的综合承载力。介绍了生态足迹模型的基本概念和计算方法,并运用该模型对兵团1995—2008年的生态足迹和生态承载力进行了计算,在此基础上对兵团的1995—2010年的生态适度人口进行了估算。结果表明,1995—1999年兵团的实际人口虽然在增加,但相对于生态适度人口并没有出现过剩;2000—2010年兵团生态适度人口在不断下降,实际人口和过剩人口却在不断增加。兵团目前已经出现了过度人口和生态赤字,人地矛盾相对紧张,生态适度人口规模是不合理的。     

和田地区人口与经济发展时空演变与分布差异研究

以和田地区七县一市作为研究基本单元,根据1995-2014 年人口、GDP和人均GDP面板数据分析了其人口与经济发展演变特征,通过人口经济一致性指数、偏离度指数和Pearson 相关系数探讨了和田地区人口经济分布的差异性,研究发现：近20 a 来和田地区人口和经济快速增长,各县市人口数量和经济发展差异很大;人口集聚与经济集聚水平差异较大并呈现扩大趋势,总体上东部地区人口集聚低于经济集聚,中部地区人口经济集聚基本一致,西部地区人口集聚高于经济集聚;人口分布与经济发展空间一致性总体呈变弱的趋势,人口经济分布差异的变大与地区经济差距的变大有非常高的相关性;地区的自然环境条件和社会经济发展条件是造成和田人口和经济分布差异性的主要原因。     

Dendrochronology in Jordan

Dendrochronology is a valuable tool for the study of past climate and increases our knowledge of climate variability beyond the short period covered by instrumental data. Two annual tree-ring width chronologies were developed for northern Jordan (Pinus halepensis and Quercus aegilops), one chronology for Carmel Mountain, Israel (Pinus halepensis), and one chronology for southern Jordan (Juniperus phoenicia). The results of our study show that the northern site chronologies are significantly correlated, but the northern and southern sites are not. A relatively high correlation was shown between October–April precipitation and a Pinus halepensis chronology, and between October–May precipitation and Quercus aegilops, both in the north. October–May precipitation was reconstructed for the time span AD 1600 to 1995 from the Juniperus phoenicia tree-ring chronology. The longest reconstructed drought, defined as consecutive years below a threshold of 80% of the 1946–1995 mean observed October–May precipitation, was 4 years, compared with 3 years for the 1946–95 instrumental data.     

Terrestrial Laser Scanning of grain roughness in a gravel-bed river

This paper demonstrates the application of Terrestrial Laser Scanning (TLS) to determine the full population of grain roughness in gravel-bed rivers. The technique has the potential to completely replace the need for complex, time-consuming manual sampling methods. Using TLS, a total of 3.8 million data points (mean spacing 0.01 m) were retrieved from a gravel bar surface at Lambley on the River South Tyne, UK. Grain roughness was extracted through determination of twice the local standard deviation (2σ_z) of all the elevations in a 0.15 m radius moving window over the data cloud. 2σ_z values were then designated to each node on a 5 cm regular grid, allowing fine resolution DEMs to be produced, where the elevation is equivalent to the grain roughness height. Comparisons are made between TLS-derived grain roughness and grid-by-number sampling for eight 2 m² patches on the bar surface. Strong relationships exist between percentiles from the population of 2σ_z heights with measured a-, b-, and c-axes, with the closest matches appearing for the c-axis. Although strong relationships exist between TLS-derived grain roughness (2σ_z), variations in the degree of burial, packing and imbrication, results in very different slope and intercept exponents. This highlights that conventional roughness measurement using gravel axis length should be used with caution as measured axes do not necessarily represent the actual extent to which the grain protrudes into the flow. The sampling error inherent in conventional sampling is also highlighted through undertaking Monte Carlo simulation on a population of 2000 clasts measured using the grid-by-number method and comparing this with the TLS-derived population of grain roughness heights. Underestimates of up to − 23% and overestimates of up to + 50% were found to occur when considering the D₈₄, and − 20% and overestimates of up to + 36% were found to occur when considering the D_50.     

