Submitted by (lucia.rodrigues@ufrpe.br) on 2017-03-16T12:53:24Z No. of bitstreams: 1 Eddy Enrique Barraza Andrion (1).pdf: 947495 bytes, checksum: aa5e0f6002d19bd71d54a71eae9dc237 (MD5) / Made available in DSpace on 2017-03-16T12:53:24Z (GMT). No. of bitstreams: 1 Eddy Enrique Barraza Andrion (1).pdf: 947495 bytes, checksum: aa5e0f6002d19bd71d54a71eae9dc237 (MD5) Previous issue date: 2009-07-31 / The cowpea (Vigna unguiculata L.) is one of the main crops in the Northeast of Brazil especially for the small farmers. The Fusarium wilt and Rhizoctonia canker caused by Fusarium oxysporum f.sp. tracheiphilum and Rhizoctonia solani, respectively are the cowpea diseases showing more frequency and intensity in the Northeast of Brazil. This work aimed to evaluate the natural suppressiveness of 66 soils of this region to the Fusarium wilt and Rhizoctonia canker, and to analyze the physical, chemical and biological characteristics of this soils associated with disease suppressiveness or conducivity. The evaluated soils were grouped from highly suppressive to highly conducive in relation to Fusarium wilt and Rhizoctonia canker severities. The main variables involved in Fusarium wilt suppressiveness were high levels of phosphorus and potassium, basal respiration (CO2 evolution) and indexes of microbial diversity and equitability. For Rhizoctonia canker important correlations were determined with levels of phosphorus, potassium and sodium, basal respiration and enzymatic activity of fluorescein diacetate. There was no correlation between physical factors and suppressiveness to Fusarium wilt, but it was possible to correlate the levels of sand, clay and silt with suppressiveness and/or conducivity of Rhizoctonia canker. Three soils previously classified as highly supressive to Rhizoctonia canker were evaluated in relation to eight strains and three inoculum densities of R. solani. There was significant difference among soils and strains in relation to levels of disease severity. In the three soils the severity levels induced by the strain CMM-1053 were similar to those observed in former studies. Most of the strains showed different behavior in relation to soils, except for CMM-1064 and CMM-1066. There was significant difference among disease severity levels and different inoculum densities. The three soils presented good stability in relation to the different R. solani strains, but the inoculum density may be a limiting factor in the implementation of the natural soil suppressiveness or the supressivity induction in conducive soils. / O caupi (Vigna unguiculata L.) é uma das culturas mais importantes da região Nordeste do Brasil, principalmente na economia de pequenos produtores rurais. A murcha-de-fusário e a rizoctoniose, causadas pelos fungos Fusarium oxysporum f.sp. tracheiphilum e Rhizoctonia solani, respectivamente, são as doenças mais freqüentes e de maior intensidade em caupi no Nordeste brasileiro. Esta tese teve como objetivos avaliar a supressividade natural de 66 solos do Nordeste brasileiro à murcha-de-fusário e rizotoniose do caupi, analisar as características físicas, químicas e biológicas dos solos associadas com a supressividade ou conducividade às doenças, bem como avaliar a estabilidade da supressividade de três solos à rizoctonose do caupi, considerando diferentes isolados e densidades de inóculo de R. solani. Em relação à severidade da murcha-de-fusário e da rizoctoniose do caupi, os solos avaliados foram agrupados desde fortemente supressivos a altamente conducivos. As principais variáveis envolvidas na supressividade da murcha-de-fusário foram elevados teores de fósforo e potássio, respiração basal (CO2 evoluído) e os índices de diversidade e eqüitabilidade microbiana. Para a rizoctoniose, foram determinadas correlações importantes com os níveis de fósforo, potássio e sódio, respiração basal e atividade enzimática de diacetato de fluoresceína. Não foram correlacionados fatores físicos com a supressividade à murcha-de-fusário, porém foi possível correlacionar os teores de areia, argila e silte com asupressividade e/ou conducividade da rizoctoniose. Três solos classificados como fortemente supressivos à rizoctoniose foram avaliados em relação a oito isolados e três densidades de inoculo de R. solani. Houve diferença significativa entre os solos e os isolados quanto aos níveis de severidade da doença. Nos três solos os níveis de severidade induzidos pelo isolado CMM-1053 foram similares aos verificados nos estudos prévios. A maioria dos isolados apresentou comportamentos diferente em função dos solos, com exceção dos isolados CMM-1064 e CMM-1066. Foi verificada diferença significativa entre os níveis de severidade da doença e as diferentes densidades de inoculo. Os três solos evidenciaram estabilidade em relação aos diferentes isolados de R. solani, porém a densidade de inóculo pode ser um fator limitante na implementação da supressividade natural dos solos ou da indução da supressividade em solos conducivos.

