Multi-model assessment of stratospheric ozone return dates and ozone recovery in CCMVal-2 models

Projections of stratospheric ozone from a suite of chemistry-climate models (CCMs) have been analyzed. In addition to a reference simulation where anthropogenic halogenated ozone depleting substances (ODSs) and greenhouse gases (GHGs) vary with time, sensitivity simulations with either ODS or GHG concentrations fixed at 1960 levels were performed to disaggregate the drivers of projected ozone changes. These simulations were also used to assess the two distinct milestones of ozone returning to historical values (ozone return dates) and ozone no longer being influenced by ODSs (full ozone recovery). The date of ozone returning to historical values does not indicate complete recovery from ODSs in most cases, because GHG-induced changes accelerate or decelerate ozone changes in many regions. In the upper stratosphere where CO2-induced stratospheric cooling increases ozone, full ozone recovery is projected to not likely have occurred by 2100 even though ozone returns to its 1980 or even 1960 levels well before (~2025 and 2040, respectively). In contrast, in the tropical lower stratosphere ozone decreases continuously from 1960 to 2100 due to projected increases in tropical upwelling, while by around 2040 it is already very likely that full recovery from the effects of ODSs has occurred, although ODS concentrations are still elevated by this date. In the midlatitude lower stratosphere the evolution differs from that in the tropics, and rather than a steady decrease in ozone, first a decrease in ozone is simulated from 1960 to 2000, which is then followed by a steady increase through the 21st century. Ozone in the midlatitude lower stratosphere returns to 1980 levels by ~2045 in the Northern Hemisphere (NH) and by ~2055 in the Southern Hemisphere (SH), and full ozone recovery is likely reached by 2100 in both hemispheres. Overall, in all regions except the tropical lower stratosphere, full ozone recovery from ODSs occurs significantly later than the return of total column ozone to its 1980 level. The latest return of total column ozone is projected to occur over Antarctica (~2045–2060) whereas it is not likely that full ozone recovery is reached by the end of the 21st century in this region. Arctic total column ozone is projected to return to 1980 levels well before polar stratospheric halogen loading does so (~2025–2030 for total column ozone, cf. 2050–2070 for Cly+60×Bry) and it is likely that full recovery of total column ozone from the effects of ODSs has occurred by ~2035. In contrast to the Antarctic, by 2100 Arctic total column ozone is projected to be above 1960 levels, but not in the fixed GHG simulation, indicating that climate change plays a significant role.

International public goods through integrated natural resources management research in CGIAR partnerships

The CGIAR System conducts research to produce international public goods (IPG) that are of wide applicability creating a scientific base which speeds and broadens local adaptive development. Integrated natural resources management (INRM) research is sometimes seen to be very location specific and consequently does not lend itself readily to the production of IPGs. In this paper we analyse ways in which strategic approaches to INRM research can have broad international applicability and serve as useful foundations for the development of locally adapted technologies. The paper describes the evolution of the IPG concept within the CGIAR and elaborates on five major types of IPGs that have been generated from a varied set of recent INRM research efforts. CGIAR networks have both strengths and weaknesses in INRM research and application, with enormous differences in relative research and development capacities, responsibilities and data access of its partners, making programme process evolution critical to acceptance and participation. Many of the lessons learnt regarding challenges and corresponding IPG research approaches are relevant to designing and managing future multi-scale, multi-locational, coordinated INRM programmes involving broad-based partnerships to address complex environmental and livelihood problems for development.

Response of a weed community to different management practice in field bean

Weed control strategies for field beans were studied in North-eastern Croatia. This study focused on how different weed management practices affect weed community composition. The recommended pre-emergence herbicide application was compared to different treatments of post-emergence herbicide (broadcasted or banded over crop rows) and mechanical weed control in order to explore the response of a weed community to different management practice. Weed density data were used to compare total community densities by weed management strategies and to calculate diversity indices (Shannon's H', Shannon's E and Margalef's D-MG). Data were analyzed using ANOVA and multivariate technique. Weed community structure was generally similar in the post-emergence herbicide treatments, which were dominated by a few species that had high relative abundance values, while most of the species were of lower abundance. Notable fluctuations in weed communities corresponded with variation in weather patterns and management practice.

A method for evaluating alternative landscape management scenarios in relation to the biodiversity conservation of habitats

A perennial issue for land use policy is the evaluation of landscape biodiversity and the associated cost effectiveness of any biodiversity conservation policy actions. Based on the CUA methodology as applied to species conservation, this paper develops a methodology for evaluating the impact on habitats of alternative landscape management scenarios. The method incorporates three dimensions of habitats, quantity change, quality change and relative scarcity, and is illustrated in relation to the alternative landscape management scenarios for the Scottish Highlands (Cairngorms) study area of the BioScene project. The results demonstrate the value of the method for evaluating biodiversity conservation policies through their impact on habitats.

