Academic literature on the topic 'Pasture plant diversity'

The invertebrate community richness diversity and abundance associated with pasture productivity and plant species richness at the Lincoln University Research Dairy Farm was examined Invertebrates were sampled in November 2010 (spring) and March 2011 (late summer) by pitfall traps in two pastures types simple (perennial ryegrass/white clover) and complex (perennial ryegrass white clover prairie grass chicory plantain red clover) Pooled across seasons invertebrate richness was greater in the complex pasture compared to the simple pasture but there were no differences in invertebrate community diversity or total abundance between pasture types However greater productivity of the complex pasture in late summer resulted in greater invertebrate abundance in this pasture type but without a concomitant increase in invertebrate species richness or diversity These preliminary results suggest that pasture productivity drives invertebrate abundance and that pasture plant richness drives invertebrate richness regardless of productivity

Grassland farmers face many challenges in pasture management including improving sustainability, reducing inputs of fertilizers and pesticides, and protecting soil resources. In this paper we provide our perspective on managing plant diversity within and among pastures as one tool to aid producers in meeting these challenges. Pasture ecosystems can be highly diverse, with a complex array of organisms contributing to ecosystem functioning. Within the broad range of plant and animal biodiversity in pastures, plant species diversity may be the most amenable to manipulation or management. Reported benefits of plant diversity in grasslands include: increased forage production, greater ecosystem stability in response to disturbance, and reduced invasion by exotic species such as weeds. Some view diversity as a sort of insurance policy where different species contribute in their own time or can take the place of species that fail from stress or mismanagement. Using mixtures of several forages in pastures, in some instances, can improve forage yield and reduce weed invasions. Pasture management for increased plant species diversity, however, is not simply mixing and planting as many forage species as possible. The kinds and amounts of different forage species along with their arrangement within and among pastures at the farm scale are critical features that must be considered. Tools must be developed to determine the appropriate species mixtures for varying soils, landscapes, climate and purposes to fulfill multiple functions for producers. Key words: Grazing ecosystem; forages; diversity; ecosystem function; ecosystem services

Ecological studies often suggest that natural grasslands with high species diversity will grow more biomass and leach less nitrogen (N). If this diversity effect also applies to fertilised and irrigated pastures with controlled removal of herbage, it might be exploited to design pastures that can assist the dairy industry to maintain production while reducing N leaching losses. The purpose of this study was to test whether pasture mixtures with a high functional diversity in ryegrass traits will confer on the system higher water- and N-use efficiency. The hypothesis was tested using a process-based model in which pasture mixtures were created with varying levels of diversity in ryegrass traits likely to affect pasture growth. Those traits were: the winter- or summer-dominance of growth, the ability of the plant to intercept radiation at low pasture mass, and rooting depth. Pasture production, leaching and water- and N-use efficiency were simulated for management typical of a dairy pasture. We found that the performance of the diverse ryegrass–clover mixtures was more strongly associated with the performance of the individual components than with the diversity across the components. Diverse pasture mixtures may confer other benefits, e.g. pest or disease resistance and pasture persistence. The testing here was within a selection of ryegrasses, and the greater possible diversity across species may produce different effects. However, these results suggest that highly performing pastures under fertilised and irrigated grazed conditions are best constructed by selecting components that perform well individually than by deliberately introducing diversity between components.

Renovating pastures to increase forage species diversity is a burgeoning practice among producers. Over a century of grassland and small-plot research suggests that increasing plant diversity can lead to improved pasture productivity, resilience, and soil health. However, it remains hard to decipher how these benefits translate to grazed production systems given the limited experimentation in realistic grazing systems. There is a disconnect between ecological and agronomic research regarding what qualifies as a “diverse” grassland or pasture. This review aims to examine the current state of research regarding plant diversity and its potential benefits for soil health in pasture systems, and outlines how we can improve our understanding and implementation of this practice in production systems.

Morphological variation, as expressed in PCA axis scores, for clovers growing in different aged pastures, was apportioned to pasture age, quadrats within pastures, intraspecific densities within quadrats, and genets within densities. Of those factors that have an effect on variation, genets is the greatest, followed by quadrats, intraspecific density, and age of the pasture. There is also an age-related decline in variation in plants of Trifolium repens as seen in genetic origin, quadrats within a pasture, and intraspecific density. These results indicate a need to determine more accurately the relationship between genetic and phenotypic responses in the decline in among-plant variation over time. Keywords: Trifolium repens, variation.

Land clearing in Queensland is often practised to enhance pasture production, and hence, increase financial returns from beef production. The benefits of clearing have been quantified in terms of short-term gains in pasture yield but have not adequately accounted for possible medium- or longer-term impediments that may be attributed to clearing. Therefore, impacts of clearing and the subsequent sowing of exotic grasses such as Cenchrus ciliaris L. on pasture composition and production were studied. To achieve this, paired sites were selected representing cleared and uncleared pastures across three different times since clearing (i.e. 5, 11–13 and 33 years since clearing) for the three dominant tree communities of central Queensland (i.e. Eucalyptus populnea F.Muell. (poplar box), E. melanophloia F.Muell. (silver-leaved ironbark) and Acacia harpophylla F.Muell. ex. Benth. (brigalow)). The results demonstrated that species diversity declined with clearing and sowing of exotic pastures. Species diversity and pasture production were negatively related. Although pasture yield was 2–3 times greater 13 years after clearing of E. populnea and A. harpohylla, the gains in pasture yield were not consistent over time, yields being only 1.5 times greater after 33 years of clearing. In E. melanophloia, an increase in the yield of only 1.5–1.8 times occurred 5 years after clearing compared with uncleared pastures, whereas 33 years after clearing, yield was 3/4 of that in uncleared pastures. The initial gains in pasture yield were accompanied by a loss of plant diversity that may affect ecosystem functions such as nutrient cycling or soil mineralisation, and the longer-term production gains.

