Green manures for maize—bean systems in eastern Uganda: Agronomic performance and farmers' perceptions

Researchers worked with farmers in eastern Uganda to develop alternatives for soil management using crotalaria (Crotalaria ochroleuca), mucuna (Mucuna pruriens var. utilis), lablab (Dolichos lablab), and canavalia (Canavalia ensiformis) as green manures in short-term fallows. The participatory research was part of a community-based approach for systems improvement. Grain yields of maize (Zea mays) and bean (Phaseolus vulgaris) following one season of crotalaria fallow were 41% and 43%, respectively, more than following a two-season weedy fallow. Grain yields of maize following a one-season fallow with mucuna and lablab were 60% and 50% higher, respectively, as compared with maize following maize. Maize and bean yield were more, although effects were small, during the second and third subsequent seasons, indicating probable residual effects of the green manures. Mucuna and lablab were successfully produced by intersowing into maize at three weeks after sowing maize, although the yields of the associated maize crop were reduced by 24% to 28%. Farmers estimated the labor requirements for mucuna and lablab to be less than for crotalaria. Farmers independently experimented on how these species can be integrated into banana (Musa spp.), coffee (Coffea robusta), sweet potato (Ipomoea batatas), and cassava (Manihot esculenta) production systems. Farmers reported that the beneficial effects of the green manures included higher food-crop yields; weed suppression; improved soil fertility, soil moisture, and soil tilth; and erosion control. Mucuna and lablab were preferred because of reduced labor requirements and increased net benefits compared with continuous cropping. Farmer participation in the green manure research resulted in efficient generation and adaptation of green manure technology now being promoted in eastern and central Uganda.This revised version was published online in November 2005 with corrections to the Cover Date.     

An evaluation of harvesting costs in present and planned operations: case study—Waston District of Mazandaran Wood and Paper Industries

Amongst all forest utilization phases, harvesting plays a key role as the beginning phase of the utilization cycle and has a significant effect on the following phases.In this research, in order to examine the reduction of costs with respect to present and planned operations, the starting time of the harvesting or cutting phase and work flow were recorded. The starting time of each phase of the entire operation was recorded as well. Before harvesting the marked tree, the appropriate felling direction was determined and the azimuth of the correct direction was taken.The results indicate that there was not a meaningful relationship between the differences in direction of a leaning tree compared with the felling direction. However, there was a significant relationship between the difference of the defined and felling direction and the difference in tree leaning and defined direction. The same trend was observed between tree leaning and felling directions and tree leaning and defined directions. On the other hand,there was no significant relationship between tree leaning and felling directions and the defined and tree felling directions. In addition, this research shows that with an increase in tree volume, the time for tree cutting rose.Furthermore, when the difference of tree leaning and felling direction decreased, the time to cut the tree declined.The regression equation is Y = 168.9–0.14(the difference between tree leaning and felling direction) + 0.7(volume).     

Carbon storage in harvested wood products: implications of different methodological procedures and input data—a case study for Portugal

This study aims to quantify the contribution of the harvested wood products (HWP) to the carbon removals/emissions by the agriculture, forestry and land-use sector (hereafter referred to as HWP contribution) using the tier 1 method proposed by the Intergovernmental Panel on Climate Change (IPCC) in the 2006 Guidelines (hereafter referred to as GL tier 1 method) and to compare it with the results obtained with the tier 2 method proposed by the IPCC in the Good Practice Guidance for Land Use, Land-Use Change and Forestry (hereafter referred to as GPG tier 2 method). The HWP contribution was calculated for three approaches: stock change, production and atmospheric flow. Another objective was to perform a sensitivity analysis in order to identify the calculation procedures and the input data that have the largest impact on the HWP contribution estimates. An uncertainty analysis was also carried out with Monte Carlo simulation. The case study of Portugal was analysed in this study. The HWP contribution obtained with the GL tier 1 method ranged from 150 to 1,240 Gg C year⁻¹, for the period from 1990 to 2004. These results are similar to those obtained with the GPG tier 2 method, except for the production approach, since the GL tier 1 method underestimated carbon accumulation in solid waste disposal sites (SWDS) under this approach. The most influential calculation procedures and input data were the algorithm used to calculate the change in carbon stocks for the pools that follow a first-order decay, the procedure to estimate the input of carbon to the pool of HWP in SWDS, the procedure to determine the change in carbon stocks of HWP in SWDS for the production approach, the type of carbon stocks considered in SWDS and the conversion factor for wood-based panels.     

