scholarly journals The impact of human activity on anthropogenic dust emission over global semi-arid regions

2016 ◽  
Author(s):  
X. Guan ◽  
J. Huang ◽  
Y. Zhang ◽  
Y. Xie ◽  
J. Liu
Keyword(s):  
Population Growth ◽  
Growth Rates ◽  
Human Activities ◽  
Arid Regions ◽  
Population Change ◽  
Dust Emission ◽  
Dust Production ◽  
Population Growth Rates ◽  
The Impact ◽  
Semi Arid

Abstract. Anthropogenic dust is acknowledged as a product of human activities on disturbed soil, and is generated mainly from sensitive and fragile regions including croplands, pastures, and urbanized regions. In this study, we analyzed the behaviour of anthropogenic dust in semi-arid region of globe, and its relationship to human activities. An obvious peak in the total anthropogenic dust column, much higher magnitude than those of wet regions, was observed in semi-arid regions with population growth rates of more than 11.46 %. Four typical semi-arid regions, East China, India, North America and North Africa were selected to explore the local difference in anthropogenic dust production. The population growth rates in these areas were approximately 6.16 %, 17.71 %, 11.21 %, and 29.26 %, and the anthropogenic dust levels were 0.17 g m−2, 0.38 g m−2, 0.10 g m−2 and 0.21 g m−2, which are higher than the natural dust column burden. The anthropogenic dust column burden is positively correlated with the population and population change, indicating a contribution from human activities to the anthropogenic dust production. Based on the fact that anthropogenic dust can act as warming aerosol, the radiative effect of anthropogenic dust in semi-arid regions can not be ignored and requires further investigation.

scholarly journals Founder effects drive the genetic structure of passively dispersed aquatic invertebrates

2018 ◽  
Author(s):  
Javier Montero-Pau ◽  
Africa Gomez ◽  
Manuel Serra
Keyword(s):  
Life Cycle ◽  
Genetic Structure ◽  
Population Growth ◽  
Local Adaptation ◽  
Growth Rates ◽  
High Population ◽  
Founder Effects ◽  
Population Growth Rates ◽  
High Population Growth ◽  
The Impact

Populations of passively dispersed organisms in continental aquatic habitats typically show high levels of neutral genetic differentiation, despite their high dispersal capabilities. Several evolutionary factors, including founder events and local adaptation, and life cycle features such as high population growth rates and the presence of propagule banks, have been proposed to be responsible for this paradox. Here, we have modeled the colonization process in these organisms to assess the impact of migration rate, growth rate, population size, local adaptation and life-cycle features on their population genetic structure. Our simulation results show that the strongest effect on population structure is caused by persistent founder effects, resulting from the interaction of a few population founders, high population growth rates, large population sizes and the presence of diapausing egg banks. In contrast, the role of local adaptation, genetic hitchhiking and migration is limited to small populations in these organisms. Our results indicate that local adaptation could have different impact on genetic structure in different groups of zooplankters.

Impact of surface roughness on dust occurrence frequency over arid regions

2021 ◽  
Author(s):  
Martina Klose ◽  
Carlos Pérez García-Pando ◽  
Paul Ginoux ◽  
Ron L. Miller
Keyword(s):  
Surface Roughness ◽  
Spatial Patterns ◽  
Arid Regions ◽  
Transport Model ◽  
Dust Emission ◽  
Occurrence Frequency ◽  
Dust Transport ◽  
Drag Partition ◽  
The Impact ◽  
Semi Arid

<p>Soil dust aerosol created by wind erosion of arid and semi-arid surfaces dominates climate effects over large areas of the Earth. To represent the dust cycle, Global Earth System Models (ESMs) typically prescribe preferential dust sources phenomenologically using empirical source scaling functions. While this approach has helped to compensate for a lack or inaccuracy of soil and surface input data to models, it potentially limits progress in the representation of the global dust cycle, because such strong empirical constraints make models less sensitive to parameters known to affect dust emission, and thus potentially insensitive to changes in climate. Here we investigate the link between surface roughness due to non-erodible elements such as vegetation, pebbles and rocks, and the spatial patterns of dust activity. Using two different satellite-based methods to represent roughness within an atmospheric dust transport model, we evaluate the impact of surface roughness on the spatial distribution of dust optical depth occurrence frequency observed from satellite by both reducing the atmospheric momentum available for particle entrainment and protecting the surface from dust emission. We test the variability of our results across conceptually different parameterizations of dust emission and drag partition. Our results suggest that the spatial patterns of dust activity are largely determined by surface roughness, not only in semi-arid, but also in arid regions, where green vegetation is sparse or absent. </p>