The pasture digression of meadows followed by soil deflation is one of the pressing environmental problems. This problem is typical for mountain pastures that are constantly in economic circulation. The article presents the results of a geobotanical survey of the Zolsky pastures on the territory of the Kabardino-Balkarian Republic in 2018-2020. The results of a geobotanical survey show that the pasture phytocenoses are characterized by high floristic diversity due to the heterogeneity of edaphic and orographic factors. The flora of the pastures is represented by postwood moist sedgy-and-tussock-grass, mesophilic woodreed-and-agrostidinic grass, cereal forb, forbs cereal mesophilic and subalpine meadows, low sedgy meadow steppes. The average yield for the pasture period varies from 7.2 to 16.6 centners/ha of dry eaten mass. The consequence of prolonged pasturage and excessive pasture load was a decrease in alpha and beta diversity, the formation of low-productive secondary plant communities of non-food, poisonous and weed grasses, the destruction of sod and soil outcropping. Restoration of degraded pasture ecosystems is possible on the basis of ecological intensification, which provides for the regulation of pasture loads, adherence to grazing terms, phytomelioration using perennial grasses, and short-term isolation of pastures from grazing. This will prevent erosion processes, increase biodiversity, productivity, forage value of grass stand and stability of pasture ecosystems.

Host-plant diversity in a mixed accession Stylosanthes spp. pasture 14 years after establishment was demonstrated in families derived from seed and in cuttings obtained from the pasture. Glasshouse examination of the progeny from 181 field plants inoculated with 4 different pathogenicity strains of Colletotrichunz gloeosporioides indicated the widest possible spread of diversity in disease reaction. The progeny exhibited wider variation in resistance to the disease than the originally sown accessions, and when transplanted to a field site, plant phenotypic variability became increasingly evident as the progenies matured. Of 1339 transplanted progeny, 369 were not able to be conclusively categorised according to the descriptions of the originally sown accessions, indicating that outcrossing had occurred. The demonstrated plant variability is, arguably, encouraging for the management of anthracnose using genotype mixtures in the vast areas of low-input beef pastures in northern Australia.

Abstract Abandonment of pastures and successional shrub expansion are widespread in European mountain regions. Moderate shrub encroachment is perceived beneficial for plant diversity by adding new species without outcompeting existing ones, yet systematic evidence is missing. We surveyed vegetation along 24 transects from open pasture into shrubland across the Swiss Alps using a new protocol distinguishing different spatial scales, shrub cover of each plot (2 × 2 m) and larger-scale zonal cover along the transect. Data were analysed using generalized linear models of shrub cover, shrub species and environmental conditions, such as geology, aspect or soil. Most shrub communities were dominated by Alnus viridis (62% of transects) and Pinus mugo (25%), and the rest by other shrub species (13%). These dominant shrub species explained vegetation response to shrub cover well, without need of environmental variables in the model. Compared to open pasture, A. viridis resulted in an immediate linear decline in plant species richness and a marginal increase in beta-diversity (maximally + 10% at 35% cover). Dense A. viridis hosted 62% less species than open pasture. In P. mugo, species richness remained stable until 40% shrub cover and dropped thereafter; beta-diversity peaked at 35% cover. Hence, scattered P. mugo increases beta-diversity without impairing species richness. In transects dominated by other shrubs, species richness and beta-diversity peaked at 40–60% shrub cover (+ 23% both). A. viridis reduced species richness in a larger area around the shrubs than P. mugo. Therefore, effects of shrub encroachment on plant diversity cannot be generalized and depend on dominant shrub species.

The lack of plant biodiversity in New Zealand pastoral ecosystems may limit the abundance and diversity of generalist parasitoids and predators, predisposing these ecosystems to pest outbreaks. To test this hypothesis, patches of turf were established in existing pasture during spring 2016. Four treatments of increasing plant complexity were established, commencing with ryegrass alone, and increasing exponentially up to eight species of forage plant per patch. In the summer of 2017, insects were collected from the patches and control plots using suction to assess whether or not plant diversity had influenced the abundance and diversity of lacewings and parasitic Hymenoptera aggregating in the patches. Plant species richness had no impact on lacewing abundance but fewer parasitic Hymenoptera were recovered from the ryegrass-only plots compared with more species rich plots. Also, a wider range of parasitoid families were represented in the more diverse plant treatments compared with the less diverse treatments. Such diversity may have beneficial impacts on the stability of pasture ecosystem and the risk of pest outbreaks.

This study records all known legume (Leguminosae/Fabaceae) species indigenous to South Africa, Lesotho and Swaziland to establish distribution patterns and optimum climatic and soil conditions for growth. The main purpose was to propose a list of legume species for further evaluation of their pasture potential. Collection data supplied by the National Herbarium (PRE) Computerised Information System were recorded to establish the distribution patterns of species based on the bioregions vegetation map. A total of 1 654 species are known to be indigenous, representing 24 tribes and 122 genera. The grouping of legume species into five main clusters and 16 Leguminochoria is ecologically described, with the highest legume species richness found in the Northern Mistbelt Forest. Key and diagnostic species are provided for each Leguminochorion. Soil pH and mean annual minimum temperature were found to be the main drivers for distinguishing between legume assemblages. The optimum climatic and soil conditions for growth are described as well as the available descriptive attributes for species recorded. Information on the range of tolerance of most species to abiotic factors is presented. Mean annual rainfall and soil pH are highly correlated with the distribution pattern of most species, followed by mean annual minimum temperature. Legume species adapted to a wide range of soil pH levels and low soil phosphorus levels are recorded. Existing data on the cultivation and grazing or browsing status of indigenous legumes were used to select 584 species found mainly in the Central Bushveld, Mopane and Lowveld Bioregions to be further evaluated for their pasture potential. Known characteristics were used to categorise species. Species contained in the tribe Phaseoleae are of special interest since it contains most of the genera with present-day agricultural value, i.e. Eriosema, Rhynchosia and Vigna species are listed as having high potential as pasture species. This study has shown that the descriptive and distribution data accumulated by botanists (notably taxonomists) could be of beneficial use in meeting agricultural objectives. Indigenous legumes are adapted to a wide range of soil and climatic conditions and represent a valuable but largely unexploited natural resource for pasture development and soil conservation practices.
Thesis (PhD)--University of Pretoria, 2013.
gm2014
Plant Science
unrestricted

