Alternative Land Use Options for Philippine Grasslands: A Bioeconomic Modeling Approach Using the WaNuLCAS Model

In the Philippines, pure grasslands occupy 1.8 million ha and another 10.8 million ha (33% of the country\u27s total land area) is under extensive cultivation mixed with grasslands and scrub. Most of these grasslands are under-utilised and dominated by Imperata cylindrica. Imperata grasslands generally represent areas of degraded soils that are acidic, low in organic matter and susceptible to erosion. However, conversion of these grassland areas into upland farms planted to annual crops and perennial trees is proliferating at a fast rate. This is triggered by the interacting factors of rapidly increasing population, the system of landholding, scarcity of jobs and the declining arable area in the lowlands

Alternative Land Use Options for Philippine Grasslands: A Bioeconomic Modeling Approach Using the WaNuLCAS Model

In the Philippines, pure grasslands occupy 1.8 million ha and another 10.8 million ha (33% of the country’s total land area) is under extensive cultivation mixed with grasslands and scrub. Most of these grasslands are under-utilised and dominated by Imperata cylindrica. Imperata grasslands generally represent areas of degraded soils that are acidic, low in organic matter and susceptible to erosion. However, conversion of these grassland areas into upland farms planted to annual crops and perennial trees is proliferating at a fast rate. This is triggered by the interacting factors of rapidly increasing population, the system of landholding, scarcity of jobs and the declining arable area in the lowlands

Hedgerow Systems and Livestock in Philippine Grasslands: GHG Emissions

Hedgerow systems are widely adopted in the smallholder farms in the sloping grassland areas of Claveria, Mindanao, Philippines. The system is effective in addressing soil erosion problems and in conserving the topsoil. Gmelina arborea and Eucalyptus deglupta are two fast-growing timber species that are planted in hedgerow systems while maize is planted in the alley areas in between the hedgerows. Livestock holdings are widespread in Claveria, with 74% of the households having livestock. Cattle and carabao are the most common livestock in smallholder farms providing draught power for land preparation and transportation. In hedgerow systems, fodder tree leaves and crop residues are fed to livestock, while animal manure is added to the soil. Thus, these systems may serve as both a source and sink of methane and nitrogen oxides, depending on the management practices and component trees and crops of the system. This study aims to estimate methane emissions from livestock holdings and nitrogen oxide emissions through fertilization, tree litterfall and decomposition, maize residue incorporation and livestock manure from G. arborea and E. deglupta hedgerow systems

Competitive abilities and divergence of 'Microlaena stipoides' populations with associated perennial grass species in New South Wales, Australia

Plant-plant interactions play an important role in the structuring of communities and in maintaining genetic diversity in populations. The reciprocal transplant technique is a powerful tool of testing fitness of populations and Connell (1980) suggested field experiments to demonstrate coevolutionary divergence of competitor plant species. This study followed Connell's (1980) proposed experimental design with the aim of determining the occurrence of microevolution among 'Microlaena stipoides' populations with four associated grass species in permanent pastures, namely 'Lolium perenne', 'Poa pratensis' (Ppr), 'Dactylis glomerata' and 'Phalaris aquatica'

VULNERABILITY ASSESSMENT USING LIDAR DATA IN SILANG-STA. ROSA SUBWATERSHED, PHILIPPINES

Silang-Sta. Rosa Subwatershed is experiencing rapid urbanization. Its downstream area is already urbanized and the development is moving fast upstream. With the rapid land conversion of pervious to impervious areas and increase frequency of intense rainfall events, the downstream of the watershed is at risk of flood hazard. The widely used freeware HEC-RAS (Hydrologic Engineering Center- River Analysis System) model was used to implement the 2D unsteady flow analysis to develop a flood hazard map. The LiDAR derived digital elevation model (DEM) with 1m resolution provided detailed terrain that is vital for producing reliable flood extent map that can be used for early warning system. With the detailed information from the simulation like areas to be flooded, the predicted depth and duration, we can now provide specific flood forecasting and mitigation plan even at community level. The methodology of using 2D unsteady flow modelling and high resolution DEM in a watershed can be replicated to other neighbouring watersheds specially those areas that are not yet urbanized so that their development will be guided to be flood hazard resilient. LGUs all over the country will benefit from having a high resolution flood hazard map

Hedgerow Systems and Livestock in Philippine Grasslands: GHG Emissions

Hedgerow systems are widely adopted in the smallholder farms in the sloping grassland areas of Claveria, Mindanao, Philippines. The system is effective in addressing soil erosion problems and in conserving the topsoil. Gmelina arborea and Eucalyptus deglupta are two fast-growing timber species that are planted in hedgerow systems while maize is planted in the alley areas in between the hedgerows. Livestock holdings are widespread in Claveria, with 74% of the households having livestock. Cattle and carabao are the most common livestock in smallholder farms providing draught power for land preparation and transportation. In hedgerow systems, fodder tree leaves and crop residues are fed to livestock, while animal manure is added to the soil. Thus, these systems may serve as both a source and sink of methane and nitrogen oxides, depending on the management practices and component trees and crops of the system. This study aims to estimate methane emissions from livestock holdings and nitrogen oxide emissions through fertilization, tree litterfall and decomposition, maize residue incorporation and livestock manure from G. arborea and E. deglupta hedgerow systems

Biochar amendment did not influence the growth of two tree plantations on nutrient‐depleted Ultisols in the south Ecuadorian Amazon region

The literature suggests that biochar increases the fertility of degraded, nutrient-poor tropical soils. We hypothesized that the addition of biochar (a) increases tree growth in two plantations on Ultisols in the south Ecuadorian Amazon region, (b) reduces litterfall during the dry season because the soil remains moister, and (c) improves the benefit–cost ratio of the plantation. We grew two tree species—the native leguminous Schizolobium parahyba var. amazonicum (Ducke) Barneby and the exotic Gmelina arborea Roxb—and used a full factorial split-split-plot design of all treatments for both tree species at each of two sites. The treatments included the amendment of mineral fertilizer plus lime, 3 and 6 t ha$^{-1}$ biochar, and a control. The plots were replicated three or four times. Tree height (TH), basal diameter (BD), and diameter at breast height (DBH) were measured several times during 51 mo after planting in September 2009 and litterfall during 12 mo (March 2012–February 2013). The site and the mineral fertilizer plus lime treatment had significant effects on TH, BD, and DBH. The amendment of mineral fertilizer plus lime increased TH, BD, and DBH by 47, 43, and 58%, respectively, relative to the control. The litterfall of G. arborea was on average 84% higher than that of S. parahyba. The amendment of biochar did not significantly influence TH, BD, DBH, or litterfall. The benefit–cost ratio of wood production was >1 in the mineral fertilizer plus lime treatment and controls but <1 in the biochar treatments and decreased with increasing addition of biochar. Our results demonstrate that the assumption that biochar can be used to improve the fertility of degraded Amazon soils cannot be generalized