The resource base that ensures food supply and the socio-economic component which depends on this resource base are the two major components that make up the food system in sub-Saharan Africa. The sequence of the food system is organized in a spatial flow framework of biomass base. The components of rural production system consist of food production biomass at homestead and farm level, and often at the communal base non-food production lands. The degree of integration between these resources base determines flows such as material cycle, energy, food and cash, and influences how the entire production system needs to be managed. The management system influences resource use efficiency and economic returns at different levels, at individual household, communities, and national levels. Efforts to developing agriculture and reducing poverty remained sectoral and focused mainly on a specific crop or individual animal level, failed to see interconnections among sub-systems and across space and time. The concept of the integrated food system has not been adequately adopted, in many sub-Saharan African countries and the agricultural system in the region continues to exhibit a low level of productivity and resource use efficiency. Hence, food insecurity and poverty remained high among smallholder farming communities producing crop and livestock despite the availability of arable land and abundance of another natural resource. This review focuses on the significance of integrated crop-livestock system in the tropics and suggests a framework to begin understanding and addressing complex problems in smallholders’ production system.
Tag: biomass production
An integrated pan-tropical biomass map using multiple reference datasets
We combined two existing datasets of vegetation aboveground biomass (AGB) (Saatchi et al., 2011; Baccini et al., 2012) into a pan-tropical AGB map at 1-km resolution using an independent reference dataset of field observations and locally-calibrated high-resolution biomass maps, harmonized and upscaled to 14,477 1-km AGB estimates. Our data fusion approach uses bias removal and weighted linear averaging that incorporates and spatializes the biomass patterns indicated by the reference data. The method was applied independently in areas (strata) with homogeneous error patterns of the input (Saatchi and Baccini) maps, which were estimated from the reference data and additional covariates. Based on the fused map, we estimated AGB stock for the tropics (23.4 N – 23.4 S) of 375 Pg dry mass, 9% – 18% lower than the Saatchi and Baccini estimates. The fused map also showed differing spatial patterns of AGB over large areas, with higher AGB density in the dense forest areas in the Congo basin, Eastern Amazon and South-East Asia, and lower values in Central America and in most dry vegetation areas of Africa than either of the input maps. The validation exercise, based on 2,118 estimates from the reference dataset not used in the fusion process, showed that the fused map had a RMSE 15 – 21% lower than that of the input maps and, most importantly, nearly unbiased estimates (mean bias 5 Mg dry mass ha-1 vs. 21 and 28 Mg ha-1 for the input maps). The fusion method can be applied at any scale including the policy-relevant national level, where it can provide improved biomass estimates by integrating existing regional biomass maps as input maps and additional, country-specific reference datasets.
Biomass of teak plantations in Tamil Nadu, India and Costa Rica compared
In the present study, prediction equations for biomass were generated from easily measurable parameters such as diameter at breast height (dbh) and total height. Cross validation was carried out between two localities to test whether equations developed for one locality could be used for other localities. Two localities were compared within India and a further comparison was made with teak growing in Costa Rica, Central America. The result showed that best-fit models developed for one zone cannot be used for other zones. The authors agree with Wang et al. (1995) that errors in biomass estimation can be reduced to a minimum only by employing site-specific equations. Hence, there is an imperative need to develop predictive equations on a regional basis in order to improve their accuracy.
Biofuel plantations on forested lands: double jeopardy for biodiversity and climate
The growing demand for biofuels is promoting the expansion of a number of agricultural commodities, including oil palm (Elaeis guineensis). Oil-palm plantations cover over 13 million ha, primarily in Southeast Asia, where they have directly or indirectly replaced tropical rainforest. We explored the impact of the spread of oil-palm plantations on greenhouse gas emission and biodiversity. We assessed changes in carbon stocks with changing land use and compared this with the amount of fossil-fuel carbon emission avoided through its replacement by biofuel carbon. We estimated it would take between 75 and 93 years for the carbon emissions saved through use of biofuel to compensate for the carbon lost through forest conversion, depending on how the forest was cleared. If the original habitat was peatland, carbon balance would take more than 600 years. Conversely, planting oil palms on degraded grassland would lead to a net removal of carbon within 10 years. These estimates have associated uncertainty, but their magnitude and relative proportions seem credible. We carried out a meta-analysis of published faunal studies that compared forest with oil palm. We found that plantations supported species-poor communities containing few forest species. Because no published data on flora were available, we present results from our sampling of plants in oil palm and forest plots in Indonesia. Although the species richness of pteridophytes was higher in plantations, they held few forest species. Trees, lianas, epiphytic orchids, and indigenous palms were wholly absent from oil-palm plantations. The majority of individual plants and animals in oil-palm plantations belonged to a small number of generalist species of low conservation concern. As countries strive to meet obligations to reduce carbon emissions under one international agreement (Kyoto Protocol), they may not only fail to meet their obligations under another (Convention on Biological Diversity) but may actually hasten global climate change. Reducing deforestation is likely to represent a more effective climate-change mitigation strategy than converting forest for biofuel production, and it may help nations meet their international commitments to reduce biodiversity loss.
