Homegarden Systems Research Articles

Home garden system dynamics in Southern Ethiopia

Home gardens in southern Ethiopia are regarded as efficient farming systems, allowing interactions and synergies between crop, tree and livestock components. However, these age-old traditional home gardens are evolving rapidly in response to changes in both the socio-economic and biophysical environment. Altered cropping patterns, farm size and component interactions may affect the systems’ sustainability. Home gardens exhibit a huge diversity in farms and farming systems, which needs to be understood in order to design interventions for improvement. Dynamics of home gardens were studied over two-decades (1991–2013) based on a survey of 240 farm households and focus group discussions. Farms were grouped into five types: Khat-based, Enset-cereal-vegetable, Enset-based, Enset-coffee and Enset-livestock. Farm trajectories revealed a shift from food-oriented Enset-based and Enset-livestock systems to (1) cash crop oriented khat-based systems, and (2) combined food and cash crop oriented Enset-cereal-vegetable systems. In densely populated, market proximate areas a major trend was expansion of khat, from 6 to 35% of the area share per farm, while the combined area share of enset and coffee decreased from 45 to 25%. Concurrently, the cattle herd size fell from 5.8 TLU to 3.9 TLU per household. In medium populated, less accessible areas the trend was consolidation of combined production of food and cash crops. Enset and coffee together maintained a share of over 45%. Easy transport and marketing of the perishable cash-generating khat compared with traditional crops favoured its cultivation among smallholders located close to markets. The insights in home garden change in response to increasing population pressure, decreasing farm size and market development may help to design interventions to increase system sustainability.

Allometric equations for yield predictions of enset (Ensete ventricosum) and khat (Catha edulis) grown in home gardens of southern Ethiopia

AbstractEnset is a large, single‐stemmed perennial herbaceous plant domesticated as a staple food crop only in Ethiopia. Khat is a perennial plant cultivated for its economically important leaves and twigs that are the sources of stimulant when chewed. We address the issue of yield estimation of both crops, as they are important for the livelihoods of smallholders in the home garden systems in Southern Ethiopia and have received little attention so far. The objective of this study was to develop linear allometric models for estimating the edible (food and feed) and commercial yields of enset and khat plants, respectively. Data were collected from 20 enset and 100 khat plants. Diameter at 50‐cm height (d50), pseudostem height (hp) and their combination were good predictor variables for the food products of enset with adjusted R2 values above 0.85, while d50, hp, edible pseudostem height (hep), total height (ht) and their combination were good predictor variables for the feed products of enset with adjusted R2 values above 0.70. For dwarf khat plants crown area (ca) combined with total height (ht) resulted in the best prediction with an adjusted R2 of 0.77, while the leaf and twig dry weight for tall khat plants was best predicted by ca with adjusted R2 of 0.43. In all cases linear models were used.

VILLAGE COMMUNITY AND FLORA BIODIVERSITY MANAGEMENT IN HOME GARDEN SYSTEM AT CENTRAL OF SUMBA REGENCY

Flora biodiversity is a strategic resource due its various potential uses for human benefit. Population growth is sometimes considered to be a contributory factor in the degradation of the biological resources, conversely, the population plays an important role in its conservation. This research aimed to understand the flora biodiversity management, structure and composition of plants in home-garden system. The research was conducted in Central Sumba Regency. Methods used were interview and observation. Data were analysed descriptively and qualitatively. The result showed that the flora biodiversity management in home garden based on poly-culture approach, a holistic beneficially as a socio-cultural-religious attribute, economic-income and ecology-conservation. The structure and composition of plant in the home-garden they include the variation of the important value index. The expansion of the residential areas positively impact the flora biodiversity conservation in home-garden system.

An Ecosystem Services Approach to Sustainable Livelihoods in the Homegardens of Kandy, Sri Lanka

