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Land-use Practices (land-use + practice)

Distribution by Scientific Domains

Life Sciences	54%
Earth and Environmental Science	36%

Selected Abstracts

Atmospheric impact of bioenergy based on perennial crop (reed canary grass, Phalaris arundinaceae, L.) cultivation on a drained boreal organic soil

GCB BIOENERGY, Issue 3 2010
NARASINHA J. SHURPALI
Abstract Marginal organic soils, abundant in the boreal region, are being increasingly used for bioenergy crop cultivation. Using long-term field experimental data on greenhouse gas (GHG) balance from a perennial bioenergy crop [reed canary grass (RCG), Phalaris arundinaceae L.] cultivated on a drained organic soil as an example, we show here for the first time that, with a proper cultivation and land-use practice, environmentally sound bioenergy production is possible on these problematic soil types. We performed a life cycle assessment (LCA) for RCG on this organic soil. We found that, on an average, this system produces 40% less CO2 -equivalents per MWh of energy in comparison with a conventional energy source such as coal. Climatic conditions regulating the RCG carbon exchange processes have a high impact on the benefits from this bioenergy production system. Under appropriate hydrological conditions, this system can even be carbon-negative. An LCA sensitivity analysis revealed that net ecosystem CO2 exchange and crop yield are the major LCA components, while non-CO2 GHG emissions and costs associated with crop production are the minor ones. Net bioenergy GHG emissions resulting from restricted net CO2 uptake and low crop yields, due to climatic and moisture stress during dry years, were comparable with coal emissions. However, net bioenergy emissions during wet years with high net uptake and crop yield were only a third of the coal emissions. As long-term experimental data on GHG balance of bioenergy production are scarce, scientific data stemming from field experiments are needed in shaping renewable energy source policies. [source]

Bush encroachment under three contrasting land-use practices in a mesic South African savanna

AFRICAN JOURNAL OF ECOLOGY, Issue 2009
B. J. Wigley
Abstract This study determined the effects of land-use practice had on the rate and extent of bush encroachment in a mesic savanna in KwaZulu-Natal, South Africa. Changes in woody cover were measured for 1 km2 sites in areas under communal, commercial and conservation land-use systems for the period between 1937 and 2000. Land users from each area were interviewed to gain the histories of each area and to determine how the changes in woody cover had impacted them and whether anything was being done to counteract the spread of trees and shrubs on their land. Bush encroachment occurred across all three of the land-use types in the 67-year period between 1937 and 2000. The results showed that land-use practice had enormous impacts on the process of bush encroachment. The communal site showed a decrease in grass (21%) and tree (5%) cover and an increase in shrub cover (13%). At the commercial site, there was a considerable decrease in grass cover (46%) and moderate increase in shrub cover (10%) and a massive increase in tree cover (36%). The area under conservation showed a substantial decrease in grass cover (47%), a slight decrease in shrub cover (19%) and a massive increase in tree cover (66%). The perceived causes of these changes were fairly similar amongst the different land users. The changes were mostly not perceived to be a problem for the communal land users. The main advantages mentioned were increased woody resources for building and firewood and increased browse availability. The commercial and conservation land users perceived the changes to have significant negative connotations including the loss of grazing land and biodiversity and secondary invasion of encroached areas by alien plant species. Despite these perceptions, very little has been done to combat bush encroachment in the commercial and conservation land use systems. [source]

Land-use and cover changes (1988,2002) around budongo forest reserve, NW Uganda: implications for forest and woodland sustainability