Copy of author's previously published work inserted. Bibliography: leaves 261-306. The objectives of the project were: i. to determine whether there are competitive interactions between Aporrectodea trapezoides and A. caliginosa and A. rosea.--ii. to investigate compeditive interactions between A. calignosa, Microscolex dubius and A. trapezoides.--iii . to determine the likely impact of A. longa on soil fauna, especially the native earthworm, Gemascolex lateralis, in native ecosystems.

In arid and semi-arid deserts, soils are commonly covered with biological soil crusts. The study of arid biocrusts and their ecological function has become increasingly common in the literature over the last several decades. Interestingly, no mention is made of biological soil crusts in forested ecosystems, raising the question as to whether they exist in these areas and if they do, why they have yet to be recognized as such? Through the use a parallel logic, this study finds that biocrusts do indeed exist in forests, a novel relationship in forest ecology and seeks to determine if there exist ecophysical explanations for the abundance and distribution throughout the forest landscape. This study examined the effects of climate variables and substrate types on the abundance, distribution and overall cover of forest soil biocrust at fifty-two sites in southern Oregon, U.S.A. Sites were randomly selected within established buffer zones in the Siuslaw, Rogue-Sisikyou, Umpqua, and Fremont-Winema National Forests. The methods of Belnap et al 2001 were tested and then modified for application in forested ecosystems. Data were collected on the relative abundance and distribution of biocrust morphological groups across available substrates, community biocrust morphology, aspect, elevation and soil texture, pH and organic matter content. Site-specific data on average annual precipitation and minimum/maximum temperatures was collected using the PRISM Climate Model. This study found substrate colonization by specific morphological groups mixed across the study; though dominant communities were observed for each substrate present, substrate availability appears to be confounded by a number of variables (climate, stand age and structure and litter layer) not controlled for in this study. Biocrust community morphologies varied across sites, primarily influenced by the surface texture of the substrate and morphology of the individual. Relatively smooth surfaces (rock, bare soil) often resulted in smooth biocrust morphologies, whereas rough surfaces (dead wood, bare soil) tended to result in a rolling morphology. Litter layer directly influenced the relative proportion of substrates colonized, notably affecting dead wood and mineral soil biocrusts. Total biocrust cover increased as precipitation increased as did biocrust preference for dead wood substrates while mineral soil remained unchanged and rock surfaces were negatively represented. Aspect generally followed the anticipated distribution of total biocrust cover with the highest cover on N and NW aspects and lowest on the W aspect. Increases in elevation were negatively related to overall biocrust cover. Soil texture was not found to be directly related to overall biocrust cover, attributed in part to the highly adaptive nature of the biocrust community. Soil organic matter (SOM) influenced total biocrust cover with positive correlations between total cover and increasing SOM content. Soil pH increased as expected across the precipitation range (17 to 159 in/yr) of the transect. Total biocrust cover was found to trend with soil pH, but is believed to be attributed to the parallel relationship between precipitation and pH, rather than pH alone given the relative moderate pH range (4.39 to 6.54) of the study. The distribution and abundance of forest soil biocrusts is strongly influenced by precipitation. The confounding influence of precipitation to litter layer depth and organic matter content (through gradients of vegetative productivity) and soil pH further are concluded to influence substrate preference by morphological groups. Across the variables examined, similarities between the two communities (arid and forest) in response to climate and soil chemistry show parallel relations, justifying the formal establishment of biological soil crust community in forested regions. The differences between communities related to the presence of trees validate the establishment of forest soil biocrusts as distinct community in both form and ecological function with the forests. / Graduation date: 2013

