Effects of Different Population Densities on Yield and Agronomic Characteristics of Mung Bean

With the methods of crop population physiology,the effects of different population densities on growth,development and yield of mung bean as well as the relationship between these indexes and density were studied.The results showed that the morphology indexes of mung bean plant changed significantly with planting density increasing：the plant height showed increasing trend,while the stem diameter of the basal intemode were gradually decreased.And these two indexes were sensitive to the density.The effects of planting densities on valid branch number and the height of the first branch had reached significant level.In the yield components,the effects of planting densities on the pod number per plant,the grain weight per plant and the hundred grain weight had achieved significant level.

An Enhanced Multiview Transformer for Population Density Estimation Using Cellular Mobility Data in Smart City

This paper addresses the problem of predicting population density leveraging cellular station data.As wireless communication devices are commonly used,cellular station data has become integral for estimating population figures and studying their movement,thereby implying significant contributions to urban planning.However,existing research grapples with issues pertinent to preprocessing base station data and the modeling of population prediction.To address this,we propose methodologies for preprocessing cellular station data to eliminate any irregular or redundant data.The preprocessing reveals a distinct cyclical characteristic and high-frequency variation in population shift.Further,we devise a multi-view enhancement model grounded on the Transformer(MVformer),targeting the improvement of the accuracy of extended time-series population predictions.Comparative experiments,conducted on the above-mentioned population dataset using four alternate Transformer-based models,indicate that our proposedMVformer model enhances prediction accuracy by approximately 30%for both univariate and multivariate time-series prediction assignments.The performance of this model in tasks pertaining to population prediction exhibits commendable results.

Classification of densities and characteristics of curve of population centers in China by GIS

In this paper, with the spatial analysis functions in ArcGIS and the county-level census data of 2000 in China, the population density map was divided and shown by classes, meanwhile, the map system of population distribution and a curve of population centers were formed; in accordance with the geographical proximity principle, the classes of population densities were reclassified and a population density map was obtained which had the spatial clustering characteristic. The multi-layer superposition based on the population density classification shows that the population densities become denser from the Northwest to the Southeast; the multi-layer clustering phenomenon of the Chinese population distribution is obvious, the populations have a water-based characteristic gathering towards the rivers and coastlines. The curve of population centers shows the population densities transit from the high density region to the low one on the whole, while in low-density areas there are relatively dense areas, and in high-density areas there are relatively sparse areas. The reclassification research on the population density map based on the curve of population centers shows that the Chinese population densities can be divided into 9 classes, hereby, the geographical distribution of Chinese population can be divided into 9 type regions： the concentration core zone, high concentration zone, moderate concentration zone, low concentration zone, general transitional zone, relatively sparse area, absolute sparse area, extreme sparse area, and basic no-man＇s land. More than 3/4 of the population of China is concentrated in less than 1/5 of the land area, and more than half of the land area is inhabited by less than 2% of the population, the result reveals a better space law of China＇s population distribution.

Effects of mepiquat chloride and plant population density on leaf photosynthesis and carbohydrate metabolism in upland cotton

