| 1. |
|
|
| 2. |
- Barron, Jennie, 1968-
(författare)
-
Dry spell mitigation to upgrade semi-arid rainfed agriculture : Water harvesting and soil nutrient management for smallholder maize cultivation in Machakos, Kenya
- 2004
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Improvements in on-farm water and soil fertility management through water harvesting may prove key to up-grade smallholder farming systems in dry sub-humid and semi-arid sub-Sahara Africa (SSA). The currently experienced yield levels are usually less than 1 t ha-1, i.e., 3-5 times lower than potential levels obtained by commercial farmers and researchers for similar agro-hydrological conditions. The low yield levels are ascribed to the poor crop water availability due to variable rainfall, losses in on-farm water balance and inherently low soil nutrient levels. To meet an increased food demand with less use of water and land in the region, requires farming systems that provide more yields per water unit and/or land area in the future. This thesis presents the results of a project on water harvesting system aiming to upgrade currently practised water management for maize (Zea mays, L.) in semi-arid SSA. The objectives were to a) quantify dry spell occurrence and potential impact in currently practised small-holder grain production systems, b) test agro-hydrological viability and compare maize yields in an on-farm experiment using combinations supplemental irrigation (SI) and fertilizers for maize, and c) estimate long-term changes in water balance and grain yields of a system with SI compared to farmers currently practised in-situ water harvesting. Water balance changes and crop growth were simulated in a 20-year perspective with models MAIZE1&2. Dry spell analyses showed that potentially yield-limiting dry spells occur at least 75% of seasons for 2 locations in semi-arid East Africa during a 20-year period. Dry spell occurrence was more frequent for crop cultivated on soil with low water-holding capacity than on high water-holding capacity. The analysis indicated large on-farm water losses as deep percolation and run-off during seasons despite seasonal crop water deficits. An on-farm experiment was set up during 1998-2001 in Machakos district, semi-arid Kenya. Surface run-off was collected and stored in a 300m3 earth dam. Gravity-fed supplemental irrigation was carried out to a maize field downstream of the dam. Combinations of no irrigation (NI), SI and 3 levels of N fertilizers (0, 30, 80 kg N ha-1) were applied. Over 5 seasons with rainfall ranging from 200 to 550 mm, the crop with SI and low nitrogen fertilizer gave 40% higher yields (**) than the farmers’ conventional in-situ water harvesting system. Adding only SI or only low nitrogen did not result in significantly different yields. Accounting for actual ability of a storage system and SI to mitigate dry spells, it was estimated that a farmer would make economic returns (after deduction of household consumption) between year 2-7 after investment in dam construction depending on dam sealant and labour cost used. Simulating maize growth and site water balance in a system of maize with SI increased annual grain yield with 35 % as a result of timely applications of SI. Field water balance changes in actual evapotranspiration (ETa) and deep percolation were insignificant with SI, although the absolute amount of ETa increased with 30 mm y-1 for crop with SI compared to NI. The dam water balance showed 30% productive outtake as SI of harvested water. Large losses due to seepage and spill-flow occurred from the dam. Water productivity (WP, of ETa) for maize with SI was on average 1 796 m3 per ton grain, and for maize without SI 2 254 m3 per ton grain, i.e, a decerase of WP with 25%. The water harvesting system for supplemental irrigation of maize was shown to be both biophysically and economically viable. However, adoption by farmers will depend on other factors, including investment capacity, know-how and legislative possibilities. Viability of increased water harvesting implementation in a catchment scale needs to be assessed so that other down-stream uses of water remains uncompromised.
|
|
| 3. |
- Barthel, Stephan, 1968-, et al.
(författare)
-
History and local management of a biodiversity-rich, urban cultural landscape
- 2005
-
Ingår i: Ecology & Society. - : The Resilience Alliance. - 1708-3087. ; 10:2
-
Tidskriftsartikel (refereegranskat)abstract
- Urban green spaces provide socially valuable ecosystem services. Through an historical analysis of the development of the National Urban Park (NUP) of Stockholm, we illustrate how the coevolutionary process of humans and nature has resulted in the high level of biological diversity and associated recreational services found in the park. The ecological values of the area are generated in the cultural landscape. External pressures resulting in urban sprawl in the Stockholm metropolitan region increasingly challenge the capacity of the NUP to continue to generate valuable ecosystem services. Setting aside protected areas, without accounting for the role of human stewardship of the cultural landscape, will most likely fail. In a social inventory of the area, we identify 69 local user and interest groups currently involved in the NUP area. Of these, 25 are local stewardship associations that have a direct role in managing habitats within the park that sustain such services as recreational landscapes, seed dispersal, and pollination. We propose that incentives should be created to widen the current biodiversity management paradigm, and actively engage local stewardship associations in adaptive co-management processes of the park and surrounding green spaces. Copyright © 2005 by the author(s). Published here under license by the Resilience Alliance.
