Memoria para optar al título profesional de Ingeniero en Recursos Naturales Renovables / Prosopis tamarugo Phil. es un árbol nativo del Desierto de Atacama, Chile. El Tamarugo presenta características y despliega mecanismos fisiológicos altamente adaptados a las condiciones extremas de La Pampa del Tamarugal. Siendo una especie estrictamente freatófita las perturbaciones sobre la disponibilidad de agua subterránea afectan directamente la condición hídrica de los individuos. Los acuíferos asociados a la Pampa del Tamarugal han presentado una disminución del nivel freático, evento asociado a una extracción de agua subterránea mayor a la recarga natural, para satisfacer la demanda doméstica de la región, la minería y agricultura. La revisión de trabajos realizados que asocian la profundidad freática con variables asociadas a la condición hídrica de los tamarugos ha demostrado que variables integradas tales como: Fracción Verde de Canopia, NDVI (Índice de la Diferencia de Vegetación Normalizada), enriquecimiento isotópico 18O en tejido foliar y Crecimiento de Ramillas, probaron ser más reactivas a la profundidad del nivel freático y presentaron valores de error menores. Junto con ello, la compilación de estudios permite describir la estrategia del Tamarugo frente a la disminución de la oferta de agua, regulando su demanda (transpiración) y disminuyendo la biomasa verde; en una primera etapa con una senescencia temprana y disminución del crecimiento de ramillas, luego con un cierre parcial de estomas que, dada la naturaleza relativamente anisohídrica del tamarugo y frente a una condición de sequía, desembocaría en cavitación xilemática que produciría muerte de ramillas reduciendo la canopia verde del árbol. Así fue posible proponer umbrales asociados a las distintas etapas de la respuesta fisiológica del tamarugo, a los 4 metros de profundidad freática el tamarugo ya presenta senescencia temprana. Pasado un umbral de 10 metros de profundidad freática se registra un nulo crecimiento de ramillas y actividad fotosintética mínima. Cercano a los 20 metros el tamarugo es incapaz de realizar movimientos pulvinares y no puede evitar la fotoinhibición, esto, junto con una reducción de la fracción verde de canopia más allá del 0,25 llevaría a la muerte del Tamarugo. El conocimiento de la estrategia del Tamarugo frente a la escasez hídrica, las etapas que cursa enfrentado a ella y los umbrales de profundidad freática asociados a estas etapas es un insumo esencial para la correcta gestión ambiental de la zona y la conservación del tamarugo.

The nutritional value for the following species have been determined: P.pallida, P.laevigata var. andicola, P.flexuosa, P.nigra, P.alba of the genus Proposis. To obtain this purpose surveys were done about the use and consumption of the Carob Tree in the High and Central Valleys of the Cochabamba Department. As a result of the surveys it was determined that the consumption of the pods made up for 54% of human nourishment. The species that were consumed the most were P.pallida and P.laevigata var. andicola. Within the uses of these leguminous pods, the pods are directly consumed in their raw form and on a lesser scale in their cooked form. It was also observed that a minority use it as flour which is then ingested principally in the form of pito and api. Afterwards a chemical bromatologic analysis was done and it was determined that there was a high content of carbohydrates and fiber, a relatively good percentage of protein and a low ethereal extract, standing out more than the minerals calcium and iron. It was also determined that the highest content of protein and ethereal extract show P.laevigata var. andicola and P.nigra, the fiber P.laevigata var. andicola, and P.pallida calories. The species with the most concentration of the minerals phosphorus, iron, and calcium were P.pallida and P.nigra. The biological tests for the protein quality performed for the two species that were the most consumed show poor results of Real Digestibility (Dr), Net Use of Real Protein (UNPr), Real Biological Value (VBr), and the Relation of the Efficiency of Protein (PER). These are considerably becoming better through a thermic process (toasted 10min). The leguminous cereal complementation (corn-carob tree), favorably increased all of the biological indexes. The species P.pallida showed superiority compared to the results obtained for P.leavigata var. andicola. In the meantime these species can be considered a good energy source and with the combination of cereals can effectively cover caloric protein deficiencies.