Tree clearing is practised for greater beef production and hence monetary gains from grazing systems of central Queensland. The high rates of clearing in the past and even recently (577, 000 ha/yr during 1999-2001) were mainly to develop land for pastures. The sustainability of cleared pasture systems over the long-term is questioned. Three major types of tree communities i.e. Eucalyptus populnea F. Muell., E. melanophloia F. Muell. and Acacia harpophylla F. Muell. ex. Benth. were selected on one property in central Queensland to quantify the impacts of clearing on pasture production and composition, and soil properties. The impacts were measured over time-since-clearing (recent (<5 years), medium (11-13years) and old (>30 years)) in unreplicated cleared pastures in comparison to their replicated uncleared/intact woodland pastures of each tree community. Measures of pasture above-ground biomass production on a single property over time-sinceclearing in cleared systems showed that gains were not sustained over the long-term. The difference in response to clearing between tree communities was evident and important to support the future policy decisions. The impact of clearing on soil properties (physicochemical and biological) was confirmed, and explained the lesser availability of nutrients with time of clearing in cleared pastures. The changes in some soil properties underscored the associated risks and changes in ecosystem functions due to clearing. Less litter was produced at cleared than uncleared pastures, but nutrient release was faster at cleared compared to uncleared systems. The overall effect of clearing in terms of pasture and litter production, and major soil parameters were analysed using multivariate analyses.

La diminution de la biodiversité compte parmi les problèmes les plus préoccupants de notre époque. En terme de conservation, il est aujourd’hui primordial de mieux comprendre les mécanismes qui créent et maintiennent la biodiversité dans les écosystèmes naturels ou anthropiques. Cette étude a pour objectif d’améliorer cette compréhension dans un écosystème complexe, riche en espèces et à forte valeur patrimoniale, les pâturages boisés jurassiens. Elle vise à explorer des patrons spatiaux de biodiversité végétale et à tester de façon empirique des hypothèses théoriques ou issues de simulation concernant le lien entre structure spatiale du paysage et biodiversité, dans un contexte multi-échelle, pour différentes mesures de biodiversité (richesse et composition en espèces). Les données de terrain ont été collectées selon un plan d’échantillonnage hiérarchique novateur et combinées à des données lidar. Leur analyse statistique à l’aide de techniques récentes a montré que : - la richesse spécifique augmente généralement avec l’hétérogénéité de l’environnement - la structure spatiale de la composition en espèces végétales est principalement liée à la topographie et à la disponibilité en lumière, respectivement aux échelles grossières et fines. La fraction non-environnementale de cette structure spatiale est liée à plusieurs traits d’espèces. - les relations deux à deux entre diversités alpha, beta et gamma, fortement dépendantes de l’échelle spatiale, ne suivent pas toujours les tendances attendues. Cette étude souligne donc le rôle essentiel joué par la structure spatiale dans la détermination de la biodiversité et l’importance de prendre en compte plusieurs échelles spatiales
The world-wide loss of biodiversity at all scales has become a matter of urgent concern, and improving our understanding of local drivers of biodiversity in natural and anthropogenic ecosystems is now crucial for conservation. The main objective of this study was to further our comprehension of the driving forces controlling biodiversity patterns in a complex and diverse ecosystem of high conservation value, wooded pastures. We tested several hypotheses relating spatial pattern scale and biodiversity and explored spatial patterns of biodiversity in a multi-scale context and using different measures of biodiversity (species richness and composition), with field data. Data were collected using an innovative hierarchical sampling design and combined with remotely-sensed lidar data. Their analysis using recent statistical tools showed that: - species richness generally increased with environmental heterogeneity. - the spatial structure of plant species composition was related to topography at the coarsest scales and insolation at finer scales. The non-environmental fraction of the spatial variation in species composition had a complex relationship with several species traits, suggesting a scale-dependent link to biological processes. - the pairwise relationships between alpha, beta and gamma diversity were strongly scale-dependent and did not follow the expected patterns, at least at certain scales. Thus, our results highlight the crucial role of spatial structure for all components of biodiversity. They also emphasize the importance of considering multiple spatial scales and multiple scale components when studying species diversity

