The 178,000-acre Grassland Ecological Area in California’s San Joaquin Valley is managed to provide overwintering habitat to waterfowl on the Pacific Flyway. The major management activity is the fall flooding and spring drawdown of wetlands, timed to optimize the availability of forage vegetation and invertebrates for ducks and shorebirds. Wetland drainage contains salt, boron, and trace elements that are, in part, derived from imported surface water but also concentrate during storage in the wetland impoundments. The spring drawdown drainage contributes to occasional water quality violations in the San Joaquin River (SJR) during dry years. Compliance with water quality objectives may be improved by delaying the traditional wetland drawdown period approximately one month to coincide with high SJR salt assimilative capacity during mid-March to mid- April when reservoir releases are increased to aid salmon migration. However, this delayed drawdown may affect the quality and quantity of wetland vegetative forage, increase wetland soil salinity, and possibly alter the concentrations of algae, invertebrates, and pollutants in the wetlands. In the research presented herein, initial data were collected on the effects of delayed drawdown on algae, invertebrates, and wetland water quality. The experimental sites chosen were three pairs of matched wetland basins (20-100 acres each) that are part of the larger Modified Hydrology Study being conducted in the Grassland Ecological Area. For each pair, one wetland was managed with a traditional March drawdown; while for the second wetland, drawdown was delayed approximately one month to coincide with the period of high SJR assimilative capacity. During the second year of the study, two drainage sites were sampled to characterize drainage flowing to the SJR from an aggregated wetland area. Soil and water column samples were collected during the flooded periods at the inlets, outlets, and along transects within the wetlands. Water quality analyses included total/volatile suspended solids, conductivity, nitrogen (NH4 +, NO2⁻+NO3⁻, organic), phosphorus (total, PO4 3-), organic carbon, alkalinity, turbidity, temperature, and pH. Planktonic and benthic invertebrates were identified and enumerated. Data were collected between February and April in 2007 and again in 2008. Identified phytoplankton were predominantly chlorophytes and diatoms. Zooplankton that feed on phytoplankton were found in abundance and consisted mostly of Cladocera. Benthic invertebrate densities were also measured to help explain the differences in algal concentrations between ponds. Benthic invertebrates were found to be predominantly Chironomidae. Seasonal loads of volatile suspended solids, total dissolved solids, and total organic carbon were estimated at the two aggregate drainage sites and at one delayed drawdown wetland during the 2008 season. For volatile suspended solids, the discharged load was 1500 lbs at the Buttonwillow drainage site, 2500 lbs at the Los Banos 38 drainage site, and upstream of those sites, 770 lbs were discharged from the Mud Slough 4b wetland. For total dissolved solids, the discharged load was 290 tons, 520 tons, and 26 tons, respectively, for the same locations. Of the factors potentially limiting phytoplankton concentrations, invertebrate grazing was likely the most important. Nutrients were not limiting in either the traditional or modified wetlands, as indicated by sufficient N and P content in the algae biomass. Likewise, inorganic C was not limiting, as indicated by pH (most <9.0 pH). Sunlight intensity was not significantly attenuated by water depth or turbidity, and thus light limitation was not indicated.

<p>The study is about how green spaces and structures of Dar es Salaam city, quantitatively and qualitatively, are browning out. It also tries to explore the different reasons behind the browning tendency, and what it means to the function of the city and to the daily form of life of the inhabitants. Finally there is a discussion about how to counteract the tendency by involving the inhabitants in planning procedures following the communicative approach to planning. The main investigations have been a) time series mapping of the browning process at city, settlement, block and plot levels; and b) interviews with inhabitants individually and as groups in two settlements. </p><p>The result is that the quantity of green spaces and structures is decreasing fast in all levels. It is also found that, concerning the browning tendency, the development in formal and informal areas is the same. The quality of the remaining green spaces and structures is also decaying. Among other things, imported plant species, in all levels, replace the indigenous ones. They often cause disturbance and extinctions to local flora and fauna. All in all, the browning tendency is a threat to the ecological functioning of the green as a system, infrastructural and health aspects on the city. It is also a threat to typical daily lifestyles in the city. Throughout, low-density with low-rise detached houses characterize the city, which expands continuously both outward and inward. So it is a sprawled city. In most of the remaining green spaces of this sprawled structure vegetables and other food plants are grown for the benefit of the urban poor, now threatened. </p><p>The inhabitants in the studied blocks seem to take responsibility of supplying, using and caring their green plants and spaces. They also often co-operate in solving ad-hoc environmental problems in their living environments. But in their plots and around them they nevertheless keep on building more and more on a limited plot space, mostly for economic reasons. Another room is more worth economically than some vegetables or the shade of a tree. Finally it seems that local community, if well empowered, have potentials in managing their own living environment. </p><p>The study concludes that in a city whose largest proportion of population is poor and unemployed, urban sprawl could offer, at the moment, an appropriate form. This conclusion challenges how the concept of the sustainable city has been elaborated and evolved in western countries.</p>

The study is about how green spaces and structures of Dar es Salaam city, quantitatively and qualitatively, are browning out. It also tries to explore the different reasons behind the browning tendency, and what it means to the function of the city and to the daily form of life of the inhabitants. Finally there is a discussion about how to counteract the tendency by involving the inhabitants in planning procedures following the communicative approach to planning. The main investigations have been a) time series mapping of the browning process at city, settlement, block and plot levels; and b) interviews with inhabitants individually and as groups in two settlements. The result is that the quantity of green spaces and structures is decreasing fast in all levels. It is also found that, concerning the browning tendency, the development in formal and informal areas is the same. The quality of the remaining green spaces and structures is also decaying. Among other things, imported plant species, in all levels, replace the indigenous ones. They often cause disturbance and extinctions to local flora and fauna. All in all, the browning tendency is a threat to the ecological functioning of the green as a system, infrastructural and health aspects on the city. It is also a threat to typical daily lifestyles in the city. Throughout, low-density with low-rise detached houses characterize the city, which expands continuously both outward and inward. So it is a sprawled city. In most of the remaining green spaces of this sprawled structure vegetables and other food plants are grown for the benefit of the urban poor, now threatened. The inhabitants in the studied blocks seem to take responsibility of supplying, using and caring their green plants and spaces. They also often co-operate in solving ad-hoc environmental problems in their living environments. But in their plots and around them they nevertheless keep on building more and more on a limited plot space, mostly for economic reasons. Another room is more worth economically than some vegetables or the shade of a tree. Finally it seems that local community, if well empowered, have potentials in managing their own living environment. The study concludes that in a city whose largest proportion of population is poor and unemployed, urban sprawl could offer, at the moment, an appropriate form. This conclusion challenges how the concept of the sustainable city has been elaborated and evolved in western countries. / QC 20101018