Kurzumtriebsplantagen (KUP) besitzen das Potenzial, beträchtliche Mengen Biomasse für die Versorgung mit erneuerbaren Energien und nachwachsenden Rohstoffen bereitzustellen. Es ist bekannt, dass KUP auf landwirtschaftlichen Flächen mehr Ökosystemdienstleistungen hervorbringen können als üblicherweise angebaute einjährige Ackerfrüchte oder Energiepflanzen wie Raps und Mais. Trotzdem gibt es nur wenige Informationen über den Wasserverbrauch und die Transpiration von Pappelarten und ihren Hybriden unter den spezifischen Standortsbedingungen in Deutschland. Darüber hinaus bestehen Wissenslücken für die Abschätzung langfristiger Auswirkungen von KUP auf bodenökologische Aspekte. Um diese Defizite zu minimieren wurden auf einem Standort im mittelsächsischen Löss-Hügelland Felduntersuchungen durchgeführt. Für die Untersuchung der Effekte von KUP auf die Bodenwasserbilanz wurden Saftfluss- und Bodenfeuchte-Messungen in einer 10jährigen Hybrid-Pappelplantage durchgeführt. Darüber hinaus wurden Biomasseakkumulation, Nährelementverteilung und bodenökologische Parameter erforscht. Die Daten wurden genutzt, um ein prozess-orientiertes Wasserhaushaltsmodell zu parametrisieren und zu kalibrieren. Das validierte Modell wurde danach für die Untersuchung und Bewertung des Einflusses von Pappel-KUP und Winterweizen auf die Wasserbilanz verschiedener sächsischer Standorte genutzt. Schließlich wurden die standortsspezifischen Biomasseerträge von KUP hergeleitet. Diese Informationen wurden mithilfe eines Geografischen Informationssystems (GIS) mit den Flächen verschnitten, auf denen der Anbau von KUP zu Synergien bzw. potenzielle Risiken für den Bodenschutz sowie den Natur- und Landschaftsschutz führen kann. Die Ergebnisse zeigen, dass Hybrid-Pappelplantagen deutlich mehr Wasser als Ackerkulturen und einheimische Forstbaumarten verbrauchen. Es kann daraus abgeleitet werden, dass die Anlage von KUP auf Ackerflächen den wassergebundenen Nährstoffaustrag sowie den Austrag von Schadstoffen reduziert. Auch das Erosionsrisiko würde verringert. Andererseits kann eine im vergleich zum Einzugsgebiet großflächige Anlage von KUP in Regionen mit negativer klimatischer Wasserbilanz zu einer geringeren Grundwasserneubildung führen. Eine ausreichende Wasserversorgung ist unverzichtbar, um die Wuchspotenziale von Pappel-Hochleistungssorten voll auszuschöpfen. Pappel-KUP können weitgehend ohne zusätzliche Düngung bewirtschaftet werden. Ehemals intensiv genutzte Ackerböden enthalten ausreichend Nährstoffe und Elemententzüge über die geerntete Biomasse werden durch atmosphärische Depositionen ausgeglichen. Auf lange Sicht kann der KUP-Anbau jedoch zu einer Verringerung des pH-Wertes und der Kationen-Austauschkapazität im Boden führen. Für die Vermeidung negativer Folgen für die Bodenfruchtbarkeit und das Pflanzenwachstum wären dann angepasste Konzepte für die Kalkung und Düngung notwendig. Die GIS-basierte Analyse unterstreicht, dass in Sachsen beträchtliche Flächenpotenziale für die Anlage von KUP existieren. Auf einem großen Teil würde die Anlage von KUP auch andere Ökosystemdienstleistungen aus dem Bereich Boden- und Naturschutz verbessern. Auch künftig sollte bei der Anlage von KUP-Flächen eine ökologische Begleitforschung erfolgen. Es besteht unter anderem der Bedarf, die ökologischen Aspekte von anderen schnell wachsenden Baumarten im Kurzumtrieb, zum Beispiel Robinie zu bewerten. Ein weiteres ziel könnte die Verbesserung von Anlage- und Rückumwandlungstechnologien sein, um die Stabilität von akkumulierter organischer Bodensubstanz zu erhalten. Es wird geschlussfolgert, dass die künftige praktische Bedeutung von KUP eher von den sozioökonomischen Rahmenbedingungen und der regionalen Umsetzung der gemeinsamen Agrarpolitik der Europäischen Union abhängen wird als von unzureichenden Standortsbedingungen. / Short rotation plantations and short rotation coppice (SRC) have the potential to contribute significant amounts of biomass to the sectors of green energy and of renewable raw materials. It is generally accepted that SRC may provide more ecosystem services on agricultural land than common annual arable or even energy crops like oil seed rape or maize do. However, only sparse information exists about the water demand and transpiration of poplar species and their hybrids for site conditions in Germany. Furthermore, there is a lack of knowledge about the long-term impact of short rotation plantations on soil ecology. To overcome these shortcomings, field investigations were conducted at a site in the hilly loess region of Saxony. To study effects of SRC on the soil water balance, sap flow and soil moisture measurements were conducted in a 10 years old hybrid poplar plantation. Moreover biomass accumulation, nutrient