Malaria affects hundreds of millions of people worldwide and equally claims hundreds of thousands of lives each year. With the current spread of drug resistance to standard antimalarial drugs like chloroquine and the emergence of artemisinin-resistant parasites, new antimalarial drugs and formulations are urgently needed. An ethnobotanical survey was carried out in this study in search of novel compounds with promising antiplasmodial activity. Using the ethnobotanical approach, a total of 61 plant species from 59 genera distributed in 34 plant families were found to be used traditionally for the treatment of malaria in Nigeria. Biological evaluation of the plant¿s methanolic extracts was assessed using the parasite lactate dehydrogenase (pLDH) assay against the chloroquine-sensitive (3D7) and chloroquine-resistant (K1) strains of Plasmodium falciparum. A total of five (5) plant species showed more potent antiplasmodial activities against the malaria parasites. These are Acanthospermum hispidum, Cassia occidentalis, Kaempferia aethiopica Prosopis africana and Physalis angulata with MIC values ranging between 7.815µg/ml to 31.25µg/ml (3D7 strain) and 15.63µg/ml to 62.50µg/ml (K1 strain) against the malaria parasites, respectively. Two plants, Prosopis africana (Leguminosae-mimosoideae) and Physalis angulata (Solanaceae) were selected for further study. The phytochemical investigation of the active chloroform extracts of P. africana and P. angulata yielded several compounds with three known alkaloids, namely, prosopinine (I), prosopine (II) and acetamide (III). Their structures were confirmed by MS, 1D and 2D NMR spectroscopy. Compounds I, II and III have moderate in vitro antiplasmodial activity against the malaria parasites. Both chloroquine and artemether were used as standard control. / Association of Commonwealth Universities and the Commonwealth Scholarship Commission in the UK (Commonwealth Scholarship Reference Number: NGCS-2005-259).

RESUME : Le Sud-Est du Niger est soumis au phénomène dérosion éolienne. Dans la zone de Gouré, les cuvettes oasiennes, principales sources de productions agricoles et de revenus, sont menacées de disparition à cause de lensablement. Des opérations de fixation de dunes sont entreprises pour sauver ce capital productif. Lévaluation de la technique de fixation mécanique des dunes utilisée dans la zone a montré que celle-ci est efficace dans la restauration écologique du milieu. Trois années après la mise en place des palissades anti-érosives, à base des branchages de Leptadenia pyrotechnica, une végétation spontanée, comprenant 58 espèces (20 familles), dont 17 pérennes, sétait installée à lintérieur du clayonnage, soit 42 espèces de plus que dans les zones non traitées. Au fil des ans, la composition floristique sest progressivement stabilisée, témoignant ainsi dune réduction notable des perturbations du milieu engendrées par laction érosive des vents. Dans une expérimentation de fixation biologique de dunes, sept espèces ligneuses, dont cinq autochtones (Acacia senegal, A. tortilis, A. nilotica, Bauhinia rufescens, Balanites aegyptiaca), et deux allochtones (Prosopis juliflora et P. chilensis) ont été testées. En pépinière, les espèces ont subi un stress hydrique par interruption darrosage durant six jours. Les taux dhydratation foliaire ont été déterminés, afin dévaluer leur capacité respective à limiter les pertes deau par transpiration. Dans un essai de terrain, les espèces ont été plantées sur un cordon dunaire, préfixé mécaniquement, en vue de tester leur aptitude à la stabilisation des dunes. Les taux de survie sur trois années ont été calculés et la croissance en hauteur mesurée. Les résultats en pépinière ont montré, quaprès six jours de stress hydrique, Acacia senegal, A. tortilis, Prosopis chilensis et A. nilotica sont les quatre espèces limitant le mieux les pertes en eau. Les résultats sur site ont montré que la meilleure combinaison en matière de fixation de dunes dans cette zone serait dassocier lespèce de Prosopis chilensis (fort taux de survie et croissance rapide) avec A. tortilis et/ou A. nilotica (survie et croissance relativement appréciables et intérêt économique plus important). Dans loptique dun essai dinoculation mycorhizienne, des échantillons de sols de Gouré ont été récoltés sous dix espèces ligneuses locales et exotiques, avec lobjectif didentifier les différents types de champignons mycorhiziens à arbuscules (CMA) et de produire un inoculum indigène par le biais de trois plantes-pièges locales ; le mil, le sorgho et le niébé. Les résultats ont mis en évidence la présence de deux familles de Glomales dans les sols du département de Gouré, Glomaceae (appartenant au genre Glomus) et Gigasporaceae. Avec plus de 56 % des spores, le genre Glomus est le plus abondant des Glomales identifiées et aussi le plus viable (55,80 % des spores vivantes). La croissance en hauteur des parties aériennes du sorgho et du niébé a été significativement stimulée par linoculation. Les trois cultures sont équivalentes dans le piégeage des spores. Un inoculum mycorhizien composite de souches indigènes a été produit à partir de cette culture sporale. Lefficacité de la mycorhization naturelle a été comparée à celles des apports de ce complexe mycorhizien indigène et du Glomus intraradices. Un substrat de culture naturel, non stérilisé, a été inoculé par le complexe mycorhizien de souches indigènes ou par du Glomus intraradices. Les effets de linoculation ont été observés sur cinq espèces ligneuses, dont trois Acacias (A. nilotica, A. tortilis, A. senegal), Bauhinia rufescens et Prosopis chilensis, en pépinière et en sol dunaire. En pépinière, les espèces ont subi un stress hydrique par interruption darrosage durant six jours. Les taux dhydratation foliaire ont été calculés, afin dévaluer les effets de la mycorhization sur la limitation des pertes deau par transpiration. Les différents taux de mycorhization ont été déterminés, ainsi que la croissance des plants et la production de la biomasse