scholarly journals Slow and Steady: Gradual Drawdown of Private Wetlands Supports Shorebirds During Northbound Migration.

2020 ◽  
Author(s):  
Ian Souza-Cole ◽  
Samantha Arthur ◽  
Laura Jensen ◽  
Kristin Sesser ◽  
Khara Strum
Keyword(s):  
Management Practice ◽  
Wetland Management ◽  
Central Valley ◽  
Water Levels ◽  
Private Landowners ◽  
Forage Production ◽  
Migratory Shorebirds ◽  
Large Populations ◽  
Wetland Complex ◽  
Shorebird Habitat

The Grasslands Ecological Area is the largest contiguous wetland complex in California's Central Valley and is a stronghold for hundreds of thousands of waterbirds. Primarily managed for waterfowl habitat and forage production, privately-owned seasonal wetlands in the Grassland Ecological Area are typically flooded in fall and dewatered the following spring in February and March. These wetlands support large populations of nonbreeding shorebirds and other waterbirds in winter. When the number of migratory shorebirds using the region peaks in mid-April, most wetlands have already been dewatered. The mismatch in the timing of available habitat and the habitat needs of migrating shorebirds contributes to the observed deficit of shorebird habitat in the Central Valley in spring. Working with private landowners, we developed and tested a wetland management practice designed to increase the amount of shallow water habitat available to shorebirds in April by delaying the drawdown and reducing water levels more slowly (gradual drawdown) relative to the traditional management practice. On average, we found that wetlands managed with gradual drawdown provided over twice as much shorebird habitat, contributing up to 26% of the overall shorebird habitat objective for the Central Valley. Wetlands managed with gradual drawdown supported up to 21 times more migratory shorebirds during peak migration and a greater number of shorebird species than traditionally-managed wetlands. Our results demonstrate the potential of working with private landowners to implement small changes in wetland management that can have a large impact in meeting regional conservation objectives for migratory shorebirds.

Determining hydrological barriers in wetlands with InSAR methods: several iconic cases worldwide

2021 ◽  
Author(s):  
Fernando Jaramillo ◽  
Dan Liu ◽  
Saeid Aminjafari ◽  
Xuan Wang
Keyword(s):  
Large Scale ◽  
Wetland Management ◽  
Northern China ◽  
Water Levels ◽  
Interferometric Synthetic Aperture Radar ◽  
Alos Palsar ◽  
Critical Determinant ◽  
Wetland Functions ◽  
Dry Seasons ◽  
Baiyangdian Wetland

<p>Hydrological connectivity is a critical determinant of wetland functions and ecosystems by controlling the movement of biogeochemical elements within wetlands and the flow of water between their hydrological units. Hydrological barriers exist when this connectivity is impaired, either by man-made infrastructure, agriculture developments, or naturally restricted by soil and ground composition. Determining hydrological barriers in wetlands is challenging due to the costs of high-resolution and large-scale monitoring, but radar observations can become a useful tool for such task. We here use an Interferometric Synthetic Aperture Radar (InSAR) to identify hydrological barriers in several iconic wetlands worldwide, with particular focus on the Baiyangdian wetland system in Northern China. For the first, we use Sentinel 1A and 1B data covering the period 2016-2019, while for the rest we rely on ALOS PALSAR data. We calculated profiles of water level change across hydrological transects showing high coherence and visualized them in maps. For instance, in the case of the Baiyangdian wetland, we find that of the 70 transects studied, 11% of all transects are permanently disconnected by hydrological barriers across all interferograms and 58% of the transects are conditionally disconnected. The occurrence of hydrological barriers varies between wetlands, with permanent barriers more related to ditches, infrastructure and the specific wetland landscape, and conditional barriers more to low water levels during dry seasons. This study highlights the potential of the application of wetland InSAR to determine hydrological barriers for wetland management and restoration.</p>

Implications of Spatio-Temporal Variation in Forage Production and Utilization for Animal Productivity in Extensive Grazing Systems.

