Improved Land Management Practices Research Articles

Cost effectiveness of design-based water quality improvement regulations in the Great Barrier Reef Catchments

Coastal and marine ecosystems are adversely affected by diffuse source pollution from agricultural activities in coastal river catchments (or watersheds). To address this issue, government policy has been designed to increase adoption of improved land management practices that are known to minimise the runoff of sediments and nutrients into waterways. Government policy can be implemented through a spectrum of approaches ranging from voluntary to regulatory, and often occurs through a mix of approaches. In this paper we argue that it makes economic and ecological sense to focus investments on those parts of the landscape with greatest potential to reduce pollutants at least cost. To examine this, a financial economic analysis is combined with agricultural production analysis and catchment scale hydrological analysis using a Bayesian belief network model. We explore and compare the cost-effectiveness of two homogenous design based approaches, aimed at reducing diffuse source nutrient pollutants exports, between two biophysically and socio-economically heterogeneous catchments in the Great Barrier Reef Catchment Area, Australia. Sugarcane production is regarded as a major source of pollutants with the dominant pollutant being nitrogen. Our results show significant differences between catchments, both in relation to costs and benefits as well as water quality improvement potential, suggesting a spatially targeted approach may lead to more cost efficient pollutant reductions.

Land use and climate change impacts on the hydrology of the upper Mara River Basin, Kenya: results of a modeling study to support better resource management

Abstract. Some of the most valued natural and cultural landscapes on Earth lie in river basins that are poorly gauged and have incomplete historical climate and runoff records. The Mara River Basin of East Africa is such a basin. It hosts the internationally renowned Mara-Serengeti landscape as well as a rich mixture of indigenous cultures. The Mara River is the sole source of surface water to the landscape during the dry season and periods of drought. During recent years, the flow of the Mara River has become increasingly erratic, especially in the upper reaches, and resource managers are hampered by a lack of understanding of the relative influence of different sources of flow alteration. Uncertainties about the impacts of future climate change compound the challenges. We applied the Soil Water Assessment Tool (SWAT) to investigate the response of the headwater hydrology of the Mara River to scenarios of continued land use change and projected climate change. Under the data-scarce conditions of the basin, model performance was improved using satellite-based estimated rainfall data, which may also improve the usefulness of runoff models in other parts of East Africa. The results of the analysis indicate that any further conversion of forests to agriculture and grassland in the basin headwaters is likely to reduce dry season flows and increase peak flows, leading to greater water scarcity at critical times of the year and exacerbating erosion on hillslopes. Most climate change projections for the region call for modest and seasonally variable increases in precipitation (5–10 %) accompanied by increases in temperature (2.5–3.5 °C). Simulated runoff responses to climate change scenarios were non-linear and suggest the basin is highly vulnerable under low (−3 %) and high (+25 %) extremes of projected precipitation changes, but under median projections (+7 %) there is little impact on annual water yields or mean discharge. Modest increases in precipitation are partitioned largely to increased evapotranspiration. Overall, model results support the existing efforts of Mara water resource managers to protect headwater forests and indicate that additional emphasis should be placed on improving land management practices that enhance infiltration and aquifer recharge as part of a wider program of climate change adaptation.

Fitzroy River Basin, Queensland, Australia. III. Identification of sediment sources in the coastal zone