Background Mepiquat chloride(MC)application and plant population density(PPD)increasing are required for modern cotton production.However,their interactive effects on leaf physiology and carbohydrate metabolism remain obscure.This study aimed to examine whether and how MC and PPD affect the leaf morpho-physiological characteristics,and thus final cotton yield.PPD of three levels(D1:2.25 plants·m^(-2),D2:4.5 plants·m^(-2),and D3:6.75 plants·m^(-2))and MC dosage of two levels(MC0:0 g·ha^(-2),MC1:82.5 g·ha^(-2))were combined to create six treatments.The dynamics of nonstructual carbohydrate concentration,carbon metabolism-related enzyme activity,and photosynthetic attributes in cotton leaves were examined during reproductive growth in 2019 and 2020.Results Among six treatments,the high PPD of 6.75 plants·m^(-2)combined with MC application(MC1D3)exhibited the greatest seed cotton yield and biological yield.The sucrose,hexose,starch,and total nonstructural carbohydrate(TNC)concentrations peaked at the first flowering(FF)stage and then declined to a minimum at the first boll opening(FBO)stage.Compared with other treatments,MC1D3 improved starch and TNC concentration by 5.4%~88.4%,7.8%~52.0% in 2019,and by 14.6%~55.9%,13.5%~39.7% in 2020 at the FF stage,respectively.Additionally,MC1D3 produced higher transformation rates of starch and TNC from the FF to FBO stages,indicating greater carbon production and utilization efficiency.MC1D3 displayed the maximal specific leaf weight(SLW)at the FBO stage,and the highest chlorophyll a(Chl a),Chl b,and Chl a+b concentration at the mid-late growth phase in both years.The Rubisco activity with MC1D3 was 2.6%~53.2% higher at the flowering and boll setting stages in both years,and 2.4%~52.7% higher at the FBO stage in 2020 than those in other treatments.These results provided a explanation of higher leaf senescence-resistant ability in MC1D3.Conclusion Increasing PPD coupled with MC application improves cotton yield by enhancing leaf carbohydrate production and utilization efficiency and delaying leaf senescence.

Home range,population density,and habitat utilization of the Sichuan Jay (Perisoreus internigrans)

We assessed habitat preference and population status of the Sichuan Jay (Perisoreus internigrans),a poorly known Chinese endemic bird,at two sites (Zhuoni and Jiuzhaigou) in the Qinghai-Tibetan plateau between 2001 and 2004.Mean group size was 3.8 jays.Each group occupied a mean home range of 42.0 ha during the breeding season,and the mean internest distance was 2.7 km.These data indicated that the jays used less than ten percent of the available habitats and occurred at an overall density of only 0.6 jays per km2.Radio-tracked Sichuan Jays had a strong preference for mature montane coniferous forests and avoided areas dominated by shrubs,while the utilization of young conifers,grassland,and human residential habitat types did not differ significantly from the values expected from the home-range availabilities of these habitats generally.

Understanding Urban Vitality from the Economic and Human Activities Perspective:A Case Study of Chongqing,China

The literature on urban vitality tends to focus on the built environment.This paper argues that some important processes in shaping vitality may be overlooked without examining the intensity and diversity of economic and human activities.Using newly developed spatial big data and adopting the methods of multi-indicator measurement and spatial analysis methods,we analyzed the pattern of urban vitality in Chongqing,a provincial city in western China and,on this basis,evaluated the creation and maintenance of urban vitality from the economic and human activities perspective.Our findings indicate that the impacts of economic and human activities are positive and significant.Among the three intensity and diversity indicators,economic intensity and population density show an effect on urban vitality stronger than that of economic diversity.However,economic diversity has the strongest superposition or interactive effect,and is thus an important foundation dynamic.The positive effect of population density on urban vitality is largely a result of Chongqing’s jobs-housing balance.The case of Chongqing highlights the importance of topographic features,historical inheritance,large-scale migration,and cultural activities in shaping the distinctive vitality pattern of a city.This study contends that the creation and maintenance of urban vitality can not be fully explained without incorporating the impacts of economic and human activities.It contributes to a comprehensive measurement of urban vitality and enriches its connotations.

Socio-economic vulnerability level in the Jeneberang watershed in Gowa Regency,South Sulawesi Province,Indonesia

