Willow short-rotation production systems in Canada and Northern United States: A review

Willow short rotation coppice (SRC) systems are becoming an attractive practice because they are a sustainable system fulfilling multiple ecological objectives with significant environmental benefits. A sustainable supply of bioenergy feedstock can be produced by willow on marginal land using well-adapted or tolerant cultivars. Across Canada and northern U.S.A., there are millions of hectares of available degraded land that have the potential for willow SRC biomass production, with a C sequestration potential capable of offsetting appreciable amount of anthropogenic green-house gas emissions. A fundamental question concerning 1 sustainable SRC willow yields was whether long-term soil productivity is maintained within a multi-rotation SRC system, given the rapid growth rate and associated nutrient exports offsite when harvesting the willow biomass after repeated short rotations. Based on early results from the first willow SRC rotation, it was found willow systems are relatively low nutrient-demanding, with minimal nutrient output other than in harvested biomass. The overall aim of this manuscript is to summarize the literature and present findings and data from ongoing research trials across Canada and northern U.S.A. examining willow SRC system establishment and viability. The research areas of interest presented here are the crop production of willow SRC systems, above- and below-ground biomass dynamics and the C budget, comprehensive soil-willow system nutrient budget, and soil nutrient amendments (via fertilization) in willow SRC systems. Areas of existing research gaps were also identified for the Canadian context

Understanding innovation platform effectiveness through experiences from west and central Africa

Innovation platforms (IPs) are a way of organizing multistakeholder interactions, marshalling ideas, people and resources to address challenges and opportunities embedded in complex settings. The approach has its roots in theories of complexity, the concept of innovation systems and practices of participatory action research. IPs have been widely adopted across Africa and beyond in recent years as a “must have” tool in a range of “for development” modes of agricultural research. Our experiences with establishing and facilitating nine IPs in local settings in west and central Africa contribute to understanding factors that impact on their effectiveness. The nine IPs were variously focused on developing dairy, crop and/or meat value chains by strengthening mixed crop-livestock production systems or seed systems. Using case study methods, we identified variables that contribute to explaining the performance of these IPs in relation to six domains of change in the agricultural system and the sustainability of changes. Thematic analysis was guided by a conceptual framework which grouped variables into four categories (context, structure, conduct, and process) that interact to influence IP performance. Stronger market connections and value chains were generated through some of these IPs but the most prevalent changes overall were in farm productivity and technical knowledge of producers. The structures evolved in some IPs, akin to those of producer collectives, suggested they were filling an institutional gap locally. The effect of the IPs on deeper level institutions that influence agricultural systems and food security was modest, constraining prospects for the IPs to generate impact at scale. Impacts from the IPs on research and development organisations were uncommon but had transformative significance. Our conceptual framework did not offer optimal guidance to understanding how the many variables that contributed to performance of these IPs combined and sequenced, but the pattern of interactions was consistent with increased social capital being the prime mediator for change. Achieving greater prospects for transformational change and impact at scale warrants at least equal attention to three other interconnected change pathways: through markets, institutions and innovation capacity. Important factors for increased impact are individuals and organisations with capacity to purposefully build and manage inter-organisational and cross-scale networks, early diagnostic studies of the institutional landscape, and adaptive processes of critical reflection and learning that continue beyond the short term

Individual tree and stand-level carbon and nutrient contents across one rotation of loblolly pine plantations on a reclaimed surface mine

While reclaimed loblolly pine (Pinus taeda L.) plantations in east Texas, USA have demonstrated similar aboveground productivity levels relative to unmined forests, there is interest in assessing carbon (C) and nutrients in aboveground components of reclaimed trees. Numerous studies have previously documented aboveground biomass, C, and nutrient contents in loblolly pine plantations; however, similar data have not been collected on mined lands. We investigated C, N, P, K, Ca, and Mg aboveground contents for first-rotation loblolly pine growing on reclaimed mined lands in the Gulf Coastal Plain over a 32-year chronosequence and correlated elemental rates to stand age, stem growth, and similar data for unmined lands. At the individual tree level, we evaluated elemental contents in aboveground biomass components using tree size, age, and site index as predictor variables. At the stand-level, we then scaled individual tree C and nutrients and fit a model to determine the sensitivity of aboveground elemental contents to stand age and site index. Our data suggest that aboveground C and nutrients in loblolly pine on mined lands exceed or follow similar trends to data for unmined pine plantations derived from the literature. Diameter and height were the best predictors of individual tree stem C and nutrient contents (R ≥ 0.9473 and 0.9280, respectively) followed by stand age (R ≥ 0.8660). Foliage produced weaker relationships across all predictor variables compared to stem, though still significant (P ≤ 0.05). The model for estimating stand-level C and nutrients using stand age provided a good fit, indicating that contents aggrade over time predictably. Results of this study show successful modelling of reclaimed loblolly pine aboveground C and nutrients, and suggest elemental cycling is comparable to unmined lands, thus providing applicability of our model to related systems