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Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
Funda??o de Amparo ? Pesquisa do Estado da Bahia - FAPEB
Eplingiella fruticosa (Salzm. Ex Benth.) Harley & JFB Pastore is an aromatic species, native, occurring in six states in northeastern Brazil (Bahia, Sergipe, Pernambuco, Paraiba, Rio Grande do Norte and Cear?). Popularly known as "alecrim de vaqueiro", is commonly found in street markets of the region and used to combat pain and seizures. Reviews in mice and in vitro studies show analgesic activity, vasodilating, cardioprotetiva, anti-inflammatory and larvicidal of its essential oil and of different types of the leaves extract. Recent studies show great variability in essential oil chemical composition of E. fruticosa, related to soil and climatic conditions and different plant organs. Thus, the species has great potential for exploration both agronomic, and by pharmaceutical companies. The aim of this study was to evaluate the vegetative propagation capacity and characterize previously Eplingiella genotypes, through morphological, agronomic, phytochemicals and molecular data. In Chapter I, two experiments were conducted: the first tested the effect of three substrates and the second evaluated five concentrations of IBA and three periods of cultivation. The design was a randomized block design with four replications. We evaluated survival percentage (% S), percentage of rooted cuttings (% EE), root length (CRE), number of shoots (NBE), dry mass of leaves (MSF), root dry weight (MSR) and total dry matter (MST). In Chapter II, twelve genotypes were collected, propagated vegetatively and transplanted. Twelve months after transplantation were assessed 12 quantitative traits, eight morphological and agronomic four. In Chapter III, the total DNA was extracted, then 20 primers were tested, of which nine were selected because they have better electrophoretic profiles agarose gel (2%). The binary matrix was computed in GEOCOMPAR II. It is estimated the diversity of the genetic structure parameters and the data were subjected to Bayesian analysis, and Neighbor-joining dendrogram and principal component analysis (PCA) based on matrix of Nei distances. And in Chapter IV, samples of 100g of leaves each repetition per genotype were used in the essential oil hydrodistillation in Clevenger type apparatus for three hours, quantifying the content. The identification of the compounds and their contents was performed by GC (FID) and GC / MS data 15 and the major compounds were used in diversity analysis. They have been made to cluster analysis and canonical variables, using as dissimilarity measure the Mahalanobis distance (D2). In the first experiment of Chapter I, significant differences were found for CRE, NBE, MSF, MSR and MST, with the best performance for the commercial substrate. In the second, positive effects have been identified both the addition of AIB as the cultivation time on the CRE variables, NBE, MSF and MSR, reaching maximum increment to the estimated concentration of 1.5 g L-1, at 60 days of cultivation. In Chapter II, there was significant variation by F test (p <0.01) for the CF features, LF, CBD, CBE, LP, and MFF MSF. The genotypes formed two groups for almost all variables, by Scott-Knott test (p <005), except for LP, which formed three. The EF002 and EF003 genotypes presented the highest levels for almost all variables. There was the formation of three groups for both UPGMA and for the canonical variables (CV). The characteristics that most contributed to the formation of groups were CBE, MFF and CF. The genotypes EF002, EF003, EF005 and EF012 stood out because they have higher genetic distances. In CHAPTER III, primers produced 131 polymorphic bands. The diversity index of Nei (Ne) ranged between 0.31 and 0.39, while Shannon (I) ranged between 0.33 and 0.48. The percentage coefficient of genetic differentiation (Gst) was 0.29. In AMOVA most of the variation was within populations (69%), while among populations was 27% and 4% among species, indicating a good genetic structure. The average value of Fst was 0.175, demonstrating intermediate differentiation between populations. The structure of the Bayesian analysis method revealed three possibilities for the formation of groups (K = 2; = 6; 8 =;), however, it presented many migrants and high level of mixing individuals. The dendrogram generated by the Neighbor-Joining method confirmed the formation of two groups, with good support for major clades (100%). PCA analysis in the first two axis explained 21.06% of the total variation among populations. Finally, in Chapter IV, the genotypes were classified into four clusters: 1 - EF001 genotypes, EF006, EF007, EF008, EF010, EF011 and EF012 with E-caryophyllene and bicyclogermacrene as major; 2 - EF002 and EF003 genotypes, with the majority same as the previous group, however, percentage with average about 30% higher; 3 - EF004 and EF005 genotypes that showed a greater production of E-caryophyllene; and 4 - with EF009 genotype, forming a single group to present ?-pinene as balanced majority and percentage among the rest. This result was confirmed by canonical variables, which explained 76% of the variation. The bicyclogermacrene compounds, 1,8-cineol, ?-copaene and spathulenol represented the most important variables for analysis.
Eplingiella fruticosa (Salzm. ex Benth.) Harley & J.F.B. Pastore ? uma esp?cie arom?tica, nativa, que ocorre em seis estados do nordeste brasileiro (Bahia, Sergipe, Pernambuco, Para?ba, Rio Grande do Norte e Cear?). Popularmente conhecida como ?alecrim de vaqueiro?, ? comumente encontrada em feiras livres da regi?o e utilizada no combate a dores e convuls?es. Avalia??es em camundongos e in vitro comprovam atividades analg?sicas, vasodilatadora, cardioprotetiva, antinflamat?ria e larvicida do seu ?leo essencial e de diferentes tipos de extrato de suas folhas. Estudos recentes apontam grande variabilidade na composi??o qu?mica do ?leo essencial de E. fruticosa, relacionada ?s condi??es edafoclim?ticas e aos diferentes ?rg?os vegetais. Sendo assim, a esp?cie apresenta grande pot?ncial de explora??o tanto agron?mica, quanto por ind?strias farmac?uticas. O objetivo geral deste estudo foi avaliar a capacidade de propaga??o vegetativa e caracterizar, previamente, gen?tipos de E. fruticosa, por meio de dados morfol?gicos, agron?micos, fitoqu?micos e moleculares. No CAP?TULO I, foram conduzidos dois experimentos: o primeiro testou o efeito de tr?s substratos e o segundo avaliou cinco concentra??es de AIB e tr?s per?odos de cultivo. O delineamento foi em blocos casualizado, com quatro repeti??es. Avaliou-se percentagem de sobreviv?ncia (%S), percentagem de estacas enraizadas (%EE), comprimento da raiz (CRE), n?mero de brota??es (NBE), massa seca de folhas (MSF), massa seca de raiz (MSR) e massa seca total (MST). No CAP?TULO II, doze gen?tipos foram coletados, propagados vegetativamente e transplantados. Doze meses ap?s o transplante foram avaliadas 12 caracter?sticas quantitativas, sendo oito morfol?gicase quatro agron?micas. No CAP?TULO III, o DNA total foi extra?do, em seguida 20 iniciadores foram testados, dos quais nove foram selecionados por apresentarem melhores perfis eletrofor?ticos em gel de agarose (2%). A matriz bin?ria foi computada no GEOCOMPAR II. Estimou-se os par?metros de diversidadee a estrutura gen?tica os dados foram submetidos ? an?lise Bayesiana, al?m de dendrograma Neighbor-joining e an?lise de componentes principais (PCA) com base na matriz de dist?ncias de Nei. E no CAP?TULO IV, amostras de 100g de folhas de cada repeti??o por gen?tipo foram utilizadas na hidrodestila??o do ?leo essencial, em aparelho tipo clevenger, durante tr?s horas, quantificando-se o teor. A identifica??o dos compostos e seus teores foi realizada por CG (DIC) e CG/EM e os dados de 15 compostos majorit?rios foram utilizados nas an?lises de diversidade. Foram procedidas an?lise de agrupamento e de vari?veis can?nicas, utilizando como medida de dissimilaridade a dist?ncia generalizada de Mahalanobis (D2).No primeiro experimento do CAP?TULO I, foram verificadas diferen?as significativas para CRE, NBE, MSF, MSR e MST, com melhor desempenho para o substrato comercial. No segundo, foram identificados efeitos positivos tanto da adi??o de AIB quanto dos tempos de cultivo sobre as vari?veis CRE, NBE, MSF e MSR, atingindo incremento m?ximo com a concentra??o estimada de 1,5 g L-1, aos 60 dias de cultivo. No CAP?TULO II, houve varia??o significativa, pelo teste de F (p<0,01), para as caracter?sticas CF, LF, CBD, CBE, LP, MFF e MSF. Os gen?tipos formaram dois grupos para quase todas as vari?veis, pelo teste de Scott-Knott (p<005), exceto para LP, que formou tr?s. Os gen?tipos EF002 e EF003 apresentaram as maiores m?dias para quase todas vari?veis. Houve a forma??o de tr?s grupos, tanto para UPGMA quanto para as vari?veis can?nicas (VC). As caracter?sticas que mais contribu?ram para a forma??o dos grupos foram CBE, MFF e CF. Os gen?tipos EF002, EF003, EF005 e EF012 se destacaram por apresentarem maiores dist?ncias gen?ticas. No CAP?TULO III, os iniciadores produziram 131 bandas polim?rficas. O ?ndice de diversidade de Nei (Ne) variou entre 0,31 e 0,39, enquanto Shannon (I) variou entre 0,33 e 0,48. O percentual do coeficiente de diferencia??o gen?tica (Gst) foi de 0,29. Na AMOVA a maior parte da varia??o ficou dentro das popula??es (69%), enquanto entre popula??es foi de 27% e entre esp?cies de 4%, indicando uma boa estrutura??o gen?tica. O valor m?dio de Fst foi 0,175, demonstrando diferencia??o intermedi?ria entre as popula??es. As an?lises de estrutura pelo m?todo Bayesiano revelou tr?s possibilidades de forma??o de grupos (K=2;=6;=8;), no entanto, apresentou muitos indiv?duos migrantes e elevado n?vel de miscigena??o. O dendograma gerado pelo m?todo de Neighbor-Joining confirmou a forma??o de dois grupos, com boa sustenta??o para os principais clados (100%). Na an?lise de PCA os dois primeiros axis explicaram 21,06% da varia??o total entre as popula??es. Por fim, no CAP?TULO IV, os gen?tipos foram classificados em quatro clusters: 1 - gen?tipos EF001, EF006, EF007, EF008, EF010, EF011 e EF012, com E-cariofileno e biciclogermacreno como majorit?rios; 2 - gen?tipos EF002 e EF003, com os mesmos majorit?rios que o grupo anterior, no entanto, com percentuais m?dios cerca de 30% superiores; 3 - gen?tipos EF004 e EF005, que evidenciaram uma maior produ??o de E-cariofileno; e 4 - com gen?tipo EF009, formando um grupo isolado por apresentar ?-pineno como majorit?rio e percentuais equilibrados entre os demais. Esse resultado foi confirmado pelas Vari?veis Can?nicas, que explicou 76% da varia??o. Os compostos biciclogermacreno, 1,8-cineol, ?-copaeno e espatulenol representaram as vari?veis de maior import?ncia para a an?lise.