ABSTRACTThe Kandyan homegardens, or forest gardens, of central Sri Lanka are diverse, smallholder agroforestry ecosystems that for 2000 years have reflected evolving environmental, economic, and social livelihood needs. An ecosystem services approach interrogated homegarden changes over the last 10 years in 31 Kandyan households. Livelihood strategies favouring homegardens were found to have broader benefits across household, national, and global scales than those favouring commercial simplification or those abandoning cultivation for alternative incomes. Livelihood benefits beyond income included resilience to economic and environmental shocks; food security; and higher stocks of biological and agricultural diversity. This revealed overlooked socio-ecological feedbacks between drivers that frustrated interventions to sustain homegarden livelihoods, including increased wild animal incursions thwarting household climate adaptation and disaster recovery; global organic and fair trade incentives reducing food security and livelihood resilience; and national seed and animal regulations counteracting homegarden sustainability programs. Despite these pressures, households maintained homegarden systems for their cultural, aesthetic and eating preferences. An ecosystem services approach can complement sustainable livelihood approaches by identifying overlooked environmental and cultural benefits; reveal livelihood feedbacks from drivers of ecosystem change; avoid unintended consequences from interventions; and capitalise on synergies between stakeholder priorities.

Can homegardens help save forests in Bangladesh? Domestic biomass fuel consumption patterns and implications for forest conservation in south-central Bangladesh

We conducted an exploratory survey in south-central Bangladesh to realize the contribution of homegardens to household domestic biomass fuel consumption. Households were placed into categories based on their land holdings. A total of thirty households were interviewed to understand their domestic fuel consumption pattern as well as the role played by homegardens in meeting their biomass fuel requirements. This study suggested that the majority of the households in the area rely extensively on homegardens to meet their domestic fuel requirements. 58% of the households biomass fuel were drawn from homegardens, followed by neighbours (16%), markets (12%) and from public/fallow land (14%). 47 species were identified from the homegardens that were used by the respondents as fuel. Fuelwood was a major type of biomass fuel used by the households, contributing to about 56% of households total biomass fuel consumption, followed by dried leaves (21%), dung cake/sticks (14%), and crop residues (6%). As homegardens were found to provide a valuable alternative source of biomass fuel, it was concluded that a rich homegarden system near forest regions should be supported in order to reduce pressure on the country’s remaining forests. Governments can facilitate this by granting marginal households access to trees in fallow lands, as well as public places including roads, railways and river banks.

Trees on farms: diversity, carbon pool and contribution to rural livelihoods in Kanchanpur District of Nepal

Trees and shrubs are important component of rural farming system in Nepal. This paper assesses tree diversity and carbon pool of trees and shrubs outside forests as well as their contribution in the rural economy of the study area. In the land use classification map derived from the high resolution ALOS Pan-sharpened imagery, random selection was made among systematic grid in the agriculture class to find out the inventory plot. The plot was designed as nested plot. Firstly, tree measurement was done and then leaves, branch samples as well as soil samples were collected from each sample plot. Structured questionnaire survey was used to assess the contribution of trees and shrubs on rural livelihoods. The biomass and soil samples were analyzed using dry combustion method to estimate the carbon content. The amount of carbon stock difference between farmland with TOF and without TOF was found 26.56 Mg (megagram) ha-1. There was 350,714.6 Mg above ground carbon, 35,103.36 Mg root carbon and 84451.18 Mg soil carbon accumulated by total trees and shrubs on farms in the District. Hence, the total carbon pool of the District in different agroforestry systems was estimated to be 470,269.18 Mg. Homegarden system was found to be a good agroforestry system in terms of having higher species richness, tree diversity and relatively higher amount of above and below ground carbon per unit area. The results also showed that the trees on farms contributed16.4% (NRs. 3689 per household/year) and 17.1% (NRs. 2613 per household/year) of farmland income and livestock income respectively. The results, thus, indicate that trees on farms have visible impacts on rural livelihoods, harboring rich plant diversity and sequestering substantial amount of carbon. Banko Janakari, Vol. 23, No. 1, Page 3-11 DOI: http://dx.doi.org/10.3126/banko.v23i1.9462

Floristic Composition of Home-garden Systems in Dumbara (Knuckles) Conservation Area with an emphasis on Endemic Species

