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This chapter provides a synthesis of the information presented in the previous chapters. First, the empirical evidence presented in Chapters 3 and 4 is evaluated in relation to the theoretical ideas described in Chapter 2. This is achieved through the evaluation of some tentative propositions, based on available theory. Selected issues that emerged during the review of empirical evidence are then considered, and an attempt is made to answer the overarching questions identified at the start of the book. A second section then examines the implications of our current understanding for conservation policy and practice. Specifically, how can we avert the collapse of ecosystems and support their recovery?
The chapter first considers the nature of ecological theory, then provides an overview of a series of different theoretical ideas in relation to ecosystem collapse and recovery. These include disturbance theory, succession, state-and-transition models, dynamical systems theory, planetary boundaries, critical loads, resilience, food webs, ecological networks and extinction cascades. A set of propositions are then presented that might provide a basis for understanding ecosystem collapse and recovery, based on these theories. These propositions are revisited in subsequent chapters, in light of the empirical evidence that is considered.
Provides a brief overview of the context of the book and the approach adopted. This chapter provides a brief introduction to the topics covered by the book and also provides an overview of how the book is structured. The IUCN Red List of Ecosystems is described and then a number of key terms are defined, including ecosystem, ecosystem collapse and ecosystem recovery. The role of metaphor in ecology is considered and then the concept of ecosystem collapse is evaluated, in terms of its relevance to environmental policy and management.
This chapter provides a brief summary of some of the key findings of this book, first by considering the answers to questions posed at the beginning, then via a series of summary statements and provocations.
This chapter profiles examples of ecosystem collapse and recovery in prehistory. First, the ‘Big Five’ mass extinction events in the fossil record are considered, both in terms of the collapses that occurred and how ecosystems subsequently recovered. Examples from the Quaternary Period are then discussed, including the extinction of the Australian megafauna and the slightly later megafauna extinctions observed in other geographic regions. Case studies profiled from the Holocene period focus on the spread of agriculture throughout the world and the specific cases of New Zealand, Madagascar and the Sahel-Sahara. At the end of the chapter, the theoretical propositions identified in Chapter 2 are then evaluated in the light of the empirical evidence available from prehistory.
This chapter profiles contemporary examples of ecosystem collapse and recovery. Case studies presented include coral reefs, marine fisheries, freshwater ecosystems (streams, rivers and lakes), forests (including tropical, temperate and boreal), savanna, and temperate agroecosystems. In each case, the available empirical evidence is reviewed in relation to the ecological mechanisms underlying both ecosystem collapse and recovery. At the end of the chapter, the theoretical propositions identified in Chapter 2 and refined in Chapter 3 are then evaluated in the light of the evidence available from these contemporary case studies.
There is a growing concern that many important ecosystems, such as coral reefs and tropical rain forests, might be at risk of sudden collapse as a result of human disturbance. At the same time, efforts to support the recovery of degraded ecosystems are increasing, through approaches such as ecological restoration and rewilding. Given the dependence of human livelihoods on the multiple benefits provided by ecosystems, there is an urgent need to understand the situations under which ecosystem collapse can occur, and how ecosystem recovery can best be supported. To help develop this understanding, this volume provides the first scientific account of the ecological mechanisms associated with the collapse of ecosystems and their subsequent recovery. After providing an overview of relevant theory, the text evaluates these ideas in the light of available empirical evidence, by profiling case studies drawn from both contemporary and prehistoric ecosystems. Implications for conservation policy and practice are then examined.
