Recent increase in forest mortality events worldwide and their relationship with drought episodes highlight the importance of understanding tree resilience to a changing climate. Empirical models of forest mortality have been typically used and were focusing on carbon related variables such as growth to predict tree death. Recent efforts have shifted toward a more mechanistic modeling of mortality. Mechanistic approaches use tree traits and climate as inputs to model processes and represent carbon and water fluxes, all necessary to plant life. The advantage of mechanistic approaches is their ability to account for potential adaptation of trees to climate change, but also to physically explore the causes of vulnerability and resilience to droughts. Mechanistically, the atmospheric demand for moisture at the canopy level is communicated to the tree through stomata, creating a water gradient between the leaves and the roots, and resulting in the ascent of sap via the plant hydraulic structure. Depending on the climate (temperature, atmospheric dryness, light, precipitation), different architectures will perform differently at maintaining the gradient. For example, deep roots can access deep water in dry regions and shallow roots can access rare precipitation events whereas larger leaf area increases the atmospheric demand for moisture. In very harsh conditions such as extreme or lasting droughts, the hydraulic structure might suffer from a steep water gradient. Protection against excessive gradients can be achieved either through an investment in a stronger structure (denser wood) or through a regulation of the pulling force at the top of the canopy (closing leaf stomata). Evolution of structures and physiological strategies have resulted in fitness advantages and partially explain the diversity of species architectures across climates. More importantly, this diversity is at the core of the vulnerability and resilience of each species to increased aridity and frequency of extreme events, and therefore its mortality. This dissertation investigates the resilience to droughts of two co-occuring species in common woodlands of New Mexico, USA. This location is of specific interest because drought conditions (high temperature and/or low precipitation) have become more frequent as a result of global warming and because these ecosystems have suffered extensive mortality in the last decades. The two species, Pinus edulis and Juniper monosperma have very different physiological strategies, which allows for an extra level of vulnerability comprehension. To further test their resilience to extreme drought and possibly future climatic conditions, I studied trees that were subject to a six-year rain-reduction experiment. In the first part we develop a mechanistic model of the tree functioning that includes water and carbon fluxes and is based on their respective supply-demand balances. We use this simplified mechanistic model to study the sensitivity of mortality to hydraulic structure variations and to the physiological strategy of each species. We find that for both species death resulted from an irreversible damage of tissues transporting water. Despite P. edulis’s ability to close stomata to reduce the atmospheric demand, they died first because of their vulnerable tissues. In the second part, I specifically investigate P. edulis’s structural response to drought at the canopy level. By dissecting branch anatomy at an annual resolution, I find that during droughts this species increase relatively more leaf area (water demand) compared to transport area (water supply). I suggest that the structural adjustments that occur at the branch level do not contribute to the protection of the tissues transporting water. In the third part, I analyze the anatomy of these tissues in branches of P. edulis. I find that in response to long-lasting drought the trees built tissues more efficient at transporting water but also more vulnerable to future drought. By contrast, a short-intense drought decreases efficiency without changing vulnerability. I hence show that during lasting drought the anatomical adjustment of branch tissues increase the vulnerability of the piñons. This study shows the importance of considering climate responses of structure and physiology together to compare resilience across species. It also shows that adjustments of hydraulic elements in response to drought tend to decrease hydraulic resilience and could favor a run-away scenario. If the population of Pinus edulis - a dominant species of the Southwest US - were to decline, major shift should be expected in related ecosystems.