Home gardens are multistoried ecosystems and are important not only for in-situ biodiversityconservation, but also as valuable food sources, fodder, medicine and spices. The main objective ofthis study was to make decisions about the variations of home garden composition and to identify theendemic species. Fifty five home gardens were studied in northern flank from January to April 2012.Two large (10x10m2) and four small (1x1m2) quadrates were studied in each home garden. Individuals≥ 1.5 m height and ≥ 1 cm DBH were measured to calculate IVI. Species identification was done onsite and further at the National Herbarium, Peradeniya. Total of 1335 individual woody-perennials and4603 herbs were found in 11,000 m2 of study area. One hundred and fifty two woody-perennial species(19 endemic, 44 naturalized exotics, 37 cultivated and 52 timber) under 54 families and 56 herbspecies (46 medicinal) belonging to 33 families were recorded. Euphorbiaceae was the dominantfamily with 15 species, followed by Fabaceae (11 species), Anacardiaceae (10 species), Rutaceae (10species), Myrtaceae (7 species), Rubiaceae (6 species), Arecaceae (6 species), Moraceae (5 species),Sapindaceae (4 species) and Zingiberaceae (4 species). Highest number of plant families (43) wasrecorded in Pitawala, while the lowest number of plant families was recorded in Polommana (24).Based on the Importance Value Index (IVI), the species to pay highest priority for conservation wereselected. According to Shannon diversity values for different villages, Rathninda is the most stable andless disturbed, whereas Polommana is the most unstable and highly disturbed village. There were fiveendemic Anacardiaceae species (Campnosperma zeylanicum, Mangifera zeylanica, Semecarpuscoriaceae, Semecarpus nigro-viridis, Semecarpus walkeri). Twelve percent of the studied populationwere interested in timber trees such as Tectona grandis, Melia azedarach, Swietenia macrophylla andChloroxylon swietenia. Twelve percent of the studied population preferred fruit trees while 5% wereinterested in some medicinal plants. Preference of this nature indicates that in the future, the plantdiversity in these home gardens is likely to decline considerably. This might even lead to theextinction of rare, endemic plant species. Therefore, people in northern flank encouraged toincorporate multipurpose endemic plants and plants with less IVI values in their home gardens inorder to maintain high diversity and to conserve endemic and relatively rare plants while gainingsubstantial income through their home gardens.Keywords: Northern Flank, Home gardens, Conservation, Woody-perennials, Endemic species

Ecological implications of village bamboo as global climate change mitigation strategy

PurposeThe present study seeks to evaluate the role of village bamboo management in the rural landscape of North East India in global climate change mitigation.Design/methodology/approachA set of 100 home gardens and 40 bamboo groves were selected from Irongmara and Dargakona village, in Cachar district, Assam, North East India through random sampling. Sampling was done mostly for smallholders. Culm growth, carbon storage, carbon sequestration and carbon in litter floor mass and soil of bamboo growing areas in homegarden was explored from 2003‐2007.FindingsCulm growth extension revealed the brief periodicity of culm growth in a single growth period. Of the total carbon storage soil contributed 84.6 per cent of the total (50.1 Mg ha−1) followed by carbon in above ground vegetation 15 per cent (9 Mg ha−1) and carbon in litter floor mass 0.4 per cent (0.2 Mg ha−1).Practical implicationsBamboo plantation development and its management in home gardens has social, ecological and economical benefits for the rural life in North East India and its promotion can become an effective choice for climate change mitigation strategy.Originality/valueBamboo forms an important component in the traditional home garden system of North East India where the practice of bamboo cultivation and management provides an important sink for CO2. Village bamboos play an important role in local economics, societies and environments and, considering its potential to mitigate global climate change, the authors recommend the promotion of bamboo in agroforestry expanding practices and rehabilitation of degraded lands. Management of village bamboos in rural landscape is highlighted in context to environmental sustainability and as a sink measure under the Clean Development Mechanism (CDM) of Kyoto Protocol.