Environmental context. The Fitzroy River Basin is a major source of suspended sediment and nutrients to the southern Great Barrier Reef lagoon. A reduction in sediment and nutrient loads is necessary to protect coastal reefs and this requires an understanding of the sediment sources. The present geochemical and modelling study provides a quantitative estimate of the spatial and temporal variations in the sources of sediment deposited in the Fitzroy River coastal zone. Abstract. Sediment sources to the Fitzroy River coastal zone have been identified and quantified using an integrated geochemical and modelling approach. The coastal sediments display little geochemical variation as a result of substantial homogenisation during hydrodynamic processes and indicate a sediment composition consistent with derivation from mixed catchment sources. A lack of substantial temporal geochemical variation in the sediment records indicates weathering regimes and hydrodynamic transport have been relatively consistent throughout the Holocene. Despite this apparent geochemical homogeneity, a modelling approach using a Bayesian statistical model revealed changes in catchment sediment sources over time. Variations in the occurrence and intensity of rainfall events in different parts of the catchment as well as land-use changes following European settlement are likely to have had a substantial effect on the relative contributions of the catchment sources delivered to and deposited in the coastal zone. Additionally, large variations in flow events and variable estuary hydrodynamics result in different catchment soil types being delivered and deposited under different conditions. The present study found that basaltic material is the dominant catchment source in the coastal surface sediments with an estimated enrichment of ~3 relative to catchment and estuary abundances. Basaltic soils present as a more recent and extensive, weathered surficial cover are more readily mobilised than other catchment soils and will be transported further within freshwater flood plumes. It is likely that in large flood events, this basaltic material may reach the coral-dominated outer shelf. Improved land management practices to reduce sediment loads can be targeted to the areas supplying the majority of sediment to the coastal zone.

Combining sediment source tracing techniques with traditional monitoring to assess the impact of improved land management on catchment sediment yields

Summary This paper aims to demonstrate the potential value of combining sediment source tracing techniques with traditional monitoring approaches, when documenting the impact of improved land management on catchment sediment yields. It reports the results of an investigation undertaken in a small (1.19 km 2 ) agricultural catchment in southern Brazil, which was monitored before and after the implementation of improved land management practices. Attention focussed on 50 storm events that occurred between May 2002 and March 2006 and which reflected the behaviour of the catchment during the pre-change, transition and post-change periods. Improved land management, involving minimum-till cultivation and the maintenance of good crop cover, was introduced in early 2003. The traditional monitoring provided a basis for evaluating the changes in storm runoff volume, storm hydrograph peak and storm-period sediment load and mean suspended sediment concentration. The results indicate that both storm runoff volumes and peak flows associated with a given amount of rainfall provided evidence of a significant decrease after the introduction of improved land management. Storm-period sediment loads showed a similar reduction, with a reduction by as much as 80% for low magnitude events and of ca. 40% for events of intermediate magnitude. However, there was no significant change in mean suspended sediment concentrations, indicating that the reductions in sediment load were primarily the result of the reduced storm runoff volume. Sediment source fingerprinting was used to explore the changes in the relative and absolute contributions to the storm sediment loads from the three key sources, namely the surface of the fields under crops, the unpaved roads and the stream channels. A comparison of the load-weighted mean contributions for the pre- and post-treatment periods indicated that the contribution from the field surfaces and unpaved roads decreased from 63% and 36% to 54% and 24%, respectively, whereas the contribution from the stream channels increased from ca. 2% to 22%. By relating the absolute amounts of sediment mobilised from each individual source group to variables representing the runoff and precipitation associated with the events, it was possible to identify changes in the response of the individual sediment sources to the changes in land management that occurred within the catchment. Sediment mobilisation from the stream channel during individual events increased substantially over the whole range of flows after the introduction of improved land management in the study catchment, whereas the amounts of sediment mobilised from the surfaces of the fields and the unpaved roads showed a significant decrease during events of low and intermediate magnitude. The short monitoring period associated with the study, coupled with inter-annual variations in rainfall, necessarily limit the scope and rigour of the study reported, but it is seen to provide a useful demonstration of how the coupling of sediment source tracing with more traditional monitoring techniques can provide an improved understanding of the impact of improved management practices on the sediment response of a catchment, as well as important information to inform the design and implementation of effective sediment management and control measures.

