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Browsing by Author "Leisz, Stephen J., advisor"

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    Land tenure security and land-cover change: a case study from protected area buffer zone communities in Madagascar
    (Colorado State University. Libraries, 2023) Chang, Stephen, author; Leisz, Stephen J., advisor; Galvin, Kathleen, committee member; Ojima, Dennis, committee member
    Tenure and property rights define the relationship that people have with land and natural resources. Customary tenure systems are predominant in Madagascar, where locally administered rule systems have the flexibility to adapt to changing conditions, inherent conflict resolution mechanisms, and often, community buy-in. However, laws and regulations at different governmental levels throughout the country's history have often caused tenure systems to overlap in rural areas, which, in turn, often causes conflict and tenure insecurity. One important alteration to existing land and natural resource tenure systems is the creation of protected areas, which are commonly created to preserve the endemic biodiversity of the country. Many investigations have attempted to link land tenure to land-cover change using earth observing satellite imagery, but the study reported here is the first of the kind for Madagascar. This study addresses the following questions: if and how a land tenure system and its relative security influence land-cover change within a community and if and how land tenure outside of a protected area influences change within. Land cover classifications created from the Landsat TM and ETM+ images achieved high accuracies despite low image availability due to the period during which the study took place and the significant cloud cover found over the study sites. Findings of the study show that protected areas are relatively unaffected by surrounding land-use and land tenure security in the villages near the protected areas, and that the protected areas are effective at conserving the forests within their boundaries. Within each community, however, conflict and tenure insecurity are associated with elevated conversion of forest areas to other land-covers, regardless of tenure. These results highlight the need to prioritize land tenure security to both ensure local communities access to land and natural resources and meet widespread goals related to conserving biodiversity held by the international conservation community through the support of customary tenure systems and the promotion of socially responsible agricultural transitions.
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    Modeling plant hotspots in New Guinea and village-scale land change dynamics in Papua New Guinea
    (Colorado State University. Libraries, 2016) Hoover, Jamie Deanne, author; Leisz, Stephen J., advisor; Laituri, Melinda, advisor; James, Shelley, committee member; Kumar, Sunil, committee member
    The island of New Guinea harbors the third largest tropical forest in the world, after Amazonia and the Congo. Forest cover changes in New Guinea are occurring at a fast rate and it is vital to improve our understanding of the drivers of forest change and identify how these changes impact human livelihoods and biotic diversity. New Guinea is politically split into two countries; the western half is Indonesia and the eastern half is Papua New Guinea. The first part of this dissertation focuses on Papua New Guinea, where logging and subsistence agriculture account for 92% of forest cover changes. Since a large majority of the population is dependent on subsistence agriculture (swidden), understanding how subsistence strategies evolve over time can be used to inform land-use and land-cover (LULC) changes. To assess how subsistence strategies relate to LULC changes, I compare remote sensing analyses alone to a mixed methods approach or participatory remote sensing (PRS) that combines land-use mapping exercises, household surveys, remote sensing classifications, and the validation of image analyses. The remote sensing analyses alone were two and a half times larger than what land managers and the PRS methods identified. The inclusion of participatory data showed that the increase in food production to support the growing population was achieved by implementing a variety of strategies rather than continual expansion of the swidden area. Participatory data also better described that swidden LULC changes were based more on social, climatic, and environmental conditions than population growth pressures. To further my investigation of subsistence strategies and swidden LULC changes I conducted a long-term swidden LULC study using 40 Landsat scenes between 1972 and 2015. We found that swidden trends were not significant over the time period and therefore there was not a causal relationship between population growth and swidden trends. This result is different than national and provincial scale observations. Overall, the inclusion of participatory information via PRS methods should be used to understand swidden system LULC complexities and land-management strategies. Such information can improve LULC trend assessments at wider extents and be more informative for national forest cover change assessments. The other part of this dissertation has a wider extent and looks at New Guinea as a whole. Although it is known for high rates of biodiversity, there are few quantitative studies that have assessed plant diversity on the island. Here, I model vascular and non-vascular terrestrial plants at the genus taxonomic level to predict the biodiversity hotspots. To do this, I used an ecological niche model called MaxEnt and occurrence data from online, herbarium, and museum databases are paired with environmental variables. The results from this study identify sampling efforts, sampling biases, and predict plant distributions and biodiversity hotspots (richness). I found that richness increases west to east along the central mountain range and increases from south to north across the island. Even though MaxEnt is capable of minimizing sampling biases, I speculate that sampling biases may influence the richness pattern observed south to north because the southern third of the island is under sampled and the geologic history is markedly different. At higher elevations in regions with complex topography the predicted genera richness are smaller in area but more numerous. Comparatively, larger areas of higher predicted richness occur at lower elevations and where the topography is more homogeneous. While modeling with genus level data supplies baseline information about plant distributions, some genera are more speciose than others, so this effort may not capture the full scope of richness or endemism in New Guinea. However, these results can be used to prioritize future sampling needs, support conservation strategies, compare genus diversity to other regions of the world, and discuss principles and drivers of biogeography.
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    Wildfires and precipitation in the lowlands of Guatemala: an analysis of precipitation and vegetation indices as potential wildfire drivers
    (Colorado State University. Libraries, 2023) Malaker, Tanmoy, author; Leisz, Stephen J., advisor; Pons, Diego, committee member; Stevens-Rumann, Camille, committee member
    Wildfire is an inevitable natural disaster that is considered exclusive to dry and temperate regions. However, the increasing wildfire occurrences in tropical and humid forest regions urge us to investigate the drivers of this natural phenomenon for a humid forest region. Although wildfire is inevitable, it can be managed with proper strategies; thus, identifying the drivers of wildfire in humid and tropical regions is imperative. This thesis focuses on identifying the role of precipitation as a driver for wildfire occurrences and fuel generation for fires in a humid forest ecological system in the lowlands of Guatemala (Petén). Using the data library and cloud computation system of the International Research Institute for Climate and Society (IRI), INAB (Instituto Nacional de Bosques/Guatemala's Forest Authority) fire records for Guatemala, and geospatial tools like GIS and Google Earth Engine, the thesis identifies the influence of precipitation on vegetation and wildfires in Petén. The findings suggest that precipitation's influence on Petén's wildfires is two-dimensional. Precipitation influences vegetation or total fuel generation and fire occurrences by influencing fuel availability by influencing green-up and the dry down of fuels in a humid forest ecosystem. This two-dimensional influence makes precipitation one of the most critical drivers of wildfire for tropical-humid forest ecology. Besides the seasonal accumulative precipitation, the precipitation pattern and amount at different times within a preceding season of the fire months highly influence vegetation conditions and fire frequencies. The findings also suggest that seasonal precipitation forecasting could potentially be a tool for wildfire management and forecasting.