Estimation of carbon stock in Kandyan Homegardens located in Kandy and Matale

Increasing levels of atmospheric greenhouse gases due to fossil fuel use, deforestation and other anthropogenic sources have changed the global climate. Global warming is the most widespread problem of the new millennium. Carbon dioxide (CO2) is the most important greenhouse gas released as a result of human activities. “Stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system” is the main objective of the UNFCCC. To help achieve this, the Protocol allows developed nations to credit removals of greenhouse gas emissions by natural sinks that store carbon. Forest based land use systems such as natural forests, forest plantations and agroforestry systems sequester CO2, through the C stored in their biomass. Management of forests and agroforestry systems is identified as the most promising option to mitigate atmospheric Carbon dioxide (CO2). The objective of the present study was to investigate the carbon sequestration potential of Kandyan Homegarden in Sri Lanka located in Kandy and Matale District. Two representative gardens were selected from each District in Kandy and Matale. After conducting a comprehensive vegetation survey done in 16, 10 x 10m plots in each garden in a 1 ha area located to capture the maximum variability in terms of tree density, topographic and edaphic differences. All the trees were measured for dbh and height and from the results dominant tree species which contribute to the long term carbon sequestration were selected using Important Value Index. Trees were then categorized into diameter classes and a tree each from each diameter class was selected for detailed measurements including stem and canopy volume. Representative number of trees per diameter class was destructively sampled to get the weight measurements and these were used to extrapolate the weight of the rest of the trees according to the volumes estimated. In this way the total aboveground biomass and carbon lodged in these gardens were arrived at. The potential to sequester carbon dioxide without being emitted to the atmosphere was also calculated for the individual gardens and extrapolated to all the Homegardens in the particular district. According to the results, average total aboveground carbon content that could be lodged in the Homegardens and total carbon dioxide that can be stored as carbon without being emitted to the atmosphere in Kandy District (Agro ecological zone WM3a) are 89.98 t C/ha and 330.23 t C/ha and are 103.89 t C/ha and 381.27 t C/ha in Matale District (Agro ecological zone IUI) respectively. According to the Forestry Sector Master Plan (1995) the total extent of the Homegardens in Kandy District is 61,029 ha and 20,258 ha in Matale District. Therefore total aboveground carbon content and carbon dioxide stored in the form of carbon in the Homegardens in Kandy District vary between 5,397,404 t C (5 x 106) – 5,585,374 (5 x 10 6) t C and 19,888,182 t C (19.89 x 106 ) – 20,499,030 t C (20.45 x 106 ) respectively. In Matale District the total aboveground carbon content and carbon dioxide stored as carbon in homegardens vary between 2,455,674 t C (2.45 x 10 6 ) – 1,753,532 t C (1.75 x 10 6) and 9,012,176 t C (9.00 x 10 6 ) – 6,435,358 t C (6.44 x 10 6 ) respectively. Annual litterfall rate of selected Homegarden system in Kandy District is 8.16 t/ha and 9.38 t/ha in selected Homegarden in Matale District. Mean annual litterfall rate in Kandyan Homegarden system is equal to 8.77 tons ha-1 year-1.

The Tswana tshimo: a homegarden system of useful plants with a particular layout and function.

The Tswana tshimo (homegarden) is a model of sustainable resource management in South Africa. However, gardens of indigenous cultures are often considered to be spontaneous and disorganized. A reconnaissance survey of homegardens of the Batswana people in the North-West Province of South Africa examined the different use categories of garden plants, the indigenous and alien composition of garden floras, and determining whether a specific homegarden layout exist with tshingwana (microgardens) containing useful species. A floristic survey was conducted of 163 randomly selected tshimo’s from three Batswana communities (deep rural, rural and peri-urban). A total of 525 useful plant species belonging to 105 plant families were recorded. These could be divided into four main plant use categories, namely 98 food, 91 medicinal, 281 ornamental and 49 structurally functional species (e.g. hedges), while six species had other uses. Deep rural and rural homegardens are characterized by a higher percentage of naturally occurring, indigenous useful plant species when compared to the predominantly alien flora of peri-urban areas. Deep rural and rural homegardens had a specific garden layout that was characterised by six micro-gardens, namely food gardens, medicinal gardens, ornamental gardens, structural species, open areas and natural areas. In contrast, peri-urban Batswana gardens had a garden layout similar to European gardens.

Spatial and temporal variation in crop diversity in agroforestry homegardens of southern Ethiopia

A key assumption in many homegarden studies is that homegardens are ecologically and socio-economically sustainable due to their species diversity. The precise relation between diversity and sustainability is still heavily debated, however. A basic question is how diversity in homegardens can best be characterized in view of the various dimensions of species diversity and their variation in time and space. This paper assesses different types of species diversity in the homegardens of Sidama region of southern Ethiopia. In a survey of crop species in 144 homegardens a total of 78 cultivated crop species (excluding trees) belonging to 10 functional groups were recorded; there were on average 16 crop species and 8 functional groups per farm. Within homegardens, plots differ in species composition and crop diversity. Four types of homegarden systems are distinguished differing in both type and area-share of dominant species, relative orientation at subsistence or cash production and overall crop diversity. The gradual replacement of enset by maize and of coffee by more financially attractive cash crops khat and pineapple causes a decrease in overall crop diversity. Our data demonstrate that it is incorrect to consider homegardens as generic systems with a uniform distribution of species diversity: important within and between homegarden variation exists. Ecological and socio-economic sustainability is not just related to species diversity per se, but rather to more specific features such as presence of keystone species and diversity in functional species groups. Socio-economic sustainability in terms of adjustment to socio-economic change implies dynamics in species diversity.