totale. Dans un essai de terrain, les espèces inoculées et non inoculées ont été plantées sur un cordon dunaire, préfixé mécaniquement, en vue dévaluer les effets des différents apports mycorhiziens au champ sur la croissance en hauteur des plants. Les résultats en pépinière ont montré que (i) le sol de pépinière non stérilisé contient des CMA (champignon mycorhizien à arbuscules) endogènes aussi infectifs que les souches contrôlées ; (ii) lapport du Glomus intraradices est efficace dans la stimulation de la production de biomasse totale et (iii) la mycorhization naturelle est quasi aussi efficace que les deux apports mycorhiziens dans la stimulation de la croissance en hauteur et dans la limitation de la perte deau des espèces par transpiration. Les résultats sur site confirment lefficacité comparable de la mycorhization naturelle et de celle des apports mycorhiziens. Bien que leffet du G. intraradices apparaisse être bénéfique en certains points chez quelques espèces, les effets observés ne justifient pas doffice de le préférer à linoculum composite de souches indigènes, ni à la mycorhization naturelle dans cette zone. -------------------------------------------------------------------------------- SUMMARY: The Southeastern of Niger Republic is subjected to the phenomenon of wind erosion. In Gouré, the oasis basins, which are the main source of agricultural productions and incomes, are threatened to disappear because of the sand silting up. Operations of sand dunes fixation are taken to save this productive capital. Assessment of the mechanical sand dunes fixation technique, used in this area, showed that this technique is effective in the ecological restoration of the environment. Three years after the implementation of the anti erosive fences, made of Leptadenia pyrotechnica branches, spontaneous floral vegetation, including 58 species (20 families) of which 17 perennials, had settled down inside the fences, owing 42 species more than in the untreated areas. Over the years, the floral composition gradually stabilized proving then a considerable reduction of the environmental disturbances caused by the erosive winds action. In a biological sand dunes fixation experiment, seven woody species, of which five natives (Acacia senegal, A. tortilis, A. nilotica, Bauhinia rufescens and Balanites aegyptiaca) and two exotic (Prosopis juliflora and P. chilensis) have been tested in that zone of the Southeastern of Niger Republic. In nursery, species underwent a water stress by interrupting the watering during six days. Foliar hydration has been determined in order to evaluate their capacity to limit water loss. In a field experiment, species have been planted on a mechanically prefixed sand dune cord in order to test their ability in sand dunes stabilization. Survival rates during the first three years have been calculated and height growth was measured. In nursery, results showed that, after six days of water stress, Acacia senegal, A. tortilis, P. chilensis and A. nilotica are the four species limiting the best the losses in water. Results on site showed that the best combination in sand dunes fixation, in this zone, would be the association of Prosopis chilensis specie (high survival rate and fast growth) with A. tortilis and/or A. nilotica (survival and growth relatively substantial and more important economic interest). In the optics of a further mycorrhizal inoculation essay, soil samples from Gouré department were collected beneath ten mature native and exotic tree species in order to identify the types of associated arbuscular mycorrhizal (AM) fungi and to produce an indigenous inoculum by growing three local trap cultures including millet, sorghum and cowpea. The results highlighted the presence of two families of Glomales in the soils including Glomaceae (belonging to the genus Glomus) and Gigasporaceae. With more than 56 % of spores, the genus Glomus is the most abundant of the identified Glomales and the most viable (55, 80 % of the live spores). The length growth of sorghum and cowpea plants was significantly stimulated by inoculation. The three trap cultures species are equivalent in the spores trapping. An indigenous mycorrhizal complex was produced from this spore culture. Effects of the natural mycorhization were compared with those of the addition of this indigenous mycorrhizal complex and Glomus intraradices. A natural unsterile culture substrate was inoculated with the indigenous inoculum or with G. Intraradices. Inoculation effects were assessed on five woody species, among which three Acacias species (A. nilotica, A. tortilis, A. senegal), Bauhinia rufescens and Prosopis chilensis, in a tree nursery and on a sand dune of Gouré. In the nursery, species underwent a water stress by interrupting the watering during six days. Foliar hydration has been determined in order to evaluate the respective effects of the mycorrhizal inoculation on the water loss limitation. Mycorrhizal root colonization has been determined as well as plant height and total biomass. In a field experiment, inoculated and non inoculated species have been planted on a mechanically prefixed sand dune portion in order to evaluate the effects of mycorrhizal inoculations on growth in the field. Results in nursery showed that (i) the non sterile soil would contain some endogenous AMF (arbuscular mycorrhizal fungi) as infectious as those in soils with mycorrhizal additions; (ii) addition of Glomus intraradices would be efficient to stimulate total biomass and (iii) natural mycorhization would be as efficient as both mycorrhizal addition in growth stimulation and water loss limitation by transpiration. Results on site confirm the comparable effectiveness of the natural mycorhization and mycorrhizal additions. Although the addition of G. intraradices appears to be slightly superior by some aspects on some species, the observed effects do not justify preferring it, when compared to indigenous composite inoculum or to natural mycorhization in this zone.

