Dacryodes edulis is a multipurpose tree integrated in the cropping system of Central African region still dominated by subsistence agriculture. Some populations grown are wild which can provide information on the domestication process, and could also represent a potential source of gene ow. Leaves samples for DNA extraction were collected from wild forms in Mbakwa supe region and from cultivated forms in Yaounde and Santchou region. Six microsatellites DNA markers were employed in genotyping to analyze population structure and gene flow. Amplification rate was high and genotyping revealed high level of genetic variation. The overall polymorphic level at the six loci was also high with average expected heterozygosity of 0.53; polymorphism of 0.46; mean allelic diversity of 0.5 and mean allele number of 8.33. There were no clear differences with only 1% variation among the three populations and 6% variation among individuals within populations. In contrast, the rate of heterozygosis was high in all the three populations. Both the number of migrant per generation (Nm=20) and the Wright’s F-statistics (FST=0.012) suggest that there was substantial gene ow among the populations. These findings indicate that D. edulis possess a great potential of pollen dispersal and dominant cross-pollination within populations. Most of the loci with private alleles (45%) were found in wild individuals which could be a source of pollen for crossing their cultivated relatives.
Tag: agriculture
The impact of selective logging and forest conversion for subsistence agriculture and pastures on terrestrial nutrient dynamics in the Amazon
The conversion of primary forests in the Amazon via selective logging, slash and burn agriculture, and pasture establishment, will continue because of the increasing demand for timber and agricultural land. Forest conversion has major impacts on the stocks and flows of essential plant nurtrients. For example, the burning of slashed vegetation results in most of the carbon and nutrients in the biomass being volatilized during burning. Nutrient stocks are further depleted by the nutrient exports in timber and crop harvests. Poor crop and pasture mamagement practices can result in rapid declines in soil fertility and reduced vegetation regrowth potential. These changes can influence the rate of secondary forest regrowth and carbon sequestration on abandoned crop and pasture lands. The dominant land use practives following forest conversion in the Amazon are identified and the data on the impact of selective logging, subsistence cropping, and extensive pastures, on nutrient stocks and budgets in terrestrial Amazonian ecosystems are reviewed.
Towards improved natural resource management in African agriculture
This paper draws together lessons learned as to how governments and donors might stimulate necessary investment in improved natural resource management (NRM) in African agriculture. Policy interventions to support improved NRM are presented. These policy interventions are built on 5 points: investment, incentives, information, inputs, and institutions.
Water productivity in forestry and agroforestry
Forests are the biggest users of water worldwide and extensive forested areas have been lost or are undergoing conversion to agriculture, creating concerns about loss of hydro logical functions and increasing the competition for scarce water between agriculture, urban centers, industries and wildlife. The challenge is to improve the sustainability and productivity of land and water use, especially for the growing populations of many developing countries. In this chapter we review recent findings on the hydrology of forests and agroforestry systems and indicate how modifications in tree-based systems might increase water productivity. In forestry, the focus of research has moved from the hydro logical functions of upland forest reserves that are close to settlements to a greater recognition of the roles played by upland communi-ties in the management of water resources. A major source of conflict over water resources is the con-trasting perceptions of ‘watershed functions’ between forest managers and local people, which are often based more on myths of forest functions than on science – for example, the idea that forests increase rainfall. These myths continue to dominate the views of policy makers and institutions and should be revised. The challenge is to gain a better insight into how farmer-developed land-use mosaics have modified watershed-protection functions. Priority must be given to the perceptions,experiences and strategies of local communities.Trees on farms have the potential for improving productivity in two ways. Trees can increase the amount of water that is used on farm as tree or crop transpiration. Trees can also increase the produc-tivity of the water that is used by increasing biomass of trees or crops produced per unit of waterused. Plot-level evidence shows that improvements in water productivity as a consequence of modifi-cations to the microclimate of the crop are likely to be limited. Instead, evidence from semi-arid India and Kenya showed that the greater productivity of agroforestry systems is primarily due to the higher amount of water used. Almost half of the total water use occurred during the dry season,when cropping was impossible, and the rest was extracted from soil reserves. This implies a high temporal complementarity between the crop and tree components of the landscape mosaic. Research is needed to examine the impact of the increased water use on the drainage and base flow at the land-scape level. This chapter also describes some of the technical approaches that can be used to improve land and water management, the role of trees and its relation to hydrology and the challenges for rational land-use decision-making.