More than a Mere Newton: Nutrient Analysis of Heirloom ‘Mission’ Fig Tree Fruits

Ficus carica L. (the common fig tree) is one of many non-native species adapted to home-garden systems within northern Mexico and southern Arizona. Along with other Mediterranean fruits such as grapes and olives, fig trees were introduced to the area through the Catholic mission system during the mid-1500s to the mid-1800s. Clonal descendents from the original ‘Mission’ fig trees persist in present-day home gardens. The objective of this study is to provide information critical for the conservation of heirloom ‘Mission’ fig trees in southern Arizona home gardens. One step in this process is the evaluation of the nutrients of heirloom fig fruits. The results from a preliminary nutrient study are presented in this paper. The results show that for fresh and dried heirloom fig fruit, sugar levels and vitamin A levels are statistically lower when compared to the U.S. Department of Agriculture's (USDA) National Nutrient Database for Standard Reference. For fresh and dried heirloom fig fruit, potassium levels are statistically higher when compared to the USDA Database. For calcium, heirloom fresh fig fruits showed statistically higher levels and heirloom dried fig fruits showed no difference when compared to the USDA Database. More studies are required to determine the causes for this variation in fig fruit nutrient levels.

Trees outside forests (TOF): a case study of the wood productionconsumption situation in Kerala

SUMMARY This paper analyses the wood production—consumption situation in Kerala state, India. Wood is defined to include all timber, industrial wood, fuelwood and charcoal. The analysis reveals a comfortable position, with a surplus of 0.027 million m3 of wood. Of the total wood production of 11.714 million m3, forests provide about 10 percent and trees outside forests contribute to the remaining 90 percent. The study shows the importance of trees outside forests, particularly in home gardens which are renowned for their mixed cropping multi-tier agro-forestry system. The ecologically rich home garden system that produces substantial quantities of wood is a traditional farming practice that evolved in Kerala. The home gardens with a variety of multi-purpose trees may be considered as a model for extension to other similarly endowed regions within and outside the country, not only for wood production but also for social and environmental benefits.

Characterizing land-use diversity in village landscapes for sustainable mountain development: a case study from Indian Himalaya

This study aimed to analyze the ecological, socio-economic and policy implications of land-use diversity in a traditional village landscape (900–1,000 m amsl.) in the Garhwal region of Indian Himalaya. The village landscape was differentiated into three major land-use types viz., forests, settled agriculture and shifting agriculture. Settled agriculture was further differentiated into four agroecosystem types viz., homegarden system (HGS), rainfed agroforestry system (RAS), rainfed crop system (RCS) and irrigated crop system (ICS), and shifting agriculture system (SAS) was differentiated into different stages of a 4-year long cropping phase and a 7-year long fallow phase, and forests into Community Forests (CF) and Reserve Forests (RF). HGS is the most productive agroecosystem, with soil organic carbon and nutrient concentrations significantly higher than all other forest/agricultural land-uses. Farmers capitalize upon crop diversity to cope with the risks and uncertainties of a monsoon climate and spatial variability in ecological factors influencing productivity. The SAS, a land-use adopted as a means of acquiring inheritable rights over larger land holdings provided in the policies during the 1890s, is less efficient in terms of land productivity than the traditional RAS and HGS but is maintained for its high labour productivity coupled with availability of high-quality fuelwood from fallow vegetation. Dominance of fodder trees in the RAS seems to derive from policies causing shortage of fodder available from forests. Cultural norms have favoured equity by allowing hiring of labour only from within the village community and income from non-timber forest products only to the weaker section of the society. Conversion of rainfed to irrigated cropping, a change facilitated by the government, improves agricultural productivity but also increases pressure on forests due to higher rates of farmyard manure input to the irrigated crops. Existing forest management systems are not effective in maintenance of a large basal area in forests together with high levels of species richness, soil fertility and resistance to invasive alien species Lantana camara. Farmers have to spend huge amount of labour and time in producing manure, managing livestock and other subsidiary farm activities. Interlinkages among agriculture, forests and rural economy suggest a need of replacing the present policies of treating agricultural development, forest conservation and economic development as independent sectors by an integrated sustainable development policy. The policy should promote technological and institutional innovations enabling parallel improvements in agricultural productivity and functions of forest ecosystems.