Fire is generally used as a management tool for different vegetation types such as savannas and grasslands in southern Africa. In the False Thornveld of the Eastern Cape, fire is commonly used to control bush encroachment and to increase grass production, as grasses are important source of forage for domestic livestock. At the University of Fort Hare farm in the Eastern Cape, a trial was set up in 1980 to investigate the effect of burning frequency on vegetation. There are six treatments replicated twice in a completely randomized design on a 100 m x 50 m plots. The treatments comprise no burn, annual, biennial, triennial, quadrennial and sexennial burns. From this trial a study was conducted to investigate long term effect of burning frequency on species and soil seed bank diversity. Two 100 m line transects located 25 m apart were laid within each plot, and the herbaceous and woody species were identified and recorded along the line transects. Relative abundances (%) for each species were calculated for each treatment. Soil samples were collected at an interval of 13.3 m along the line transects. The samples were placed in paper bags and kept for use in a germination experiment. The seedling emergence germination method was used in the glasshouse to determine emerging seedlings, pots were filled with Hygromix growth medium and the soils from the fire trials 12 X 6 = 72 were spread on top. Soil from the control plots were also pre-treated with heat, smoke and the combination of heat and smoke. The experiment started in January 2010 and was terminated in April 2010. The Shannon-Weaver Diversity Index was used to determine species diversity for standing vegetation and germinated seedlings. Data were tested for normality and species abundances were transformed. Analysis of Variance (ANOVA) was applied to test treatment effects on geminated seedlings, species abundance and diversity at α = 0.05 significance level. Significant differences between treatment means were determined by post v hoc tests using Fischer‟s Least Significant Difference test at α = 0.05. The Pearson Moment Correlation test was used to test the relationship between vegetation and soil seed banks. Treatments had significant effects on herbaceous, woody species abundance and diversity (P < 0.05), but there was no significant treatment effect on soil seed bank diversity and on pre-germination treatments (P > 0.05). The annual, biennial and triennial burns were dominated by Themeda triandra while the quadrennial, sexennial and the control treatments were dominated by Sporobolus fimbriatus and Melica decumbens. A. karroo dominated the woody component across all treatments, but it did not change in abundance. S. fimbriatus was the most abundant in the soil seed bank across all the treatments and also in all pre-germination treatments. Species diversity was high in standing vegetation in the quadrennial, sexennial and the control treatments. There was no significant correlation between the standing vegetation and soil seed bank diversities (P > 0.05). Based on these findings it is apparent that fire can change vegetation in an area to be dominated by fire tolerant or fire intolerant species. Fire frequency, heat and smoke affects soil seed banks to a lesser extent in the False Thornveld. For the management of the False Thornveld of the Eastern Cape, less frequent burning is recommended as it increases aboveground species diversity.

