Literatura académica sobre el tema "Transect altitudinal"
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Artículos de revistas sobre el tema "Transect altitudinal"
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Bender, O. G. "Assessment of acclimation of Pinus sibirica mountain ecotypes ex situ on CO2 -gas exchange parameters". Проблемы ботаники южной сибири и монголии 20, n.º 1 (14 de septiembre de 2021): 66–69. http://dx.doi.org/10.14258/pbssm.2021014.
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Carbon dioxide gas exchange of vegetative scion Siberian stone pine ecotypes (Pinus sibirica Du Tour)from the West Sayan mountains altitudinal transect grown on the geographical grafting plantation in the south of theTomsk Region were studied. The altitudinal transect was represented by two ecotypes: low mountain zone and alpine zone.The age of the grafted trees was 20 years. It was shown that the photosynthesis intensity did not differ between ecotypessignificantly, and respiratory activity increased significantly along altitudinal transect and the differences were 40 %between ecotypes. The results of the experiment revealed that the respiration / photosynthesis ratio was 1.5 times higher inalpine ecotype than in low mountain ecotype, which indicates a lower plant productivity of the alpine ecotype. The resultsof measuring stomatal and mesophyll conductance showed that these values differ between ecotypes significantly. Alpineecotype was characterized with more high values of stomatal conductance, but low values of mesophyll conductancerelatively low-mountain ecotype. Alpine ecotype had more high values of CO2 in chloroplasts and electronic transportrates. The obtained data indicate the photosynthetic acclimation when ecotypes were moved to the warmer climate. Therespiratory activity are largely regulated by hereditary factors.
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Frahm, Jan-Peter y Ralf Ohlemüller. "Ecology of bryophytes along altitudinal and latitudinal gradients in New Zealand. Studies in austral temperate rain forest bryophytes 15." Bryophyte Diversity and Evolution 20, n.º 1 (31 de diciembre de 2001): 117–37. http://dx.doi.org/10.11646/bde.20.1.20.
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Six altitudinal transects through temperate rain forests were studied at different latitudes in the South and North Island of New Zealand with respect to species numbers of bryophytes, cover and phytomass of epiphytic bryophytes, composition of life forms and ratio liverworts : mosses. Phytodiversity of bryophytes is almost constant from the lowlands to the high montane belt but decreases in the subalpine belt. Similarly, phytomass and cover increase with elevation but decrease in the subalpine belt. The percentage of liverworts increases accordingly and can reach maxima of 80-90%. The most significant life forms are tails and wefts characteristic for hyperhygric conditions, pendents for cloud belts and cushions for subalpine belts. The altitudinal gradient is much stronger then the latitudinal gradient, that means the differences between the elevations within a transect are more important than the differences between the transects. They are attributed to the humidity. The temperate rain forests of New Zealand have similar bryological characteristics as the tropical rain forests in equatorial latitudes in 2000 – 3000 m altitude but differ in the drier subalpine belt and higher phytomass.
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Perales R., Hugo, S. B. Brush y C. O. Qualset. "Landraces of Maize in Central Mexico: An Altitudinal Transect". Economic Botany 57, n.º 1 (enero de 2003): 7–20. http://dx.doi.org/10.1663/0013-0001(2003)057[0007:lomicm]2.0.co;2.
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Choden, Kelzang, Jambay, Arjun Nepal, Choden y Bhagat Suberi. "Habitat Ecology of Epiphytic & Terrestrial Orchids in Langchenphu, Jomotsangkha Wildlife Sanctuary, Bhutan". Indonesian Journal of Social and Environmental Issues (IJSEI) 2, n.º 2 (22 de agosto de 2021): 143–54. http://dx.doi.org/10.47540/ijsei.v2i2.256.
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Orchids are the largest and diverse families of flowering plants. Orchids are found growing mostly in tropical climates affecting various communities socio-economically. Among many protected areas in Bhutan, Jomotshangkha Wildlife Sanctuary (JWS) is the least explored in terms of flora and fauna. The study was carried out to assess diversity, host tree preferences and to determine the growth zone of epiphytic orchids along the altitudinal gradient in Langchenphu gewog in JWS. Transect technique was used in which three trails transect were laid out with 10 sampling plots in each transect. Plots size of 20 m × 20 m along the altitudinal gradients were established maintaining an altitudinal interval of 100 meters between each sample plot. A total of 42 species of epiphytic orchids from 20 genera was recorded of23 host tree species under 15 families were recorded. A significant correlation between diversity of orchid and altitude was observed (r = .927, p < .05). Myrtaceae and Theaceae were the most preferred host tree families (14%) followed by Bignoniaceae (13%) and others respectively. The Study concludes that 57% of total species encountered prefers higher canopy & on a tree with rough bark, Pearson chi-square test (X2(1) = 4.7, p< .05) showed a significant difference between trunk, branches, and canopy. Many epiphytic orchids prefer dense canopy (n = 73, 47%) and living trees (99%). Future studies should be focused more on the flowering season for obtaining better information on orchid diversity in the study area.