Submitted by (edna.saturno@ufrpe.br) on 2016-12-19T15:34:38Z No. of bitstreams: 1 Orlando de Oliveira dos Santos.pdf: 1008703 bytes, checksum: 47b747aa1eaa483ff683caadd85cd715 (MD5) / Made available in DSpace on 2016-12-19T15:34:38Z (GMT). No. of bitstreams: 1 Orlando de Oliveira dos Santos.pdf: 1008703 bytes, checksum: 47b747aa1eaa483ff683caadd85cd715 (MD5) Previous issue date: 2013-07-30 / This study aimed to evaluate the ecophysiological characteristics of the species Zea mays, Sorghum bicolor and Brachiaria decumbens under water stress conditions in a greenhouse. The experiment was conducted in a completely randomized design, using three species, Zea mays, Sorghum bicolor and Brachiaria decumbens, with 10 plants of each species under two water regimes (control and stress). The parameters evaluated were: soil moisture (Smoisture) vapor pressure deficit (VPD), leaf water potential (Ψleaf); gas exchange (net CO2 assimilation (A), stomatal conductance (gs), transpiration (E) and intrinsic water use efficiency (WUEi)), chlorophyll a fluorescence (photochemical quenching (qP), non-photochemical quenching (NPQ), electron transport rate (ETR) and maximum quantum efficiency in Photosystem II (Fv / Fm)); and biochemical analysis (total soluble carbohydrate (TSC), total free aminoacids (TFA), total soluble protein (TSP), chlorophyll a (Chla), chlorophyll b (Chlb) and carotenoids (car). The data of leaf water potential and soil moisture were submitted to Student's T test with a significance level of 5%. When subjected to 21 days of water deficit, the species Z. mays declined 248% in Ψleaf, 87% in stomatal conductance, 53% in net CO2 assimilation, 84% in transpiration, 156% in intrinsic water use efficiency, 54% in photochemical quenching, 67% in electron transport rate, 10% in Fv / Fm and 17% in chlorophyll a; S. bicolor showed a decrease in Ψleaf about 212%, 42% in stomatal conductance, 26% in net CO2 assimilation, 31% in transpiration, and 40% in electron transport rate; and in the species B. decumbens was observed a decrease in Ψleaf about 105%, 36% in stomatal conductance, 31% in net CO2 assimilation, 24% in transpiration, 34% in intrinsic water use efficiency, 53% in photochemical quenching, 56% in electron transport rate, 54% in total free amino acid content. The species which presented the smallest decrease related to the evaluated parameters was S. bicolor. From 14 analyzed parameters, S. bicolor showed decrease in 5 of them, while the other two species reduced their rates in 9 at least. / Este trabalho teve como objetivo avaliar as características ecofisiológicas das espécies Zea mays, Sorghum bicolor e Brachiaria decumbens sob condição de déficit hídrico em casa de vegetação. O experimento foi conduzido em delineamento inteiramente casualizado, utilizando três espécies forrageiras- Zea mays, Sorghum bicolor e Brachiaria decumbens- com 10 plantas de cada espécie sob dois regimes hídricos (controle e estresse). Os parâmetros avaliados foram: umidade do solo (Usolo), deficit de pressão de vapor (DPV), potencial hídrico foliar (Ψfoliar); trocas gasosas (assimilação líquida de CO2 (A), condutância estomática (gs), transpiração (E) e eficiência intrínseca do uso da água (EUA)); fluorescência de clorofila a (quenching fotoquímico (qP), quenching não fotoquímico (NPQ), taxa de transporte de elétrons (ETR) e eficiência quântica máxima no fotossistema II (Fv / Fm)); e análises bioquímicas (carboidratos solúveis totais (CST), aminoácidos livres totais (ALT), proteínas solúveis totais (PST), clorofila a (Chla), clorofila b (Chlb) e carotenóides (car)). Os dados de potencial hídrico foliar e umidade do solo foram submetidos ao teste T, com nível de significância de 5%. Os demais parâmetros foram submetidos à ANOVA fatorial (Regime hídrico x Turno diário) e quando necessário às médias foram comparadas pelo teste de Student Newman Keul’s com nível de significância de 5%. Quando submetida à 21 dias de déficit hídrico, a espécie Z. mays apresentou uma queda no Ψ foliar de 248%, na condutância estomática de 87 %, na assimilação líquida de CO2 de 53%, na transpiração de 84%, na eficiência do uso da água de 156%, no quenching fotoquímico de 54%, na taxa de transporte de elétrons de 67%, na Fv / Fm de 10% e na Clorofila a de 17%; já o S. bicolor apresentou queda no foliar de 212%, na condutância estomática de 42%, na assimilação líquida de CO2 de 26%, na transpiração de 31% e na taxa de transporte de elétrons de 40%; E na espécie B. decumbens foi observado queda no Ψ foliar de 105%, na condutância estomática de 36%, na assimilação líquida de CO2 de 31%, na transpiração de 24%, na eficiência do uso da água de 34%, no quenching fotoquímico de 53%, na taxa de transporte de elétrons de 56% e no teor de aminoácidos livres totais de 54%. A espécie que apresentou a menor queda relacionada aos parâmetros avaliados foi o S. bicolor. De 14 parâmetros analisados S. bicolor apresentou queda em 5, enquanto que as outras duas espécies avaliadas suas taxas reduziram pelo menos em 9 parâmetros.

