Eddie Bevilacqua

Diversity of cuticular wax among Salix species and Populus species hybrids.

The leaf cuticular waxes of three Salix species and two Populus species hybrids, selected for their ability to produce high amounts of biomass, were characterized. Samples were extracted in CH(2)Cl(2) three times over the growing season. Low kV SEM was utilized to observe differences in the ultrastructure of leaf surfaces from each clone. Homologous series of wax components were classified into organic groups, and the variation in wax components due to clone, sample time, and their interaction was identified. All Salix species and Populus species hybrids showed differences in total wax load at each sampling period, whereas the pattern of wax deposition over time differed only between the Salix species. A strong positive relationship was identified between the entire homologous series of alcohols and total wax load in all clones. Similarly strong relationships were observed between fatty acids and total wax load as well as fatty acids and alcohols in two Salix species and one Populus species hybrid. One Salix species, S. dasyclados, also displayed a strong positive relationship between alcohols and alkanes. These data indicate that species grown under the same environmental conditions produce measurably different cuticular waxes and that regulation of wax production appears to be different in each species. The important roles cuticular waxes play in drought tolerance, pest, and pathogen resistance, as well as the ease of wax extraction and analysis, strongly suggest that the characteristics of the cuticular wax may prove to be useful selectable traits in a breeding program.

Social Heterogeneity and Community Forestry Processes: Reflections from Forest Users of Dhading District, Nepal

Community forestry has been characterized as a successful model of community-based forest governance in Nepal that shifts forest management and use rights to local users, often socially heterogeneous in caste, gender and wealth status. This heterogeneity forms the basis of social groups, which differ in their needs, priorities and perceptions regarding community forestry implementation processes. This paper explores the dynamics of three community forestry processes—users’ participation, institutional development, and decision-making and benefit-sharing—among forest user groups as perceived by three social groups of forest users—elite, women and disadvantaged—from eight community forests of Dhading district, Nepal, using qualitative and quantitative techniques. It is found that social groups have differing levels of perception about community forestry processes occurring in their user groups. In particular, social elites differ from women and disadvantaged members of the group in users’ participation in community forestry activities and institutional development of forest user groups. An important policy implication of the findings is that social inclusiveness is central to the effective implementation of community forestry processes, not only to safeguard its past successes but also to internalize the economic opportunities it poses through reducing deforestation and forest degradation in the future.

Allometric biomass equations for tree species used in agroforestry systems in Uganda

Estimates of above-ground biomass are required for better planning, sustainable management and monitoring of changes in carbon stocks in agroforestry systems. The objective of this study was to develop and compare biomass equations for Markhamia lutea, Casuarina equisetifolia, Maesopsis eminii and Grevillea robusta grown in a linear simultaneous agroforestry system in Uganda. These species were established in single rows in the middle of fields in 1995 from four-month old seedlings. A total of 57 trees were sampled for this study, 13 for M. lutea, 12 for C. equisetifolia, 16 for M. eminii and 16 for G. robusta. Biomass values of the various tree components (stem, branches and foliage) as well as the total above-ground biomass were fitted to linear and non-linear allometric models using total height, diameter-at-breast height (DBH), crown width as predictor variables. Although both DBH and height are typically used as independent variables for predicting above-ground biomass, the addition of height in biomass equations did not significantly improve model performance for M. eminii, M. lutea and G. robusta. However, addition of height significantly increased the proportion of variation explained in above-ground biomass for C. equisetifolia, while DBH did not significantly improve the prediction of biomass. The study confirmed the need for developing species-specific biomass equations.

Soil CO2 effluxes, temporal and spatial variations, and root respiration in shrub willow biomass crops fields along a 19-year chronosequence as affected by regrowth and removal treatments.

In shrub willow biomass crop (SWBC) production systems, the soil CO2 efflux (Fc) component in the carbon cycle remains poorly understood. This study assesses (i) differences of Fc rates among the 5‐, 12‐, 14‐, and 19‐year‐old SWBCs with two treatments: continuous production (regrowth) willow fields that were harvested and allowed to regrow, and willow fields that were harvested, killed, and then stools and roots were ground into the soil (removal); (ii) temporal and spatial variations of Fc rates; (iii) root respiration contributions to total Fc; and (iv) climatic variables affecting Fc. During the growing season (May to September), Fc rates showed no statistically significant differences across different ages (P = 0.664), and between treatments (P = 0.351); however, there was an interaction between age and treatment (P = 0.001). Similarly, during the dormant season (October to April), Fc rates revealed no statistically significant differences across different ages (P = 0.305) and treatment interaction with age (P = 0.097). Fc rates differed significantly (P < 0.001) among different times of the day and times of the year. Fc rates, between 00 and 1059 h, between 1100 and 1659 h, and between 1700 and 2400 h displayed consistency from May to November; however, Fc rates in these three time intervals showed significant differences (P < 0.0001). In December, Fc rates remained constant over 24 h. Fc rates demonstrated higher temporal and spatial variations among willow age classes than between regrowth and removal treatments. Temporal and spatial variations of Fc were higher during the dormant season than during the growing season. The proportion of root respiration to total Fc ranged from 18 to 33% across age classes. Fc rates showed strong association with soil and air temperatures, and relative humidity.

Prior Experience Alters the Behavioral Response of Prey to a Nonnative Predator

Abstract Anuran larvae (tadpoles) can alter their behavior and morphology in response to predators with which they have coevolved. Furthermore, tadpoles of a few species are capable of learning, which can elicit or reinforce predator-avoidance behaviors. However, it remains unclear how widespread this capacity for learning is among anurans and whether it is biased in favor of evolutionarily familiar predators. Here, we test whether prior experiences will modify the behavioral response of Lowland Leopard Frog Lithobates (Rana) yavapaiensis tadpoles to Green Sunfish Lepomis cyanellus, a recently introduced predator. We exposed focal tadpoles for 10 days to the chemical and visual cues of one of three conditioning treatments: a cricket-fed Green Sunfish, a tadpole-fed Green Sunfish, or a control tank without predator. Subsequently, we measured the swimming activity of focal tadpoles in response to a neutral cue (water) and the chemical cues of Green Sunfish. No difference between conditioning treatments was observed in response to the water cue. In contrast, tadpoles that had previously experienced either of the sunfish conditioning treatments displayed significantly higher swimming activity than control tadpoles for 2–4 min after exposure to the sunfish chemical cues. Our results indicate that the behavior of tadpoles can be altered by prior experiences, even in the absence of alarm cues. In addition to providing another example of learning in tadpoles, our results suggest that tadpoles may have a broad learning template that can be applied to organisms with which they have recently come into contact.