Anthropogenic activities are responsible for increases in atmospheric CO₂ and climate change. These increases are partly counterbalanced by natural processes, such as carbon uptake in land surfaces. These processes are themselves subject to climate change, creating a coupled carbon-climate system. I investigated the carbon sink that woody encroachment represents, using a Central Texas savanna as study site, and studied how climatic factors influence this carbon sink. Woody plant encroachment, a worldwide structural change in grassland and savanna ecosystems, alters many ecosystem properties, but the net effect on the carbon balance is uncertain. Woody encroachment represents one of the key uncertainties in the US carbon balance, and demands a more detailed understanding. To come to a process-based understanding of the encroachment effect on carbon dynamics, I analyzed patterns of carbon exchange using eddy-covariance technology. I expected the imbalance between carbon uptake and release processes associated with the encroaching trees specifically, to be responsible for the carbon sink. I also expected that the sink would vary in time, due to strong links between carbon fluxes and soil water in this semi-arid ecosystem. I further studied the ecophysiology of the dominant species, as well as soil respiration processes under different vegetation types, and scaled these findings in space and time. I found that the ecosystem was a significant carbon sink of 405 g C m⁻² yr⁻¹. The encroaching trees increased photosynthesis by 180% and decreased soil respiration by 14%, compared to the grassland, resulting in a strong carbon sink due to the encroachment process. The encroaching process also altered carbon dynamics in relation to climatic drivers. The evergreen species Ashe juniper effectively lengthened the growing season and widened the temperature range over which the ecosystem acts as a carbon sink. The drought resistance of the encroaching trees reduced the sensitivity of this savanna to drought. I conclude that encroachment in Central Texas savannas increased the carbon sink strength by increasing the carbon inputs into the ecosystem. Woody encroachment also reduced the sensitivity to climatic drivers. These two effects constitute a direct effect, as well as a negative feedback to the coupled carbon-climate system. / text

<p>Land use and land cover changes significantly affect C storage in terrestrial ecosystems. Programs intended to compensate land owners for the maintenance or enhancement to C stocks are promising, but require detailed and spatially explicit C distribution estimates to monitor the effectiveness of management interventions. Savanna ecosystems are significant components of the global C cycle, however, they have not received much attention for the development of C monitoring approaches. In this dissertation I have investigated three of the aspects related to woody plant cover dynamics in semiarid savannas of central Argentina: spatio-temporal dynamics, precise field surveying and scaling from field to region with the use of freely available remotely sense data. </p><p>To examine the long term changes in woody plant cover, I first carefully extracted information from historical maps of the Caldenal savannas of central Argentina (190,000 km2) in the 1880s to generate a woody cover map that was compared to a 2000s dataset. Over the last ~120 years, woody cover increased across ~12,200 km2 (14.2 % of the area). During the same period, ~5,000 km2 of the original woody area was converted to croplands and ~7,000 km2 to pastures, about the same total land area as was affected by woody plant encroachment. A smaller area, fine scale analysis between the 1960s and the 2000s revealed that tree cover increased overall by 27%, shifting from open savannas to a mosaic of dense woodlands along with additional agricultural clearings. Statistical models indicate that woody cover dynamics in this region were affected by a combination of environmental and human factors.</p><p>To assess the consequences of woody cover dynamics on C, we also measured ecosystem C stocks along a gradient of woody plant density. I characterized changes in C stocks in live biomass (woody and herbaceous, above- and belowground), litter, and soil organic carbon (to 1.5 m depth) pools along a woody plant cover gradient (0 to 94 %). I found a significant increase in ecosystem C stocks with increasing woody cover, with mean values of 4.5, 8.4, 12.4, and 16.5 kg C m-2 for grasslands, shrublands, open and closed forests, respectively. Woody plant cover and soil silt content were the two primary factors accounting for the variability of ecosystem C. I developed simple regression models that reliably predict soil, tree and ecosystem C stocks from basic field measurements of woody plant cover and soil silt content. These models are valuable tools for broad scale estimation if linked to regional soil maps and remotely sensed data, allowing for precise and spatially explicit estimation of C stocks and change at regional scales.</p><p>Finally, I used the field survey data and high resolution panchromatic images (2.5 m resolution) to identify tree canopies and train a regional tree percent cover model using the Random Forests (RF) algorithm. I found that a model with summer and winter tasseled cap spectral indices, climate and topography performed best. Sample spatial distribution highly affected the performance of the RF models. The regression model built to predict tree C stocks from percent tree cover explained 83 % of the variability, and the spatially explicit tree C model prediction presented an root mean squared error (RMSE) of 8.2 tC/ha which represented ~30% of the mean C stock for areas with tree cover. Our analysis indicates that regionally over the last ~120 years, increases in woody plant cover have stored significant amounts of C (95.9 TgC), but not enough to compensate for in C generated by the conversions of woodlands and natural grasslands to croplands and pastures (166.7 TgC), generating a regional net loss of 70.9 TgC. C losses could be even larger in the future if, as predicted, energy crops would trigger a new land cover change phase in this region.</p> / Dissertation