Esta tese trata das escolhas léxico-estilísticas na obra Vidas secas de Graciliano Ramos. Sabemos que o texto é o lugar em que se processa o novo e para que esse novo possa ser construído é preciso que o sujeito produtor tenha competência lexical, pois o ato de textualização está relacionado com as escolhas feitas pelo sujeito produtor ao mediatizar-se com o mundo, com o universo referencial. Essa mediatização implica um recorte e a partir desse recorte o sujeito produtor reconceptualiza o referente, tendo, por conseguinte, o novo. Todavia, essa reconceptualização implica uma escolha e é essa escolha que vai determinar a visão de mundo e o estilo do sujeito produtor. Como sabemos, o estilo como objeto da estilística, ainda não foi satisfatoriamente delimitado, mas nessa pesquisa estamos entendendo-o como escolha que abrange tanto o conteúdo quanto a maneira como esse conteúdo é organizado e apresentado. Desse modo, os recursos estilísticos, a escolha de um tipo de gênero discursivo e a seleção lexical estão implicitamente relacionados ao estilo, à criatividade do sujeito produtor uma vez que a forma entrelaçada ao conteúdo determinará a seleção lexical do discurso enunciado, pois como sabemos, as experiências sócio-histórico-culturais-ideológicas e cognitivas do falante de uma determinada língua vêm marcadas pelo léxico que mostra, não só sua visão de mundo, mas também a sua criatividade em representar esse mundo. Nesse sentido, esta tese tem por tema o estudo do léxico, na obra Vidas secas, de Graciliano Ramos, buscando verificar como as escolhas lexicais dão ao contexto expressividade e revelam a visão de mundo do sujeito produtor. Os resultados obtidos apontam que o estilo conciso, enxuto e preciso na obra Vidas secas se deve, não só ao fato de o sujeito produtor procurar narrar uma história usando uma linguagem tão seca quanto o meio ambiente retratado na narrativa, mas também porque busca se colocar como porta-voz de personagens não alfabetizadas, agindo como procurador dessas personagens. As escolhas lexicais em Vidas secas apontaram que as personagens têm uma vida seca em todos os sentidos seca de água, seca de amor, seca de conhecimento letrado, seca de socialização. Essas secas vão despersonalizando as personagens, aproximando-as cada vez mais de animais para que possam sobreviver no meio hostil. É preciso ressaltar também que o estudo do campo lexical da seca apontou que esse fenômeno climático para a população pobre como a família de Fabiano simboliza a morte, sendo necessário em tempos de longas estiagens saírem em busca da sobrevivência em outras regiões a verdade é que não queria afastar-se da fazenda. A viagem parecia sem jeito, nem acreditava nela, e só resolvera partir quando estava definitivamente perdido. Podia continuar a viver num cemitério? Nada o prendia àquela terra dura, acharia um lugar menos seco para enterrar-se (RAMOS, 1985, p.117). / This thesis has for objective to treat choicess lexical-stylistics in the literary work Vidas secas by Graciliano Ramos. We know that the text is the place in where it processes the new and that the new can be built it is necessary that the producers subject has lexical competence as the textualization act is related to the choices made by the producers subject when mediates with the world, with the referential universe. This mediatization implies act of cut the experiential world, this acts producer subject reconceptualizes the referent, and he has therefore \"the new\". But, this reconceptualization implies a choice and it is this choice that will determine the worlds view and the style producers subject. As we know, the style, as stylistics object wasnt yet satisfactorily delimited, but in this research we understand it as a choice that covers so much both the content and how as that content is organized and presented. Thus, the stylisticss recourses, the choice of discursive style and the lexical selection are implicitly related to style, to creativitys producer subject once the form interlaced to content will determine the lexical selection of the utterance discourse, because as we know the speakers experiences socio-historical-cultural-ideological and cognitive that given to language have been marked by the lexicon that shows not only their view world, but also their creativity to represent this world. Thus, this thesis has for theme the lexicons study in the literary work Vidas secas, by Graciliano Ramos, it searches to investigate as the lexical choices give the expression to context and reveal the views world producers subject. The results suggest that the concise, succinct and precise style in literary work Vidas secas it dues to the fact producers subject to tell a story using a dry language as the environment depicted in the narrative, and also because it seeks to position itself as characters spokesman illiterate, acting as attorney of those characters. Lexical choices in literary work Vidas secas pointed out that the characters have a dry life in every senses drys water, drys love, drys literate knowledge, drys socialization. These \"dry\" will depersonalize the characters, approaching more and more animals so that they can survive in the hostile environment. One should also point out that the study of lexical drys field pointed out that this weather phenomenon for the poor as familys Fabiano symbolizes the death, if need be in droughts long time out in search survival in other regions, \"the truth is did not want to move away from the farm. The trip seemed embarrassed, could not believe it, and just decided to leave when was definitely lost. Could continue to live in a cemetery? Nothing held him to that hard earth, would find a less dry place to bury \"(RAMOS, 1985, p.117).