|
|
| 4. |
- Barthel, Stephan, 1968-
(författare)
-
Recalling Urban Nature : Linking City People to Ecosystem Services
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Societal development is dependent on the generation of ecosystem services (ES) to sustain it; however, many ES are degrading. This thesis investigates how social-ecological features behind practices of actor groups shape the generation of ES. The empirical basis is case studies in the urban landscape of Stockholm, Sweden, and the methodological approach is interdisciplinary. Paper I shows that the urban landscape owes it current flow of ES to co-evolutionary processes and that governance with the aim of sustaining ES must take into account historical property rights and the involvement of a diversity of actor groups, as well as ecological processes of the larger landscape. Paper II studies allotment gardens, cemeteries and city parks in relation to the generation of pollination, seed dispersal and pest regulation. Differences in social features behind practice are reflected primary as higher abundance of pollinators in the informally managed allotment gardens and as differences in the compositions of seed dispersers and insectivores’ birds. Thus, voluntary and often ignored actor groups, motivated by sense-of-place, support the generation of some ES here. Paper III shows how practice, linked to ES generation, is retained and stored among allotment gardeners, and modified and transmitted through time, by means of social-ecological memory (SE-memory). SE-memory is an emergent property of a dual process of participation and reification and it facilitates monitoring of local change and links practice, often in habits, to place specific processes that underlie provisioning ES. Paper IV explores how spatial scale mismatches between ecological process and processes of management can be bridged by a spatially explicit and flexible social network structure of governance. Urban ES are a product of human driven co-evolution, consequently sustaining ES in urban landscapes is not about conservation without people, but shaped by and dependent on management practice by people. Practice that links to generation of ES are facilitated by SE-memory of local actors that holds long term management rights. Consequently, local communities of ecosystem practice, which contribute to the production of ES should explicitly be taken into account in urban green governance.
|
|
| 5. |
- Berkenstam, Anders, et al.
(författare)
-
The thyroid hormone mimetic compound KB2115 lowers plasma LDL cholesterol and stimulates bile acid synthesis without cardiac effects in humans
- 2008
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 105:2, s. 663-667
-
Tidskriftsartikel (refereegranskat)abstract
- Atherosclerotic cardiovascular disease is a major problem despite the availability of drugs that influence major risk factors. New treatments are needed, and there is growing interest in therapies that may have multiple actions. Thyroid hormone modulates several cardiovascular risk factors and delays atherosclerosis progression in humans. However, use of thyroid hormone is limited by side effects, especially in the heart. To overcome this limitation, pharmacologically selective thyromimetics that mimic metabolic effects of thyroid hormone and bypass side effects are under development. In animal models, such thyromimetics have been shown to stimulate cholesterol elimination through LDL and HDL pathways and decrease body weight without eliciting side effects. We report here studies on a selective thyromimetic [KB2115, (3-[[3,5-dibromo-4- [4-hydroxy-3-(1-methylethyl)-phenoxy]-phenyl]-amino]-3-oxopropanoic acid)] in humans. In moderately overweight and hypercholesterolemic subjects KB2115 was found to be safe and well tolerated and elicited up to a 40% lowering of total and LDL cholesterol after 14 days of treatment. Bile acid synthesis was stimulated without evidence of increased cholesterol production, indicating that KB2115 induced net cholesterol excretion. KB2115 did not provoke detectable effects on the heart, suggesting that the pharmacological selectivity observed in animal models translates to humans. Thus, selective thyromimetics deserve further study as agents to treat dyslipidemia and other risk factors for atherosclerosis. © 2007 by The National Academy of Sciences of the USA.
|
|
| 6. |
- Berkes, Fikret, et al.
(författare)
-
Introduction
- 2002. - 1
-
Ingår i: Navigating Social-Ecological Systems. - Cambridge : Cambridge University Press. - 9780521061841 - 9780511541957 ; , s. 1-29
-
Bokkapitel (refereegranskat)abstract
- A common perspective until recently was that our problem-solving abilities have been improving over the years. In the area of resource and environmental management, for example, there was a great deal of faith in our growing scientific understanding of ecosystems, our bag of increasingly sophisticated tools and technologies, and the application of market mechanisms to problems such as air pollution control and fishery management through individually allocated quotas. However, the experience over the last few decades does not support such optimism (e.g., Clark and Munn, 1986; Ludwig, Hilborn, and Walters, 1993; Gunderson, Holling, and Light, 1995). Many of our resource and environmental problems are proving resistant to solutions. A gap has developed between environmental problems and our lagging ability to solve them. This is coming at a time when the Earth has become an increasingly human-dominated system. Many of the changes in the biosphere, including the modification of landscapes, loss of biodiversity and, according to some, climate change, are driven by human activities. Furthermore, changes are occurring at an increasingly faster rate than previously experienced in human history.There is an emerging consensus regarding the need to look for broader approaches and solutions, not only with resource and environmental issues but along a wide front of societal problems. A survey of senior American Association for the Advancement of Science (AAAS) scientists revealed an intriguing insight.
|
|
| 7. |
- Berkes, Fikret, et al.