Changing livelihoods on the slopes of Mt. Kilimanjaro, Tanzania: Challenges and opportunities in the Chagga homegarden system

Mt. Kilimanjaro area with the old Chagga agroforestry system has been one of the most productive agricultural areas is Tanzania. Today the area is facing several challenges that affect people’s livelihoods. To study implications of low coffee price, population pressure and ensuing land use change on the farming systems and livelihoods of the people of the southern slopes of Mt. Kilimanjaro, Tanzania, an interview survey was conducted. A multivariate regression analysis was used in studying and testing the interrelationships between farm production and some socio-economic variables (assets). From nine different independent variables only land size and farmers age had statistically significant influence on revenue from the main crops grown. This suggests that families have so many different combinations of assets and farm-specific temporally varying strategies and objectives that it is not possible to find clear patterns of assets and strategies that would lead to successful livelihood outcomes. Due to sinking coffee prices in the world market, farmers have been looking for alternatives to earn cash. As land scarcity hinders both expansion of cultivation and expansion of animal keeping, more intensified and diversified production and off-farm activities have become crucial. There is an urgent need for technical research and experimentation on new agricultural options for the area and a need of understanding and creation of marketing channels.

Land use change patterns and livelihood dynamics on the slopes of Mt. Kilimanjaro, Tanzania

This study is about changes in land use and interactions of land use change and livelihoods in the Chagga farming system on the slopes of Mt. Kilimanjaro, Tanzania. An aerial photo interpretation and fragmentation analysis of the years 1961, 1982 and 2000 was conducted covering approximately the Kirua Vunjo Division, a transect of 152 km 2 from the forest reserve edge to the plains. Earlier changes were traced from literature review. The results show the expansion of cultivation to more marginal land down the slope, the disappearance and extreme fragmentation of bush land and appearance and expansion of settlements. The home garden area has experienced some specific internal change, but has not expanded down the slope. In the 1960s there were small open fields and patches of grazing lands amongst home gardens. In the 1980s the area was more uniformly covered by homegardens. Since then it has become patchy again as new homesteads have been built on subdivided farms and more food is produced on the higher slopes. Population pressure and the ensuing expansion of agriculture to more marginal land, intensification of the homegarden system, together with climate changes affecting the water supplies, have caused changes in farmers’ livelihoods. As land scarcity now hinders expansion of agriculture, farm size has seriously decreased, common resources have become scarce, and prices of coffee in the world market remain low, farmers are trying to intensify and diversify their farm production. Local initiative is leading to change, but the locally conceived alternatives are too few and lack integrated approaches of technical agricultural research, economic analysis, and policy studies and reforms. Non-agricultural activities and paid employment are becoming increasingly important. However, due to considerable entry barriers to remunerable off-farm jobs, not all households enjoy equal access to attractive non-farm opportunities. The future welfare of the area will depend on increasing the marketable knowledge and skills of the population that will enable it to become integrated in the economy of the region and the country.

Energy and Economic flow in homegardens in Subtropical Yunnan, SW China: A case study on Sanjia village

SUMMARY We studied the energy and economic flow of six types of homegardens in Sanjia village, SW China. Our study showed that the energy input of six types of homegardens averaged 99.11-175.65 x 1010J/ha, the energy output was 102.30-159.83 x 1010J/ha and the ratio of input/output ranged between 1:0.880-1:1.416. The ratios of input to output of home-gardens that prioritized cultivation of crops were higher than for homegardens that prioritized animal husbandry or other economic activities. The economic ratio of input/ output of six types of homegardens varied between 1:0.997-1:1.376 and the economic output ranged between 2480.0-10131.5 RMB/yr. We concluded that the homegarden systems of Sanjia village are high in the input and output of energy and cash flow, and can provide a basis for designing models of farm economy in rural subtropical areas.

Carbon stocks in Indonesian homegarden systems: Can smallholder systems be targeted for increased carbon storage?