Building resilient communities has emerged as a dominant agenda in the policy arena and in academia in the wake of recent disasters. However, there is a lack of clarity on the specific interventions required to build resilience. Current challenges associated with resilience include ambiguity, unclear measures, and problematized applicability. This thesis evaluates the determinants of resilience to drought in community food systems as a basis for contributing towards a more advanced understanding of resilience. A schematic model linking the key concepts associated with resilience was developed on the basis of literature review. This model was subsequently applied to a sample of 195 farm households, 16 community meetings and about 45 interviews with key informants across eight villages in Nsanje and Mzimba districts in Malawi interviewed between October 2010 and February 2011. Analysis at household level focused on exploring the causes of vulnerability, the role of livelihood assets and institutions in shaping coping and adaptation, and the implication of these to the meaning of resilience. The thesis concluded that vulnerability to food insecurity was produced by an interaction of slow and fast moving factors and processes, some of which were highly persistent. Access to livelihood assets and institutions increased short term coping and adaptive capacity but did not effectively predict resilience given unknowns regarding asset availability and liquidity over the long term. Different socio-economic groups associated different meanings with the concept of resilience, and in some cases, one group achieved ‘resilience’ at the expense of the larger community. In integrating vulnerability into resilience thinking, the analysis suggested that resilience could be analysed as existing in desirable and undesirable forms. Undesirable resiliencies reinforced the vulnerable state. By addressing the factors that sustain vulnerability, response capacity could be enhanced. This being the case, advanced by this thesis is a shift from focusing on resilience as a utopian goal, in favour of practices that enhance response capacity and letting communities learn for themselves and transform their value sets to ones that are more likely to ensure coping with adverse conditions. The study concludes that the concept of resilience in its current form is of more value as an organising framework within the re-engineering of food, agricultural, development and disaster management policy can be undertaken.

The aim of this study was to examine pictures from the swedish morning newspaper Barometern regarding their publication about the summer drought 2018 on two of theirplatforms; the ordinary printed newspaper and their Instagram account. The purpose of the study was to track down if there were any obvious differences aboutthe pictures that Barometern publishes in their printed newspaper and Instagramaccount. This study was conducted through a quantitative analysis with help of ancoding scheme. A delimitation was made to investigate only the publications during the four summermonths may, june, july and august. This limit was necessary with the reason to give ourstudy a relevant starting point. The result of this essay shows that in the printed version of the newspaper are they morelikely to publish pictures about the summer drought, as in the Instagram account arethey more likely to publish pictures with a positive vibe instead. A another conclusionwith this study is that almost half of the pictures that Barometern published about thesummer drought is manipulated in some way.