A general allometric equation for estimating biomass in Acacia mangium plantations
Acacia Mangium Willd. is one of the most important tree species grown in commercial plantation in Monsoon Asia. Recently, the need for accurate information in the biomass in plantations has become more urgent, especially since the amount of carbon sequestered in afforestation/reforestation Clean Development Mechanism (AR-CDM) projects in developing countries can be included under the Kyoto Protocol. We present here a general allometric equation for estimating aboveground biomass (AGB) of A. mangium plantations from the diameter of the trees recorded at the respectives sites. Destructive samplings were conducted in Papua New Guinea, Vietnam, and Indonesia. At each site, 4-12 trees were felled, their trunks, branches and leaves were separately weighed, and allometric models for estimating AGB was determined. A general allometric equation (A log-log model) was developed from an overall total of 26 sample trees from sampled sites. No significant differences were found between the biomass estimations derived from the site-specific and the general allometric equations. The general allometric equation may allow us to estimate AGB of A. mangium plantations in Monsoon Asia without destructive sampling.
Aboveground biomass of Tectona grandis plantations in Costa Rica
There are few studies on biomass distribution for Tectona grandis plantations in Costa Rica. This paper reports the distribution of total aboveground biomass of T. grandis and its relationship with diameter at breast height (dbh), age and stand density in plantations across Costa Rica. Foliage, branch, stem and total aboveground biomass were highly correlated both with dbh (r > 0.91) and with age (r < 0.85). Foliage dry biomass represented between 1 and 6% of the total tree dry biomass, while 5 to 30% corresponded to branches and 70 to 90% to stem dry weight. Per hectare aboveground biomass tended to incease with increasing age class (young, intermediate and mature). Foliage dry biomass varied between 3 and 9 Mg Ha-1, branch dry biomass between 11 abd 54 Mg Ha-1, stem dry biomass between 70 and 221 Mg ha-1, and total aboveground dry biomass between 84 and 284 Mg ha-1, and total aboveground dry biomass between 84 and 284 Mg ha-1. Significant relations between crown diameter and aboveground biomass with dbh, age and stand density, useful for the management of stand competition, are the main results of this study.
Biomass and potential nutrient removal by harvesting in short-rotation plantations
Data on standing biomass, mean annual increment of carbon stock, and nutrient accumulation in 40 industrial plantations at 21 sites in 11 countries are summarised. Aboveground biomass and mean annual increment of carbon near the harvest age, of these plantations ranged from 44 to 324 t ha-1 and from 3.1 to 22.9 tC ha-1 yr-1, respectively. Plantations managed on a short rotation are expected to accumulate carbon rapidly. However, there are large variations of biomass accumulation depending on site conditions. There is concern about the potential decrease of productivity caused by nutrient loss by intensive and repeated harvesting. It is important to determine the nutrients removed and conserve them as much as possible to prevent productivity loss and for sustainable management of industrial plantations. Careful management of the nutrient cycle through residue retention and fertiliser application is necessary to maintain high productivity.
Comparative analysis of climate change impact on livestock in relation to biomass base feed availability using standardized precipitation index in south-western Ethiopia
The standardized precipitation index and normalized difference vegetation index on event incidences (at different time scale) and biomass feed dry matter production, were used to assess climate change influences on feed availability. A significant decline (p<0.05) in feed dry matter availability indices across years was observed. The deviation from normality shows that the biomass feed production could vary significantly during drought occurrence years and this accelerates profoundly over time as drought frequency is expected to increase over time. The highest significant decline was observed in 2015 followed by 2006 and 2014. The results of analysis of the impact of climate change on livestock in relation to biomass dry matter production discretely subdivide different agro-ecological zones into land use land cover classes in southwestern Ethiopia. As represented by temporal scale drought, flooding and landslides were incidences considered as the major climatic risks in the study area. The risks threaten the livelihoods and even the security of the socio-ecological systems in general and such marginalized segments of the farming society in particular. The future needs effective action on environment management, devising adaptive and mitigation mechanism and change should aim at managing the occurrence and effects of extremes.
Growth and timber quality of Tectona grandis in high input plantations of Costa Rica
Linking forest management to timber industry requirements is fundamental. Connections of silvicultural activities with wood quality are often limited to size-related characteristics, such as minimum DBH. Restrictions set by international markets (e.g. minimum log dimensions, heartwood content and wood defects) limit seriously the marketing options of several forest companies in Costa Rica and many other countries in the area. Therefore, efficient management practices are urgently needed to lead not only to a maximization of per-hectare volume but also to the production of desirable individual-tree dimensions and high quality commercial timber. This paper discusses following topics: aboveground biomass and the applicability on stand density management; wood quality of young and advance aged plantations; effects of stand density on wood quality, results from a thinning trial; effects of stand density on growth and yield, results from a thinning trial; preliminary pruning program, pruning intensity and timing; and total and merchandable volume equations.