Studies on weed infestation and tea growth under various weed management methods in a young Tea (Camellia sinensis [L.] kuntze) plantation

A field experiment was conducted in the low country of Sri Lanka, during the period 1994–1995 to investigate the severity of weed infestation and tea growth in relation to weed management methods in newly established tea (Camellia sinensis[L.] Kuntze). Manual weeding (hand and slash weeding) at various intervals was compared with various herbicides, with or without mulching. Weed control with herbicides was superior to that of hand weeding at 6-week intervals or more. Weed control with oxyfluorfen at 0.29 kg ai ha−1 + paraquat at 0.17 kg ai ha−1 or glyphosate at 0.99 kg ai ha−1 + kaolin at 3.42 kg ha−1 were superior. Plots unweeded for 12 weeks or more produced significantly greater (P < 0.05) weed biomass than plots unweeded for 6 weeks. Although the least weed dry weight (P < 0.05) and the greatest number of weed species were recorded with hand weeding at 2 week intervals, there was no particular benefit on tea growth when compared with hand weeding at 6 and 12 week intervals. Inter row mulching in chemically treated plots was more favorable for tea growth than no mulching, while living weed cover in unmulched slash weeded plots suppressed tea growth. A combination of mulching and herbicides, particularly oxyfluorfen and paraquat, followed by hand weeding at least every 6–8 weeks was considered the most appropriate weed management system for young tea.

Effects of resistant starch type III polymorphs on human colon microbiota and short chain fatty acids in human gut models

This study probed the possible effects of type III resistant starch (RS) crystalline polymorphism on RS fermentability by human gut microbiota and the short chain fatty acids production in vitro. Human fecal pH-controlled batch cultures showed RS induces an ecological shift in the colonic microbiota with polymorph B inducing Bifidobacterium spp. and polymorph A inducing Atopobium spp. Interestingly, polymorph B also induced higher butyrate production to levels of 0.79 mM. In addition, human gut simulation demonstrated that polymorph B promotes the growth of bifidobacteria in the proximal part of the colon and double their relative proportion in the microbiota in the distal colon. These findings suggest that RS polymorph B may promote large bowel health. While the findings are limited by study constraints, they do raise the possibility of using different thermal processing to delineate differences in the prebiotic capabilities of RS, especially its butryrogenicity in the human colon.

Robust identification for linear-in-the-parameters models

In this paper new robust nonlinear model construction algorithms for a large class of linear-in-the-parameters models are introduced to enhance model robustness, including three algorithms using combined A- or D-optimality or PRESS statistic (Predicted REsidual Sum of Squares) with regularised orthogonal least squares algorithm respectively. A common characteristic of these algorithms is that the inherent computation efficiency associated with the orthogonalisation scheme in orthogonal least squares or regularised orthogonal least squares has been extended such that the new algorithms are computationally efficient. A numerical example is included to demonstrate effectiveness of the algorithms. Copyright (C) 2003 IFAC.

A nutrient increment method for reducing bias in global biogeochemical models

Assimilation of physical variables into coupled physical/biogeochemical models poses considerable difficulties. One problem is that data assimilation can break relationships between physical and biological variables. As a consequence, biological tracers, especially nutrients, are incorrectly displaced in the vertical, resulting in unrealistic biogeochemical fields. To prevent this, we present the idea of applying an increment to the nutrient field within a data assimilating model to ensure that nutrient-potential density relationships are maintained within a water column during assimilation. After correcting the nutrients, it is assumed that other biological variables rapidly adjust to the corrected nutrient fields. We applied this method to a 17 year run of the 2° NEMO ocean-ice model coupled to the PlankTOM5 ecosystem model. Results were compared with a control with no assimilation, and with a model with physical assimilation but no nutrient increment. In the nutrient incrementing experiment, phosphate distributions were improved both at high latitudes and at the equator. At midlatitudes, assimilation generated unrealistic advective upwelling of nutrients within the boundary currents, which spread into the subtropical gyres resulting in more biased nutrient fields. This result was largely unaffected by the nutrient increment and is probably due to boundary currents being poorly resolved in a 2° model. Changes to nutrient distributions fed through into other biological parameters altering primary production, air-sea CO2 flux, and chlorophyll distributions. These secondary changes were most pronounced in the subtropical gyres and at the equator, which are more nutrient limited than high latitudes.