Esta tese trata das escolhas léxico-estilísticas na obra Vidas secas de Graciliano Ramos. Sabemos que o texto é o lugar em que se processa o novo e para que esse novo possa ser construído é preciso que o sujeito produtor tenha competência lexical, pois o ato de textualização está relacionado com as escolhas feitas pelo sujeito produtor ao mediatizar-se com o mundo, com o universo referencial. Essa mediatização implica um recorte e a partir desse recorte o sujeito produtor reconceptualiza o referente, tendo, por conseguinte, o novo. Todavia, essa reconceptualização implica uma escolha e é essa escolha que vai determinar a visão de mundo e o estilo do sujeito produtor. Como sabemos, o estilo como objeto da estilística, ainda não foi satisfatoriamente delimitado, mas nessa pesquisa estamos entendendo-o como escolha que abrange tanto o conteúdo quanto a maneira como esse conteúdo é organizado e apresentado. Desse modo, os recursos estilísticos, a escolha de um tipo de gênero discursivo e a seleção lexical estão implicitamente relacionados ao estilo, à criatividade do sujeito produtor uma vez que a forma entrelaçada ao conteúdo determinará a seleção lexical do discurso enunciado, pois como sabemos, as experiências sócio-histórico-culturais-ideológicas e cognitivas do falante de uma determinada língua vêm marcadas pelo léxico que mostra, não só sua visão de mundo, mas também a sua criatividade em representar esse mundo. Nesse sentido, esta tese tem por tema o estudo do léxico, na obra Vidas secas, de Graciliano Ramos, buscando verificar como as escolhas lexicais dão ao contexto expressividade e revelam a visão de mundo do sujeito produtor. Os resultados obtidos apontam que o estilo conciso, enxuto e preciso na obra Vidas secas se deve, não só ao fato de o sujeito produtor procurar narrar uma história usando uma linguagem tão seca quanto o meio ambiente retratado na narrativa, mas também porque busca se colocar como porta-voz de personagens não alfabetizadas, agindo como procurador dessas personagens. As escolhas lexicais em Vidas secas apontaram que as personagens têm uma vida seca em todos os sentidos seca de água, seca de amor, seca de conhecimento letrado, seca de socialização. Essas secas vão despersonalizando as personagens, aproximando-as cada vez mais de animais para que possam sobreviver no meio hostil. É preciso ressaltar também que o estudo do campo lexical da seca apontou que esse fenômeno climático para a população pobre como a família de Fabiano simboliza a morte, sendo necessário em tempos de longas estiagens saírem em busca da sobrevivência em outras regiões a verdade é que não queria afastar-se da fazenda. A viagem parecia sem jeito, nem acreditava nela, e só resolvera partir quando estava definitivamente perdido. Podia continuar a viver num cemitério? Nada o prendia àquela terra dura, acharia um lugar menos seco para enterrar-se (RAMOS, 1985, p.117). / This thesis has for objective to treat choicess lexical-stylistics in the literary work Vidas secas by Graciliano Ramos. We know that the text is the place in where it processes the new and that the new can be built it is necessary that the producers subject has lexical competence as the textualization act is related to the choices made by the producers subject when mediates with the world, with the referential universe. This mediatization implies act of cut the experiential world, this acts producer subject reconceptualizes the referent, and he has therefore \"the new\". But, this reconceptualization implies a choice and it is this choice that will determine the worlds view and the style producers subject. As we know, the style, as stylistics object wasnt yet satisfactorily delimited, but in this research we understand it as a choice that covers so much both the content and how as that content is organized and presented. Thus, the stylisticss recourses, the choice of discursive style and the lexical selection are implicitly related to style, to creativitys producer subject once the form interlaced to content will determine the lexical selection of the utterance discourse, because as we know the speakers experiences socio-historical-cultural-ideological and cognitive that given to language have been marked by the lexicon that shows not only their view world, but also their creativity to represent this world. Thus, this thesis has for theme the lexicons study in the literary work Vidas secas, by Graciliano Ramos, it searches to investigate as the lexical choices give the expression to context and reveal the views world producers subject. The results suggest that the concise, succinct and precise style in literary work Vidas secas it dues to the fact producers subject to tell a story using a dry language as the environment depicted in the narrative, and also because it seeks to position itself as characters spokesman illiterate, acting as attorney of those characters. Lexical choices in literary work Vidas secas pointed out that the characters have a dry life in every senses drys water, drys love, drys literate knowledge, drys socialization. These \"dry\" will depersonalize the characters, approaching more and more animals so that they can survive in the hostile environment. One should also point out that the study of lexical drys field pointed out that this weather phenomenon for the poor as familys Fabiano symbolizes the death, if need be in droughts long time out in search survival in other regions, \"the truth is did not want to move away from the farm. The trip seemed embarrassed, could not believe it, and just decided to leave when was definitely lost. Could continue to live in a cemetery? Nothing held him to that hard earth, would find a less dry place to bury \"(RAMOS, 1985, p.117).