L'objectiu d'aquesta tesi és investigar el paper dels grups funcionals de plantes (GFP) en relació a l’estabilitat de la comunitat vegetal, els fluxos de GEH i les funcions del sòl, i com aquestes interaccions es regulen pel clima. La composició de GFP va influenciar els GEH i les funcions del sòl però les variables ambientals van regular aquest efecte. L’escalfament va afavorir la dominància d’espècies oportunistes i de creixement ràpid en detriment d’espècies més conservatives, causant una reducció en la diversitat específica. La composició i l’estructura funcional van tenir una major influencia en la productivitat i l’estabilitat de la comunitat que la diversitat específica. Els GEH es van reduir amb l’altitud, i incrementar durant l’estiu. La interacció entre GFP va afavorir l’assimilació de CH4 i N2O en comparació a la dominància d’un sòl GFP. Les interaccions entre GFP van també afavorir les funcions de sòl relacionades amb el cicle del N.
El objetivo principal de esta tesis fue investigar el efecto de los grupos funcionales de plantas sobre la estabilidad de la vegetación, los flujos de GEI y las funciones del suelo, y cómo las condiciones climáticas regulan sus interacciones. La estructura funcional de las plantas en pastos influyó la estabilidad de la vegetación, los flujos de GEI, la actividad y fertilidad del suelo, y ese efecto está regulado por el clima. El calentamiento causó la dominancia de especies oportunistas sobre las más conservadoras; reduciendo así la riqueza específica. Los rasgos funcionales tuvieron una mayor influencia en la productividad y estabilidad de las comunidades frente al efecto de la diversidad. Los flujos de GEI aumentaron en verano y disminuyeron con la altitud. La interacción entre grupos funcionales incrementó la absorción de CH4 y N2O respecto a grupos individuales. Las interacciones entre grupos funcionales favorecieron también las funciones de suelo relacionadas con el ciclo de N.
The main objective of this thesis is to investigate how plant functional types (PFT) affect vegetation stability, greenhouse gas (GHG) fluxes and soil functions, and how these interactions are regulated by climatic conditions. We found that plant functional structure strongly influences vegetation stability, GHG fluxes, and soil activity and fertility in grassland, but this relationship is regulated by climate. Warming lead to the dominance of acquisitive fast growing species over conservative species; thus reducing species richness. The functional traits structure in grasslands had greater influence on the productivity and stability of the community under warming, compared to diversity effects. GHG fluxes decreased with altitude- the colder the grassland site the lower the fluxes-, and increased during summer. The interaction between PFTs enhanced CH4 and N2O uptake compared to single PFTs. Also, PFT evenness and pairwise interactions between PFTs enhanced soil functions related to the N cycle.