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Drapikowska, Maria. "Variability of Anthoxanthum species in Poland in relation to geographical-historical and environmental conditions: morphological and anatomical variation". Biodiversity: Research and Conservation 30, n.º 1 (1 de junio de 2013): 3–61. http://dx.doi.org/10.2478/biorc-2013-0010.
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Abstract Three Anthoxanthum species are found in Poland: the native A. odoratum L. s. str. and A. alpinum Á. Löve & D. Löve, and the alien A. aristatum Boiss. Major problems within this genus concern: (1) population variation of the native A. odoratum, representing various phases of ecological expansion to anthropogenic habitats; (2) population variation of A. odoratum and A. alpinum along the altitudinal transect; and (3) variation between populations of A. aristatum colonizing new areas and habitats outside its natural range of distribution (chorological expansion). In this study, morphological and anatomical variation of the three Polish Anthoxanthum species was analysed in detail. The variation of A. odoratum and A. aristatum was analysed in respect of environmental differences: habitat types and soil parameters. In the Babia Góra massif, variability distribution along the altitudinal transect was analysed for two vicariants: A. odoratum and A. alpinum. A odoratum in this massif does not cross the upper forest limit (i.e. forest line), and lower montane populations are morphologically very similar to lowland populations. Morphological and anatomical differences were detected between populations of A. alpinum along the altitudinal transect in the Babia Góra massif, with distinct upper montane populations. Moreover, clear morphological differences were found between the two altitudinal vicariants. Lowland populations of A. odoratum are characterized by great morphological variation, only weakly correlated with the type of occupied habitat and the phase of ecological expansion. The detected morphological variation reflects only to a limited extent the environmental variation of occupied habitats, and is not significantly correlated with the phase of chorological expansion. Some soil parameters are significantly correlated with some morphological characters studied in all the Anthoxanthum species. The analysed anatomical features of stems and leaves show continuous variation in the three species.
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Zelazowski, Przemyslaw, Stefan Jozefowicz, Kenneth J. Feeley y Yadvinder Malhi. "Establishing the Position and Drivers of the Eastern Andean Treeline with Automated Transect Sampling". Remote Sensing 15, n.º 10 (22 de mayo de 2023): 2679. http://dx.doi.org/10.3390/rs15102679.
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The eastern Andean treeline (EATL) is the world’s longest altitudinal ecotone and plays an important role in biodiversity conservation in the context of land use/cover and climate change. The purpose of this study was to assess to what extent the position of the tropical EATL (9°N–18°S) is in near-equilibrium with the climate, which determines its potential to adapt to climate change. On a continental scale, we have used land cover maps (MODIS MCD12) and elevation data (SRTM) to make the first-order assessment of the EATL position and continuity. For the assessment on a local scale and to address the three-dimensional nature of environmental change in mountainous environments, a novel method of automated delineation and assessment of altitudinal transects was devised and applied to Landsat-based forest maps (GLAD) and fine-resolution climatology (CHELSA). The emergence of a consistent longitudinal gradient of the treeline elevation over half of the EATL extent, which increases towards the equator by ~30 m and ~60 m per geographic degree from the south and north, respectively, serves as a first-order validation of the approach, while the local transects reveal a more nuanced aspect-dependent pattern. We conclude that the applied dual-scale approach with automated mass transect sampling allows for an improved understanding of treeline dynamics.
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Tariq, Akash, Muhammad Adnan, Naser M. AbdElsalam, Hassan Fouad, Kamran Hussain, Riaz Ullah y Ahsan Ullah. "Richness and Cover of Nontimber Economic Plants along Altitude in Temperate Himalayan Forest-Use Types". Scientific World Journal 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/748490.