LAND DEGRADATION AND DEVELOPMENT, Issue 6 2008
E. N. Mwavu
Abstract Land-use and cover changes around Budongo Forest Reserve (BFR) were analysed from multi-temporal LandSat images (1988 and 2002) and associated field-based studies in 2003,2004. Three major land-use and cover classes: forest/woodland, sugarcane plantations and grassland/shifting-cultivation/settlements were clearly discriminated. The area under sugarcane cultivation increased over 17-fold, from 690,ha in 1988 to 12729,ha in 2002, with a concomitant loss of about 4680,ha (8·2 per cent) of forest/woodland, mainly on the southern boundary of BFR. Land-use and cover changes were a result of (a) agricultural expansion, (b) increasing human population, exacerbated by large influxes of refugees, (c) conflicts of interest and political interference in the management of BFR and (d) unclear land tenure. Agriculture is the main land-use practice and source of income to local people, with commercial sugarcane and tobacco as the primary cash crops. Individual smallholder sugarcane plantations covered distances ranging from 30 to 1440,m along the BFR edge, with no buffer zone, resulting in direct conflicts between farmers and forest wild animals. There is an ever-increasing need for more land for agricultural expansion, resulting in continued loss of forest/woodland on private/communal lands and encroachment into BFR. This unsustainable agricultural expansion and the local people's perception of BFR as an obstacle to agriculture, threatens the conservation of its threatened wild plants (e.g. Raphia farinifera) and the endangered chimpanzees. Therefore, their sustainable management for both development and conservation will require strong and incorruptible institutions that will seek a balance between resource exploitation and conservation. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Net changes in regional woody vegetation cover and carbon storage in Texas Drylands, 1937,1999

GLOBAL CHANGE BIOLOGY, Issue 3 2003
GREGORY P. ASNER
Abstract Although local increases in woody plant cover have been documented in arid and semiarid ecosystems worldwide, there have been few long-term, large-scale analyses of changes in woody plant cover and aboveground carbon (C) stocks. We used historical aerial photography, contemporary Landsat satellite data, field observations, and image analysis techniques to assess spatially specific changes in woody vegetation cover and aboveground C stocks between 1937 and 1999 in a 400-km2 region of northern Texas, USA. Changes in land cover were then related to topo-edaphic setting and historical land-use practices. Mechanical or chemical brush management occurred over much of the region in the 1940,1950s. Rangelands not targeted for brush management experienced woody cover increases of up to 500% in 63 years. Areas managed with herbicides, mechanical treatments or fire exhibited a wide range of woody cover changes relative to 1937 (,75% to + 280%), depending on soil type and time since last management action. At the integrated regional scale, there was a net 30% increase in woody plant cover over the 63-year period. Regional increases were greatest in riparian corridors (33%) and shallow clay uplands (26%) and least on upland clay loams (15%). Allometric relationships between canopy cover and aboveground biomass were used to estimate net aboveground C storage changes in upland (nonriparian) portions of regional landscapes. Carbon stocks increased from 380 g C m,2 in 1937 to 500 g C m,2 in 1999, a 32% net increase across the 400 km2 region over the 63-year period. These plant C storage change estimates are highly conservative in that they did not include the substantial increases in woody plant cover observed within riparian landscape elements. Results are discussed in terms of implications for ,carbon accounting' and the global C cycle. [source]

Bush encroachment under three contrasting land-use practices in a mesic South African savanna

Painful Steps of Progress from Crisis Planning to Contingency Planning: Changes for Disaster Preparedness in Turkey

JOURNAL OF CONTINGENCIES AND CRISIS MANAGEMENT, Issue 1 2002
Murat Balamir
Excessive losses in natural disasters in Turkey are, to a large extent, a consequence of omissions and deficiencies in the structuring of ,disasters' and ,development' laws, as well as negligent land-use practices and avoidance of control in building processes. Two extreme forms of legal and organizational structures in disasters policy could be formulated as the ,fatalist' and ,self-reliance, models. Their contrasts can be investigated in terms of (a) the use of information concerning natural phenomena in formal planning procedures; (b) pre- or post-disaster emphasis in preparations; (c) the political or technical basis of decisions; (d) the extraordinary or routine nature of responses; (e) the general or specialized nature of financial sources used; (f) and their compatibility with the order of priorities in risk management. An evaluation of the conventional policy in Turkey clarifies a position closer to the ,fatalist' model and indicates the lines of action for improvements. However, after the 1999 earthquakes, the conventional approach in disaster policy has been restructured. With the newly introduced ,Obligatory Building Insurance', ,Building Control', and ,Professional Proficiency' systems, greater emphasis is now given to mitigation efforts, and the introduction of contingency planning practices is more likely to happen. [source]

Effects of two contrasting agricultural land-use practices on nitrogen leaching in a sandy soil of Middle Germany

