seasonal wetlands
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Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1767
Author(s):  
Yoshihiro Hirooka ◽  
Simon K. Awala ◽  
Kudakwashe Hove ◽  
Pamwenafye I. Nanhapo ◽  
Morio Iijima

The production of pearl millet (Pennisetum glaucum (L.) R.Br.) is important in Namibia, in sub-Saharan Africa, owing to the prevailing low precipitation conditions. Most fields supporting crop production in northern Namibia are located in a network of seasonal wetlands. The aim of the present study was to evaluate the effects of ridging and fertilizer application on the yield and the growth of pearl millet in the seasonal wetlands under different rainfall conditions. The study was conducted for two years (2017–2018) in the experimental fields in northern Namibia, and yield, yield components, and growth parameters were evaluated in relation to the application of different fertilizers (manure and mineral) with and without ridge-furrows. Manure fertilizer application presented the highest yield in 2018, whereas mineral fertilizer application showed the highest yield in 2017. The proportion of rainfall was the highest during the mid-growth period in 2017, and the reproductive stage in 2018. Thus, pearl millet plants under manure fertilization overcame damage resulting from waterlogging stress during the seed setting stage by improving the soil and plant nutrient conditions. In contrast, the plants under mineral fertilization were more tolerant to large amounts of rain during the mid-growth period. In this study, yield was mainly determined by total dry weight, and it was closely related to panicle density in both years. Therefore, we concluded that fertilizer application, including additional fertilizer based on the growth diagnostic, could be important for improving crop production in seasonal wetlands.


Author(s):  
Ian Matthew Miller

Over the last seven thousand years, humans have gradually domesticated the environment of South China. Transitioning from a reliance on wild environments, humans tamed plants and animals and transformed the landscapes and waterscapes to better fit their needs. Rice paddies, orchards, and artificial ponds and forests replaced naturally seeded woodlands and seasonal wetlands. Even the Yangzi River, and many of the other rivers, lakes, and seashores, were transformed by polders, dikes, and seawalls to better support human activities, especially rice agriculture. In the last thousand years, farmers intensified their control of the cultivated landscape through terracing, irrigation, flood prevention, and new crop rotations. They planted commercial crops like cotton, fruits, oilseeds, tea, and sugar cane in growing concentrations. Migrants and merchants spread logging, mining, and intensive agriculture to thinly settled parts of the south and west. Since the 17th century, New World crops like sweet potatoes, chilis, maize, and tobacco enabled a further intensification of land use, especially in the mountains. Since the early 1800s, land clearance and river diking reached extremes and precipitated catastrophic flooding, social unrest, and a century of warfare. Since 1950, the People’s Republic has overseen three further waves of degradation accompanying the mass campaigns of the Mao era and the market reforms under Deng Xiaoping. Following catastrophic flooding in 1998, the government has increasingly worked to reverse these trends. Nonetheless, South China remains one of the most intensively cultivated environments in the world and continues to feel the effects of new attempts to tame and expropriate the forces of nature.


The Condor ◽  
2021 ◽  
Vol 123 (1) ◽  
Author(s):  
Tasso C Cocoves ◽  
Mark I Cook ◽  
Jeffrey L Kline ◽  
Lori Oberhofer ◽  
Nathan J Dorn

Abstract As avian reproductive success is generally prey limited, identifying important prey types or sizes and understanding mechanisms governing prey availability are important objectives for avian conservation ecology. Irruptive White Ibis (Eudocimus albus) nesting at coastal colonies in the southern Everglades numbered over 100,000 nests in the 1930s. A century of drainage and altered hydrologic patterns reduced aquatic prey availability and eliminated large nesting events; nesting activity in recent decades has been typically less than 5% of historical peaks. Hydrologic restoration is expected to increase ibis nesting activity, but which prey types will support high nesting effort is less clear. In 2017 and 2018, we collected food boluses from White Ibis chicks at coastal colonies in Everglades National Park. We also monitored regional nesting activity from 1999 to 2018. In 2017, the region had 1,075 nests, typical of the past several decades; but in 2018, there were 30,420 nests, representing the highest recorded nesting activity in 87 yr. Prey composition varied between years; estuarine crabs dominated nestling boluses in 2017, while crayfish and fish were dominant prey in 2018. Crayfish, especially Procambarus alleni, were heavily exploited by ibis early in the 2018 breeding season, while fish were used more at the end. Crayfish abundances in wetlands near the colonies were higher prior to 2018, and more crayfish-producing short-hydroperiod wetlands remained available for ibis foraging in 2018. Our results support previous studies indicating that crayfish are important prey for breeding ibises and suggest that unprecedented, extensive flooding of seasonal wetlands promoted crayfish production and initiated the irruptive breeding in 2018. Our observations indicate that rehydration of the southern Everglades could restore ibis nesting activity at coastal colonies, but further investigations of hydrologic variation, crayfish production, and ibis foraging and nesting activity will be helpful to understand these dynamics and the importance of short-hydroperiod wetlands.