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Pakistani Himalaya stretches over a wide range of altitudinal gradients and supports high diversity of medicinal plants that are an important source for rural livelihood. Altitudinal effects on ground vegetation have already been indicated but ground vegetation is also under severe threat of grazing and over collection. The present study investigated the effect of altitude on medicinal plants abundance in both old-growth and derived woodland forests. Each of the five line transects was selected in old-growth and derived woodland forests. Each line transect consisted of four plots distributed at four altitudinal levels (2200, 2300, 2400, and 2500 m asl). Species richness under derived woodland had shown strong negative correlation (r=-0.95) with altitude while it was found to be nonsignificant under old-growth. Cover of most of the species such asVeronica laxa(r=-0.95,P≤0.05) had shown significant negative correlation with altitude under derived woodland. Cover abundance of some species likeValeriana jatamansiand Violacanescenshas also shown significant negative correlation under old-growth forest. Derived woodland can decrease the cover abundance of valuable medicinal plants towards extension at higher altitudes. Thus, protection of the derived woodland could serve as a tool for the improvement of rural livelihood and ecological restoration.
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Zhong, Mengying, Xinqing Shao, Ruixin Wu, Xiaoting Wei, Richard S. P. van Logtestijn y Johannes H. C. Cornelissen. "Contrasting altitudinal trends in leaf anatomy between three dominant species in an alpine meadow". Australian Journal of Botany 66, n.º 5 (2018): 448. http://dx.doi.org/10.1071/bt17247.
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Variation in leaf anatomical traits underpins the adaptations and phenotypic responses of plant species to their different natural environments. Temperature is a primary driver of plant trait variation along altitudinal gradients. However, other environmental drivers may also play important roles, and the interactions between drivers may have different effects on leaf anatomy for different species of the same larger clade. Such interactions might be especially important along shorter altitudinal (i.e. temperature) gradients. We predicted, therefore, that different monocot species could show idiosyncratic responses of leaf anatomical traits to a short altitudinal gradient. Moreover, for a species in which vegetative growth and reproduction are separated in time, its anatomical responses to altitude may differ and trade-offs between leaf and flowering stem anatomy may occur. To test these hypotheses, we examined leaf anatomy and δ13C signature (a possible indicator of anatomy-related water use efficiency or indicator of response to a decrease in CO2 concentration with altitude) of three dominant and widely distributed monocot species (Scirpus distigmaticus, Elymus nutans, Carex moorcroftii) from seven elevations in an alpine meadow on the Qinghai-Tibetan Plateau. In addition, we examined the flowering stem anatomy of S. distigmaticus, across a short altitudinal gradient (four elevations) in the same region. Leaf anatomical traits (e.g. epidermal cell area, epidermal cell thickness, cuticular layer thickness, xylem transect area, phloem transect area) varied with altitude, but the patterns varied substantially among species and among anatomical traits within species. Additionally, for S. distigmaticus, (allometric) coordination between leaves and flowering stems was apparent for xylem transect area and phloem transect area. Trade-offs between leaf and flowering stem traits were also found for epidermal cell area, epidermal cell thickness and mesophyll cell area. Leaves were more responsive to altitude in their anatomical traits than flowering stems in S. distigmaticus, perhaps reflecting their relatively short period of stem development during a climatically relatively favourable season compared with that for leaves, which already start growing earlier in the year. Further research is needed on the interactive effects of environmental variables, as well as vegetative versus reproductive phenology both across and within suites of species to better understand and upscale plant anatomical responses to climate warming in alpine environments.
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Kürschner, Harald. "Wissenschaftliche Ergebnisse der BRYOTROP-Expedition nach Zaire und Rwanda 5. Höhengliederung epiphytischer Moose im östlichen Kongobecken und den angrenzenden Gebirgsstöcken (Parc National de Kahuzi-Biega/Zaire, Forêt de Nyungwe/Rwanda)." Bryophyte Diversity and Evolution 11, n.º 1 (31 de diciembre de 1995): 77–85. http://dx.doi.org/10.11646/bde.11.1.5.
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By mean of a line-taxation (ordination), the floristic discontinuities of epiphytic bryophytes were shown within an altitudinal gradient from the eastern Congo basin to the mountains of the Riftvalley (Mt. Kahuzi) (BRYOTROP III-transect). By this ordination, the epiphytic vegetation can be grouped into four ecological groups, indicating the climatic factors. They show a strong correlation to the known altitudinal zonation, the different forest zones, and the plantsociological classification. These groups consist of taxa of different relationships which grow and evolve under similar environmental conditions.