Use of 7Be to document soil erosion associated with a short period of extreme rainfall

Intensification and expansion of agricultural production since the 1970s have increased soil erosion problems in south-central Chile. Quantitative information on soil loss is needed for erosion risk assessment and to establish the effectiveness of improved land management practices. Since information from traditional sources, such as erosion plots, is limited, attention has been directed to the use of environmental radionuclides for documenting erosion rates. Cs-137 has been successfully utilised for this purpose, but only provides information on medium-term erosion rates. There is also a need to document event-related soil erosion. This paper outlines the basis for using 7Be measurements to document short-term erosion and reports its successful use for quantifying the erosion that occurred within an arable field, as a result of a period of heavy rainfall (400 mm in 27 days) occurring in May 2005. The study field had been under a no-till, no-burning system for 18 years, but immediately prior to the period of heavy rainfall the harvest residues were burnt. The erosion recorded therefore reflected both the extreme nature of the rainfall and the effects of the burning in increasing surface runoff and erosion. The sampled area corresponded to that used previously by the authors to document the medium-term erosion rates associated with both conventional tillage and the subsequent switch to a no-till system. Comparisons between the erosion documented for the period of heavy rainfall in 2005 with these medium-term erosion rates permits some tentative conclusions regarding the importance of extreme events and the impact of burning in increasing the erosion associated with the no-till system.

Working with Communities and Building Local Institutions for Sustainable Land Management in the Ethiopian Highlands

Land management is a multi-dimensional and multi-institutional engagement that demands collective analysis, design, and implementation of innovations. Its importance for Ethiopia cannot be overemphasized, as land degradation threatens food security and environmental sustainability. Building on a specific case study of a project in Southern Ethiopia, the present article describes how the government and non-state agencies are collaborating to learn together while promoting improved land management practices and implementing land rehabilitation programs in communal areas and farmlands in the Ethiopian highlands. Ensuring full involvement and commitment of stakeholders at different levels, building the capacity of local institutions, and redefining the role of communities and the state in a dynamic way are essential prerequisites for success. Suggestions have also been formulated to facilitate wider adoption and scaling up of improved land management innovations.

Public policy, private landholders: Perspectives on policy mechanisms for sustainable land management

A variety of tools can be employed in support of environmental policy objectives, but achieving preferred outcomes also requires the cooperation of private landholders and others with vested interests in the land. The Land Stewardship project in the state of Victoria, Australia, is an initiative devoted to exploring the ways in which private landholders could be encouraged towards more sustainable land management. Following the view that the success of policy initiatives is contingent on effective stakeholder engagement, a component of the Land Stewardship project involved a dialogue with landholders about policy tools (e.g., regulation, economic instruments) that might be deployed to encourage improved land management practices. This paper provides an account of the views and attitudes of landholders, as revealed in a series of three workshops, which consisted of discussions about the factors influencing agriculture, participants’ interpretations of sustainability, and policy methods. The focus of the paper is on what landholders believe to be the strengths and limitations of standard policy tools, and the essential requirements for these tools to deliver the best land management outcomes. One of the main findings of the project was a ‘preference hierarchy’ in respect of policy methods, according to which the strongest support was expressed for voluntary and education-based tools, followed by market-based instruments, with command-and-control regulation identified as a measure of ‘last resort’. In the paper we reflect also on how the views and outlook of landholders should be positioned relative to other inputs in the design of policy interventions.

Climatic trends associated with summerfallow in the Canadian Prairies

The Canadian Prairies have undergone important land use changes over the past 150 years. Beginning in the early 20th century, a significant portion of agricultural land was under summerfallow primarily to conserve soil moisture. The area under fallow grew to over 11 Mha, which constitute about 25% of Canada's cultivated land, and mostly remained at that level until 1975, subsequent to which improved land management practices led to significant reductions in areas under summerfallow. By 2001 summerfallow area had been reduced to 5.4 Mha, and future projections expect it to fall to 3.5 Mha. Numerous modeling studies and observations have shown that land use change can have a significant impact on regional and local climate. In the Canadian Prairies, these effects would likely be seen during the mid-June to mid-July period, when agricultural crops undergo rapid foliar expansion and substantial transpiration, thus contributing to significantly higher latent heat fluxes. Observations of 1976–2000 climate trends in the black, dark brown and brown soil zones of the Canadian Prairies showed that there have been substantial reductions in maximum temperature (1.7 °C decade −1), diurnal temperature range (1.1 °C decade −1) and solar radiation (1.2 MJ m −2 decade −1), as well as a corresponding increase in precipitation (10.3 mm decade −1) during the mid-June to July period. These findings are in opposition to trends that would be expected from climate change from an enhanced greenhouse effect, and suggest that there is substantial correspondence between reductions in summerfallow and changes in climate in the agricultural regions of the Canadian Prairies.