1998 ◽  
Vol 20 (1) ◽  
pp. 3 ◽  
Author(s):  
DA Roshier ◽  
HI Nicol
Keyword(s):  
Temporal Variation ◽  
Management Practice ◽  
Animal Production ◽  
Forage Production ◽  
Forage Availability ◽  
Typical Experiment ◽  
Grazing Systems ◽  
Spatio Temporal ◽  
The Difference ◽  
Plant Animal Interactions

In this paper we examine patterns of utilisation at the level of individual plants and forage availability at the paddock scale on five commercial sheep grazing properties that all experienced drought during the course of the study. Specifically, patterns of forage availability and pasture utilisation in large paddocks are examined against the assumptions of established models of animal productivity and grazing management practice. Forage resources in the rangelands can have dynamics independent of stock density and are not distributed evenly in time or space. Therefore, the extrapolation of known plant-animal interactions across scales is questionable and it is yet to be demonstrated how measures of animal productivity on small trial paddocks relate to production outcomes in large paddocks. A model is proposed for understanding animal production outcomes that incorporates variation in both pasture biomass and stock density. The scales, both spatial and temporal, at which pastoralists and scientists integrate ecological and animal productivity information usually differ. The understanding that each holds of the processes that limit animal productivity and the relationships between different elements of the production system is a product of the perspective from which they view the system. It is concluded that the difference between the 'scale of exploitation' and the scale at which heterogeneity is sufficient for survival of livestock is probably crucial to determining animal production outcomes in grazing systems subject to a high degree of temporal variation in forage availability. In these systems it seems reasonable to suggest that grazing experiments that vary the 'spatial scale of exploitation' while maintaining stock density constant may give as many insights into the limitations on animal productivity as the more typical experiment that only varies stock density. Key words: grazing models, animal productivity, heterogeneity, scale, utilisation, forage availability, stocking rates.

Reproductive strategy and growth of the Australian smelt, Retropinna semoni (Weber) (Pisces : Retropinnidae), and the olive perchlet, Ambassis nigripinnis (De Vis) (Pisces : Ambassidae), in Brisbane, south-eastern Queensland

1985 ◽  
Vol 36 (3) ◽  
pp. 329 ◽  
Author(s):  
DA Milton ◽  
AH Arthington
Keyword(s):  
Native Species ◽  
Juvenile Fish ◽  
Open Water ◽  
Water Levels ◽  
South Eastern ◽  
Large Populations ◽  
Coastal Streams ◽  
Littoral Vegetation ◽  
Suitable Habitats ◽  
Eggs And Larvae

The reproductive biology and growth of R. semoni and A. nigripinnis were studied in Brisbane, south- eastern Queensland, over a 20-month period (1981-1982). R. semoni began to breed in winter at water temperatures exceeding 15�C, reflecting its salmoniform affinities and temperate distribution. A. nigripinnis, a subtropical species of Indo-Pacific origin, required a period of rising temperature before breeding began in spring at 22�C. Both species concentrated their breeding activity into the months that precede summer storms and high, variable stream discharges, which can generate fluctuating water levels, destruction of weedbeds and instability of the stream substrate. Pre-flood spawning also occurs in three other small-bodied native species in the region, and appears to have adaptive value in the seasonally unstable environments of coastal streams. Dispersal of juvenile fish may be facilitated by rising water levels during summer months following spawning. R. semoni grew faster and to larger sizes than A. nigripinnis and growth of both species was adequately described by the von Bertalanffy equation. Male and female R. semoni and male A. nigripinnis live and breed for 2 years but female A. nigripinnis survive and may breed into their third year. These patterns of survivorship and reproduction are consistent with the contention that natural mortality is higher in open-water foragers such as R. semoni than in species like A. nigripinnis, which tends to forage amongst littoral vegetation and in mid-water. Differences in the sizes of eggs and larvae of the two species are also consistent with the probability that they experience different relative exposure to predation. These and other attributes, coupled with pre-flood spawning, enable both species to achieve large populations in suitable habitats within coastal streams, in spite of their relatively low fecundities.

Nutrients in Salmonid Ecosystems: Sustaining Production and Biodiversity

2003 ◽  
Keyword(s):  
Primary Production ◽  
Sockeye Salmon ◽  
Secchi Depth ◽  
Zooplankton Biomass ◽  
Snake River ◽  
Forage Production ◽  
Meteorological Forcing ◽  
Kokanee Salmon ◽  
Compensation Depth ◽  
Large Populations

