scholarly journals Long-Term Population Dynamics of Namib Desert Tenebrionid Beetles Reveal Complex Relationships to Pulse-Reserve Conditions

Insects ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 804
Author(s):  
Joh R. Henschel
Keyword(s):  
Heavy Rain ◽  
Population Variation ◽  
Population Bottlenecks ◽  
Namib Desert ◽  
Winter Rainfall ◽  
Rainfall Events ◽  
High Species Diversity ◽  
Complex Relationships ◽  
Coleoptera Tenebrionidae

Noy-Meir’s paradigm concerning desert populations being predictably tied to unpredictable productivity pulses was tested by examining abundance trends of 26 species of flightless detritivorous tenebrionid beetles (Coleoptera, Tenebrionidae) in the hyper-arid Namib Desert (MAP = 25 mm). Over 45 years, tenebrionids were continuously pitfall trapped on a gravel plain. Species were categorised according to how their populations increased after 22 effective rainfall events (>11 mm in a week), and declined with decreasing detritus reserves (97.7–0.2 g m−2), while sustained by nonrainfall moisture. Six patterns of population variation were recognised: (a) increases triggered by effective summer rainfalls, tracking detritus over time (five species, 41% abundance); (b) irrupting upon summer rainfalls, crashing a year later (three, 18%); (c) increasing gradually after series of heavy (>40 mm) rainfall years, declining over the next decade (eight, 15%); (d) triggered by winter rainfall, population fluctuating moderately (two, 20%); (e) increasing during dry years, declining during wet (one, 0.4%); (f) erratic range expansions following heavy rain (seven, 5%). All species experienced population bottlenecks during a decade of scant reserves, followed by the community cycling back to its earlier composition after 30 years. By responding selectively to alternative configurations of resources, Namib tenebrionids showed temporal patterns and magnitudes of population fluctuation more diverse than predicted by Noy-Meir’s original model, underpinning high species diversity.

Foraging behaviour of mulga birds in Western Australia. I. Use of resources and temporal effects

2018 ◽  
Vol 24 (1) ◽  
pp. 74 ◽  
Author(s):  
Harry F. Recher ◽  
William E. Davis Jr
Keyword(s):  
Climate Change ◽  
Foraging Behaviour ◽  
Management Practices ◽  
Bird Species ◽  
Heavy Rain ◽  
Winter Rainfall ◽  
Extreme Heat Events ◽  
Use Of Resources ◽  
Heat Events

The foraging behaviour of mulga birds in the Murchison and Gascoyne Bioregions was studied in 1999 following a period of heavy rain and again in 2002 when it was dry. Mulga birds allocated foraging resources in a similar fashion to other bird communities, with species differing in the way that prey were taken, the substrates and plant species on which prey were found, and the heights at which prey were sought. The numbers of birds and bird species in the study areas declined with drier conditions and there was less breeding activity. Nomadic species, including honeyeaters, seed-eaters, and insect-eaters, largely left the area as it became drier and food resources changed. The birds that remained foraged differently when it was drier than when conditions were wetter and food more abundant. These observations illustrate the fragility of the mulga avifauna and its likely sensitivity to long-term climate change with predicted increasing temperatures, more extreme heat events, and reduced winter rainfall. Conservation of mulga birds and associated flora and fauna requires a whole-of-landscape approach and the adoption of land management practices by Australian governments and land managers that will allow species to adapt to climate change and guarantee their right to evolve.

scholarly journals Trends in the Frequency of Intense Precipitation Events in Southern and Southeastern Brazil during 1960–2004

2011 ◽  
Vol 24 (7) ◽  
pp. 1913-1921 ◽  
Author(s):  
Mateus da Silva Teixeira ◽  
Prakki Satyamurty
Keyword(s):  
Extreme Rainfall ◽  
Southeastern Brazil ◽  
Extreme Rainfall Event ◽  
Southern Brazil ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Annual Frequency ◽  
Long Term Trends ◽  
Increasing Trends