A low-cost technique named ‘on-farm’ seed priming is increasingly being recognized as an effective approach to maximize crop establishment. It consists of anaerobically soaking seeds in water before sowing resulting in rapid and uniform germination, and enhanced seedling vigour. The extent of these benefits depends on the soaking time. The current determination of optimal soaking time by germination assays and mini-plot trials is resource-intensive, as it is species/genotype-specific. This study aimed to determine the potential of the seed respiration rate (an indicator of metabolic activity) and seed morphological changes during barley priming as predictors of the priming benefits and, thus, facilitate the determination of optimal soaking times. A series of germination tests revealed that the germination rate is mostly attributable to the rapid hydration of embryo tissues, as the highest gains in the germination rate occurred before the resumption of respiration. Germination uniformity, however, was not significantly improved until seeds were primed for at least 8 h, that is, after a first respiration burst was initiated. The maximum seedling vigour was attained when the priming was stopped just before the beginning of the differentiation of embryonic axes (20 h) after which vigour began to decrease (‘over-priming’). The onset of embryonic axis elongation was preceded by a second respiration burst, which can be used as a marker for priming optimization. Thus, monitoring of seed respiration provides a rapid and inexpensive alternative to the current practice. The method could be carried out by agricultural institutions to provide recommended optimal soaking times for the common barley varieties within a specific region.
This study aimed to explore barriers and facilitators of the provision of dairy and plant-based dairy alternatives (PBDA) by parents of preschool-age children, a previously unexplored area of research.
Five focus groups of parents were conducted and audio-recorded. Verbatim transcripts were analysed using thematic analysis.
University of Guelph, in Guelph, ON, Canada in 2019.
Thirty-two (n 19 mothers, 13 fathers) parents of preschool-age children. Most (59 %) were university or college educated.
Facilitators common to both dairy and PBDA provision included perceived nutritional benefits, such as dairy’s Ca, protein and fat content, and PBDA’s protein content, and the perception that PBDA adds variety to the diet. Facilitators unique to dairy v. PBDA provision included the taste of, familiarity with, and greater variety and accessibility of dairy products, specifically child-friendly products. A facilitator unique to PBDA v. dairy provision was ethical concerns regarding dairy farming practices. Barriers common to both dairy and PBDA provision included perceived cost, concerns regarding the environmental impact of production, and high sugar content. Barriers specific to dairy included use of antibiotics and hormones in dairy production. A barrier specific to PBDA was the use of pesticides.
Behaviour change messages targeting parents of preschoolers can emphasise the nutrition non-equivalence of dairy and some PBDA and can educate parents on sources of affordable, unsweetened dairy and PBDA.
The burden of disease attributable to alcohol and other drug (AOD) use in young people is considerable. Prevention can be effective, yet few programs have demonstrated replicable effects. This study aimed to replicate research behind Climate Schools: Alcohol and Cannabis course among a large cohort of adolescents.
Seventy-one secondary schools across three States participated in a cluster-randomised controlled trial. Year 8 students received either the web-based Climate Schools: Alcohol and Cannabis course (Climate, n = 3236), or health education as usual (Control, n = 3150). Outcomes were measured via self-report and reported here for baseline, 6- and 12-months for alcohol and cannabis knowledge, alcohol, cannabis use and alcohol-related harms.
Compared to Controls, students in the Climate group showed greater increases in alcohol- [standardised mean difference (SMD) 0.51, p < 0.001] and cannabis-related knowledge (SMD 0.49, p < 0.001), less increases in the odds of drinking a full standard drink[(odds ratio (OR) 0.62, p = 0.014], and heavy episodic drinking (OR 0.49, p = 0.022). There was no evidence for differences in change over time in the odds of cannabis use (OR 0.57, p = 0.22) or alcohol harms (OR 0.73, p = 0.17).
The current study provides support for the effectiveness of the web-based Climate Schools: Alcohol and Cannabis course in increasing knowledge and reducing the uptake of alcohol. It represents one of the first trials of a web-based AOD prevention program to replicate alcohol effects in a large and diverse sample of students. Future research and/or adaptation of the program may be warranted with respect to prevention of cannabis use and alcohol harms.