Fitzroy River, Queensland, Australia. II. Identification of Sources of Estuary Bottom Sediments

Environmental Context. The Fitzroy River Basin constitutes a major source of suspended sediment and nutrient fluxes to the southern Great Barrier Reef. Improved land management practices to ameliorate these catchment loads require an understanding of the sediment sources and dynamics. This multidisciplinary geochemical and modelling study provides for the first time a quantitative estimate of sediment sources delivered to, and their degree of retention in, the Fitzroy River Estuary. Abstract. Sources of sediment deposited in the Fitzroy River Estuary (FRE) have been identified and quantified using an integrated geochemical, modelling and reconnaissance soil sampling approach. A companion paper (this volume) identifies the major sources of sediments in impoundments on the major river systems and sediment sampled from flood events in the Fitzroy River Basin (FRB). Sediment within the FRE may display distinct longitudinal variation with little basaltic material retained. Sediments derived from the Bowen Basin, which occupies the greatest portion of the FRB, and from the Surat Basin display the greatest longitudinal variation. All FRB soils have a similar total phosphorus (P) concentration. Thus, in considering P export from the catchment it is the total sediment flux which is of major importance, rather than the relative proportions of individual catchment soils. This research provides crucial new regional scale information on the sediment sources deposited within the FRE.

The Development And Adoption Of Improved Land Management Practices Under The Intensified Agricultural Production System In Anambra State, Nigeria

In present day Anambra State, increased population densities, growing food and market demands, urbanization, proximity to major road infrastructure, soil conditions and deterioration in quality of land for agricultural purposes have brought about reduced agricultural productivity. These changes have resulted to increasing socio-economic pressure on land and differential access to farmland and intensification of cultivation with far-reaching consequences for land-use management practices and the sustainability of the agricultural system. Severe soil fertility and productivity decline, ecological damages including soil erosion losses, flood and gullies are some of the out comes of the uncontrolled land-use and agricultural intensification in the state. These problems might worsen in future due to the fragile, heavily weathered and leached nature of the soil. This situation can only be corrected by the incorporation of improved soil conservation practices in our farming system through acceleration of farmer\'s adoption rates of the recommended innovations.

Land degradation processes in Portugal: farmers' perceptions of the application of European agroforestry programmes

AbstractThis paper examines the effectiveness of European Union (EU) agroforestry programmes in reversing land degradation processes in the Mação region of central Portugal. Since the 1980s, the region has experienced severe forest fires, which have had serious consequences for the local ecosystem in terms of land degradation processes and changes in the hydrological cycle. In an attempt to reverse this situation, agroforestry programmes and aid schemes have been introduced to improve land management practices and increase the forest area and stabilize soil. However, evaluations of the environmental, economic and social impacts of these schemes have been limited. This paper considers the effectiveness of agroforestry programmes from the perspectives of farmers in the area, as revealed by a detailed survey of land users' perceptions of these measures. The paper also reflects on the implications for current and future policy. The results suggest that present assistance regimes may be insufficient to ensure adequate forest management in the future. A new approach to forest management is proposed involving greater cooperation among local farmers, diversification of species in new afforestation and the establishment of demonstration projects. Copyright © 2002 John Wiley & Sons, Ltd.