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2009
Christian Böhm
Abstract The objective of this study is to evaluate different agricultural land-use practices in terms of N leaching and to give recommendations for a sustainable agriculture on sandy soils in Middle Germany. Soil mineral N (Nmin) and leachate N were quantified at a sandy soil in N Saxony during 3 years. Two treatments were applied: intensive (I),using inorganic and organic fertilizer and pesticides, and organic (O),exclusively using organic fertilizer, legume-based crop rotation, and no pesticides. Split application of mineral fertilizers did not result in substantial N losses at treatment I. Legumes induced a considerable increase of soil mineral N and particularly of leachate mineral N (Nmin_perc) at treatment O. High Nmin_perc concentrations (up to 78 mg N L,1) were observed during as well as after the cultivation of legumes. These high Nmin_perc concentrations are the reason why clearly higher Nmin_perc losses were determined at treatment O (62 kg N ha,1 y,1) compared to treatment I (23,kg N ha,1 y,1). At both treatments, the quantity of N losses was strongly affected by the precipitation rates. Concentrations and losses of dissolved organic N (DONperc) were assessed as above average at both treatments. The results suggest that the DONperc concentration is influenced by precipitation, soil coverage, and organic fertilizers. Higher values were determined in the percolation water of treatment O. The average annual DONperc losses amounted to 15,kg N ha,1 at I and to 32 kg N ha,1 at O. The average monthly percentage of DONperc losses on the loss of the dissolved total N of percolation water (DTNperc) ranged between <1% and 55% at O and between 2% and 56% at I. For the whole measuring period of 29 months, the relative amounts of DONperc of DTNperc (21% at O and 25% at I) were more or less the same for both treatments. The results show that DONperc can contribute significantly to the total N loss, confirming the importance to consider this N fraction in N-leaching studies. It was concluded that at sandy sites, a split application of mineral fertilizers, as applied at treatment I, seems to be more expedient for limiting the N leaching losses than legume-based crop rotations. [source]

Environment, disturbance history and rain forest composition across the islands of Tonga, Western Polynesia

JOURNAL OF VEGETATION SCIENCE, Issue 2 2006
Janet Franklin
Abstract Questions: How do forest types differ in their distinctiveness among islands in relation to environmental and anthropogenic disturbance gradients? Are biogeographic factors also involved? Location: Tonga, ca. 170 oceanic islands totalling 700 km2 spread across 8° of latitude in Western Polynesia. Method Relative basal area was analysed for 134 species of woody plants in 187 plots. We used clustering, indirect gradient analysis, and indicator species analysis to identify continuous and discontinuous variation in species composition across geographical, environmental and disturbance gradients. Partial DCA related environmental to compositional gradients for each major forest type after accounting for locality. CCA and partial CCA partitioned observed compositional variation into components explained by environment/disturbance, locality and covariation between them. Results: Differences among forest types are related to environment and degree of anthropogenic disturbance. After accounting for inter-island differences, compositional variation (1) in coastal forest types is related to substrate, steepness and proximity to coast; (2) in early-successional, lowland rain forest to proximity to the coast, steepness and cultivation disturbance; (3) in late-successional, lowland forest types to elevation. For coastal/littoral forests, most of the compositional variation (71%) is explained by disturbance and environmental variables that do not covary with island while for both early and late-successional forests there is a higher degree of compositional variation reflecting covariation between disturbance/environment and island. Conclusions: There are regional similarities, across islands, among littoral/coastal forest types dominated by widespread seawater-dispersed species. The early-successional species that dominate secondary forests are distributed broadly across islands and environmental gradients, consistent with the gradient-in-time model of succession. Among-island differences in early-successional forest may reflect differences in land-use practices rather than environmental differences or biogeographical history. In late-successional forests, variation in composition among islands can be partly explained by differences among islands and hypothesized tight links between species and environment. Disentangling the effects of anthropogenic disturbance history versus biogeographic history on late-successional forest in this region awaits further study. [source]

A transcriptomic analysis of land-use impacts on the oyster, Crassostrea virginica, in the South Atlantic bight