Abstract A new approach to define heavy and extreme rainfall events based on cluster analysis and area-average rainfall series is presented. The annual frequency of the heavy and extreme rainfall events is obtained for the southeastern and southern Brazil regions. In the 1960–2004 period, 510 (98) and 466 (77) heavy (extreme) rainfall events are identified in the two regions. Monthly distributions of the events closely follow the monthly climatological rainfall in the two regions. In both regions, annual heavy and extreme rainfall event frequencies present increasing trends in the 45-yr period. However, only in southern Brazil is the trend statistically significant. Although longer time series are necessary to ensure the existence of long-term trends, the positive trends are somewhat alarming since they indicate that climate changes, in terms of rainfall regimes, are possibly under way in Brazil.

scholarly journals Determination of NPS Pollutant Unit Loads from Different Landuses

2021 ◽  
Vol 13 (13) ◽  
pp. 7193
Author(s):  
Jiyeon Choi ◽  
Baekyung Park ◽  
Jinsun Kim ◽  
Soyoung Lee ◽  
Jichul Ryu ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Oxygen Demand ◽  
Runoff Coefficient ◽  
Forest Land ◽  
Event Mean Concentration ◽  
Rainfall Events ◽  
Total Phosphorous ◽  
Mean Concentration

This study aimed to estimate pollutant unit loads for different landuses and pollutants that reflected long-term runoff characteristics of nonpoint source (NPS) pollutants and recent environmental changes. During 2008–2014, 2026 rainfall events were monitored. The average values of antecedent dry days, total rainfall, rainfall intensity, rainfall duration, runoff duration, and runoff coefficient for each landuse were 3.8–5.9 d, 35.2–65.0 mm, 2.9–4.1 mm/h, 12.5–20.4 h, 12.4–27.9 h, and 0.24–0.45, respectively. Uplands (UL) exhibited high suspended solids (SS, 606.2 mg/L), total nitrogen (TN, 7.38 mg/L), and total phosphorous (TP, 2.27 mg/L) levels, whereas the runoff coefficient was high in the building sites (BS), with a high impervious surface ratio. The event mean concentration (EMC) for biological oxygen demand (BOD) was the highest in BS (8.0 mg/L), while the EMC was the highest in BS (in the rainfall range <10 mm) and UL and forest land (in the rainfall range >50 mm). The unit loads for BOD (1.49–17.76 kg/km2·d), TN (1.462–10.147 kg/km2·d), TP (0.094–1.435 kg/km2·d), and SS (15.20–327.70 kg/km2·d) were calculated. The findings can be used to manage NPS pollutants and watershed environments and implement relevant associated management systems.

Soil Moisture Responses Under Different Vegetation Types to Winter Rainfall Events in a Humid Karst Region

2021 ◽  
Author(s):  
Weihong Yan ◽  
Qiuwen Zhou ◽  
Dawei Peng ◽  
Xiaocha Wei ◽  
Xin Tang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Vegetation Type ◽  
Arable Land ◽  
Karst Region ◽  
Control Group ◽  
Vegetation Types ◽  
Recovery Model ◽  
Winter Rainfall ◽  
Rainfall Events ◽  
Karst Ecosystems

Abstract Humid karst ecosystems are fragile, with precipitation being the main source of soil moisture recharge. The process of soil moisture recharge and usage varies by vegetation type. To analyze the dynamics of soil moisture under different vegetation types during rainfall events, we continuously monitored soil moisture in arable land, grassland, shrub, and forest areas at 10-minute intervals from November 6, 2019, to January 6, 2020.The arable land was used as a control group. Soil moisture under the different vegetation types responded to light, moderate, and rainstorm events with large rainfall amounts. However, only the soil moisture in the grassland areas responded to a light rainfall event with a rainfall amount of 0.87 mm. The largest soil moisture recharge (12.63 mm) and decline (2.08%) were observed for the grassland areas, with the smallest observed for the forest areas. While the grassland areas showed the greatest decline in soil moisture following rainfall, they were more easily recharged during the winter rainfall events. Soil moisture in forests and shrubs was less recharged than in grasslands but also declined less. Therefore, forests and shrubs are better at retaining soil moisture in winter, which is informative for the formulation of a regional vegetation recovery model.