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Osono, Takashi y Dai Hirose. "Altitudinal distribution of microfungi associated with Betula ermanii leaf litter on Mt. Rishiri, northern Japan". Canadian Journal of Microbiology 55, n.º 7 (julio de 2009): 783–89. http://dx.doi.org/10.1139/w09-030.
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The altitudinal distribution of microfungi associated with Betula ermanii Cham. leaf litter was investigated on Mt. Rishiri (1719 m), northern Japan. Fallen leaves were collected at five sites of different altitudes (appoximately 300, 600, 900, 1200, and 1500 m above sea level) along a transect on the northern slope of Mt. Rishiri. A total of 35 species were isolated from Betula leaf litter of which 12 occurred frequently and were regarded as dominant microfungi. Species richness, diversity, and equitability of microfungal assemblages were lower at Site 1500 than at the other sites. Similarities in species composition were relatively high among Sites 300, 600, and 900, but similarities between these sites and sites at the higher altitudes (i.e., Sites 1200 and 1500) were relatively low. Similarity of species composition was relatively low between Sites 1200 and 1500. Cluster analysis showed that the 12 major microfungal species were classified into four groups according to their pattern of altitudinal distribution that peaked at Sites 600, 900, 1200, and 1500, respectively. These results suggest that the diversity and species composition of Betula microfungi are sensitive to environmental changes along the altitudinal transect on Mt. Rishiri, and this is especially so at the altitudes higher than approximately 1200 m. This implies that future environmental changes will have impacts on mountainous ecosystems through the changes in diversity and functional aspects of microfungal assemblages.
Tesis sobre el tema "Transect altitudinal"
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Scott, Tanya. "Birds along a transect across KwaZulu-Natal: altitudinal preference and altitudinal migration". Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/27946.
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The special ornithological advantage of KwaZulu-Natal is the massive altitudinal gradient between the coastline and the Drakensberg Mountains, an altitudinal range in excess of 3000 m. It is one of the best places in the world to study altitudinal bird migration. This dissertation uses the bird data from the Second Southern African Bird Atlas Project (SABAP2), and altitudinal data from a Digital Elevation Model to try to understand altitudinal migration in a band of KwaZulu-Natal between 29°S and 30°S. The bird atlas provides data on a five minute grid, grid cells with sides of c. 9km, known as pentads. The Digital Elevation Model gives spot heights at 0.5 minute intervals. It therefore provides 100 altitudes in each pentad. There is a description of the data analysis approach used to relate bird species abundance to altitude and selected examples to show how the method works, illustrating the strengths and weakness of the approach. The developed method is then applied to the study area to investigate altitudinal migration. For each of the 304 species which occur with some regularity in the study area, the altitudinal height preferences in summer and winter are plotted and compared. Some species, such as African Dusky Flycatcher, are definite altitudinal migrants, and some species are definite residents having essentially identical altitudinal distributions in summer and winter, such as Black-bellied Starling. There are also many intermediate strategies. Numerous species have been proposed as altitudinal migrants in KwaZulu-Natal. These claims are evaluated against the results obtains in this dissertation. For some species, the suggestion that they are altitudinal migrants is clearly incorrect, and for other species the hypotheses are confirmed by the bird atlas data. The project attempted to determine if there were common factors that helped explain which species engaged in altitudinal migration. A set of life history characteristics for each species, including aspects such as diet, mass, habitat, etc, was used to evaluate if there was a relationship between the extent of altitudinal migration and these explanatory variables. No meaningful relationships were found. Explanations of altitudinal migrations therefore remain an enigma.
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Bierman, Stefni. "Synoptic circulation patterns and its relationship with ground thermal characteristics along an altitudinal transect on sub-Antarctic Marion Island". Thesis, University of Fort Hare, 2014. http://hdl.handle.net/10353/d1015532.