<em>Abstract.</em>—Snake River sockeye salmon <em>Oncorhynchus nerka </em>once inhabited five prealpine lakes in the Sawtooth Valley, Idaho, but are presently reduced to the Redfish Lake stock. Declining returns to Redfish Lake in the 1980s prompted the National Marine Fisheries Service to list Snake River sockeye salmon as endangered under the Endangered Species Act, and a multi-agency effort was initiated in 1991 to prevent their extinction. The recovery effort focused on the development of a captive broodstock coupled with evaluation and enhancement of nursery lake habitats. Large populations of nonendemic kokanee salmon <em>O. nerka </em>and the oligotrophic conditions of these lakes raised concerns about overstocking sockeye salmon and causing the collapse of macrozooplankton populations. To minimize these risks and to improve sockeye salmon forage production, the Shoshone- Bannock Tribes initiated a 4-year nutrient enrichment program in Redfish Lake. Liquid fertilizer (20:1, N:P by wt) was added weekly during the growing season from 1995 to 1998 to the surface of Redfish Lake with Stanley Lake (unfertilized) acting as a control. During the fertilization of Redfish Lake, Secchi depth decreased by 13% and compensation depth by 24%, while increases were observed for surface chlorophyll <em>a </em>(106%) and primary production (117%). Uniformity of phytoplankton communities throughout the experiment indicated that the Redfish Lake food web was efficient (without major carbon sinks) and improved forage conditions for macrozooplankton. Total macrozooplankton biomass increased 31%, and <em>Daphnia </em>spp<em>. </em>biomass increased by 225%, simultaneous to a 26% increase in <em>O. nerka </em>density. Also, during fertilization, overwinter survival of supplemented sockeye salmon increased 192% in Redfish Lake. However, meteorological conditions were partly responsible for these changes. In unfertilized Stanley Lake, during the same time periods, Secchi depth declined 27%, and compensation depth was reduced by 28%; chlorophyll <em>a </em>increased 16%, primary production increased 14%, and zooplankton biomass was stable. These changes highlight the importance of climate (meteorological forcing) and the need for a control when attempting to identify impacts from lake fertilization. Disproportionately larger increases in Redfish Lake chlorophyll <em>a</em>, primary productivity, and zooplankton biomass relative to observed changes in Stanley Lake provide evidence for the efficacy of nutrient supplementation in Redfish Lake.

Wintering Behaviour and Spatial Ecology of Eurasian Wigeon Anas Penelope in a Coastal Mediterranean Wetland Complex (Guerbes-Sanhadja) of Northeastern Algeria

2017 ◽  
Vol 10 (2) ◽  
pp. 84-91 ◽  
Author(s):  
Laid Bouchaala ◽  
Ali Elafri ◽  
Nabil Charchar ◽  
Mohamed Boukhemza ◽  
Moussa Houhamdi
Keyword(s):  
Spatial Ecology ◽  
Wetland Management ◽  
Common Species ◽  
Sensitive Species ◽  
Bird Abundance ◽  
Wetland Complex ◽  
Anas Penelope ◽  
Migration Phenology ◽  
Northeastern Algeria

As rare and threatened species, ecological information about common waterbirds is needed to assess priorities for wetland management. In this study, we attempt to provide information about the spatial ecology and wintering behaviour of one of the most common species of the coastal Mediterranean wetland complex of northeastern Algeria, the Eurasian Wigeon Anas penelope. Over the three winters of the study the maximum number of recorded Eurasian Wigeon across all sites rose from 1,096 in 2010/11 to 1,397 in 2012/13. This represents a 27% increase over three years in the Guerbes-Sanhadja region. Among these wetland complex sites abundance varied markedly during the three wintering periods of study, being highest in Garaet Hadj-Tahar and Garaet Beni Mhamed (ranging from 300–700 individuals), and lowest in the remaining sites, which never exceeded 150 individuals. Bird abundance often peaked in January of each year and decreased as winter progressed. Wigeon have similar patterns of migration phenology among years at Garaet Hadj-Tahar and Garaet Beni Mhamed. At the remaining sites, they exhibited a different pattern. The multiple regression analysis for all seasons showed a marginally significant correlation between Wigeon abundance changes and three environmental variables of the wetland complex exclusively in the spring seasons (depth, vegetation and temporariness). A roosting area is identified as a functional role of the Guerbes-Sanhadja wetland complex for this anatid, since they spent all of the daytime sleeping, swimming (ranged from 30 to 40%), and resting (from 15 to 25%) in all winters. Despite their semi-permanent and unprotected status (apart from only three sites), these patched wetlands provide suitable conditions for this sensitive species, and therefore should receive the attention of wetland management.

Mapping foraging habitat for migratory shorebirds in their Australian non-breeding grounds and prioritising sites for conservation and management

2017 ◽  
Vol 23 (1) ◽  
pp. 32 ◽  
Author(s):  
Amanda Lisson ◽  
Kathryn H. Taffs ◽  
Leslie Christidis
Keyword(s):  
Wildlife Conservation ◽  
Conservation Status ◽  
River Estuary ◽  
Breeding Habitat ◽  
Foraging Habitat ◽  
Coastal Habitat ◽  
Management Actions ◽  
Migratory Shorebirds ◽  
Trade Offs ◽  
Shorebird Habitat