Jeneberang watershed is vital,particularly for people living in Gowa Regency(South Sulawesi Province,Indonesia),who benefit from its many advantages.Landslides and floods occur every year in the Jeneberang watershed,so it is imperative to understand the socio-economic vulnerability of this region.This research aims to identify the vulnerability level of the Jeneberang watershed so that the government can prioritize areas with high vulnerability level and formulate effective strategies to reduce these the vulnerability.Specifically,this study was conducted in 12 districts located in the Jeneberang watershed.The primary data were collected from questionnaires completed by community members,community leaders,and various stakeholders,and the secondary data were from the Landsat satellite imagery in 2020,the Badan Push Statistic of Gowa Regency,and some governmental agencies.The socio-economic vulnerability variables were determined using the Multiple Criteria Decision Analysis(MCDA)method,and each variable was weighted and analyzed using the Geographical Information System(GIS).The study reveals that the levels of socio-economic vulnerability are affected by variables such as population density,vulnerable groups(disabled people,elderly people,and young people),road network and settlement,percentage of poor people,and productive land area in the Jeneberang watershed.Moreover,all of the 12 districts in the Jeneberang watershed are included in the medium vulnerability level,with the mean percentage of socio-economic vulnerability around 50.92%.The socio-economic vulnerability of Bajeng,Pallangga,and Somba Opu districts is categorized at high level,the socio-economic vulnerability of Bungaya,Parangloe,and Tombolo Pao districts is classified as medium level,and the remaining 6 districts(Barombong,Bontolempangan,Bontomarannu,Manuju,Parigi,and Tinggimoncong)are ranked as low socio-economic vulnerability.This study can help policy-makers to formulate strategy that contributes to the protection of biodiversity and sustainable development of the Jeneberang watershed,while improving disaster resilience and preparedness of the watershed.

Himalayan Monal(Lophophorus impejanus):distribution,habitat and population status in Tibet,China

The Himalayan Monal (Lophophorus impejanus) is a national first grade protected species in China.So far,current knowledge of the Himalayan Monal in China is still poor.An estimate of its distribution,numbers and habitat was conducted during a two-year investigation from 2008 to 2009 in southern Tibet,especially in Lhozhag,Cona and Yadong counties.In total,12 sightings of the Himalayan Monal were recorded during the study period.Our data suggest that this bird is mainly found in Medog,Zayu,Cona,Lhunze,Lhozhag,Nyalam,Dingjie,Gamba and Yadong counties on the southern slopes of the Himalayas.Its western-most location was confirmed to be Nyalam County.The bird ranges in elevation from 3800 to 4300 m in the summer and from 3200 to 3500 m in the winter.We sighted 36-37 individual birds,consisting of 8-10 males,16-20 females and 7-8 sub-adults inhabiting the area around the Kajiu Monastery in Lhozhag County.The birds are mainly found in rocky forests,interspersed with steep slopes,cliffs and alpine meadows at elevations between 3800 and 4000 m.The population density of the Himalayan Monal near the Kajiu Monastery is 2.03 individual birds per km2,much larger than that of Yadong and Cona counties (0.052 individuals per krn2).

Dynamical Behaviors of a Modified Leslie-Gower Predator-Prey System with Fear Effect and Prey Refuge

In this paper, the dynamical behaviors of a modified Leslie-Gower predator-prey model incorporating fear effect and prey refuge are investigated. We delve into the construction of the model and its biological significance, with preliminary results encompassing positivity, boundedness, and persistence. The stability of the system’s boundary and positive equilibrium points is proven by calculating the real part of the eigenvalues of the Jacobian matrix. At the positive equilibrium point, we demonstrate that the system’s unique positive equilibrium is globally asymptotically stable by using the Dulac criterion. Furthermore, at this equilibrium point, we employ the Implicit Function Theorem to discuss how fear effects and prey refuges influence the population densities of both prey and predators. Finally, numerical simulations are conducted to validate the above-mentioned conclusions and explored the impact of Predator-taxis sensitivity αon dynamics of the system.

Nutrient deficiency limits population development,yield formation,and nutrient uptake of direct sown winter oilseed rape