There is a growing body of evidence highlighting the presence of a single general dimension of psychopathology that can account for multiple associations across mental and substance use disorders. However, relatively little evidence has emerged regarding the validity of this model with respect to a range of factors that have been previously implicated across multiple disorders. The current study utilized a cross-sectional population survey of adolescents (n = 2,003) to examine the extent to which broad psychopathology factors account for specific associations between psychopathology and key validators: poor sleep, self-harm, suicidality, risky sexual behavior, and low self-esteem. Confirmatory factor models, latent class models, and factor mixture models were estimated to identify the best structure of psychopathology. Structural equation models were then estimated to examine the broad and specific associations between each psychopathology indicator and the validators. A confirmatory factor model with three lower-order factors, representing internalizing, externalizing, and psychotic-like experiences, and a single higher-order factor evidenced the best fit. The associations between manifest indicators of psychopathology and validators were largely nonspecific. However, significant and large direct effects were found between several pairwise associations. These findings have implications for the identification of potential targets for intervention and/or tailoring of prevention programs.
Little data exists about the methodology of contextualizing version two of the Mental Health Gap Action Programme Intervention Guide (mhGAP-IG) in resource-poor settings. This paper describes the contextualisation and pilot testing of the guide in Kilifi, Kenya.
Contextualisation was conducted as a collaboration between the KEMRI-Wellcome Trust Research Programme (KWTRP) and Kilifi County Government's Department of Health (KCGH) between 2016 and 2018. It adapted a mixed-method design and involved a situational analysis, stakeholder engagement, local adaptation and pilot testing of the adapted guide. Qualitative data were analysed using content analysis to identify key facilitators and barriers to the implementation process. Pre- and post-training scores of the adapted guide were compared using the Wilcoxon signed-rank test.
Human resource for mental health in Kilifi is strained with limited infrastructure and outdated legislation. Barriers to implementation included few specialists for referral, unreliable drug supply, difficulty in translating the guide to Kiswahili language, lack of clarity of the roles of KWTRP and KCGH in the implementation process and the unwillingness of the biomedical practitioners to collaborate with traditional health practitioners to enhance referrals to hospital. In the adaptation process, stakeholders recommended the exclusion of child and adolescent mental and behavioural problems, as well as dementia modules from the final version of the guide. Pilot testing of the adapted guide showed a significant improvement in the post-training scores: 66.3% (95% CI 62.4–70.8) v. 76.6% (95% CI 71.6–79.2) (p < 0.001).
The adapted mhGAP-IG version two can be used across coastal Kenya to train primary healthcare providers. However, successful implementation in Kilifi will require a review of new evidence on the burden of disease, improvements in the mental health system and sustained dialogue among stakeholders.
Dementia, a term that describes a variety of brain conditions marked by gradual, persistent and progressive cognitive decline, affects a significant proportion of older adults. Older adults with dementia are sometimes perceived less favourably than those without dementia. Furthermore, compared to persons without dementia, those with dementia are often perceived by others as having reduced personhood. This study was aimed at investigating whether differences in attitudes towards dementia and personhood perceptions vary as a function of age group, care-giver status, attitudes towards ageing, dementia knowledge, gender and education. In total 196 younger, middle-aged and older adults were recruited. Findings revealed that being a care-giver as well as having less ageist attitudes were predictive of being more comfortable around persons with dementia, having more knowledge about dementia and ascribing greater personhood to people with dementia. Those with more dementia knowledge (prior to the study) were less comfortable around people with dementia. Finally, when controlling this prior dementia knowledge, older adults were more comfortable around people with dementia compared to younger and middle-aged adults. Gender and education were not associated with any of the variables under study. Findings contribute to a better understanding of the role of age- and care-giver-related factors in the determination of attitudes towards dementia.
Cultivar mixtures of winter barley and spring barley, together with their component monocultures, were grown in field trials to assess the effect of cultivar combinations on both straw and grain yield. The overall grain yields for all trials were significantly higher for the cultivar mixtures than for the corresponding component monocultures. Also, significant decreases in rhynchosporium disease severity for cultivar mixtures were recorded for most non-fungicide treatments. The size of these responses was often significantly correlated with the component number of the mixtures. The amount of straw produced in mixtures was sometimes changed significantly, but not always in a positive direction and it was only correlated with increasing mixture component number in two environments. No correlation of straw yield potential of cultivars with performance in mixtures was found. Cultivar × cultivar mixture × environment interactions appeared to affect the relative yield of grain and straw differentially and therefore it was not possible to predict the effect of mixtures on the harvest index.