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The climate of Marion Island is driven by synoptic weather patterns which have also been suggested to influence the soil thermal characteristics. The primary aim of this work was to examine the effect of synoptic weather systems on soil temperature dynamics on an altitudinal gradient on the eastern side of Marion Island. The study specifically addresses the implications of climate change on future soil thermal dynamics in a maritime sub-Antarctic environment. Ground temperature were obtained from three ground temperature monitoring stations on the eastern side of Marion Island, which were established along an altitudinal gradient at Long Ridge North (200m a.s.l.), Katedraalkrans (750m a.s.l) and at Delta Extension (1000m a.s.l.). To assess the synoptic weather circulation patterns, a synoptic climate classification methodology that is based on the single station principal component (PCA) and cluster analysis were used. Results show that certain clusters were more dominant than others and over the measured time span certain synoptic weather patterns, mainly cyclonic air circulation types, have decreased while anticyclonic circulation have increased. Soil frost occurs at all three stations on Marion Island, not only under cyclonic circulations (as previously suggested) but significantly under anticyclonic air mass circulation as well. Soil frost is dependent on the duration of post-cyclonic Antarctic air mass circulation. Synoptic weather patterns are also affecting ground surface lapse rates. Changes from positive to negative lapse rates were observed and this predominantly occurred under the atmospheric circulation pattern associated with clusters that are predominantly anticyclonic. Long term climatic change as predicted by the PCA show a reduction in low pressure systems or more anticyclonic conditions affecting the island. These change will significantly affect the soil thermal dynamics at an altitudinal scale on sub-Antarctic Marion Island.
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Véquaud, Pierre. "Développement et application de nouveaux marqueurs d’environnement d’origine bactérienne en milieu terrestre". Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS475.
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A ce jour, les seuls biomarqueurs organiques utilisables pour la reconstruction de la température et du pH en milieu terrestre sont les alkyl tetraéthers de glycérol bactériens (GDGTs ramifiés ou brGDGTs). Ce travail de thèse s’est intéressé au développement et à l’application d’autres marqueurs bactériens, les acides gras 3-hydroxylés (3-AGH). L’analyse de l’abondance des 3-AGHs et des brGDGTs dans 49 sols prélevés dans les Alpes françaises a permis de quantifier l'influence de paramètres environnementaux autres que la température sur la distribution des brGDGTs et des 3-AGHs. En parallèle, des expériences de microcosmes menées sur 4 de ces sols pendant 1 an à différentes températures n’ont pas permis d’observer une évolution des abondances relatives de 3-AGHs mais une augmentation de la proportion de certains brGDGTs. Une première calibration globale des 3-AGHs comme marqueurs de température et de pH a été proposée à partir de 168 échantillons de sols provenant du monde entier. Ce travail a démontré l’intérêt de nouvelles approches utilisant l’apprentissage automatisé pour établir des calibrations de marqueurs. Enfin une calibration globale améliorée des brGDGTs comme marqueurs de température et de pH en milieu terrestre a été proposée (modèle FROG). Ces différentes calibrations ont été appliquées sur des archives paléoclimatiques. L’ensemble des connaissances acquises ont permis d’affiner la compréhension de l’influence de différentes variables environnementales sur la distribution des lipides membranaires utilisés comme marqueurs d’environnements en milieu terrestre, et de proposer de nouvelles approches statistiques pour établir des calibrations de marqueursTo date, the only biomarkers that can be used for temperature and pH reconstruction in terrestrial environments are bacterial glycerol dialkyl glycerol tetraethers (branched GDGTs or brGDGTs). This PhD work focused on the development and application of other proxies of bacterial origin, 3-hydroxy fatty acids (3-OH FAs). The analysis of the abundance of 3-OH FAs and brGDGTs in 49 soils sampled in the French Alps made it possible to quantify the influence of environmental parameters other than temperature on the distribution of brGDGTs and 3-OH FAs. In parallel, microcosm experiments carried out on 4 of these soils for 1 year at different temperatures did not reveal any change in the relative abundances of 3-OH FAs but an increase in the proportion of certain brGDGTs. A first global calibration of 3-OH FAs as temperature and pH proxies was proposed from 168 soil samples globally distributed. This work demonstrated the interest of new approaches using machine learning to establish biomarker calibrations. Finally, an improved global calibration of brGDGTs as temperature and pH proxies in terrestrial environments was proposed (FROG model). These different calibrations were successfully applied and validated on paleoclimatic archives. This work enabled to refine the understanding of the influence of different environmental variables on the distribution of membrane lipids (3-OH FAs and brGDGTs) used as environmental proxies in terrestrial environments, and to propose new statistical approaches to establish environmental proxies calibrations
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Zamora, Allendes Andrés Felipe. "Primera reconstrucción paleoclimática cuantitativa : del polen de madriguera al clima pasado en un transecto altitudinal del altiplano de Chile, Pozo Almonte-Salar del Huasco. Región de Tarapacá". Tesis, Universidad de Chile, 2013. http://www.repositorio.uchile.cl/handle/2250/115513.