Direct-sowing establishment method has great significance in improving winter oilseed rape（Brassica napus L.） production and guaranteeing edible oil security in China. However, nutrient responses on direct sown winter oilseed rape（DOR） performance and population development dynamic are still not well understood. Therefore, five on-farm experiments were conducted in the reaches of the Yangtze River（RYR） to determine the effects of nitrogen（N）, phosphorus（P）, and potassium（K） deficiencies on population density, dry matter production, nutrient uptake, seed yield, and yield components of DOR plants. Four fertilization treatments included the balanced NPK application treatment（NPK, 180 kg N, 39.3 kg P, 100 kg K, and 1.8 kg borax ha–1） and three nutrient deficiency treatments based on the NPK treatment, i.e., –N, –P, and –K. The results indicated that DOR population density declined gradually throughout the growing season, especially at over-wintering and pod-development stages. Nutrient deficiency decreased nutrient concentration in DOR plants, limited dry matter production and nutrient uptake, and thereby exacerbated density reduction during plants growth. The poor individual growth and reduced population density together decreased seed yield in the nutrient deficiency treatment. Averaged across all the experiments, seed yield reduced 61% by N deficiency, 38.3% by P deficiency, and 14.4% by K deficiency. The negative effects of nutrient deficiency on DOR performances followed the order of –N–P–K, and the effects were various among different nutrient deficiencies. Although N deficiency improved DOR emergence, but it seriously limited dry matter production and nutrient uptake, which in turn led to substantial plants death and therefore resulted in a very low harvested density. The P deficiency significantly reduced initial density, limited plants growth, and exacerbated density reduction. The K deficiency mainly decreased individual growth and yield, but did not affect density dynamic. Our results highlighted the importance of balanced NPK application in DOR production, suggesting that management strategy of these nutrients should be comprehensively considered with an aim to build an appropriate population structure with balanced plant density and individual growth.

Relief Degree of Land Surface and Population Distribution of Mountainous Areas in China

Evaluation on the population pressure in the mountainous areas is a necessary condition for the protection and good governance. The evaluation depends on accurate population density assessment. Traditional methods used to calculate population density often adopt the administrative region as a scale for statistical analysis. These methods did not consider the effects of the relief degree of land surface(RDLS) on the population distribution. Therefore they cannot accurately reflect the degree of population aggregation, especially in mountainous areas. To explore this issue further, we took the mountainous areas of China as the research area. China has A total area of 666 km2 can be classified as mountainous area,accounting for 69.4% of the country's total landmass. The data used in this research included the digital elevation model(DEM) of China at a scale of 1:1,000,000, National population density raster data, the DEM and the national population density raster data. First, we determined the relief degree of land surface(RDLS). Next, we conducted a correlation analysis between the population distribution and the RDLS using the Statistical Package for Social Science(SPSS). Based on the correlation analysis results and population distribution, this new method was used to revise the provincial population density of themountainous areas. The revised results were used to determine the population pressure of different mountainous areas. Overall, the following results were obtained:(1) The RDLS was low in most mountainous areas(with a value between 0 and 3.5) and exhibited a spatial pattern that followed the physiognomy of China;(2) The relationship between the RDLS and population density were logarithmic, with an R2 value up to 0.798(p<0.05), and the correlation decreased from east to west;(3) The difference between the revised population density(RPD) and the traditional population density(PD) was larger in the southeastern region of China than in the northwestern region;(4) In addition, compared with traditional results, the revised result indicated that the population pressure was larger. Based on these results, the following conclusions were made:(1) the revised method for estimating population density that incorporates the RDLS is reasonable and practical,(2) the potential population pressure in the southeastern mountainous areas is substantial,(3) the characteristics of the terrain in the high mountainous areas are important for the scattered distribution of the population, and(4) the population distribution of mountainous areas in China should be guided by local conditions, such as social, economic, and topographic conditions.

Character and Causes of Population Distribution in Shenyang City,China

Character of population distribution is one of the focuses studied by urban geography. Using the fifth national census data as basic data and using areal interpolation method, this paper analyzes character of urban population dis- tribution of Shenyang City, Northeast China, in terms of three aspects of statistical character, spatial auto-correlation and spatial structure. Furthermore, this research analyzes the factors affecting the population distribution of the city. The main conclusions include: 1) There is an obvious structure character of population distribution in the grid with a grain of 300m, which is appropriate scale when researching population distribution in Shenyang City. 2) Urban population dis- tribution has the character of assembling while population density distribution takes on variability in Shenyang City. 3) Population density distribution shows spatial auto-correlation within 7.36km. Spatial heterogeneity of population density is low. 4) Urban center, population distribution barycenter and population density maximum points separate each other. Population density distribution has multi-cores character. 5) Layout of governments, primary schools, middle schools, colleges, hospitals and marketplaces affects population distribution directly. With the increase of distance to these factors, population density decreases as logarithm.