Homegardens are a common smallholder agroforestry system in Indonesia and throughout the tropics. These species- rich, tree-based systems produce non-wood and wood products for both home use and market sale. Due to their high biomass, these systems simultaneously offer potential for carbon (C) storage. While small size limits the amount of C stored by individual smallholder agroforestry systems, on a per area basis these systems can storage as much C as some secondary forests. In aggre- gate, smallholder homegarden agroforestry systems can contribute significantly to a region's carbon budget while simultaneously enhancing smallholder livelihoods. A field study in Lampung, Indonesia indicates that homegardens with an average age of 13 years store 35.3 Mg C ha -1 in their above-ground biomass, which is on par with the C stocks reported for similar-aged secondary forests in the same area. However, to compare accurately the C stocks of different land-use systems a scale is required that adjusts C stocks of the systems' ages and rotation lengths to a common base. The time-averaged C stock, which is half the C stock at the maximum rotation length, serves this purpose. Our projections reveal that, depending on management options, the time-averaged above-ground C stocks of homegarden systems could vary from 30 to 123 Mg C ha -1 . These projected time-aver- aged above-ground C stocks of homegardens are substantially higher than those of Imperata-cassava systems (2.2 Mg C ha -1 ), which is an extensive vegetation type in the study area. If homegarden systems and other smallholder tree-based systems were to expand in currently degraded and underutilized lands, such as Imperata grasslands, the C sequestration potential would be about 80 Mg C ha -1 , with considerable variation depending on species composition and management practices. Clear opportunity exists

Ecological rationalities of the traditional homegarden system in the Chao Phraya Basin, Thailand

Although the homegarden systems in the tropics are claimed to sustain basic community needs without environmental deterioration, the ecological rationalities behind the harmony between the humans, homegardens, and the environment are not well understood. Four study sites (Sukhothai, Srisatchanalai, Ayudhaya, and Nonthaburi) representing the four Thai eras in the Chao Phraya Basin were selected for studying these rationalities. The size and physical stature of the homegardens, their plant association and community features, physical environmental factors, nutrient and soil fertility parameters, and cultivation practices were studied. The major factor that determines species selection in homegardens is the utilization of the products, while the various practices within the homegardens are determined by such factors as the species, the system, and the environment. All homegardens had four vertical stratifications, with physical structures almost similar to that of dry dipterocarp forest, but with lower height for each layer, lower diversity of plants, and sparser crown layer. The analysis also shows a high possible utilization efficiency for space, light, water and nutrients in the soil in the homegardens. Shannon-Wiener's indices of species diversity of the homegardens were close to those of dipterocarp forest. The homegardens are in-situ reservoirs for biodiversity at genetic-, species-, and ecological levels. There was no complete harvesting from these homegardens. This practice ensured minimal nutrient export from the systems, while high amounts and diversity of litter biomass should contribute to high efficiency of nutrient cycling. Futhermore, phosphorus availability could be better in homegardens. The homegardens had more favorable microenvironment with lower soil and atmospheric temperature and higher relative humidity than outside. There has been no single incident of a pest outbreak at a threatening level.

Kandyan gardens of Sri Lanka

Kandyan Gardens (KG) or Kandyan Forest Gardens (KFG) of Sri Lanka represent a traditional system of perennial cropping which has been in practice for several centuries. It is essentially a system of mixed cropping with a variety of economically valuable groups of tree crops such as spices, fruits, medicinal plants and timber species. However, these systems are usually in small homestead holdings and are practised in a few districts, especially Kandy, Matale and Kurunegalle in the 'mid-country' region of Sri Lanka. In the district of Kandy, this is the most predominant cropping system and hence the name 'Kandyan Gardens' or 'Kandyan Forest Gardens'. The mixed forest-gardening system offers a highly diversified and economically viable form of land use. Similar systems are also being practised in several other densely populated parts of humid lowlands, for example, in India, Thailand, Malaysia, Indonesia and Papua New Guinea in South-east Asia [4, 5, 8, 9]. However, the Kandyan forest garden system is different from these other homegarden systems mostly in terms of the variety of plants grown. Moreover the farmers who practise the Forest garden systems in Sri Lanka enjoy a 'relatively better' level of living by virtue of returns from both the economic cash crops and the subsistence products. Presumably, with improved management, the system has the potential for increased production and better returns. This paper examines the situation with respect to the Kandyan garden system and endeavours to identify the directions of research for the improvement of the system. The data presented in the paper are based on a survey of 30 farms of the locality [7] and on results of mixed cropping experiments conducted by the minor export crops research project [2, 4,5,6].