(författare)
-
Living with disturbance : Building resilience in social-ecological systems
- 2002. - 1
-
Ingår i: Navigating Social-Ecological Systems. - Cambridge : Cambridge University Press. - 9780521061841 - 9780511541957 ; , s. 163-186
-
Bokkapitel (refereegranskat)abstract
- Disturbances such as fire, cyclones, and pest outbreaks create variation in natural systems and ecosystem renewal that may be important for the maintenance of biological diversity. Many natural disturbances are inherent in the internal dynamics of ecosystems, and often set the timing of ecosystem renewal processes fundamental for maintaining resilience in ecosystems (Holling et al., 1995).By disturbance we mean ‘any relatively discrete event in time that disrupts ecosystem community or population structure and changes resources, substrate availability, or the physical environment’ (White and Pickett, 1985: 7). We distinguish between abiotic and biotic disturbances. Abiotic disturbances are those where the direct cause of disturbance is generated by nonbiotic agents. Examples include fires, hurricanes, volcanic eruptions, earthquakes, flooding, and drought. Examples of biotic disturbances include insect and pest attacks, predators, invasion of exotic species, and the grazing and browsing of herbivores.Conventional resource management, based on economic production targets, commonly seeks to reduce natural variation in target resources, because fluctuations impose problems for the industry dependent on the resource (Holling and Meffe, 1996). Control of resource stock variability and flows can be achieved in a number of ways. For instance, by increasing financial investments in technologies for harvesting, a modern fishing industry can invest in larger fleets and more effective gear in order to maintain an even flow of production. Maintenance of high and even flows of monoculture crops in large-scale agriculture may be achieved by investing in various energy inputs, such as insecticides, pesticides, and irrigation.
|
|
| 8. |
- Berkes, F., et al.
(författare)
-
Rediscovery of Traditional Ecological Knowledge as adaptive management
- 2000
-
Ingår i: Ecological Applications. - : Ecological Society of America. - 1051-0761 .- 1939-5582. ; 10:5, s. 1251-1262
-
Tidskriftsartikel (refereegranskat)abstract
- Indigenous groups offer alternative knowledge and perspectives based on their own locally developed practices of resource use. We surveyed the international literature to focus on the role of Traditional Ecological Knowledge in monitoring, responding to, and managing ecosystem processes and functions, with special attention to ecological resilience. Case studies revealed that there exists a diversity of local or traditional practices for ecosystem management. These include multiple species management, resource rotation, succession management, landscape patchiness management, and other ways of responding to and managing pulses and ecological surprises. Social mechanisms behind these traditional practices include a number of adaptations for the generation, accumulation, and transmission of knowledge; the use of local institutions to provide leaders/stewards and rules for social regulation; mechanisms for cultural internalization of traditional practices; and the development of appropriate world views and cultural values. Some traditional knowledge and management systems were characterized by the use of local ecological knowledge to interpret and respond to feedbacks from the environment to guide the direction of resource management. These traditional systems had certain similarities to adaptive management with its emphasis on feedback learning, and its treatment of uncertainty and unpredictability intrinsic to all ecosystems.
|
|
| 9. |
- Berkes, Fikret, et al.
(författare)
-
Synthesis : Building Resilience and Adaptive Capacity in Social-Ecological Systems
- 2002. - 1
-
Ingår i: Navigating Social-Ecological Systems. - Cambridge : Cambridge University Press. - 9780521061841 - 9780511541957 ; , s. 352-387
-
Bokkapitel (refereegranskat)abstract
- A weekly magazine on business development issued an analysis of Madonna, the pop star, and raised the question ‘How come Madonna has been at the very top in pop music for more than 20 years, in a sector characterized by so much rapid change?’ A few decades ago, successful companies developed their brand around stability and security. To stay in business this is no longer sufficient, according to the magazine. You must add change, renewal, and variation as well. However, change, renewal, and variation by themselves will seldom lead to success and survival. To be effective, a context of experience, history, remembrance, and trust, to act within, is required. Changing, renewing, and diversifying within such a foundation of stability and maintaining high quality have been the recipe for success and survival of Madonna, and for rock stars such as Neil Young and U2. It requires an active adaptation to change, not only responding to change, but also creating and shaping it. In the same spirit, Sven-Göran Eriksson, coach of several soccer teams in Europe, claimed that it is the wrong strategy not to change a winning team. A winning team will always need a certain amount, but not too much, of renewal to be sustained as a winning team. Sustaining a winning team requires a context for renewal, or ‘framed creativity,’ borrowing from the language of the advertiser.
|
|
| 10. |
- Carpenter, Stephen R., et al.
(författare)
-
Resilience : Accounting for the Noncomputable
- 2009
-
Ingår i: Ecology & Society. - 1708-3087. ; 14:1, s. 13-
-
Tidskriftsartikel (refereegranskat)abstract
- Plans to solve complex environmental problems should always consider the role of surprise. Nevertheless, there is a tendency to emphasize known computable aspects of a problem while neglecting aspects that are unknown and failing to ask questions about them. The tendency to ignore the noncomputable can be countered by considering a wide range of perspectives, encouraging transparency with regard to conflicting viewpoints, stimulating a diversity of models, and managing for the emergence of new syntheses that reorganize fragmentary knowledge.
|
|
