Agroforestry Systems

Prospects for in vitro micrografting shoot apices of mature Acacia mangium trees were investigated with the use of 432 micrografts. Overall success rates of 51.5%s% were obtained for shoot apices ranging from 200 to 400 μm in length, and a short basal wedge of underlying tissues top-grafted in aseptic conditions onto 2-to-3-month old in vitro grown Acacia mangium seedlings. The successfully established micrografts displayed, however, substantial variability in terms of further scion elongation as 41% of these micrografts, or 21.2% only of the total amount of the micrografts performed, had resumed growth two months after micrografting. The elongated scions exhibited different types of morphology, ranging from juvenile-like type composed leaves to the predominant mature-like phyllode morphology. Side-grafting, a more difficult procedure to perform than top-grafting, or placing the micrografts for 2 weeks in darkness after grafting, did not improve the scores. Moreover, attempts to micrograft meristems (150–200 μm) resulted in 5% success only.

Litter decomposition and nutrient release are key factors in the nutrient cycling and availability in land uses and sustainable production systems. In three land uses systems (native forest—NF, coffee agroforestry system C-AFS, and pasture monoculture–PM), litter decomposition rate and nutrient release were estimated during 120 days. A total of 216 litterbags were systematically placed with 20 g of litter in dry matter basis each, which were extracted at 8, 23, 35, 50, 91, and 120 days later to estimate remnants dry matter (RDM %). No interaction was detected in litter decomposition rate between land use systems and decomposition time, presenting a different behavior between land uses in time. In contrast, land uses and time statistically affected (p < 0.01) litter decomposition. The exponential model (RDM = 100.0e(−0.0056t), SME = 23.5 for NF; RDM = 100.0e(−0.0064t), SME = 25.5 for C-AFS; and RDM = 100.0e(−0.0457t), SME = 136.8 for PM) presented the best fit to estimate the relative RDM (%) over time (t in days) in the three land uses. PM presented the greatest turnover rate at 120 days compared to AFS-C and NF (with a RDM of 14, 51 and 52%, respectively). The process of nutrient release was also faster in PM than in the other systems, with potassium as the fastest nutrient. These results suggest that the intervention in land use has an impact on rates of litter decomposition and nutrient, which affects nutrient cycling. The litter decomposition and nutrient release in agroforestry systems with coffee were similar to those in native forests which explain its contribution to sustainability of these production systems.

Peach palm (Bactris gasipaes) was domesticated as a fruit crop by the first Amazonians in traditional Neotropical agroforestry systems, but research and development (R&D) to date has not transformed its fruit into a modern success story. The fruit is really a tree ‘potato,’ competing with traditional starches rather than with succulent fruits. R&D efforts have focused more on production than on product transformation, commercialization and the consumer, thus failing to fill gaps in the production-to-consumption chain. Consumer demands are only now getting more consideration, and clear identification of the smallholder farmer as the R&D client is not yet generalized. Too many, often large germplasm collections have biased R&D programs away from smallholder farmers and did not pursue the quality and uniformity that consumers want. The general lessons learnt from 25 years of R&D efforts on peach palm that should guide the development of other indigenous agroforestry fruit tree species are: 1) identify market demands, whether subsistence or market-oriented; 2) identify clients and consumers, and their perceptions of the product; 3) work on food and nutritional security aspects of the species and let entrepreneurs be attracted, rather than vice versa; 4) take up species improvement in a moderately sized effort, using a participatory approach tightly focused on clients' demands; and 5) reappraise the priorities from time to time.

The purpose of natural fallow in bush-fallow cultivaton systems is to improve soil fertility following a phase of cultivation and to provide useful forest products, including livestock feed. When natural fallow fails to serve these purposes, it can be supplemented or replaced by planted trees. This paper describes the development and function ofAcacia fallow in the Soli tribal land of central Zambia and examines the supplementary role of planted trees. The 31 woody species at five fallow sample sites were dominated byAcacia polyacantha. Thirty-nine percent of the species are leguminous and N-fixing while 42% are fodder plants. These species make thisAcacia fallow suitable for regeneration of soil fertility and production of fodder. The dominant species,A. polyacantha, has an extensive lateral root system and may attain a mean maximum girth at breast height (BH) of 125 cm within 20 years. In the study areaAcacia fallow regenerates from seed and root-stocks and with a maximum annual stem basal area increment of 0.87 m2ha−1 at BH can acumulate a total of 17.4 m2ha−1 in 20 years. However,Acacia fallow is poor in edible wild fruits and durable construction wood. The scarcity of fruits in the study area has been compensated by widespread planting of exotic fruit trees. Ninety percent of households have fruit trees (mean 2.3 fruit species per household). However, in spite of the scarcity of good construction wood in the Soli tribal land, no local initiative has developed to plant timber trees. A clear opportunity therefore exists to promote timber tree planting. Such a tree planting programme was started in the study area during the 1985/86 planting season (December-February) when 25,100 seedlings ofEcualyptus grandis, Gmelina arborea andLeuceana leucocephala were distributed, free of charge and the programme will continue until 1988. A survey carried out five to seven months after planting revealed that the survival ofE. grandis, L. leucocephala andG. arborea seedlings was 65%, 90% and 92%, respectively. The high mortality ofE. grandis seedlings was due to termite damage.