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-09-25T17:18:51Z No. of bitstreams: 1 HERMEVAL JALES DANTAS – TESE (PPGEP) 2013.pdf: 2896032 bytes, checksum: 137d385a4e870d4c6e3dccb8fa4f36c8 (MD5) / Made available in DSpace on 2018-09-25T17:18:51Z (GMT). No. of bitstreams: 1 HERMEVAL JALES DANTAS – TESE (PPGEP) 2013.pdf: 2896032 bytes, checksum: 137d385a4e870d4c6e3dccb8fa4f36c8 (MD5) Previous issue date: 2013-02 / Capes / O objetivo deste trabalho foi produzir aguardente bidestilada de algaroba e armazená-la em três diferentes tipos de madeiras (algarobeira, carvalho e cerejeira) com aplicação de três níveis de tosta, exercido por diferentes tempos de queima, na superfície interna de cada barrica. Determinaram-se as características físico-químicas (teor de água, proteína, açúcares redutores, açúcares não redutores e açúcares totais, minerais, carboidratos e acidez total) das vagens de algaroba in natura, após a prensagem e do caldo da algaroba na primeira e na segunda extração. Do caldo da algaroba foi selecionada uma cepa de levedura, a qual foi isolada e analisada do ponto de vista genético, por meio da metodologia de amplificação de DNA por eletroforese usando-se como iniciador (GTG)5 identificada como uma linhagem da Saccharomyces cerevisiae. Estudou-se a influência da velocidade de destilação e de aeração sobre os parâmetros físico-químicos, aplicando-se um planejamento fatorial 22 com três pontos centrais, na produção de aguardente bidestilada de algaroba Utilizaram-se barricas de algarobeira, cerejeira e carvalho, com tempos de um, dois e três minutos de queima na superfície interna da aduela. Na vagem de algaroba foram encontrados valores de açúcares totais, proteínas e minerais, de 35,9, 8,46 e 7,8% respectivamente, o que comprova seu potencial para a produção de aguardente; uma extração foi conseguida a partir da vagem hidratada, com valores de 17,92, 15,36 e 2,56% de açúcares totais, açúcares não redutores e de açúcares redutores, respectivamente. Selecionou-se uma linhagem de levedura existente no seu caldo de algaroba caracterizada como sendo Saccharomyces cerevisiae. A aguardente bidestilada de algaroba se encontra dentro dos parâmetros físico-químicos analisados e exigidos pelo M.A.P.A (Ministério da Agricultura, Pecuária e Abastecimento) exceto quanto aos congêneres de álcoois superiores de 584,50 mg.100mL-1 e soma dos componentes secundários de 627,29 mg.100mL-1. Quanto ao contaminante carbamato de etila, foram registrados níveis abaixo de 50 μg.L-1 quando se avaliou o efeito da velocidade de destilação e de 69,8 μg.L-1 quando se utilizou a aeração, sendo esses valores inferiores aos 150 μg.L-1 exigidos pela legislação. Dentre as aguardentes de algaroba submetidas a diferentes tipos de barricas estudadas (Algaroba, Carvalho e cerejeira) a de carvalho, submetida à queima da aduela por 2 minutos (c2) foi a que obteve melhor aceitação com valores de 74% para aparência, 76% para o aroma, 58% para o sabor e 64% para a impressão global / This study aimed to produce double-distilled spirits of algaroba (Prosopis juliflora (Sw.) DC.) and store it in barrels made of three different types of wood (algarobeira‟, cherry tree and oak), subjected to three burning levels, during different times, on the inner surface of each cask. Physicochemical characteristics (water, protein, reducing, non-reducing, and total sugars, minerals, carbohydrates contents and as well as the total acidity) of the pod in natura, after pressing, and of the algaroba juice, in the first and second extractions, were determined. A yeast strain of the algaroba juice was selected, isolated and genetically analyzed through the DNA amplification by electrophoresis, using (GTG)5 as a primer. The analyzed yeast was identified as a strain of Saccharomyces cerevisiae. The distillation speed and aeration influence on the physicochemical parameters of algaroba double-distilled spirit were analyzed, using a factorial design 22 with three central points. Casks of „algarobeira‟, cherry tree and oak were used, subjected to one, two and three minutes of burning on the stave inner surface. Values of total sugars, proteins, and minerals of 35.9, 8.46 and 7.8%, respectively, were found in the algaroba pod, evidencing its potential in the production of spirit. An extraction was made from the hydrated pod, obtaining values of total, non-reducing, and reducing sugars of 17,92, 15,36 and 2,56%, respectively. A yeast strain of algaroba juice was selected and characterized as Saccharomyces cerevisiae. The double-distilled spirit made from algaroba is within the physicochemical parameters analyzed and required by the MAPA (Ministry of Agriculture, Livestock, and Food Supply) except for the high congener of alcohols of 584.50 mg.100mL-1 and the sum of the secondary components of 627.29 mg.100mL-1. As for the contaminant ethyl carbamate, levels lower than 50 μg.L-1 and equal to 69,8 μg.L-1 were recorded by analyzing the effect of the distillation speed and aeration, respectively. These values are lower than 150 μg.L-1, which is required by the legislation. The algaroba spirit stored in the oak barrel, of which stave was subjected to burning for 2 minutes (c2), had the best acceptance of appearance (74%), aroma (76%), taste (58%), and overall impression (64%).