MOLECULAR ECOLOGY, Issue 11 2009
ROBERT W. CHAPMAN
Abstract Increasing utilization and human population density in the coastal zone is widely believed to place increasing stresses on the resident biota, but confirmation of this belief is somewhat lacking. While we have solid evidence that highly disturbed estuarine systems have dramatic changes in the resident biota (black and white if you will), we lack tools that distinguish the shades of grey. In part, this lack of ability to distinguish shades of grey stems from the analytical tools that have been applied to studies of estuarine systems, and perhaps more important, is the insensitivity of the biological end points that we have used to assess these impacts. In this study, we will present data on the phenotypic adjustments as measured by transcriptomic signatures of a resilient organism (oysters) to land-use practices in the surrounding watershed using advanced machine-learning algorithms. We will demonstrate that such an approach can reveal subtle and meaningful shifts in oyster gene expression in response to land use. Further, the data show that gill tissues are far more responsive and provide superior discrimination of land-use classes than hepatopancreas and that transcripts encoding proteins involved in energy production, protein synthesis and basic metabolism are more robust indicators of land use than classic biomarkers such as metallothioneins, GST and cytochrome P-450. [source]

Land-use legacies in a central Appalachian forest: differential response of trees and herbs to historic agricultural practices

APPLIED VEGETATION SCIENCE, Issue 2 2010
James M. Dyer
Abstract Question: Are contemporary herb and tree patterns explained by historic land use practices? If so, are observed vegetation patterns associated with life-history characteristics, soil properties, or other environmental variables? Location: Southeastern Ohio, USA. Methods: Using archival records, currently forested sites were identified with distinct land use histories: cultivated, pasture (but not plowed), and reference sites which appear to have never been cleared. Trees were recorded by size and species on twenty 20 m × 20 m plots; percent cover was estimated for each herb species in nested 10 m × 10 m plots. Environmental characteristics were noted, and soil samples analysed for nutrient availability and organic matter. Nonmetric multidimensional scaling ordination was performed separately on both tree and herb datasets to graphically characterize community composition among plots. Life-history traits were investigated to explain observed compositional differences. Results: Vegetation patterns were explained by current environmental gradients, especially by land-use history. Cultivated and pasture sites had similar tree composition, distinct from reference sites. Herb composition of pasture and reference sites was similar and distinct from cultivated sites, suggesting the ,tenacity' of some forest herbs on formerly cleared sites. Tilling removes rhizomatous species, and disfavors species with unassisted dispersal. These life-history traits were underrepresented on cultivated sites, although ant-dispersed species were not. Conclusions: Historic land-use practices accounted for as much variation in species composition as environmental gradients. Furthermore, trees and herbs responded differently to past land-use practices. Life-history traits of individual species interact with the nature of disturbance to influence community composition. [source]

Establishment of native perennial shrubs in an agricultural landscape

AUSTRAL ECOLOGY, Issue 6 2007
NATHAN K. WONG
Abstract Native vegetation has been destroyed or dramatically modified throughout agricultural regions of southern Australia. Extensive restoration of native perennial vegetation is likely to be crucial in these areas for the persistence of native plant and animal species, to ameliorate dryland salinity and soil degradation, and to maintain long-term agricultural production. The long-term resilience of these systems will be dependent on the ability of key functional taxa, such as perennial shrubs, to recruit and persist. In this study, we examine the factors limiting establishment of two perennial shrubs in formerly cropped land, the rare Maireana rohrlachii and the common Maireana decalvans. Field and laboratory observations suggest that establishment of both species is not limited by life-history traits following cultivation. Both species established and persisted under varying levels of plant competition. Similarities existed between species in their initial germination rates. Weak differences were found between species in the growth and survival rates under different levels of competition. The main difference between the two species was in the decline of germinability of fruits with increasing fruit age. From the data, it is difficult to determine what factors limit the establishment of perennial shrubs in these landscapes. The main hypothesis that can be advanced is that establishment of shrub species appears to be limited by propagule availability and this is likely to be a function of past and present grazing management rather than cultivation per se. Further investigation of these land-use practices may give greater insight into the factors affecting the establishment of this life form across these landscapes. [source]