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GeógrafoLa utilización de madrigueras actuales y fósiles de roedores, permite obtener registros polínicos que reflejan adecuadamente la vegetación local en zonas áridas donde existen vacios de información. Además la cuantificación de los rangos de distribución climática actual de cada tipo polínico permite determinar con gran precisión las condiciones paleoclimáticas a través de una función de transferencia, la misma que realiza la estimación a partir de la frecuencia relativa de polen fósil. Se presenta una reconstrucción cuantitativa de la temperatura media anual y la precipitación anual para el transecto Altiplánico ubicado entre Pozo-Almonte y Salar del Huasco, usando la función de transferencia polen-clima de los Promedios Ponderados (PP ó WA- Weighted Averaging-, por su significado original en inglés). Según los resultados obtenidos, el clima imperante hace unos 10.000-10.500 años cal A.P. (Holoceno Temprano) fue 5,2°-9,5°C más frío y tuvo una precipitación 3,5-6,3mm mayor que la actual; entre 8.000 y 3.000 años cal A.P. (Holoceno Medio) los escasos registros dan cuenta de un agudo proceso de sequía cuyo peak se encuentra representado en torno a 3.800 años cal A.P. con una temperatura 14°C mayor y una disminución de las precipitaciones cercana a los 12mm; finalmente, los últimos 2.500 años cal A.P. se presentan como un período de gran oscilación entre momentos (más) húmedos/fríos y secos/cálidos. Este escenario es caracterizado por la mayor humedad del presente registro en torno a 2.000 y 1.000 años cal A.P. con temperaturas menores 12,6°-13°C y con un gran incremento en las precipitaciones de 8-8,1mm; luego de lo cual se instauraron las actuales condiciones de aridez.
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Coffinet, Sarah. "Validation and application of lipid biomarkers to reconstruct past environmental changes in East Africa". Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066500/document.
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La Province Volcanique du Rungwe (PVR) en Afrique de l’Est abrite diverses archives continentales (séquence de loess-paléosols, tourbières, lacs) permettant d’étudier les changements environnementaux passés des zones tropicales continentales. Ce travail s’est intéressé à l’applicabilité des alkyl tetraéthers de glycérol (tetraéthers) et des n-alcanes comme biomarqueurs de ces changements passés. Leur analyse le long de transects altitudinaux a permis de rendre compte de la capacité des tetraéthers à enregistrer de faibles changements de température de l’air dans la région. En conséquence, une calibration régionale a été établie afin d’améliorer les reconstructions de température de l’air en Afrique de l’Est. Au contraire, il est apparu que la composition isotopique de l’hydrogène des n-alcanes (δ²Hwax) était impactée par des paramètres physiques et biologiques supplémentaires ce qui complique son utilisation pour suivre les changements de température à l’échelle régionale. L’étude des variations de ces deux biomarqueurs le long d’une carotte de tourbe et d’une carotte de sédiment lacustre prélevées dans la PVR a révélé l’existence synchrone d’une période climatique plus chaude au cours de l’Holocène tardif. Par ailleurs, il a été observé dans la carotte de tourbe une transition d’un lac à une tourbière il y a ca. 2000 ans BP. Le présent travail démontre donc que les tetraéthers et les n-alcanes sont des biomarqueurs prometteurs, notamment parce qu’ils sont sensibles à de faibles variation climatiques ; cependant, afin de les interpréter correctement, il est nécessaire d’adopter une approche multi-marqueursThe Rungwe Volcanic Province (RVP) in East Africa offers a wide diversity of continental archives (loess-paleosols sequences, peatlands, lakes), allowing the investigation of past environmental changes in tropical continents. This work focused on the validation of glycerol dialkyl glycerol tetraether- (GDGT) and n-alkane-derived proxies. Analyses of these two biomarkers along altitudinal transects allowed assessing their ability to record temperature changes in the region. GDGTs were found to be robust temperature proxies in East Africa, and a regional calibration was established to improve temperature reconstructions from soil archives. In contrast, investigation of n-alkane hydrogen isotopic composition (δ²Hwax) in surface soils revealed that its variations seemed to be impacted by additional biological and physical parameters than temperature, preventing its generalization at a regional scale. Application of GDGT and n-alkane proxies to continental archives revealed past environmental changes over the Late Holocene in the RVP. A late Holocene synchronous temperature maximum was especially observed in a peat core and sediment core from two sites of the RVP. A multi-proxy approach was applied to the peat core, revealing that an ecosystem change from a lake to a peatland occurred ca. 2000 yrs BP ago. The present work showed that GDGTs and n-alkanes are promising biomarkers because of their sensitivity to slight climate variations, but that they need to be combined with other proxies to accurately reconstruct environmental changes
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Coffinet, Sarah. "Validation and application of lipid biomarkers to reconstruct past environmental changes in East Africa". Electronic Thesis or Diss., Paris 6, 2015. http://www.theses.fr/2015PA066500.