In the scope of this study, a interdisciplinarity approach was sought for sustainable practices in the construction of fences and conservation with native species. The objectives of this work were to uncover the preferences of the rural owners of the Paulo Afonso-BA region, as well as the native species used in the construction of their dead fences and qualitatively evaluate the state of conservation of these woods. The interdisciplinary methodology allowed the discovery of the use of 8 species of wood being an exotic, The two species preferred by the rural producers, Braúna, Schinopsis brasiliensis Engl. Native species, and Algaroba, Prosopis julifora (Sw) DC, an exotic species from the Peruvian semi - arid and invasive of the NEB Caatinga. The scarcity of the native species in the fences, however, was verified through the process of replacing the native cuttings by the use of the cuttings of the exotic Algaroba. We evaluated interdisciplinary dendroecological, anatomical and technological aspects (physical and chemical) in the stage of living and dead wood (stakes) in order to validate the state of conservation of dead wood, and adaptive survival strategies and their responses to climatic conditions in Living wood. The results obtained for the anatomical, physical and chemical study of the state of biodegradation of the cuttings, indicated exhaustion of the native species used in the fences. The current stage of conservation of the fences compromises the native species, due to the imminent need for substitution of these stakes, suggesting immediate management of the P. juliflora species. The construction of chronologies of growth rings of these two species allowed to evaluate locally the influence of the climate of the region on its growth in the Caatinga, from the evaluation of different local environmental variables and global climatic events for ENSO and TSA. The chronology of P. juliflora occurred between the period 1975-2015, with an inter-correlation of 0.531 and an average annual rate of increase of 3.71 mm, while the chronology of S. brasiliensis occurred between 1963-2015, with inter- Correlation of 0.560, and mean annual rate of increase of 3.33 mm. P. juliflora showed a correlation with annual precipitation (52%), autumn / winter rainy season (0.57) and thunderstorms (0.35), being inversely correlated with mean temperature (-0.47), Maximum temperature (-0.31) and insolation (-0.43). The growth of S. brasiliensis showed a correlation with annual precipitation (0.71), rainy season autumn / winter (0.64), humidity (0.39) and thunderstorms (0.46), being inversely correlated with temperature Of the air (average: -0.59, maximum: -0.41), insolation (-0.51) and evaporation (-0.35). The conclusions reached were that the P. juliflora species, since its introduction in the mid-1960s, have expanded their living area by favoring them as a function of local climatic conditions and the action of the anthropic degradation processes of the Caatinga through the withdrawal of their Which is leading to scarcity of native species. On the other hand, the low cost of the P. juliflora cuttings, wood technologically resistant to biodegradation has enabled the process of native wood substitution. From the ecological and conservation point of view, mitigating measures of control of this exotic species are necessary. / No escopo deste estudo buscou-se na interdisciplinaridade uma solução para práticas sustentáveis na construção de cercas e conservação com as espécies nativas. Os objetivos deste trabalho foram desvendar as preferências dos proprietários rurais da região de Paulo Afonso-BA, quanto as espécies nativas utilizadas na construção de suas cercas mortas e avaliar qualitativamente o estado de conservação dessas madeiras. A metodologia interdisciplinar permitiu a descoberta de uso de oito espécies de madeiras sendo uma exótica, As duas espécies preferidas pelos produtores rurais foram a Braúna, Schinopsis brasiliensis Engl. espécie nativa, e a Algaroba, Prosopis julifora (Sw) DC, espécie exótica do semiárido Peruano e invasora da Caatinga do NEB. A escassez das espécies nativas nas cercas, no entanto, foi constatada através do processo de substituição das estacas nativas pelo uso das estacas da exótica Algaroba. Avaliou-se interdisciplinarmente os aspectos dendroecológicos, anatômicos e tecnológicos (físicos e químicos) em estágio de madeira viva e morta (estacas) com a finalidade de validar o estado de conservação da madeira morta, e as estratégias adaptativas de sobrevivência e suas respostas às condições climáticas em madeira viva. Os resultados obtidos para o estudo anatômico, físico e químico do estado de biodegradação das estacas, indicaram esgotamento das espécies nativas utilizadas nas cercas. O estagio atual de conservação das cercas compromete as espécies nativas, em função da necessidade iminente de substituição dessas estacas, sugerindo manejo/controle imediato da espécie P. juliflora. A construção de