Historical genetics on a sediment core from a Kenyan lake: intraspecific genotype turnover in a tropical rotifer is related to past environmental changes

Using molecular genetic methods and an ancient DNA approach, we studied population and species succession of rotifers of the genus Brachionus in the Kenyan alkaline-saline crater lake Sonachi since the beginning of the 19th century as well as distribution of Brachionus haplotypes in recent and historic sediments of other lakes of the East African Rift System. The sediment core record of Lake Sonachi displays haplotypes of a distinct evolutionary lineage in all increments. Populations were dominated by a single mitochondrial haplotype for a period of 150 years, and two putatively intraspecific turnovers in dominance occurred. Both changes are concordant with major environmental perturbations documented by a profound visible change in sediment composition of the core. The first change was very abrupt and occurred after the deposition of volcanic ash at the beginning of the 19th century. The second change coincides with a major lake level lowstand during the 1940s. It was preceded by a period of successively declining lake level, in which two other haplotypes appeared in the lake. One of these putatively belongs to another species documented in historical and recent Kenyan lake sediments. The analysis of plankton population dynamics through historical time can reveal patterns of population persistence and turnover in relation to environmental changes.     

Seasonal fluctuations in the plankton community in a hypersaline temporary lake (Honda, southern Spain)

Honda saline lake is located in an endorheic basin in the south of Spain. The lake is very shallow, with frequent seasonal drought and a high degree of unpredictability. It was sampled monthly during a relatively dry year (1994–1995, 5 months permanence). To establish a relationship between environmental variables (temperature, depth, salinity and conductivity), variables related to biological activity (organic matter, total solids suspension, and pH) and the planktonic community in the sampled months, various uni-and miltivariate statistical methods were carried out.Dunaliella salina, D. viridis, and ciliates sp. 2 is the principal species group used to average out the dissimilarity between the samples. Muttivariate analysis showed that salinity (as TDS), conductivity and pH made major and significant contributions to the explanation of the variance in the sample data.     

Local government perspectives on rural retirement migration and social sustainability

Within the policy and academic literature, the impact of rural retirement migration (RRM) on community sustainability has been questioned. This qualitative study investigated the perceived impact of retirement migration on rural social sustainability from a local government perspective. Focus groups were conducted with local government senior managers and community services staff (n = 39) across six rural local government areas in one Australian state. Data were analysed against the three components of rural social sustainability (equity, community and rurality) proposed by Jones and Tonts [1995. “Rural Restructuring and Social Sustainability: Some Reflections on the Western Australian Wheatbelt.” Australian Geographer 26: 133–140]. While RRM is perceived to benefit rural community capacity to facilitate or maintain equity, community and rurality, it also presents challenges for local government. Participants suggested that capacity to facilitate equity, community and rurality in contexts of RRM was impacted by uncertainty around future impacts of RRM on population ageing, increasing advocacy and expectations of older in-migrants, and the impact of RRM on rural heterogeneity. These issues required local governments to think critically about how to accommodate and manage the needs and expectations of older in-migrants, while mediating potential impacts associated with RRM.     

Mongolian gerbils and Daurian pikas responded differently to changes in precipitation in the Inner Mongolian grasslands

Mongolian gerbils (Meriones unguiculatus) and Daurian pikas (Ochotona dauurica) are two key small mammal species in the Inner Mongolian grasslands, China. Mongolian gerbils displayed density-dependent population growth, but the time lag of density dependence was short and within season. The spring–autumn population growth rate was inversely related to population density in Mongolian gerbils of the Erdos desert grasslands. The autumn–spring population growth rate of Mongolian gerbils was inversely related to winter precipitation. Precipitation had stronger effects on the population growth of gerbils during the non-breeding season. The monthly population growth rate of Daurian pikas was positively related to the monthly precipitation and was inversely related to population density in central Inner Mongolia. Daurian pikas select habitats with tall plants. Increased precipitation enhances plant production and increases the height of plants in arid and semi-arid regions. This enhancement of plant height might increase the population growth of Daurian pikas. Mongolian gerbils live in short grasslands. Increased winter precipitation might result in higher winter mortality of Mongolia gerbils, or taller plants might supress gerbil population growth in wet years. Therefore, responses of small mammal species to changes in precipitation depend on the life history of small mammals and changes in vegetation induced by climatic changes.     