Florida scrub is a xeromorphic upland shrub community dominated by evergreen oaks that resprout after fire, occurring on moderately to excessively well-drained nutrient-poor sand. Scrub is home to several threatened and endangered animal species (e.g., Florida scrub-jay, gopher tortoise, and indigo snake) and rare and endemic plants. Urban development and agriculture has greatly reduced and fragmented scrub habitat, and because of this Florida scrub is considered one of the most endangered ecosystems in the United States. Climate change is a further threat to Florida scrub. Under a warmer and drier climate, scrub species will be exposed to more frequent and more severe droughts. In order to understand how scrub will respond to a changing climate, we must first have a better understanding of how scrub species respond to climate and water availability. In this dissertation, I use a combination of dendrochronology and plant physiological techniques to examine species responses to climate and water availability. In chapter two, I use dendrochronology to examine the importance of seasonal climate on growth of three co-occurring species in Florida scrub, myrtle oak (Quercus myrtifolia Willd.), Chapman oak (Quercus chapmanii Sarg.), and south Florida slash pine (Pinus elliottii Engelmann var. densa Little & K.W. Dorman). This is the first dendrochronology study on co-occurring scrub species. Therefore, my first goal was to ask whether Chapman oak and myrtle oak put on distinct annual rings with year to year variability that would enable successful crossdating. Because I found that each species does have annual rings that can be crossdated, my second goal was to ask how growth in each species responds to climate and its extremes, drought and extreme precipitation. Growth in both oaks was positively correlated with spring precipitation, while slash pine total and latewood growth was positively correlated with April and September precipitation. Slash pine earlywood growth was positively correlated associated with increased winter precipitation. In all three species, growth was sensitive to both annual and spring droughts. However, only slash pine exhibited increased growth with precipitation associated with tropical weather during July-September. Earlywood growth of slash pine was positively correlated with the Ni[ntilde]o 3.4 index: colder, wetter winters tended to be associated with increased earlywood growth. The between-species differences in response to seasonal climate may be due to differences in growth phenology. For both oaks, the climatic limiting factor was water availability in the spring, which is when the majority of radial growth occurs. By contrast, for slash pine, growth was limited by precipitation in the spring and late summer, its peak growth period. During the period for which we have a dendrochronological record (1920 to present), precipitation in April has become increasingly correlated with growth for all three species; as it has become the driest spring month during this period. In chapter three, I use dendrochronology to determine the climate-growth relationships of the dominant oak in Florida scrub, myrtle oak, for five sites occurring on three different scrub ridges in central Florida. My goals were twofold: 1) to ask whether the climate-growth responses of myrtle oak were robust across sites and 2) to ask how myrtle oak growth was affected by droughts (determined on both seasonal and annual basis). Myrtle oak growth increased with increased spring precipitation; temperature had little effect on myrtle oak growth. The growth response of myrtle oak to moisture availability (measured by the standardized precipitation index (SPI)) in March, April, May, and June, was robust across sites, with the exception of Malabar West. Myrtle oaks at Malabar West grew on poorly drained soils and were less responsive to precipitation and drought than were oaks growing on the other sites. March, April, May, and June SPI explained between 21.5 to 58.3% of the variation in myrtle oak growth for each site. Seasonal droughts explained more of the variation in growth than annual droughts. Spring droughts decreased myrtle oak growth at all sites, and drought during the previous summer decreased growth at Malabar West. Drought impacted growth for a single year; growth was normal or greater than normal during the year after drought. These results suggest that the timing of drought is important for myrtle oak growth, and that seasonal measures of drought are more important than annual measures of drought for determining growth impacts. In chapter four, I examine how the distribution and physiological functioning of scrub species vary along the ridge-swale topography at the Kennedy Space Center. Climatic factors often limit species distributions and plant physiological functions over large elevation gradients. However, on small elevation gradients, hydrologic variation may have strong effects on the distribution of species and the physiological function within a species. I used point-intercept sampling along a ridge-swale gradient at Kennedy Space Center on Merritt Island, Florida, to study how species distribution varied over a 1.2 m elevation gradient. Data from water monitoring wells along the elevation gradient were used to ask whether elevation may serve as a proxy for depth to water table. Elevation served as a good proxy for depth to water table; water table depth increased with elevation. I focused especially on understanding how the distribution and physiological functioning of three co-occurring Florida scrub oak species (Chapman oak, sand live oak (Quercus geminata) and myrtle oak) varied along the elevation gradient. Cover of all three scrub oaks increased with increasing elevation. Only sand live oak exhibited differences in physiological functioning along the elevation gradient; individuals at lower elevations were more sensitive to drought than individuals on the ridge. All three oaks exhibited stomatal regulation of water use efficiency drought. Chapman oak did not exhibit decreased photosynthetic activity during drought. Leaf phenology may play a role in the different responses to drought exhibited.