Streamflow and Population Change in the Lower Salt River Valley of Central Arizona, ca. A.D. 775 to 1450

2008 ◽  
Vol 73 (1) ◽  
pp. 136-165 ◽  
Author(s):  
Scott E. Ingram
Keyword(s):  
Population Growth ◽  
Growth Rates ◽  
Population Change ◽  
River Valley ◽  
Channel Changes ◽  
Population Growth Rates ◽  
Salt River ◽  
Floods And Droughts ◽  
Salt River Valley ◽  
Irrigation Agriculture

Floods and droughts and their effects on Hohokam canal systems and irrigation agriculture play a prominent role in many cultural-historical interpretations of the Hohokam trajectory in the lower Salt River valley (modern-day Phoenix, Arizona metropolitan area). Catastrophic floods and associated geomorphic stream channel changes may have contributed to settlement and population changes and the substantial depopulation of the lower Salt River valley ca. A.D. 1450 or later. In this study, archaeological data on Hohokam domestic architecture is used to infer changes in prehistoric population growth rates from ca. A.D. 775 through 1450 in the most thoroughly documented canal system in the Salt River valley. Changes in growth rates are compared to the retrodictions of annual streamflow discharge volumes derived from tree-ring records. Contrary to expectations, population growth rates increased as the frequency, magnitude, and duration of inferred flooding, drought, and variability increased. These results challenge existing assumptions regarding the relationship among floods and droughts, conditions for irrigation agriculture, and population change in the lower Salt River valley.

scholarly journals The relationship between anthropogenic dust and population over global semi-arid regions

2016 ◽  
Vol 16 (8) ◽  
pp. 5159-5169 ◽  
Author(s):  
Xiaodan Guan ◽  
Jianping Huang ◽  
Yanting Zhang ◽  
Yongkun Xie ◽  
Jingjing Liu
Keyword(s):  
Population Density ◽  
Arid Regions ◽  
Population Change ◽  
Dominant Role ◽  
Positive Contribution ◽  
Regional Population ◽  
Semi Arid Region ◽  
The Impact ◽  
The Relationship ◽  
Semi Arid

Abstract. Although anthropogenic dust has received more attention from the climate research community, its dominant role in the production process is still not identified. In this study, we analysed the relationship between anthropogenic dust and population density/change over global semi-arid regions and found that semi-arid regions are major source regions in producing anthropogenic dust. The results showed that the relationship between anthropogenic dust and population is more obvious in cropland than in other land cover types (crop mosaics, grassland, and urbanized regions) and that the production of anthropogenic dust increases as the population density grows to more than 90 persons km−2. Four selected semi-arid regions, namely East China, India, North America, and North Africa, were used to explore the relationship between anthropogenic dust production and regional population. The most significant relationship between anthropogenic dust and population occurred in an Indian semi-arid region that had a greater portion of cropland, and the high peak of anthropogenic dust probability appeared with 220 persons km−2 of population density and 60 persons km−2 of population change. These results suggest that the influence of population on production of anthropogenic dust in semi-arid regions is obvious in cropland regions. However, the impact does not always have a positive contribution to the production of anthropogenic dust, and overly excessive population will suppress the increase of anthropogenic dust. Moreover, radiative and climate effects of increasing anthropogenic dust need more investigation.

scholarly journals Population growth rates: issues and an application

2002 ◽  
Vol 357 (1425) ◽  
pp. 1307-1319 ◽  
Author(s):  
H. Charles J. Godfray ◽  
Mark Rees
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Population Growth ◽  
Growth Rates ◽  
Population Growth Rate ◽  
Population Change ◽  
Evolutionarily Stable Strategy ◽  
Model Systems ◽  
Population Growth Rates

Current issues in population dynamics are discussed in the context of The Royal Society Discussion Meeting 'Population growth rate: determining factors and role in population regulation'. In particular, different views on the centrality of population growth rates to the study of population dynamics and the role of experiments and theory are explored. Major themes emerging include the role of modern statistical techniques in bringing together experimental and theoretical studies, the importance of long-term experimentation and the need for ecology to have model systems, and the value of population growth rate as a means of understanding and predicting population change. The last point is illustrated by the application of a recently introduced technique, integral projection modelling, to study the population growth rate of a monocarpic perennial plant, its elasticities to different life-history components and the evolution of an evolutionarily stable strategy size at flowering.