cronologias de anéis de crescimento dessas duas espécies permitiu avaliar localmente a influência do clima da região sobre seu crescimento na Caatinga, a partir da avaliação das diferentes variáveis ambientais locais e eventos climáticos globais para o ENSO e a TSA. A cronologia de P. juliflora se deu entre o período de 1975-2015, com intercorrelação de 0,531 e taxa média de incremento anual de 3,71 mm, enquanto a cronologia de S. brasiliensis ocorreu entre 1963-2015, com intercorrelação de 0,560, e taxa média de incremento anual de 3,33 mm. O crescimento da espécie P. juliflora apresentou correlação com a precipitação anual (52%), estação chuvosa outono/inverno (0,57) e trovoadas (0,35), estando inversamente correlacionada com a temperatura média (-0,47), temperatura máxima (-0,31) e a insolação (-0,43). O crescimento da espécie S. brasiliensis apresentou correlação com a precipitação anual (0,71), estação chuvosa outono/inverno (0,64), umidade (0,39) e trovoadas (0,46), estando inversamente correlacionada com a temperatura do ar (média: - 0,59; máxima: -0,41), insolação (-0,51) e evaporação (-0,35). As conclusões observadas foram que a espécie P. juliflora, desde sua introdução em meados da década de 60, ampliou sua área de vida através do seu favorecimento em função das condições climáticas locais e ação dos processos de degradação antrópica da Caatinga através da retirada de suas madeiras, o que está levando a escassez das espécies nativas. Por outro lado o baixo custo das estacas de P. juliflora, madeira tecnologicamente resistente à biodegradação tem viabilizado o processo de substituição das madeiras nativas. Do ponto de vista ecológico e de conservação, são necessárias medidas mitigadoras de controle dessa espécie exótica.

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La interacción entre especies es un fenómeno ecológico habitual en la naturaleza. En sistemas donde las plantas leñosas forman parte de la comunidad vegetal, como sucede en el sur del Distritito Fitogeográfico del Caldén (Caldenal), su presencia altera el medio ambiente de forma tal que influyen sobre los organismos vegetales bajo su área de influencia. Las relaciones leñosas/gramíneas incluyen efectos positivos (facilitación) y negativos (competencia) que ocurren simultáneamente. Así, el efecto neto de una planta sobre otra estará determinado por el balance de diferentes mecanismos en determinadas condiciones físicas y bióticas. El objetivo general del presente trabajo fue estudiar el efecto de las especies leñosas Prosopis caldenia (caducifolia) y Larrea divaricata (perennifolia) sobre el crecimiento aéreo de las macollas, la producción de biomasa aérea y la calidad forrajera de Piptochaetium napostaense y Nassella clarazii, dos gramíneas perennes forrajeras nativas del Caldenal. Además, se evaluaron las modificaciones de las condiciones microambientales y edáficas debajo y fuera de la canopia de ambas especies leñosas. La altura, la longitud del tallo más vainas, la longitud de láminas verdes y la longitud total verde de las macollas de las plantas de P. napostaense y N. clarazii que crecieron debajo de la canopia de P. caldenia y L. divaricata fueron en general mayores que las registradas en las macollas de aquellas plantas que crecieron en los sitios abiertos entre individuos de esas especies leñosas. Asimismo, las macollas de las plantas de P. napostaense y N. clarazii que crecieron debajo de la canopia de P. caldenia tendieron a mostrar una mayor longitud total verde que las macollas de aquellas plantas que crecieron debajo de la canopia de L. divaricata. La biomasa aérea mostró un comportamiento diferencial entre P. napostaense y N. clarazii en función de la especie leñosa considerada. La presencia de L. divaricata habría favorecido la producción de biomasa aérea de P. napostaense; mientras que, la presencia de P. caldenia habría favorecido la producción de biomasa aérea de N. clarazii. El contenido de proteína bruta, al final del período de crecimiento vegetativo, en las plantas de P. napostaense que crecieron debajo de la canopia de ambas especies leñosas estudiadas fue menor que el de aquellas plantas que crecieron en los sitios abiertos. Sin embargo, el contenido de proteína bruta de las plantas de N. clarazii que crecieron debajo de la canopia de P. caldenia fue mayor que el de aquellas plantas que crecieron debajo de la canopia de L. divaricata. Al final del período de crecimiento vegetativo, el mayor porcentaje de fibra detergente neutra y ácida en las gramíneas estudiadas se registró en las plantas que crecieron debajo de la canopia de L. divaricata. Al final del período de crecimiento reproductivo, el porcentaje de fibra detergente neutra en las plantas de N. clarazii que crecieron debajo de las canopias de P. caldenia fue mayor que el de las plantas que crecieron debajo de la canopia de L. divaricata. El porcentaje de lignina detergente ácida de la plantas de P. napostaense y N. clarazii, al final de ambos períodos