Proton spin–lattice relaxation time measurements of solid wood and its constituents as a function of pH: Part I*

Summary  By measuring the proton spin–lattice relaxation times (T_1H) in the solid-state for black spruce softwood, the molecular mobilities of carbohydrates and lignin have been evaluated as a function of pH. These studies have shown that the mobility of the polymeric constituents of wood is affected by the ionization of the different functional groups at different pH's. The analyses of the proton-spin–lattice relaxation time data at constant humidity revealed that the maximum T_1H for both carbohydrates and lignin occurs at about neutrality, while it was found to be depressed at the two extremes of the pH range. By treating a wood sample with propylene oxide, the esterification of the acid groups was affected, thus deactivating the ionization process and their contribution to T_1H. The experimental T_1H values for cellulose and lignin after the esterification were significantly decreased at pH 6 confirming that their ionization plays a very significant role in determining chain mobility. Received 1 December 1998     

Determining Young’s modulus of timber on the basis of a strength database and stress wave propagation velocity I: an estimation method for Young’s modulus employing Monte Carlo simulation

In this article, we report on an estimation method for Young’s modulus that entails measuring only the stress wave propagation velocity of timber built into structures such as wooden buildings. Methods of estimating Young’s modulus that use the stress wave propagation velocity and characteristic frequency of timber in conjunction with timber density have long been used. In this article, we propose a method of easily and accurately estimating Young’s modulus from the stress wave propagation velocity without knowing the timber density. This method is based on a database of wood strength performance and density accumulated from a variety of research data and the method estimates Young’s modulus by a simulation method. We compared the Young’s moduli estimated by this method with those obtained by the bending test and by the measurement of the stress wave propagation velocity and density, and found similar results. This coincidence suggests that the method of estimating Young’s modulus presented in this article is valid. For example, the method is effective for convenient evaluation on site when determining whether a wooden building’s structural components should be reused or replaced when repairing or remodeling a building.     

Variable-top stem biomass equations at tree-level generated by a simultaneous density-integral system for second growth forests of roble,raulí,and coigüe in Chile

Variable-top stem biomass models at the tree level for second growth forests of roble(Nothofagus obliqua), raulí(Nothofagus alpina), and coigüe(Nothofagus dombeyi) were fitted by a simultaneous density-integral system, which combines a stem taper model and a wood basic density model. For each model, an autoregressive structure of order 2 and a power equation of residual variance were incorporated to reduce residual autocorrelation and heteroscedasticity, respectively. By using dummy variables in the regression analysis, zonal effects on the parameters in the variable-top stem biomass equations were detected in roble. Consequently, equations for clusters of zones were obtained. These equations presented significant parameters and a high precision in both fitting and validation processes(i.e., CV11.5% and CVp11.9%, respectively), demonstrating that they are unbiased. The advantage of these types of functions is that they provide estimates of volume and biomass of sections of the stem, defined between any two points of the stem in the three species. Thus, depending on the final use of the wood and the dimensions of the tree, a stem fraction can be quantified in units of volume and the remaining fraction in units of weight.     

Integrated pest control in forest management — Combined use of pheromones and insecticides for attracting and killing the Bark Beetle Ips typographus I. Studies with 32P-labelled methamidophos in the ascending sap of spruce

In 1984–1986, ³²P-labelled methamidophos was used to investigate the translocation, distribution and breakdown of this systemic insecticide after penetration into the ascending sap of spruce (Picea abies Karst.), following bark treatment with an adhesive paste of 15% active ingredient. The β-radiation of ³²P permits a semi-quantitative measurement on the bark of standing trees as well as quantitative sample analysis and autoradiography. The following results are given: method of application and total ³²P in the ascending sap; distribution of ³²P in trunk cross-sections and in bark/needles; ³²P in the killed beetles corresponding to the toxic dose, separation of methamidophos and breakdown products; halflife of breakdown in vitro and in vivo; and environmental implications. From the xylem, methamidophos penetrates into the phloem, but no ³²P appears outside on the surface of the bark, so that only insects mining inside the bark are killed and no hazards for useful insects, birds and wildlife animals can arise. Traces of ³²P were measured in air and water, and no ³²P was found in the soil due to the translocation upwards only. The approximate oral toxicity of methamidophos to Ips typographus was estimated to be < 5 mg/kg and the half-life in spruce was 45 days (15°C), indicating a sufficient biological effectiveness over several months, preferably in areas of low average temperatures and in trees impaired by environmental pollution.     

“A Privilege and a Challenge”: Valuation of Heirs’ Property by African American Landowners and Implications for Forest Management in the Southeastern U.S.

African Americans have historically struggled to retain land that has been held in their families for generations as heirs’ property, or land held collectively by heirs of the original owners without clear title. Ethnographic interviews with sixty landholding African American families in North Carolina, South Carolina, and Alabama reveal the cultural meanings associated with family land, forestland in particular, and the role of heirs’ property in inhibiting forest management, including the threat of land loss, intra-family conflict, and legal limitations on forestry activities. The majority of interviewees have a strong desire to pass family land on to their heirs, but they also need the land to be economically productive. Sustainable forest management offers both an incentive to obtain clear title to heirs’ property land and a means of paying property taxes and generating intergenerational wealth within families. The U.S. Endowment for Forestry and Communities is currently collaborating with local institutions in several states in an innovative program designed to help African American landowners navigate the legal system in order to obtain clear title and provide educational workshops about the financial and ecological benefits of sustainable forestry as well as site visits by consulting foresters. Analysis of the situations faced by African Americans with heirs’ property adds to the diversity of our understandings of the complex relationships between land tenure and forestry, with potential application for other minority communities in the U.S. and elsewhere.