Shorebird populations are declining worldwide as a result of the loss of the intertidal habitats upon which they depend. Conservation status is particularly dire for shorebirds on the East Asian–Australasian Flyway. While the flyway transects many international boundaries and involves numerous bilateral conservation agreements, management of remaining habitat at a local scale is imperative to conserving these species. Coastal habitat is affected by multiple anthropogenic stressors, including loss and degradation due to increasing demand for coastal land. In Australia, migration coincides with the summer holiday season when shorebirds are significantly impacted by human disturbance. Managers are frequently required to make trade-offs between wildlife conservation and anthropogenic land uses and when specific quantitative shorebird habitat data and mapping are absent, human interests will naturally take precedence. This paper demonstrates a method for mapping and prioritising management of shorebird non-breeding habitat using an Australian coastal site, the Richmond River estuary. Foraging habitat was surveyed and mapped using GIS with a range of attributes including habitat types, foraging values, disturbance levels and specific foraging distribution of each species. The results highlighted several important foraging areas that were impacted by disturbance and would require intervening management actions to reduce impacts on shorebirds. The GIS data created provide local managers with an effective tool to consider shorebird habitat in the decision-making process. This method could be replicated at other important shorebird habitat sites, leading to enhanced conservation of these declining species.

scholarly journals Differences of Regulative Flexibility between Hydrological Isolated and Connected Lakes in a Large Floodplain: Insight from Inundation Dynamics and Landscape Heterogeneity

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 991
Author(s):  
Jiakun Teng ◽  
Shaoxia Xia ◽  
Yu Liu ◽  
Peng Cui ◽  
Jiang Chen ◽  
...  
Keyword(s):  
Habitat Quality ◽  
Yangtze River ◽  
Vegetation Index ◽  
Poyang Lake ◽  
Wetland Management ◽  
Google Earth ◽  
Dongting Lake ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Jianghan Plain

The inundation areas of floodplains are crucial to wetland ecosystems, especially in supporting biodiversity. Accurately identifying the spatial and temporal patterns of inundation areas is important for understanding floodplain ecosystem processes. Here, lakes in the Yangtze River Floodplain were divided into two types according to hydrological conditions: the natural connected lakes (Dongting Lake and Poyang Lake) with natural water level fluctuations and the isolated lakes (lakes in Jianghan Plain) with stable water levels. We established a method to identify inundation areas using multi-sources remote sensing data based on the Google Earth Engine. The dynamics of inundation areas were determined, and the relative indices were calculated in common year (2017) and a drought year (2018). The differences between the connected lakes and the isolated lakes were analyzed, and impacts of hydrological fluctuations on inundation area and habitat quality were evaluated. The results show that lakes with natural hydrological fluctuations have a greater regulative flexibility, with both patch density (PD) and submerged elasticity index (SEI) values higher than that of isolated lakes. The trend of the vegetation index in the connected lakes and in the isolated lakes is also different. The mean EVI in Dongting Lake and Poyang Lake showed a U-shaped trend which is similar to the shape of the trend of PD. The trend of mean enhanced vegetation index (EVI) in the isolated lakes is the opposite and has a lower range of variation over a year. This study provides new indicators and rapid methods for habitat quality assessment in floodplains, as well as presenting scientific information useful for improving wetland management in the middle and lower Yangtze River.

scholarly journals The greenhouse gas balance of European grasslands

2010 ◽  
Vol 7 (4) ◽  
pp. 5997-6050 ◽  
Author(s):  
P. Ciais ◽  
J. F. Soussana ◽  
N. Vuichard ◽  
S. Luyssaert ◽  
A. Don ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Eddy Covariance ◽  
Net Primary Productivity ◽  
Carbon Sink ◽  
Management Practice ◽  
Carbon Sinks ◽  
Forage Production ◽  
Greenhouse Gas Balance ◽  
Ch4 And N2o ◽  
Gas Balance