The aim of this thesis was to explore the distribution of the taxonomic, phylogenetic and functional components of plant diversity in high mountains, and to show how different components of diversity have responded to land-use and climate change over the last two decades. To address this aim, we used a multiple approach at different scales, by combining information from biodiversity databases and descriptive and experimental data gathered in the field. Some methodological improvements were implemented to account for the main sources of uncertainty inherent in the baseline data. The study was conducted in the Central Pyrenees, mainly in the Ordesa-Monte Perdido National Park (OMPNP). In Chapter 1 we developed a novel method to assess the effect of the sampling effort when using information of classical databases to analyze spatial diversity patterns. Such method was used in chapter 2 to identify hotspots, and results were compared with the ones produced by an unbiased database information (standardized community surveys), Finding an overall spatial mismatch among the different diversity components at small scale (Chapter 2). Grasslands resulted to be the richest habitat in terms of species and endemisms, whereas the highest values of phylogenetic and functional diversity were observed in some forests, specially among the mixed ones. The second part of the thesis analyzed recent trends of the richest plant communities in high mountain ranges, alpine grasslands, to the generalized reduction in grazing and climate warming. In chapter 3 we compared plant community composition and tree cover in the upper limit of the treeline ecotone between 1998 and 2009. A weak effect of the increase in tree cover on the dynamics of Field layer vegetation was found, evidencing the slow response of alpine plant communities to drastic structural changes in the habitat. In chapter 4, we revisited after two decades 12 sites along an elevational gradient in two valleys of the Central Pyrenees. After accounting for the effect of the resampling error and the natural fluctuations of communities, we found that alpine grasslands were relatively stable over time at community, species and trait level. Evidences of the large ecological inertia of alpine grasslands were also Found in two experimental exclusion of herbivores set 20 years ago where species richness did not significantly differ from control grasslands (Chapter 5). Differences in the community trajectories of ungrazed and control grasslands occurred only during a sequence of warm and dry growing seasons, which led us to conclude that the effects of the grazing reduction and climate warming acted synergistically. Taken together, these results indicate that the response of alpine grasslands to land-use and climate change may be weaker and slower than expected according to predictive models and observations made in several grasslands below the treeline (rapid ecological succession after abandonment) and mountain summits (thermophilization) in the Central Pyrenees. The apparent stability of alpine grasslands depicted in our studies may revert as some tipping points are exceed. However, the smooth response of grasslands may provide a good opportunity to implement timely management actions for the conservation of this exceptionally rich habitat. The maintenance, and in some cases restoration, of traditional grazing activities, might be the simpler and more efficient strategy in the Face of global change, and perhaps the only possible to alleviate the impact of climate warming on plant diversity.
En esta tesis investigamos la distribución de los componentes taxónomico, filogenético y funcional de la diversidad vegetal en la alta montaña, y cómo ha respondido a los principales motores de cambio global en montañas (cambio climático y de uso de suelo) en las últimas décadas. Para abordar estas dos cuestiones usamos una aproximación a varias escalas, combinando información recopilada en bases de datos con datos descriptivos y experimentales obtenidos en campo, poniendo especial énfasis en mejorar los métodos analíticos de las aproximaciones utilizadas. Nuestra investigación se llevó a cabo en el Pirineo Central, especialmente en el Parque Nacional de Ordesa y Monte Perdido (PNOMP). En el primer capítulo examinamos el sesgo del esfuerzo de muestreo en una clásica base de datos de herbario, y cómo éste puede afectar a los análisis de los patrones de diversidad. Desarrollamos un método nuevo que permitió detectar diferencias importantes en la distribución del esfuerzo de muestreo a lo largo del PNOMP. Esta información fue usada en el segundo capítulo, donde demostramos por primera vez que, además de la riqueza específica, el patrón de distribución del resto de los componentes de la diversidad puede verse distorsionado por el sesgo de muestreo. Tras utilizar una base de datos elaborada a partir de inventarios de comunidades, observamos que los diferentes componentes de la diversidad presentaron una distribución distinta a lo largo del PNOMP. Este resultado demuestra que nuestra habilidad para identificar áreas prioritarias para la conservación a partir de bases de datos clásicas de diversidad es muy limitada. Los pastos resultaron ser el hábitat más rico en término de número de especies y endemismos, mientras que algunos tipos de bosques de hoja caduca fueron identificados como puntos calientes de historia evolutiva y funcional. En los siguientes capítulos examinamos la respuesta de las comunidades más ricas, los pastos de alta montaña, al descenso generalizado del pastoreo y el calentamiento climático. En el capítulo tercero analizamos los resultados de la revisita de transectos de vegetación situados en el ecotono del límite del bosque superior, muestreados 11 años antes. El escaso efecto del incremento de la cobertura arbórea sobre las comunidades pone de manifiesto la lenta respuesta de las comunidades alpinas a cambios estructurales del hábitat. En el cuarto capítulo examinamos la respuesta de los pastos alpinos a lo largo de dos décadas, tras revisitar una docena de parcelas permanentes distribuidas a lo largo de un gradiente altitudinal en dos valles del Pirineo Central. Tras considerar el error de muestreo y la fluctuación interanual de las comunidades, no observamos señales evidentes de cambios ni a nivel de comunidad ni de especies, ni tampoco un aumento de especies leñosas. Los grupos de especies con tendencias opuestas no mostraron rasgos funcionales significativamente diferentes, cuando fue considerada la abundancia y autocorrelación evolutiva de éstos. La gran inercia ecológica de los pastos alpinos fue también confirmada en un experimento de exclusión de herbivoría que duró 19 años (quinto capítulo), donde la riqueza de especies no mostró un efecto significativo en respuesta al tratamiento. La ausencia de ganado sólo resultó en una trayectoria divergente de la comunidad tras una década, y coincidiendo con un periodo excepcionalmente cálido y seco. Este resultado sugiere que el cese del pastoreo y el aumento de las temperaturas podrían tener un efecto aditivo sobre las comunidades vegetales. En conjunto, todos estos resultados ponen de manifiesto que las comunidades de pastos alpinos frente a los principales motores de cambio en montaña puede ser más lenta de lo que se esperaba según los modelos predictivos, la rápida sucesión ecológica (matorralización) observada en varios pastos subalpinos y montanos a lo largo del Pirineo, y los cambios en las comunidades de cumbres (termofliación) descritos en el propio PNOMP. La aparente estabilidad registrada en nuestro estudio podría revertir si se sobrepasan puntos de inflexión críticos. Sin embargo, la lenta dinámica aquí observada sugiere que no es tarde para tomar medidas de gestión para garantizar la conservación de estos pastos excepcionalmente ricos. El mantenimiento o restauración de las actividades del pastoreo tradicional se vislumbra como una solución simple y efectiva para paliar los efectos de los principales motores de cambio global sobre las comunidades alpinas.

The overall effect of tree clearing on pasture, litter production and major soil parameters were analysed using multivariate analysis.. "Tree clearing is practised for greater beef production and hence monetary gains from grazing systems of central Queensland. The high rates of clearing in the past and even recently (577, 000 ha/yr during 1999-2001) were mainly to develop land for pastures. The sustainability of cleared pasture systems over the long-term is questioned. Three major types of tree communities i.e. Eucalyptus populnea F. Muell., E. melanophloia F. Muell. and Acacia harpophylla F. Muell. ex. Benth. were selected on one property in central Queensland to quantify the impacts of clearing on pasture production and composition, and soil properties. The impacts were measured over time-since-clearing (recent (<5 years), medium (11-13years) and old (>30 years)) in unreplicated cleared pastures in comparison to their replicated uncleared/intact woodland pastures of each tree community. Measures of pasture above-ground biomass production on a single property over time-sinceclearing in cleared systems showed that gains were not sustained over the long-term. The difference in response to clearing between tree communities was evident and important to support the future policy decisions. The impact of clearing on soil properties (physicochemical and biological) was confirmed, and explained the lesser availability of nutrients with time of clearing in cleared pastures. The changes in some soil properties underscored the associated risks and changes in ecosystem functions due to clearing. Less litter was produced at cleared than uncleared pastures, but nutrient release was faster at cleared compared to uncleared systems. The overall effect of clearing in terms of pasture and litter production, and major soil parameters were analysed using multivariate analyses. -- abstract