Topographic and lithologic controls behind mountain depopulation in Zlatibor District(Western Serbia)

Mountain depopulation is a worldwide phenomenon observed in all continents. It has varied socio-economic reasons;among others, the low profitability of traditional agriculture, the better job possibilities and the higher level of services in urban settlements. However, it is often recognized that depopulation is related to natural factors such as elevation, slope or lithology. It is also observed that protected areas are frequently established in depopulated mountain regions. Their primary aim is the conservation of nature, but they may help tourism development as well. Tourism, in turn, may slow down or even reverse the process of depopulation. In this study, we investigate the impact of topographic and lithologic factors, namely of karst settings, on mountain demographic processes and the relationship of protected areas and tourism through the example of the northern part of Zlatibor District(Western Serbia). The study area is characterized by mountains and hills at elevations from 200 to 1600 m a.s.l. Our aim is to find GIS-based statistical relationships between topographic, lithologic factors and demographic characteristics. In this area, mountain depopulation started after WWII, and weproved that this process was strongly controlled by topographic factors. The higher and more dissected the area, the more significant is the decrease of the population and the more advanced is the ageing. As a result, population density contrasts are much more pronounced now than 70 years ago. After WWII, depopulation and ageing became gradually more serious on karstic terrains than on non-karst. However, by using compound topographic and lithologic types, we proved that it is not the effect of karst, but the effect of topography. The flow of population from hills and mountains to valleys and basins are closely related to the restructuring of the economic sectors. At present, for the study area, the development of tourism is unequivocally naturebased and connected to protected areas, namely to Tara National Park, Zlatibor Nature Park and ?argan–Mokra Gora Nature Park. In this paper, we also demonstrate how lithology influences tourism possibilities. The leading role of Zlatibor in tourism development is largely thanks to its favourable position on a main transit route.

Population distribution and threats to sustainable management of selected non-timber forest products in tropical lowland rainforests of south western Nigeria

Uncontrolled harvesting of non-timber forest products （NTFPs） poses a serious risk of extermination to several of these species in Nigeria. Yet, there is a paucity of information on the distribution, population status and sustainable management of NTFPs in most of the tropical lowland rainforests. We, therefore, assessed the population, distribution and threats to sustainable management of NTFPs within the tropical lowland rainforests of Omo and Shasha Forest Reserves, south western Nigeria. Data were obtained through inventory surveys on five top priority species including： bush mango （Irvingia gabonensis （Aubry-Lecomte ex O’Rorke） Baill）, African walnut （Tetracarpidium conophorum （Mull. Arg.） Hutch. ＆ Dalziel syn. Plukenetia conophora）, chew-stick （Massularia acuminata （G. Don） Bullock）, fever bark （Annickia chlorantha Setten ＆ P.J.Maas syn. Enantia chloranta） and bush pepper （Piper guineense Schumach. ＆ Thonn.）. Purposive and stratified random sampling techniques were used for the inventory. Each forest reserve was stratified into three, viz： less disturbed natural forest （for areas that have been rested for at least ten years）, recently disturbed natural forest （for areas that have suffered one form of human perturbation or the other in the last five years）, and plantation forest （for areas carrying forest plantation）. Data were collected from eighteen 10 m × 500 m belt transects located in the above strata. The species were generally fewer in both plantation and recently disturbed natural forest than the less disturbed natural forest, suggesting that forest disturbances （habitat modification） for other uses may have an effect on the occurrence and densities of the NTFPs. Exceptions to this trend were found for P. guineense and T. conophorum, which were fairly common in both plantation and recently disturbed natural forest. Among three tree NTFP species （i.e. I. gabonensis, M. acuminata and A. chlorantha）, only I. gabonensis showed a significant difference in overall DBH size classes for both reserves （t=？2.404; df =21; p=0.026）. Three tree NTFP species in both reserves further showed differences from the regular patterns of distribution of trees. The fairly regular reverse J-shaped size class distribution observed for M. acuminata in the study sites, however, suggests a recuperating population. In general, destructive harvesting of species, logging operations, low population size, narrow distribution ranges and habitat degradation are the major threats to the population of NTFPs in the study area. The implications of our findings for sustainable management of NTFPs in the study area are discussed and recommendations are made for a feasible approach towards enhancing the status of the species.