The role of dew as a moisture source for sand microbiotic crusts in the Negev Desert, Israel

Dew and fog were measured periodically during the years 1992–1995 at the Hallamish dune field, western Negev Desert (average annual rain precipitation ca. 95 mm). A major portion of the dunes are covered by cyanobacterial and moss-dominated microbiotic crusts. Chlorophyll- a measurements and microscopic examination were carried out in order to detect the possible changes in crust biomass and phenological changes of the mosses following the occurrence of dew and fog. Dew and/or fog were present in over 50% of the late summer and fall mornings with an average yield of 0·1 mm on cloth attached to glass plates. This corresponds to ca. 0·03 mm for the upper 0·5 cm of the crust, and is less than the 0·1 mm threshold which implies liquid water and which was also found necessary for net photosynthesis of the cyanobacterial crust. This threshold was met only during heavy dew or fog events, during which 10–40% of the crust surface area was moistened. It was estimated that dew and fog could account for upto 3·2–9·4% of the total annual time of crust wetness and consequently activity due to liquid water. Nevertheless, microscopic examination of the dominant moss species at Nizzana, Bryum dunense, disclosed phenological changes, mainly resulting in growth of vegetative reproduction organs (bulbils), and sexual organs, gametangia (antheridia and archegonia). B.dunense may thus be adapted to the utilization of dew and fog precipitation for the production of nearly mature sexual organs. The moss may thus be capable of already utilizing the first winter rains for fertilization and sporophyte formation.     

<Emphasis Type="Italic">Salvinia natans</Emphasis> in medieval wetland deposits in Gdańsk,northern Poland: evidence for the early medieval climate warming

Large numbers of sub-fossil remains of the aquatic fern Salvinia natans (L.) All. have been found in several early medieval sites in Gdańsk, N. Poland. This record indicates a population expansion of this species around 7th–8th century A.D., similar to the recently observed rapid spread and high population dynamics of S. natans in northern Poland, which recent studies have attributed to climate warming. Our results suggest that in the Vistula deltaic area the S. natans expansion in the Early Middle Ages (7th–8th century A.D.) was similarly stimulated by climate warming, while its subsequent decline was mainly due to climate cooling, especially during the Little Ice Age. Warmer winters and springs and a longer growing season seem to be the most important factors forcing the expansion of S. natans in medieval times. According to our data, the co-occurrence of S. natans with other aquatic plant species was similar in both the medieval and present-day vegetation. Also, the high density of S. natans in the medieval population caused impoverishment of the local ecosystems in a way that has been observed in recent water bodies affected by invasive pleustophytes (free-floating plants).     

The spatial patterns and determinants of internal migration of older adults in China from 1995 to 2015

Although China was one of the countries with the fastest-growing aging population in the world, limited scholarly attention has been paid to migration among older adults in China. The full picture of their migration in the entire country over time remains unknown. This study examines the spatial patterns of older interprovincial migration flows and their drivers in China over the period 1995 to 2015, using four waves of census data and intercensal population sample survey data. Results from eigenvector spatial filtering negative binomial regressions indicate that older adults tend to migrate away from low cost-of-living rural areas to high cost-of-living urban and rural areas, moving away from areas with extreme temperature differences. The location of their grandchildren is among the most important attractions. Our findings suggest that family-oriented migration is more common than amenity-led migration among retired Chinese older adults, and the cost-of-living is an indicator of economic opportunities for adult children and the quality of senior care services.     

Differential responses of zooplankton populations (Bosmina longirostris) to fish predation and nutrient-loading in an introduced and a natural sockeye salmon nursery lake on Kodiak Island, Alaska, USA

Stratigraphic changes in the remains of Bosmina longirostris from a lake with an introduced sockeye salmon population and a lake with a natural salmon run on Kodiak Island demonstrated markedly different responses to past fluctuations in salmon populations. In both lakes, there was a positive correlation between the density of Bosmina microfossils and the abundance of sockeye salmon. However, opposite size trends were observed in the two lakes. In Karluk Lake, which has a native sockeye salmon population, Bosmina mean carapace lengths were largest at high salmon densities, and mean mucro and antennule lengths were also large, suggesting strong predation pressure from cyclopoid copepods, and less intense pressure from juvenile sockeye salmon. As salmon-derived nutrients are important in driving primary productivity in this system, changes in zooplankton productivity track salmon escapement, but grazing pressure on Bosmina from juvenile salmon is less important than that from cyclopoid copepods. In Frazer Lake, a lake with an introduced salmon population, Bosmina morphologies were smallest during periods of high sockeye salmon in the lake, suggesting much stronger predation effects from sockeye salmon due to the suppression of Cyclops columbianus. Latent development of compensatory mechanisms and the delayed recovery of copepod populations to salmon introductions has resulted in zooplankton populations that are still recovering from shifts in fish populations that occurred decades earlier. The differential response of Bosmina populations between the natural and manipulated lakes suggests that care must be taken when attempting to extrapolate results from whole-lake manipulations and short-term experiments to natural systems.