Treatment of Acne Keloidalis Nuchae: A Systematic Review of the Literature

Acne keloidalis nuchae (AKN) is a chronic inflammatory condition that leads to fibrotic plaques, papules and alopecia on the occiput and/or nape of the neck. Traditional medical management focuses on prevention, utilization of oral and topical antibiotics, and intralesional steroids in order to decrease inflammation and secondary infections. Unfortunately, therapy may require months of treatment to achieve incomplete results and recurrences are common. Surgical approach to treatment of lesions is invasive, may require general anesthesia and requires more time to recover. Light and laser therapies offer an alternative treatment for AKN. The present study systematically reviews the currently available literature on the treatment of AKN. While all modalities are discussed, light and laser therapy is emphasized due to its relatively unknown role in clinical management of AKN. The most studied modalities in the literature were the 1064-nm neodymium-doped yttrium aluminum garnet laser, 810-nm diode laser, and CO(2) laser, which allow for 82–95% improvement in 1–5 sessions. Moreover, side effects were minimal with transient erythema and mild burning being the most common. Overall, further larger-scale randomized head to head control trials are needed to determine optimal treatments

Spatial and temporal patterns of root distribution in developing stands of four woody crop species grown with drip irrigation and fertilization.

Abstract In forest trees, roots mediate such significant carbon fluxes as primary production and soil C02 efflux. Despite the central role of roots in these critical processes, information on root distribution during stand establishment is limited, yet must be described to accurately predict how various forest types, which are growing with a range of resource limitations, might respond to environmental change. This study reports root length density and biomass development in young stands of eastern cottonwood (Populus deltoidies Bartr.) and American sycamore (Platanus occidentalis L.) that have narrow, high resource site requirements, and compares them with sweetgum (Liquidambar styraczj7ua L.) and loblolly pine (Pinus taeda L.), which have more robust site requirements. Fine roots (5 mm) were sampled to determine spatial distribu-tion in response to fertilizer and irrigation treatments delivered through drip irrigation tubes. Root length density and biomass were predominately controlled by stand development, depth and proximity to drip tubes. After accounting for this spatial and temporal variation, there was a significant increase in RLD with fertilization and irrigation for all genotypes. The response to fertilization was greater than that of irrigation. Both fine and coarse roots responded positively to resources delivered through the drip tube, indicating a wholeroot- system response to resource enrichment and not just a feeder root response. The plastic response to drip tube water and nutrient enrichment demonstmte the capability of root systems to respond to supply heterogeneity by increasing acquisition surface. Fineroot biomass, root density and specific root length were greater for broadleaved species than pine. Roots of all genotypes explored the rooting volume within 2 years, but this occurred faster and to higher root length densities in broadleaved species, indicating they had greater initial opportunity for resource acquisition than pine. Sweetgum's root characteristics and its response to resource availability were similar to the other broadleaved species, despite its hnctional resemblance to pine regarding robust site requirements. It was concluded that genotypes, irrigation arid fertilization significantly influenced tree root system development, which varied spatially in response to resource-supply heterogeneity created by dnp tubes. Knowledge of spatial and temporal patterns of root distribution in these stands will be used to interpret nutrient acquisition and soil respiration measurements

Measuring the Productivity from Indiginous Soil and Water Conservation Technologies with Household Fixed Effects: A Case Study of Hilly Mountainous Areas Benin

In this article, we examine the productivity of indigenous soil and water conservation (SWC) investments in the Boukombé region in Northwest Benin, using an in-depth survey among 101 farmers on farm inputs, outputs, and SWC investments. We show that positive effects of SWC investments are only observed if one controls for household-specific constraints. We use a production function approach to relate SWC to farm output, and we control for observable and unobservable household characteristics with household fixed effects. The results show that (1) there are large productivity effects from indigenous SWC investments in the Boukombé region of Benin, (2) there is a positive interaction between plot size and SWC on productivity, and (3) SWC tends to be most productive on plots with flat or light slopes but less effective on steep plots. Misspecification tests for omitted variable bias, endogeneity bias, and selection bias are performed and show that the results are robust. The structure of this article is as follows: in Section II we start with a discussion of the role of indigenous SWC techniques for agricultural intensification. We will argue that there is a strong rationale behind the promotion of indigenous SWC techniques in areas with unfavorable natural conditions and poor infrastructure. In Section III, we discuss the different types and adoption rates of the most important indigenous SWC techniques that can be observed in the Boukombé region of Northwest Benin. In Section IV, we use a production function approach to relate farm output to inputs and SWC investments to measure the productivity of indigenous SWC investments. Section V concludes. © 2004 by The University of Chicago. All rights reserved