scholarly journals Spatial structures and directionalities in Monsoonal precipitation over South Asia

2010 ◽  
Vol 17 (5) ◽  
pp. 371-381 ◽  
Author(s):  
N. Malik ◽  
N. Marwan ◽  
J. Kurths
Keyword(s):  
Indian Subcontinent ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Heavy Rain ◽  
Data Sets ◽  
Spatial Structures ◽  
Break Phase ◽  
Rainfall Events ◽  
Monsoonal Precipitation ◽  
Rain Events

Abstract. Precipitation during the monsoon season over the Indian subcontinent occurs in form of enormously complex spatiotemporal patterns due to the underlying dynamics of atmospheric circulation and varying topography. Employing methods from nonlinear time series analysis, we study spatial structures of the rainfall field during the summer monsoon and identify principle regions where the dynamics of monsoonal rainfall is more coherent or homogenous. Moreover, we estimate the time delay patterns of rain events. Here we present an analysis of two separate high resolution gridded data sets of daily rainfall covering the Indian subcontinent. Using the method of event synchronization (ES), we estimate regions where heavy rain events during monsoon happen in some lag synchronised form. Further using the delay behaviour of rainfall events, we estimate the directionalities related to the progress of such type of rainfall events. The Active (break) phase of a monsoon is characterised by an increase(decrease) of rainfall over certain regions of the Indian subcontinent. We show that our method is able to identify regions of such coherent rainfall activity.

scholarly journals Long-term Prescription? Digital Surveillance is Here to Stay

2021 ◽  
Vol 56 (4) ◽  
pp. 105-118
Author(s):  
Žilvinas Švedkauskas ◽  
Ahmed Maati
Keyword(s):  
Public Health ◽  
The State ◽  
Digital Data ◽  
Stanford University ◽  
Digital Surveillance ◽  
Complex Relationships ◽  
The Impact ◽  
Everyday Communication

An emerging literature has shown concerns about the impact of the pandemic on the proliferation of digital surveillance. Contributing to these debates, in this paper we demonstrate how the pandemic facilitates digital surveillance in three ways: (1) By shifting everyday communication to digital means it contributes to the generation of extensive amounts of data susceptible to surveillance. (2) It motivates the development of new digital surveillance tools. (3) The pandemic serves as a perfect justification for governments to prolong digital surveillance. We provide empirical anecdotes for these three effects by examining reports by the Global Digital Policy Incubator at Stanford University. Building on our argument, we conclude that we might be on the verge of a dangerous normalization of digital surveillance. Thus, we call on scholars to consider the full effects of public health crises on politics and suggest scrutinizing sources of digital data and the complex relationships between the state, corporate actors, and the sub-contractors behind digital surveillance.

scholarly journals La paradoja de mezquites (Prosopis spp.): La invasión de especies o potenciadores de la biodiversidad?

2017 ◽  
pp. 23 ◽  
Author(s):  
Jordan Golubov ◽  
María C. Mandujano ◽  
Luis E. Eguiarte
Keyword(s):  
Keystone Species ◽  
Arid Environments ◽  
Perennial Species ◽  
Semiarid Environments ◽  
High Species Diversity ◽  
Ecological Importance ◽  
Associated Species ◽  
Semi Arid ◽  
Arid And Semiarid

Arid and semi-arid environments contain relatively high species diversity and are subject to intense use, in particular extensive cattle grazing. The expansion of perennial species in to the grasslands decreases the value of the rangeland, because it makes necessary to control the shrubs, which is not practical in the long term. This paper is a bibliographic review of the ecological importance of the Prosopis (mequite) genus. We compiled information on all the species associated to mesquite (ca. 208 genera and 600 species from different taxa) and we propase that it is important to conserve the mesquites in order to maintain the diversity of the other associated species. We also stress the importance of mesquite as a keystone species in the balance of nitrogen and carbon in the arid and semiarid environments soils. We conclude that the conservation of the mesquites is very relevant, in particular in areas where people want to remove them and convert the environment to grasslands.

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