Overwintering parasitism is positively associated with population density in diapausing larvae of Chilo suppressalis

The suppression of overwintering population is essential in integrated pest management,but little is known about the biological mortality factors that reduce the overwintering density of Chilo suppressalis.Here,we examine the parasitism of overwintering larvae,and assume that key parasitoids strengthen the over-wintering population suppression.The natural parasitism incidence and related dominant parasitoids in overwintering larvae were investigated in two successive winters,in 2015-2016 and 2016-2017.Parasitism rates were also assessed in larvae collected from 15 different counties in 2016.The results showed that the parasitism incidence and dominant parasitoids in overwintering C.suppressalis larvae were significantly different for different sampling dates and sites.Overwintering larvae of C.suppressalis were mainly parasitized by Cotesia chilonis,and less often by Eriborus sinicus and Microgaster russata.Regression analysis indicated that the natural incidence of parasites in overwintering C.suppressalis larvae was positively correlated with the over-wintering larval density.The current work provides support for overwintering pest management strategies by showing the effectiveness of parasitoid communities as a bio-mortality factor for suppressing overwintering density.

Socio-economic influences of population density

While population density represents an important socio-economic parameter, its role is rarely studied in the economic literature （contrary to natural sciences）. Population density plays an important role in harvesting societies, i.e. those that depend on agriculture and natural resources. With the development of industry and services and emergence of urban areas, population density becomes less economically important unless we consider aspects related to pollution. There exists a phase transition between rural and urban area which makes population density less important in urban area contrary to rural. However, the economic influence of population density in harvesting societies is also not straight forward. Too high population density decreases the natural endowment per capita, but eases the development of infrastructure, leading to existence of an optimal population density for economic growth. It also influences the demand for a monopolistic product, where too little density can lead to non-survival of a monopoly. Emergence of ethnic communities is based on more cooperative behavior in the case of low cultural and physical distances. At the same time, higher probability of large projects （like infrastructure） leads to development of cooperative behavior in the society. Elaboration along these lines leads to the conclusion that population density positively correlates with individualistic （non-cooperative, non-altruistic） behavior, through less time spent in cooperative infrastructure projects and higher frequency of meetings between individuals that with some probability lead to non-cooperative games.

A new approach on seismic mortality estimations based on average population density

This study examines a new methodology to predict the final seismic mortality from earthquakes in China. Most studies established the association between mortality estimation and seismic intensity without considering the population density. In China, however, the data are not always available, especially when it comes to the very urgent relief situation in the disaster. And the popu- lation density varies greatly from region to region. This motivates the development of empirical models that use historical death data to provide the path to analyze the death tolls for earthquakes. The present paper employs the average population density to predict the final death tolls in earthquakes using a case-based reasoning model from realistic perspective. To validate the forecasting results, historical data from 18 large-scale earthquakes occurred in China are used to estimate the seismic morality of each case. And a typical earthquake case occurred in the northwest of Sichuan Province is employed to demonstrate the estimation of final death toll. The strength of this paper is that it provides scientific methods with overall forecast errors lower than 20 %, and opens the door for conducting final death forecasts with a qualitative and quantitative approach. Limitations and future research are also analyzed and discussed in the conclusion.