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La Province Volcanique du Rungwe (PVR) en Afrique de l’Est abrite diverses archives continentales (séquence de loess-paléosols, tourbières, lacs) permettant d’étudier les changements environnementaux passés des zones tropicales continentales. Ce travail s’est intéressé à l’applicabilité des alkyl tetraéthers de glycérol (tetraéthers) et des n-alcanes comme biomarqueurs de ces changements passés. Leur analyse le long de transects altitudinaux a permis de rendre compte de la capacité des tetraéthers à enregistrer de faibles changements de température de l’air dans la région. En conséquence, une calibration régionale a été établie afin d’améliorer les reconstructions de température de l’air en Afrique de l’Est. Au contraire, il est apparu que la composition isotopique de l’hydrogène des n-alcanes (δ²Hwax) était impactée par des paramètres physiques et biologiques supplémentaires ce qui complique son utilisation pour suivre les changements de température à l’échelle régionale. L’étude des variations de ces deux biomarqueurs le long d’une carotte de tourbe et d’une carotte de sédiment lacustre prélevées dans la PVR a révélé l’existence synchrone d’une période climatique plus chaude au cours de l’Holocène tardif. Par ailleurs, il a été observé dans la carotte de tourbe une transition d’un lac à une tourbière il y a ca. 2000 ans BP. Le présent travail démontre donc que les tetraéthers et les n-alcanes sont des biomarqueurs prometteurs, notamment parce qu’ils sont sensibles à de faibles variation climatiques ; cependant, afin de les interpréter correctement, il est nécessaire d’adopter une approche multi-marqueursThe Rungwe Volcanic Province (RVP) in East Africa offers a wide diversity of continental archives (loess-paleosols sequences, peatlands, lakes), allowing the investigation of past environmental changes in tropical continents. This work focused on the validation of glycerol dialkyl glycerol tetraether- (GDGT) and n-alkane-derived proxies. Analyses of these two biomarkers along altitudinal transects allowed assessing their ability to record temperature changes in the region. GDGTs were found to be robust temperature proxies in East Africa, and a regional calibration was established to improve temperature reconstructions from soil archives. In contrast, investigation of n-alkane hydrogen isotopic composition (δ²Hwax) in surface soils revealed that its variations seemed to be impacted by additional biological and physical parameters than temperature, preventing its generalization at a regional scale. Application of GDGT and n-alkane proxies to continental archives revealed past environmental changes over the Late Holocene in the RVP. A late Holocene synchronous temperature maximum was especially observed in a peat core and sediment core from two sites of the RVP. A multi-proxy approach was applied to the peat core, revealing that an ecosystem change from a lake to a peatland occurred ca. 2000 yrs BP ago. The present work showed that GDGTs and n-alkanes are promising biomarkers because of their sensitivity to slight climate variations, but that they need to be combined with other proxies to accurately reconstruct environmental changes
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Munyai, Aubrey. "Biodiversity of terrestrial small mammals along an altitudinal transect in the Western Soutpansberg, Limpopo Province, South Africa". Diss., 2015. http://hdl.handle.net/11602/279.
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Unger, Malte Arne. "Relationships between soil chemical properties and forest structure, productivity and floristic diversity along an altitudinal transect of moist tropical forest in Amazonia, Ecuador". Doctoral thesis, 2010. http://hdl.handle.net/11858/00-1735-0000-0006-ADA3-B.
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Unger, Malte Arne [Verfasser]. "Relationships between soil chemical properties and forest structure, productivity and floristic diversity along an altitudinal transect of moist tropical forest in Amazonia, Ecuador / vorgelegt von Malte Arne Unger". 2010. http://d-nb.info/1007243716/34.
Texto completoLibros sobre el tema "Transect altitudinal"
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Ingvar, Aune Egil y Tveito Ole Einar, eds. Altitudinal distribution patterns of alpine plants: Studies along a coast-inland transect in southern Scandes, northern Europe. Trondheim, Norway: Tapir Academic Press, 2011.