The importance of several factors in limiting recovery from defoliation was investigated in field-grown plants of Agropyron desertorum and Agropyron spicatum exposed to drought , natural or irrigated conditions. Leaf extension rate, components of leaf area production, number of metabolically active axillary buds and carbohydrate availability were examined on the same plants immediately after defoliation and/or in the following spring from 1984 until 1986. The diurnal course of leaf growth did not relate to turgor pressure in the expanded portion of leaf laminae. Rather growth was apparently associated with air temperature. Leaf extension rate was lower under drought than under better moisture levels during 1984 to 1986. For both species, reduced growth rates and shorter growth periods resulted in reduced tiller height, leaf number and leaf size under drought compared with natural or irrigated conditions in 1985 and 1986, but not in 1984. As a result, leaf area and/or yields were also lower under drought in 1985 and 1986, and lowest under drought plus defoliation in 1986. Production of daughter tillers immediately after defoliation was also lowest under drought. Regrowth capacity of both species was not limited by axillary bud number, size or viability immediately after defoliation under any water level in 1986. In early spring, however, tiller number and growth were lower on clipped than on unclipped plants of both species under drought and irrigated conditions in 1986, and under all water levels in 1987; this resulted in considerably reduced photosynthetic canopies on clipped plants. Crown and root total nonstructural carbohydrate (TNC) pools were higher under drought than under better moisture levels in A. desertorum and A. spicatum in early spring 1986. These high pools of TNC apparently enhanced the production of etiolated regrowth in both species when meristematic limitations did not exist in early spring. The productive potential of both Agropyron species will probably not be affected following a late and severe defoliation under drought. However, vegetative growth and/or productivity, and probably the persistence of these species in the community, will be reduced after two or more years of late and heavy defoliations under drought.

Twenty-nine Rhizobium leguminosarum biovar trifolii strains were tested for acidity tolerance in acidified liquid medium. Only 41\ of the strains grew at pH 4.1. One acid-tolerant strain, USDA 2160, and one acid-sensitive strain, 162-X-103 from Nitragin Co., were inoculated on seeds of 'Nungarin', 'Seaton Park' and 'Clare' subclover cultivars. The inoculated and pelleted seeds were sown in potted Cluff soil with pH 5. 7. Three desiccation levels were imposed by delaying watering for 0, 15 or 30 days. Four gravimetric soil water contents (6.0, 6.6, 10.5 and 12.5\) were maintained under a greenhouse line-source sprinkler system for 7 weeks. The desiccation treatments were more detrimental to the survival of the acid-tolerant Rhizobium strain (USDA 2160) than they were for the acid sensitive strain (162-X-103). Symbiotic effectiveness, measured as shoot dry weight, was higher with strain 162-X- 103 than with strain USDA 2160 and was comparable to the Nfertilized control at the highest water level (12.5 %). At the lower water levels (6.0, 6.6 %) symbiotic N2-fixation was more affected than N-uptake. The Rhizobium strains were able to survive and grow even at the lowest soil water level. The number of rhizobia in the soil and nodulation of the subclover plants had a correlation of 0.56.

The history of Mozambique has been punctuated by episodes of warfare and natural calamities. This study looks at the history of the civil war that affected Mozambique from 1976 to 1992 beyond the framework of national state and global politics. It attempts to make the voices of villagers who suffered the hardship of war more audible through the exploration of histories of life. It offers a more complex discussion of social relationships and social change during the war by looking at villagers and their environments beyond victimization narratives. It contends that apart from being the major targets of the war, villagers and their environments had agency in the conflict. It argues that environmental factors influenced the course of war and exacerbated the harmful effects of war on local people and natural resources. It observes that the civil war affected an agrarian society which was particularly dependent on a rich and diverse yet disrupted ecosystem therefore, studying the civil war with focus on the environmental context shows the true cost of warfare, and how it was experienced by rural society. It shows that humans and wildlife were in times of peace interconnected in symbiotic relationship which included episodes of cooperation and conflict. Elephants, hippos, monkeys, bush pigs, and birds invaded farms in search of food. Humans relied on wild animals and plants to improve their diet and to mitigate the impact of drought and disease. These symbiotic relationships were heavily disturbed by warfare and drought as villagers were displaced from lands about which they had micro-geographical knowledge to mitigate the effects of recurrent droughts.