Water Quality in the Great Barrier Reef World Heritage Area: Past Perspectives, Current Issues and New Research Directions

Elevated sediment and nutrient concentrations have long been regarded as the pre-eminent water quality threats to the Great Barrier Reef, with the potential risk posed by other pollutants such as heavy metals, persistent chlorohydrocarbons, PCBs and petroleum related compounds considered to be of lesser consequence. However, the management focus on these latter types of pollutants has recently shifted to acknowledge the potential impact posed by diuron, dioxins, dieldrin, and mercury and cadmium concentrations detected in sediments and biota along the Great Barrier Reef and southern Queensland coastline. In general, these threats originate from areas dominated by intensive cropping agriculture and are exacerbated by high rainfall and erosion rates in the wet tropics region of the Queensland coast. Maintenance of long-term monitoring programmes, which utilize innovative data acquisition techniques will enable assessment of change in environmentally relevant pollutant concentrations over time. However, improved land management practices, which include an immediate minimization of vegetation clearance and responsible use of pesticides and fertilizers in Queensland are essential if water quality in the Great Barrier Reef World Heritage Area is to be maintained and protected.

Review of the 1977?87 decade of action to combat desertification

Desertification has been a concern of the Committee on Arid Lands (COAL) as a subset of its wide ranging interest in problems of arid and semi-arid lands, resources, management, and human occupation. Deserti fication problems are basic in arid lands and their control can lead to ef fective land management. Actions to combat the effects of desertification have been included in the agenda of the Committee on Arid Lands since its inception in 1974. COAL has published many symposia not only at American Association for the Advancement of Science (AAAS) meetings, but also at regional meetings convened for the purpose of examining arid land problems. Three years ago the Committee on Arid Lands sponsored a symposium, entitled "Whatever Happened to Desertification?" The re sponse at that time by the selected speakers was that processes of desertifi cation were often activated by unwise management processes. However, concurrent research and improved land management practices are actively at work to control desertification and mitigate adverse land use. The key note speaker was the president of New Mexico State University, Dr. Gerald Thomas who at one time was President of the Society for Range Management. The sense of his presentation was that things are improving in the arid and semi-arid lands of the United States.

Historic Trends in the Sediment Flow Regime of the Mississippi River

Prior to cultural development in the Mississippi River Basin, the main stem was a heavy sediment carrier due to the character of the climate and soils in the basin. The placement of flood control structures and other channel improvement features and the implementation of improved land management practices have significantly changed the suspended‐sediment flow regime of the main stem. The estimated annual sediment yield of the basin is 900 million (817 million metric) tons. That portion of the yield passing into the Gulf of Mexico, as monitored at suspended‐sediment sample collection stations near the mouths of the Mississippi and Atchafalaya rivers, totaled 434 million (394 million metric) tons prior to 1963; however, this value has now declined to 225 million (204 million metric) tons. Long‐term trends in the bed material gradation of the Lower Mississippi downstream from the mouth of the Arkansas River have remained relatively constant; however, from Donaldsonville, Louisiana, downstream to Head of Passes, there has been a pronounced shift from the sand to silt fraction.

Sediment Retention Efficiency of Synthetic Filter Fabrics

ABSTRACT IMPROVED land management practices are needed to reduce the excessive erosion resulting from rapidly changing land use. Several researchers have successfully used synthetic filter fabrics as soil retention barriers in subsurface drainage applications. Hence, synthetic filter fabrics have the potential to remove suspended soil particles resulting from erosion. Six synthetic filter fabrics were investigated for particle retention and water transmissibility when subjected to a flowing soil suspension. Four replicate tests were performed with sand, coarse silt, and silt-clay soil suspensions. All fabrics successfully removed sand particles (> 75 ^m) from suspension. Various amounts of coarse silt particles (75 to 37 jLtm) were removed by the fabrics tested and these filter fabrics were generally ineffective filters of silt-clay particles (< 37 jLtm). When significant quantities of soil particles were retained, filter clogging reduced each fabric's ability to transmit water. Hence, a definite compromise exists between a filter fabric's ability to remove soil particles while transmitting water flow.