Land Cover Loss Research Articles

Analysis of Land Use/Land Cover Pattern along the River Benue Channel in Adamawa State, Nigeria

Uncontrolled human development without adequate consideration for the environment has led to incessant loss of land cover and natural resources such as water in many parts of the world. Consequently, human and environmental challenges of varying magnitude are rapidly emerging. Interestingly, only few efforts are channelled towards the reclamation of the deteriorating land cover pattern and control of future environmental damages, particularly in the developing countries. This study analyses the land use and land cover pattern along the River Benue channel in Adamawa State, Nigeria between 1988 and 2003. Landsat TM satellite image of 1988, Landsat ETM of 2003, and Shuttle Radar Topographic Mission (SRTM) image of the Upper Benue Catchment area were utilize in the study. The study was carried out with a view of classifying the land use and land cover types in the area; examination of land use and land cover changes between 1988 and 2003; generation of contour and elevation maps for the area; and modelling of the terrain of the area using the Digital Terrain Model (DTM). The Upper Benue catchment area was extracted from the Nigeria catchment map, contour map and DTM were also generated in ArcView 3.2 GIS environment. Supervised classification method was adopted to classify the landsat imageries into six (6) classes using ILWIS 3.2 academic GIS software. The implication of the spatial pattern of land use and land cover in the area are accelerated socio-economic activities, shortage of food, prevalence of drought conditions, paralyzed inland water transportation, desertification and increase in temperature. The study concluded that there is need for a balance between human development, land use planning, and water resource management. Therefore, recommendations were given to ensure sustainable development in the region. DOI: 10.5901/ajis.2013.v2n5p95

A new bully on the block: Does urbanization promote Bewick’s wren (Thryomanes bewickii) aggressive exclusion of Pacific wrens (Troglodytes pacificus)?

Human conversion of land cover alters biotic communities and sets the stage for ongoing change as species interact within new environments. We studied the response of a native forest specialist, the Pacific wren (Troglodytes pacificus), to immediate and ongoing environmental changes facilitated by urbanization. We found evidence of a synergistic effect of native land cover loss followed by increased aggressive interactions with a native generalist, the Bewick’s wren (Thryomanes bewickii), resulting in the decline of Pacific wrens in urbanizing environments. Pacific wren relative abundance decreased dramatically during and after development, while Bewick’s wrens increased and persisted at greater abundance post-relative to pre-development. Breeding territories of the two species overlapped minimally, suggesting spatial segregation either by differential resource use or territorial aggression. A comparison of territory characteristics revealed the species generally used different resources, although territory composition was increasingly similar at urbanizing sites where the species co-occurred. Territorial playback experiments confirmed that the two species interact aggressively. Analyses of body size, body condition and reproductive success did not suggest Bewick’s wrens negatively impact fitness of Pacific wrens at sites where they co-occurred. In established subdivisions (>10years old) Bewick’s wrens appear to limit the abundance of Pacific wrens, however this was not yet the case at sites we studied immediately after development. Although the results of this study are not conclusive, our findings are consistent with the hypothesis that new environmental gradients and communities created by urbanization increase competitive interactions among native species.

Riparian habitat changes across the continental United States (1972–2003) and potential implications for sustaining ecosystem services

Riparian ecosystems are important elements in landscapes that often provide a disproportionately wide range of ecosystem services and conservation benefits. Their protection and restoration have been one of the top environmental management priorities across the US over the last several years. Despite the level of concern, visibility and management effort, little is known about trends in riparian habitats. Moreover, little is known about whether or not cumulative efforts to restore and protect riparian zones and floodplains are affecting the rates of riparian habitat change nationwide. To address these issues, we analyzed riparian land cover change between the early 1970s and the late 1990s/early 2000s using existing spatial data on hydrography and land cover. This included an analysis of land cover changes within 180 m riparian buffer zones, and at catchment scales, for 42,363 catchments across 63 ecoregions of the continental US. The total amount of forest and natural land cover (forests, shrublands, wetlands) in riparian buffers declined by 0.7 and 0.9%, respectively across the entire study period. Gains in grassland/shrubland accounted for the 0.2% lower percentage of total natural land cover loss relative to forests. Conversely, urban and developed land cover (urban, agriculture, and mechanically disturbed lands) increased by more than 1.3% within riparian buffers across the entire study period. Despite these changes, we documented an opposite trend of increasing proportions of natural and forest land cover in riparian buffers versus the catchment scale. We surmise that this trend might reflect a combination of natural recovery and cumulative efforts to protect riparian ecosystems across the US. However, existing models limit our ability to assess the impacts of these changes on specific ecosystem services. We discuss the implications of changes observed in this study on the sustainability of ecosystem services. We also recommend opportunties for future riparian change assessments.

Deforestation and forest degradation as measures of Popa Mountain Park (Myanmar) effectiveness

SUMMARYThe effectiveness of protected areas (PAs) has often been measured by comparing deforestation or land cover loss before and after PA establishment or within and outside the PA. Such evaluations ignore forest degradation or the decline in quality of the ecological values of the forest. Landsat image processing and geographical information systems were used to study forest cover changes in and around Popa Mountain Park (central Myanmar). Deforestation inside the Park was lower than outside the Park, but forest degradation, namely the net area that changed from dense forest to open forest, within the Park had grown at rates exceeding those outside the Park. The effectiveness of the PA was overestimated by adopting deforestation as the only indicator of conservation effectiveness. Forest degradation studies can be used to evaluate the effectiveness of PAs.

Effect of land use change on methane oxidation in temperate forest and grassland soils

Evidence is accumulating that land use changes and other human activity during the past 100 to 200 years have contributed to decreased CH 4 oxidation in the soil. Recent studies have documented the effect of land use change on CH 4 oxidation in a variety of ecosystems. Increased N additions to temperate forest soils in the northeastern United States decreased CH 4 uptake by 30 to 60%, and increased N fertilization and conversion to cropland in temperate grasslands decreased CH 4 uptake by 30 to 75%. Using these data, we made a series of calculations to estimate the impact of land use and management changes which have altered soil the CH 4 sink in temperate forest and grassland ecosystems. Our study indicates that as the atmospheric mixing ratio of CH 4 has increased during the past 150 y, the temperate CH 4 sink has risen from approximately 8 Tg y −1 to 27 Tg y −1, assuming no loss of land cover to cropland conversion. The net effect of intensive land cover changes and extensive chronic disturbance (i.e., increased atmospheric N deposition) to these ecosystems have resulted in about 30% reduction in the CH 4 sink relative to the soil sink assuming no disturbance to any of the temperate ecosystems. This will impact the global CH 4 budget even more as atmospheric CH 4 concentrations increase and as a result of further disturbance to other biomes. Determining the reasons for the decreased CH 4 uptake due to land disturbance is necessary to understand the role of CH 4 uptake in conjunction with the increasing atmospheric CH 4 concentrations. Without accounting for this approximately 20 Tg y −1 temperate soil sink, the atmospheric CH 4 concentration would be increasing about 1.5 times the current rate.