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Lidiando con el clima de hoy en pequeñas comunidades. Enseñanzas sobre la adaptación y la capacidad de respuesta al cambio climático en el contexto de Michoacán. Universidad Nacional Autónoma de México, Centro de Investigaciones en Geografía Ambiental, 2020. http://dx.doi.org/10.22201/ciga.9786073033145e.2020.
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Este libro es resultado de ocho casos de estudio. Siete de ellos se localizan a lo largo de un transecto altitudinal en Michoacán y uno en Jalisco. La mayoría de las investigaciones abordan la forma en que las personas, de diferentes contextos socioeconómicos y realidades ambientales, perciben y manejan los impactos del cambio climático. También incluye tres revisiones de discursos sobre políticas públicas ante el mencionado fenómeno. A partir del trabajo realizado se encontró que ciertos efectos del cambio climático afectan y son percibidos tanto a nivel de hogar como de comunidad. Pero por lo general dichos efectos forman parte de complejas interrelaciones con la globalización, la migración, la marginación y la seguridad. Lo que es alentador, como se muestra a lo largo del libro, es la variedad de iniciativas que la gente ha encontrado para abordar y lidiar con los impacto
Capítulos de libros sobre el tema "Transect altitudinal"
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Wilcke, W., S. Yasin, A. Schmitt, C. Valarezo y W. Zech. "Soils Along the Altitudinal Transect and in Catchments". En Ecological Studies, 75–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-73526-7_9.
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Leuschner, Christoph, Alexandra Zach, Gerald Moser, Jürgen Homeier, Sophie Graefe, Dietrich Hertel, Bärbel Wittich et al. "The Carbon Balance of Tropical Mountain Forests Along an Altitudinal Transect". En Ecosystem Services, Biodiversity and Environmental Change in a Tropical Mountain Ecosystem of South Ecuador, 117–39. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-38137-9_10.
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Castaldini, M., A. Mirabella, G. Sartori, A. Fabiani, F. Santomassimo y N. Miclaus. "Soil development and microbial community along an altitudinal transect in trentino mountains". En Developments in Soil Science, 217–28. Elsevier, 2002. http://dx.doi.org/10.1016/s0166-2481(02)80019-8.
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Aguirre, Zhofre, Maritza Vaca, Johana Muñoz y Luis Muñoz. "COMPOSICIÓN FLORÍSTICA Y ESTRUCTURA DE LA VEGETACIÓN EN ÁREAS CON Y SIN EFECTO DE BORDE, CONSIDERANDO EL GRADIENTE ALTITUDINAL EN LA HOYA DE LOJA, ECUADOR". En Botânica, Ecologia e Sustentabilidade: uma perspectiva multidisciplinar, 145–65. Editora Científica Digital, 2023. http://dx.doi.org/10.37885/230914374.
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Los bosques andinos poseen potencial para el turismo, educación e interpretación ambiental; pero al hacer accesible al público las áreas naturales para estos fines se provocan efectos de borde, que generan impactos en la biodiversidad. El objetivo de esta investigación fue determinar y comparar la composición florística y estructura de la vegetación en áreas bajo efecto y sin efecto de borde, considerando el gradiente altitudinal. Se instalaron 18 transectos de 20 x 10 m, 9 en áreas con efecto de borde y 9 sin efecto de borde, considerando tres pisos altitudinales; se obtuvo la composición florística, parámetros estructurales e índice de valor de importancia (IVI), índice de Sorensen cualitativo y se elaboraron dendrogramas usando el programa BioDiversity Pro 2.0. En el área con efecto de borde se registraron 60 especies dentro de 50 géneros y 38 familias, con un total de 2 727 individuos. Y en el área sin efecto de borde 60 especies dentro de 50 géneros y 32 familias, con 2 521 individuos. La especie ecológicamente importante según el mayor IVI, en el área con efecto y sin efecto de borde fue Alnus acuminata. No se observa diferencias notables en la composición florística y estructura de la vegetación en las dos áreas con y sin efecto de borde, pero si en la abundancia de individuos, en las áreas cercanas al borde hubo más individuos que al interior del bosque. La gradiente altitudinal es una variable que provoca cambios importantes en la composición florística y estructura de la vegetación.
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Boix, C., A. Calvo, A. Cerdá, A. C. Imeson, M. D. Soriano y I. R. Tiemessen. "Vulnerability of Mediterranean ecosystems to Climatic Change, study of soil degradation under different climatological conditions in an altitudinal transect in the south east of Spain". En Studies in Environmental Science, 763–66. Elsevier, 1995. http://dx.doi.org/10.1016/s0166-1116(06)80105-6.
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