Shifting Cultivation in Vietnam: Impacts of various policy reforms
Based on literature reviews, recent surveys and interviews with local farmers and provincial officials in Vietnam’s northwest region between April and June 2012, this chapter provides an overview of shifting cultivation practices in Vietnam, the key policy interventions and their impacts on livelihoods, land use and the environment, as well as insights into how shifting cultivators could benefit from new incentives such as REDD+.
Hyperspectral narrowband and multispectral broadband indices for remote sensing of crop evapotranspiration and its components (transpiration and soil evaporation)
Evapotranspiration (ET) is an important component of micro- and macro-scale climatic processes. In agriculture, estimates of ET are frequently used to monitor droughts, schedule irrigation, and assess crop water productivity over large areas. Currently, in situ measurements of ET are difficult to scale up for regional applications, so remote sensing technology has been increasingly used to estimate crop ET. Ratio-based vegetation indices retrieved from optical remote sensing, like the Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index, and Enhanced Vegetation Index are critical components of these models, particularly for the partitioning of ET into transpiration and soil evaporation. These indices have their limitations, however, and can induce large model bias and error. In this study, micrometeorological and spectroradiometric data collected over two growing seasons in cotton, maize, and rice fields in the Central Valley of California were used to identify spectral wavelengths from 428 to 2295 nm that produced the highest correlation to and lowest error with ET, transpiration, and soil evaporation. The analysis was performed with hyperspectral narrowbands (HNBs) at 10 nm intervals and multispectral broadbands (MSBBs) commonly retrieved by Earth observation platforms. The study revealed that (1) HNB indices consistently explained more variability in ET (ΔR2 = 0.12), transpiration (ΔR2 = 0.17), and soil evaporation (ΔR2 = 0.14) than MSBB indices; (2) the relationship between transpiration using the ratio-based index most commonly used for ET modeling, NDVI, was strong (R2 = 0.51), but the hyperspectral equivalent was superior (R2 = 0.68); and (3) soil evaporation was not estimated well using ratio-based indices from the literature (highest R2 = 0.37), but could be after further evaluation, using ratio-based indices centered on 743 and 953 nm (R2 = 0.72) or 428 and 1518 nm (R2 = 0.69).
Learning pathway: Course flows & blueprint
This course is a pivotal contribution to FAO’s vision of fostering a Better Environment, particularly focusing on Biodiversity for food and agriculture. Aligned with FAO’s strategic initiatives, the course is fortified by the approval of the FAO Strategy on Mainstreaming Biodiversity Across Agricultural Sectors and the 2021-23 Action Plan, emphasizing the importance of targeted policies and practices for sustainable use, conservation, and restoration of ecosystems.
Learning pathway: Course flows & blueprint
This course is a pivotal contribution to FAO’s vision of fostering a Better Environment, particularly focusing on Biodiversity for food and agriculture. Aligned with FAO’s strategic initiatives, the course is fortified by the approval of the FAO Strategy on Mainstreaming Biodiversity Across Agricultural Sectors and the 2021-23 Action Plan, emphasizing the importance of targeted policies and practices for sustainable use, conservation, and restoration of ecosystems.
Learning pathway: Course flows & blueprint
This course is a pivotal contribution to FAO’s vision of fostering a Better Environment, particularly focusing on Biodiversity for food and agriculture. Aligned with FAO’s strategic initiatives, the course is fortified by the approval of the FAO Strategy on Mainstreaming Biodiversity Across Agricultural Sectors and the 2021-23 Action Plan, emphasizing the importance of targeted policies and practices for sustainable use, conservation, and restoration of ecosystems.
Learning pathway: Course flows & blueprint
This course is a pivotal contribution to FAO’s vision of fostering a Better Environment, particularly focusing on Biodiversity for food and agriculture. Aligned with FAO’s strategic initiatives, the course is fortified by the approval of the FAO Strategy on Mainstreaming Biodiversity Across Agricultural Sectors and the 2021-23 Action Plan, emphasizing the importance of targeted policies and practices for sustainable use, conservation, and restoration of ecosystems.