de crecimiento, que crecieron debajo de la canopia de P. caldenia y en los sitios abiertos entre individuos de esta leñosas fue mayor que el de aquellas plantas que crecieron debajo de la canopia de L. divaricata y en los sitios abiertos entre individuos de la misma. En ambos períodos de crecimiento evaluados, la menor digestibilidad in vitro de P. napostaense y N. clarazii se registró en las plantas que crecieron debajo de la canopia de P. caldenia y en los sitios abiertos de esta leñosa. En general, los resultados obtenidos en este estudio sugerirían que P. caldenia y L. divaricata al mejorar en su área de influencia el contenido de nitrógeno, materia orgánica y densidad aparente del suelo tendrían un cierto nivel de facilitación sobre P. napostaense y N. clarazii; sin embargo, esta mejora no favoreció significativamente el crecimiento aéreo de sus macollas, la producción de biomasa aérea y/o algunos parámetros asociados con su calidad forrajera. En conjunto los resultados obtenidos, bajo las condiciones en que se desarrolló el presente estudio, sugieren que P. caldenia y L. divaricata tienen un efecto neutro o negativo sobre el crecimiento, la producción de biomasa aérea y la calidad de P. napostaense y N. clarazii en los pastizales naturales semiáridos del sur del Caldenal / The interaction between woody and grass species is a common feature of semi-arid rangelands, as is southern Caldenal in central Argentina. Woody species can exert positive and/or negative influence on the growth of neighbouring grass species through imposing changes in the abiotic conditions in which the latter species grow, leading to a balance in which either facilitative or competitive interactions prevail. The objective of this work was to assess the impact of woody species on grass growth over a 2-y period. The study comprised two morpho-physiologically different woody species and two cool-season perennial grass species highly preferred by domestic livestock. The species chosen for the study were Prosopis caldenia and Larrea divaricata, a warm-season deciduous and an evergreen woody species, respectively; and Nassella clarazii and Piptochaetium napostaense as representatives of perennial grasses highly preferred by livestock. The study involved the assessment of tiller growth parameters, biomass production and forage quality in grasses growing beneath the canopy of woody species and in open rangeland areas. Tiller growth was evaluated through measurements of height, pseudostem length, green blade length and total green length as the sum the latter two parameters. In addition, soil temperature, pH and water, nitrogen, phosphorus and organic matter content were estimated at the same study sites. Tiller growth parameters of grasses growing beneath the canopy of woody species were generally higher than those of grasses growing in open areas. Also, total green legth of grass tillers tended to be higher when growing beneath the canopy of P. caldenia than L. divaricata. Biomass production differed between grasses and woody species under consideration for L. divaricata might have favoured biomass production of P. napostaense while P. caldenia might have favoured that of N. clarazii. At the end of vegetative growth period, crude protein content of P. napostaense was lower beneath the canopy of woody species than in open areas. Whereas, crude protein content of N. clarazii was higher beneath the canopy of P. caldenia than L. divaricata. Fiber content, both acid and neutral detergent, at the end of vegetative growth period was highest in grasses growing beneath the canopy of L. divaricata. At the end of reproductive growth period, neutral detergent fiber content in N. clarazii was higher beneath the canopy of P. caldenia than L. divaricata. Acid detergent fiber content at the end of both growth periods was higher beneath the canopy of P. caldenia and in open areas between individuals of this species than beneath the canopy and open areas between individuals of L. divaricata for both grass species. The lowest records of in vitro digestibility were registered beneath the canopy and open areas between individuals of P. caldenia for both grass species and for both growth periods. In general, the results obtained in this study suggest that P. caldenia and L. divaricata, when improving in their area of influence the nitrogen content, organic matter and apparent density of the soil will have a certain level of facilitation on P. napostaense and N. clarazii. However, this improvement did not favor substantially the aerial growth of their tillers, the production of aerial biomass and / or some parameters associated with their forage quality. The results obtained, under the conditions under which the present study was carried out, suggest that P. caldenia and L. divaricata have a neutral or negative effect on growth, aerial biomass production and quality of P. napostaense and N. clarazii in the semi-arid natural grasslands of southern Caldenal.