Current Status of Population Density of Mediterranean Fruit Fly （Ceratitis capitata） in Fruit Orchards in Central Iraq

In the recent years The Mediterranean Fruit fly Ceratitis capitata is distributed in the orchards of central Iraq and caused highly economic losses. This study was conducted in orchards in central Iraq during 2009 and 2010 and made field survey of the insect in four types of orchards （Citrus, Apricot, Figs ＆ Citrus and A mixture of fruit trees） and used for this purpose Tephri Traps supplied with Q-Lure and dimethyl dichloroviny phosphate （DDVP）. The present preliminary study has shown that the Mediterranean fruit fly C. capitata has a year round presence in fruit orchards in central Iraq and reached its highest ntunerical density of the pest in citrus orchards during of November and December were 345 and 363 insect/trap per month in citrus orchards and the least numerical density during of January and February while the highest numerical density of the insect in orchards of Apricot in March 2010, Figs ＆ Citrus in August 2009 and a Mixture of fruit trees in November 2009 were 45, 116, 311 insect/trap per month respectively. The population density of the pest was highest is started 2010 compared with 2009, but the high temperature degree （46-51℃） in August 2010 caused decreasing the population density of this pest. C. capitata caused highly economic losses in citrus reached 68% and 71% of the Mandarin and Kaki fruits respectively Currently in Iraq to fight no control method to reduce the economic losses caused by this pest except the use of pesticides GF-120.

An examination of the population dynamics of syngnathid fishes within Tampa Bay,Florida,USA

Seagrass ecosystems worldwide have been declining, leading to a decrease in associated fish populations, especially those with low mobility such as syngnathids （pipefish and seahorses）. This two-year pilot study investigated seasonal patterns in density, growth, site fidelity, and population dynamics of Tampa Bay （FL） syngnathid fishes at a site adjacent to two marinas under construction. Using a modified mark-recapture technique, fish were collected periodically from three closely located sites that varied in seagrass species （Thalassia spp., Syringodium spp., and mixed-grass sites） and their distance from open water, but had consistent physical/chemical environmental characteristics. Fish were marked, photographed for body size and gender measurements, and released the same day at the capture site. Of the 5695 individuals surveyed, 49 individuals were recaptured, indicating a large, flexible population. Population density peaks were observed in July of both years, with low densities in late winter and late summer. Spatially, syngnathid densities were highest closest to the mouth of the bay and lowest near the shoreline. Seven species of syngnathid fishes were observed, and species-specific patterns of seagrass use emerged during the study. However, only two species, Syngnathus scovelli and Hippoeampus zosterae, were observed at high frequencies. For these two species, body size decreased across the study period, but while S. scovelli＇s population density decreased, H. zosterae＇s increased. Across six of the seven species, population size declined over the course of this preliminary study; however, seasonal shifts were impossible to distinguish from potential anthropogenic effects of construction [Current Zoology 56 （1）： 118-133, 2010].

Long-term monitoring data reveal effects of age,population density,and environmental aspects on hatching success of Common Cranes(Grus grus)

Facing climate and land use change,a species’ability to successfully adapt to changing environments is crucial for its survival.Extensive drainage and intensification of agriculture and forestry set wetlands and associated species at risk of population declines.The population of Common Cranes(Grus grus)has experienced considerable fluctuations over the last century.Despite increasing population numbers,hatching success seemed to have decreased over the last years.The aim of this study was to identify factors influencing hatching success and nest survival of Common Cranes based on analyses of long-term individual-based monitoring data from northeastern Germany and evaluate the species ability to adapt to changing environments.Hatching success decreased over the course of the study period from 0.75 to 0.55.Surprisingly,nest survival and hatching success did not vary across different nesting habitats,whereas factors such as female age,timing of nest initiation and breeding pair density were found to have significant effects on hatching success.Older females showed higher hatching success,even though the proportion of unhatched eggs was highest in females aged 20 years or older.Early nest initiation had a positive effect on hatching success.Water levels are more favorable early in the nesting season,whereas increasing evaporation with time causes water levels to decrease,granting easier access for predators.Independently of female age,hatching success decreased with increasing numbers of breeding pairs within a 2-km radius around a nesting site.High population densities intensify competition for resources and promote intraspecific interactions,affecting reproductive outcome negatively.This study gives first insights into mechanisms behind population regulation in Common Cranes,highlighting the importance of population dynamics and individual features.We suggest to further investigate density dependent effects including landscape and habitat features as well as reproductive success in terms of chick survival,since successfully raising juveniles is crucial for a species survival.