Willows (Salix spp.) have excellent capacity for acquiring nutrients, and are widely used for removing excess nutrients in wastewater purification system. In this study, 18 willow clones were evaluated in terms of growth parameters, nitrogen (N) accumulation and N use efficiency under two N regimes (low N and high N) with a sand culture system. Clonal differences were observed in biomass production, relative growth rate, N accumulation and use efficiency under two N regimes, which were contributed to the clone level. For all clones, nitrogen use efficiency was lower under high N condition than under low N condition. Nitrogen removal efficiency differed by 7-fold (low N regime) and 10-fold (high N regime) based on shoot N contents between the lowest and the highest clone. Among all the clones, J799 had the highest N content in shoots, showing largest N removal potential. These results confirmed that growth analysis and nutrient use strategy are efficient method of selecting Salix clones for improving the N removal potential.

Farm household characteristics determine the success of programs promoting agroforestry systems and practices. This paper reports household and farm factors affecting the adoption of timber management practices by smallholders in the Gunungkidul region, Central Java, Indonesia. The research used three logistic regression analysis models—based on each household and farm characteristic, and a composite of both together—to identify the key factors influencing farmers’ adoption and management decisions, and their relative importance. A sample of 152 farmers who managed their trees primarily for timber production was compared to a sample of 115 farmers with similar socio-economic characteristics who did not. The household condition and composite models identified both on-farm and off-farm gross incomes as significant factors affecting farmers’ decisions to manage timber trees. The models confirmed that farmers with larger farms, and with higher on- and off-farm incomes, were more likely to manage their trees for timber production. These results have implications for extension programs that promote adoption of commercial timber management by smallholders in the case study and similar regions.

The aim of this study was to evaluate the in vitro lethal effect of a hydroalcoholic extract (HAE) from C. coriaria fruit against eggs and larvae of H. contortus of domestic ruminants. The HAE was assessed using five concentrations: 50, 25, 12.5, 6.15 and 3.12 mg/mL to eggs and 100, 125, 175, 150 and 200 mg/mL to larvae, respectively; 0.5% ivermectin was used as positive control and 4% methanol in distilled water as negative control. The data of larvicidal and ovicidal effect were analysed with a completely randomised design by ANOVA analysis using the general linear model, while lethal concentrations (LC50 and LC90) were estimated by a Probit analysis of the SAS programme. A clear HAE-increased concentration dependence effect was observed on eggs and larvae. The highest activity of the HAE was obtained at the highest concentration (P < 0.05) to obtain a similar effect as the positive control (ivermectin), with LC50 = 22.93 and 10.3 mg/mL and LC90 = 44.0 and 84.18 mg/mL, respectively, for larvae and eggs. The results indicate that the HAE of C. coriaria fruit possesses in vitro ovicidal and larvicidal properties (total phenols methyl gallate) against H. contortus, and it becomes an alternative for in vivo research for the control of gastroenteric nematodes in ruminants, either whole fruits or extracts administered orally. In this context, in vivo studies with this legume are thus necessary.

Production of native and hybridized varieties of Populus has received considerable interest in temperate regions as an alternative to agricultural crops and an additional wood source, while acting as a potential carbon (C) sink to offset emissions of fossil fuel-based greenhouse gases. Research of root system dynamics in Populus species is expanding, however, our understanding of the nature and role of fine roots (FR) is incomplete. The study objective, therefore, was to review the literature regarding FR production, mortality and longevity in Populus, and evaluate the magnitude and significance of the FR fraction to C sequestration. FRs, conventionally defined as less than 2 mm in diameter and responsible for water and nutrient uptake, are an essential component of the tree. Populus FRs are relatively short-lived, with reported lifespans ranging from 30 to 300 days, depending on root diameter, tree species and age, and soil environmental factors. Standing FR biomass fluctuates throughout the growing season. Fine root production generally peaks in mid-summer, and ranges between 1.0 and 5.0 mg ha−1 yr−1, while FR mortality has less seasonal amplitude. Production and mortality dynamics in Populus are highly plastic in response to soil environmental conditions, and although opposing conclusions have been proposed, research suggests soil moisture and nitrogen to be most important. Results from the literature indicate annual FR turnover to the soil C pool may be small (0.2–1.6 mg C ha−1 yr−1), but substantial in maintaining or enhancing C levels in natural and managed stands of Populus.