A degree of in-crop management could provide growers with the option to manipulate growth and development in line with ambient weather conditions. Studies presented in this thesis explored this opportunity, and data so far collected support the 'nutrient diversion' hypothesis that internal resource availability and allocation play important roles in regulation of growth partitioning and phenological development. Different levels of defoliation were conducted on maize and cotton plants growing under contrasting water conditions to measure the effect of partial defoliation on their growth and production. In the environment of water stress with low average control yield, defoliation significantly diminished the negative impact caused by water deficit and led to smaller water-deficit-induced decrease of grain yield of maize plants and harvestable product of cotton plants. The relative yield advantage of defoliated plants in the water deficit environment can be attributed to defoliation-induced improvement in water status later in the growth cycle as reflected in measures of photosynthetic rate and stomatal conductance. Early-stage defoliation, removing different parts of maize plants, resulted in varied developmental responses. Removing only the fully exposed leaf blades did not delay the onset of tassel initiation, but tassel initiation and tassel emergence were significantly delayed by either removal of all the shoot tissues above the second ligule or removal of only the expanding leaves at a height just above the soil surface(with the first three or four fully exposed leaves left intact). Continued removal of the expanding leaves delayed tassel initiation further. This indicates the important role that expanding leaves play in control of the transition to reproductive growth. The elongation rate of leaf primordia underwent a gradual decrease as maize plants increased in size with time. The gradual decrease in rate of leaf primordium elongation and the resultant change in shoot apical architecture (described by relative length of leaf primordia) were strongly associated with floral induction. It is proposed that plant internal resource competition lessened the nutrient supply to the shoot apices and, therefore, affected leaf primordium growth and meristem identity simultaneously. The dynamic competition and interdependency among various plant parts were explored using a dynamic model constructed to simulate resource allocation and growth partitioning at the whole plant level.

Today’s intensified agricultural production is characterized by crop and pasture monocultures, which have a significant impact on soil microbial diversity and abundance. This chapter provides a case study in which the relative importance of brome grass (Bromus inermis) monoculture pasture versus intra-site microhabitat diversity is explored using fatty acid methyl ester (FAMEs) assay to delineate the presence and abundance of several classes of soil microbes instrumental in soil nutrient cycling, plant health, plant organic matter decomposition, and soil stabilization. The chapter explores spatio-temporal variability of bacteria, actinomycetes, saprophytes, mycorrhizae, and micro-eukaryotes over two durations (summer and fall) collected using two distinct sampling methods. One of the methods is commonly employed, namely, transect-based, while the other is informed by soil electroconductivity measurements conducted over the entire pasture site from a previous survey.

The demand for illicit drugs can leverage dramatic changes in land cover and associated native biological diversity. These changes, in turn, can lead to loss of critical habitats and rare species of plants and animals, in addition to the degradation of remaining habitats and the contamination of water bodies. Concomitantly, demand can transform social and economic processes, acting against the interests of long-time residents, such as indigenous groups, by attracting new colonists and fomenting crime and violence. Given these potential interconnections between illicit drugs and grave social and environmental consequences, it is more than peculiar that so much scholarly work on environmental transformations does not consider drug-related causes in those countries that supply or transship the drugs. Examples of this myopia include most of the literature on tropical deforestation, where illicit drugs are ignored (e.g., Anderson 1990; Wood 1990; Dove 1993; Myers 1993; Place 1993; Rudel 1993; Brown and Pearce 1994; Jepman 1995; Goldsmith 1998; Barraclough and Ghimere 2000; Horta 2000). The chapters in this book partly correct this deficit and I provide here information for the case of Peru and for “coca/cocaine.” In this chapter, I provide an overview of the way these processes have acted in Peru in relation to the demand for coca leaves, which are transformed into cocaine paste and cocaine. I find great spatial heterogeneity in the negative impacts, at least some of which can be explained by the values and practices of particular social groups. A political ecology approach is helpful in this assessment because by definition illicit drugs intermix the power of governments and economic forces with outcomes toward and resistance by local peoples. I begin by characterizing “coca/ cocaine,” first disaggregating the two words and then showing how the associated processes have affected geopolitics acting upon and within Peru. Then, I examine the evidence available for the effects of coca/cocaine on local landscapes inhabited by indigenous and other social groups. Finally, I outline the known environmental consequences. In the conclusion, I provide the elements necessary for a more complete research agenda that, in turn, could provide the information needed to explore policy alternatives for the social actors involved.

The Heartland Inventory and Monitoring Network monitors plant communities at Tallgrass Prairie National Preserve and evaluates a variety of environmental variables that affect vegetation patterns, including climate and ecological disturbances such as fire and grazing. Here we report on 2002–2018 trends in management actions (fire and grazing) and key plant community indicators. Temperature has increased over the past 50 years in the region. Precipitation and a standardized precipitation-evapotranspiration index included a high degree of interannual variability and did not demonstrate directional change. We documented a decline in disturbance intensity (i.e., less frequent prescribed fire and lower stocking rates) since 2006. A preserve goal is to maintain 30 to 60% of the area as bare ground (soil and rock) for ideal greater prairie-chicken habitat. Bare areas have been in decline and minimally meet the goal preserve wide. Bare areas vary by pasture and year, with bare areas exceeding the threshold in earlier years and Big Pasture and Red House Pasture falling short in some recent years. Although the preserve-scale mean minimally met the objective, there was a great deal of heterogeneity across monitoring sites. Litter cover and depth were greater than ecological recommendations for the greater prairie-chicken, especially in 2018. Litter depth demonstrated a great deal of variability and included deep litter. Woody plants were targeted to remain below 5% cover. Preserve- and pasture-scale cover means were well below this threshold but are increasing. Species richness on a per site basis (alpha diversity) and preserve-wide richness (gamma diversity) showed no apparent directional change when corrected for differences in sample size. Comparison of native species composition between 2002 and 2018 revealed a 36.9% difference in the Sørensen Index, although observer error accounted for almost 2/3 of this apparent change. The preserve continues to have characteristic tallgrass prairie species, and nonnative species continue to be low. Similar to targeted invasive plant monitoring, we found the target species Kentucky bluegrass to be below park thresholds. Continued evaluation of fire frequency and grazing intensity will be critical to achieving ecological goals including conserving the greater prairie-chicken. Development of a grazing plan may assist with prescribing stocking rates that are consistent with the preserve’s ecological and cultural objectives and could include alternative herbivores, such as goats or expansion of bison.