Road mortality reduces survival and population growth rates of tammar wallabies on Garden Island, Western Australia

2010 ◽  
Vol 37 (7) ◽  
pp. 588 ◽  
Author(s):  
Brian Chambers ◽  
Roberta Bencini
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Western Australia ◽  
Growth Rates ◽  
Survival Rates ◽  
Habitat Modification ◽  
Road Mortality ◽  
Population Growth Rates ◽  
The Impact ◽  
Naval Base

Context Although road mortality has the potential to affect the fate of populations, it is often confounded with other forms of environmental change. Therefore determining its impact separately from other factors is difficult because it requires an understanding of how road mortalities affect age- and sex-specific survival rates. Aims We determined the impact of high numbers of road-kills and habitat modification on the growth and survival of the population of tammar wallabies (Macropus eugenii) on Garden Island, off the coast of Western Australia. The increased supply of food from large areas of fertilised and irrigated lawns on a naval base was expected to increase the population growth rate (λ) and the road-kills were expected to offset the population response. Methods We conducted a mark-and-recapture study over three years to estimate rates of survival, reproduction and population growth rates in areas of the island that were either heavily affected by the presence of a naval base that included a network of roads and buildings, close enough to the naval base that animals could be affected by the disturbance there, and completely unaffected and lacking major roads or buildings. All road-kills were collected to estimate the impact of road mortality on the survival and growth rates of the population. Key results The growth rate, λ, for the population on the naval base was 1.02 ± 0.083 (s.e.) per year, which was much higher than in an area of adjacent bushland at 0.92 ± 0.065 per year and in undisturbed bushland at 0.93 ± 0.100 per year. When the impact of road mortality was removed, λ increased to 1.15 ± 0.101 per year on the naval base and 0.96 ± 0.076 per year in the bushland adjacent to the naval base. On the naval base road mortality reduced survival rates of one-year-old and adult animals by 0.14 ± 0.087 and 0.12 ± 0.012 per year (mean ± s.e.). Conclusions Road mortality counteracted the increase in the size of the tammar population caused by the habitat modification on the naval base. The impact of road mortality on the adjacent bushland population may result in its long-term decline, as the population may not be able to recover from the reduction in survival rates. Implications Road mortality has the potential to threaten susceptible populations but its impact should be quantified so that mitigation measures can be implemented where they will achieve the greatest benefits.

scholarly journals Founder effects drive the genetic structure of passively dispersed aquatic invertebrates

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e6094 ◽  
Author(s):  
Javier Montero-Pau ◽  
Africa Gómez ◽  
Manuel Serra
Keyword(s):  
Life Cycle ◽  
Genetic Structure ◽  
Population Growth ◽  
Local Adaptation ◽  
Growth Rates ◽  
High Population ◽  
Founder Effects ◽  
Population Growth Rates ◽  
High Population Growth ◽  
The Impact

Populations of passively dispersed organisms in continental aquatic habitats typically show high levels of neutral genetic differentiation despite their high dispersal capabilities. Several evolutionary factors, including founder events, local adaptation, and life cycle features such as high population growth rates and the presence of propagule banks, have been proposed to be responsible for this paradox. Here, we have modeled the colonization process to assess the impact of migration rate, population growth rate, population size, local adaptation and life-cycle features on the population genetic structure in these organisms. Our simulations show that the strongest effect on population structure are persistent founder effects, resulting from the interaction of a few population founders, high population growth rates, large population sizes and the presence of diapausing egg banks. In contrast, the role of local adaptation, genetic hitchhiking and migration is limited to small populations in these organisms. Our results indicate that local adaptation could have different impact on genetic structure in different groups of zooplankters.

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