2020 ◽  
Vol 43 ◽  
pp. 75-88
Author(s):  
A Bouma ◽  
G Kuchling ◽  
SY Zhai ◽  
N Mitchell

Species with restricted ranges and long generation times are vulnerable to climate change due to limited opportunity to disperse or adapt. Australia’s rarest reptile, the western swamp turtle Pseudemydura umbrina, persists naturally in only one seasonal swamp that holds water in the Austral winter and spring. A marked reduction in winter rainfall in recent decades has shortened the swamp hydroperiod, restricting when turtles are able to feed, grow and reproduce. To mitigate possible future loss of reproductive capacity in the native habitat, assisted colonisation was trialled in 2016 using 35 captive-bred juveniles. Here, we report the outcomes of this 6 mo trial, which compared the growth of turtles released approximately 300 km south of the species’ indigenous range with growth of turtles released at an existing northern translocation site. We showed that growth rates comparable to those at warmer northern translocation sites can be achieved in the south, even in an atypically cool spring as occurred in 2016. Microclimates available to P. umbrina at 2 southern sites were suitable for foraging and growth in late spring and early summer, but juvenile growth at one southern site was significantly better than at the other, likely due to higher prey biomass when water temperatures were suitable for foraging. These early results suggest that introduction of P. umbrina to seasonal wetlands near the south coast of Western Australia could be considered in the immediate future, but further trials are recommended to assess growth and survivorship over longer periods.


2020 ◽  
Vol 56 (4) ◽  
Author(s):  
Christian Birkel ◽  
Clément Duvert ◽  
Alicia Correa ◽  
Niels C. Munksgaard ◽  
Damien T. Maher ◽  
...  

2020 ◽  
Author(s):  
Emmanuel Ogunyomi ◽  
Byongjun Hwang ◽  
Adrian Wood

<p>Many areas in Malawi undergo extreme seasonality: floods in the wet season and drought in the dry season. Each year, this extreme seasonality poses formidable challenges for local farmers to sustain their crops. Often in the dry season, farmers use the water in the surrounding seasonal wetlands (dambos) for small-scale irrigation to supplement their rainy season harvest. In Malawi, the agricultural use of wetland is growing year by year and these areas play significant roles in regulating food price shocks and price. Such intensive use of wetlands can negatively affect the sustainability of wetland eco-system and their crop production, with communities even affected by the drying up of wells. Farmers, especially small-scale farmers, will face even more challenges for sustaining wetland production, as climate changes cause more frequent occurrence of droughts as Malawi has experienced in recent years. With the increasingly intensive use of these seasonal wetlands for agricultural purpose and the expansion of wetland degradation generally across the country, more attention is required toward effective management of these wetlands through identification, mapping, monitoring and data analysis. To achieve the sustainable use of these seasonal wetlands, it is essential to establish systematic monitoring and assessment procedures. Widely used assessment protocols (i.e., WET-Health) which evaluate the wetlands based on physical indicators such as land cover, hydrology, geomorphology, soil organic matter and natural vegetation have been successfully implemented in South Africa. However, obtaining those indicators across the full length of an individual wetland, let alone all wetlands in one district in Malawi, is labour intensive and time-consuming and difficult to complete. In this research, we utilise both unmanned aerial vehicle (UAV) and satellite imageries. These data sources are being tested in nine different seasonal wetlands in central Malawi to provide an accurate derivation of key indicators such as gully formation, sedimentation, water extent, changes in land use and natural vegetation. Additionally, using satellite imageries and GIS, the condition of each individual wetland has been quantified, with land cover and the extent of inundation determined through multi-temporal data analysis. Our results can be applied across a larger area, i.e. several districts to help identify where more detailed ground assessment is needed and technical support required to improve wetland management, feeding into both policy and technical guidance which can help sustain the range of ecosystems services of these important areas.</p>


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