Abstract. The long-term carbon balance (NBP) of grasslands is estimated by combining scarce multi-year eddy-covariance observations at ecosystem observation sites where information on carbon inputs and harvesting removals is available. Following accounting for carbon leached to rivers, we estimated grasslands to be net carbon sinks of 74±10 g C m−2 yr−1. Uncertainties arise from the small number of sites and the short measurement period. Only 11 sites, out of a total of 20 grassland sites in Europe where eddy covariance systems are installed, were set-up for estimating NBP. These 11 selected sites are representative of intensive management practice and we lack information on disturbance history, such as plowing. This suggests that the grassland NBP estimate is likely biased towards overestimating the sink, compared to the European average. Direct measurements of Net Primary Productivity (NPP) are not possible in grasslands given permanent biomass removal by grazing and mowing, uncertainties in rhizodeposition and production of volatile organic carbon compounds lost to the atmosphere. Therefore, the grassland process-based ecosystem model PASIM was used to estimate the spatial-temporal distribution of NPP, providing a European average value of 750±150 g C across extensively grazed, intensively grazed pastures, and forage production systems. In Europe the NPP of grasslands seems higher than that of croplands and forests. The carbon sequestration efficiency of grasslands, defined as the ratio of NBP to NPP, amounts to 0.09±0.10. Therefore, per unit of carbon input, grasslands sequester 3–4 times more carbon in the soil than forests do, making them a good candidate for managing onsite carbon sinks. When using the 100 yr greenhouse warming potential for CH4 and N2O, their emissions due to management of grasslands together offset roughly 70–80% of the carbon sink. Uncertainties on the European grassland greenhouse gas balance, including CO2, CH4 and N2O fluxes are likely to be reduced in the near future, with data being collected from more sites, and improved up-scaling methods.

scholarly journals Numerical Response of Migratory Shorebirds to Prey Distribution in a Large Temperate Arid Wetland, China

Scientifica ◽  
2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Yamian Zhang ◽  
Yi Zhu ◽  
Aojie Zuo ◽  
Li Wen ◽  
Guangchun Lei
Keyword(s):  
Total Phosphorus ◽  
Benthic Macroinvertebrates ◽  
Prey Density ◽  
Sediment Quality ◽  
Migratory Shorebirds ◽  
Water And Sediment Quality ◽  
Stopover Habitat ◽  
High Concentrations ◽  
Shorebird Habitat ◽  
Very High

Wuliangsuhai Lake provides important breeding and stopover habitats for shorebirds. The health of this wetland ecosystem is rapidly deteriorating due to eutrophication and water pollution and environmental management is urgently needed. To explore the connections among ecosystem health, prey density, and shorebird populations, we conducted surveys of both the benthic macroinvertebrates and shorebirds in the shorebird habitat of the wetland during the 2011 autumn migration season. The abundance of both shorebirds and benthic macroinvertebrates varied significantly in both space and time. Our data showed a clear association between shorebird populations and the density of benthic macroinvertebrates, which explained 53.63% of the variation in shorebird abundance. The prey density was strongly affected by environmental factors, including water and sediment quality. Chironomidae were mainly found at sites with higher total phosphorus, but with lower sediment concentrations of Cu. Lymnaeidae were mainly found at sites with a higher pH, lower salinity, and lower concentrations of total phosphorus and Cu. Habitats with very high concentrations of total phosphorus, heavy metals, or salinity were not suitable for benthic macroinvertebrates. Our findings suggest that the reductions of nutrient and heavy metal loadings are crucial in maintaining the ecological function of Wuliangsuhai as a stopover habitat for migratory shorebirds.

The benefits of crops and field management practices to wintering waterbirds in the Sacramento–San Joaquin River Delta of California

2015 ◽  
Vol 31 (6) ◽  
pp. 495-506 ◽  
Author(s):  
W. David Shuford ◽  
Matthew E. Reiter ◽  
Khara M. Strum ◽  
Michelle M. Gilbert ◽  
Catherine M. Hickey ◽  
...  
Keyword(s):  
Management Practices ◽  
Management Practice ◽  
Bird Species ◽  
Central Valley ◽  
Agricultural Landscapes ◽  
Wildlife Habitat ◽  
River Delta ◽  
Waterbird Species ◽  
San Joaquin River ◽  
Field Management

AbstractAgricultural intensification has been a major factor in the loss of global biodiversity. Still, agricultural landscapes provide important habitat for many bird species, particularly in the Central Valley of California, USA, where >90% of the natural wildlife habitat has been lost. As wildlife professionals increasingly work with agricultural producers to promote ‘wildlife-friendly’ farming, it is important to understand the relative value of specific crops and field management practices to birds. The value to wintering waterbirds of seven treatments (crop and management practice combinations) across two crops (corn and winter wheat) was assessed at Staten Island in the Sacramento–San Joaquin River Delta of the Central Valley. Significant variation in the relative abundance of waterbirds was found among management practices, and post-harvest flooding and chopping and rolling (mulching) of corn were most beneficial to waterbirds. As expected, most waterbirds were common in flooded treatments, but geese, cranes and long-legged waders also were numerous in some dry treatments. Our data suggest that a greater waterbird species richness and abundance can be achieved by maintaining a mosaic of dry and flooded crop types, varying water depths and continuing the chop-and-roll practice for flooded corn. The observed benefits of particular crops and field management practices in this study should aid in the development of incentive-based programs to improve the habitat value of other working lands both within, and outside, the Delta.

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