allocation and soil ecological parameters were determined. The data were used to parameterize and calibrate a process-oriented hydrological model. The validated model was subsequently used to determine and assess the impact of short rotation poplar plantations and winter wheat on the water balance of different sites in Saxony Finally, site specific yields of SRC were determined and areas with synergies and potential risks for soil protection, nature conservation at the regional scale were identified using Geographical Information Systems. The results show that hybrid poplar plantations consume significantly more water than arable crops and native tree species. Thus, it can be expected that the establishment of short rotation coppice may reduce the export of nutrients and pollutants or lower the risk of soil erosion. On the other hand, the large-scale establishment of short rotation coppice at catchments with negative climatic water balance may lead to a decrease of groundwater recharge. A sufficient water supply is indispensable in order fully to exploit the growth potential of high yielding polar clones. Short rotation plantations with poplar on arable land may be extensively managed without fertilization. Former intensively used agricultural soils provide sufficient nutrients and element exports by harvested biomass may be balanced by atmospherical deposition. However, it might be that in the long run cation exchange capacity and pH of the soils will decrease. This would require appropriated concepts for liming and fertilization. The GIS based analysis shows that there exist a substantial potential of arable land for the cultivation of SRC in Saxony. There, the establishment of SRC may improve other ecosystem services as soil protection and nature conservation too. Future research should be included into the ecological evaluation of new SRC plots. There is a need to asses ecological aspects of other fast growing tree species in SRC, in particular Black Locust. Another task could be the improvement of conversion practices to ensure the stability of accumulated soil organic matter during establishment and reconversion of SRC sites. It can be concluded that the future practical relevance of SRC is rather dependant on socio-economic framework conditions and the regional implementation of the common agricultural policy within the European Union than on insufficient site condition.

Copy of author's previously published work inserted. / Bibliography: leaves 261-306. / xxix, 308 leaves : ill. (some col.), maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The objectives of the project were: i. to determine whether there are competitive interactions between Aporrectodea trapezoides and A. caliginosa and A. rosea.--ii. to investigate compeditive interactions between A. calignosa, Microscolex dubius and A. trapezoides.--iii . to determine the likely impact of A. longa on soil fauna, especially the native earthworm, Gemascolex lateralis, in native ecosystems. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1996

La gestion des nématodes phytoparasites (NPP) est un enjeu capital pour de nombreux opérateurs agricoles. Au Maroc, le développement d’une agriculture intensive dans le cadre du « Plan Maroc Vert » va nécessairement induire l’émergence de pathologies végétales, dont des nématoses. Dans le cas de l’olivier, ils mettent en péril la production en pépinière et dans les vergers à haute-densité. D’autre part, les pépinières sont une source majeure d’introduction des NPP en vergers, par transplantation de plants enracinés.C’est la raison pour laquelle une étude de la diversité des communautés de NPP a été conduite dans 25 pépinières localisées dans les régions les plus productrices au Maroc (Souss, Haouz, Guérouane, Jbala). Un total de 305 échantillons de sol ont été analysés. Les NPP détectés appartiennent aux familles des Hoplolaimidae (Helicotylenchus spp., Rotylenchus spp.), des Telotylenchidae (Tylenchorhynchus spp.), des Meloidogynidae (Meloidogyne spp.) et des Tylenchidae (Trichotylenchus spp.), etc. Bien qu’aucun symptôme n’ait été observé sur les racines, l’abondance moyenne de ces genres était très élevée (jusqu'à 56.640 individus/dm3 de sol). Une étude biochimique (PAGE) et moléculaire (SCARS) a également porté sur la diversité des nématodes à galles du genre Meloidogyne, principaux ravageurs de l’olivier. Elle a indiqué une dominance de M. javanica (72%) sur M. incognita (25.5%), tandis que M. arenaria n’a été détectée que dans une seule pépinière. Cette étude montre la nécessité absolue pour les pépiniéristes de proposer une garantie sanitaire des plants à travers une traçabilité des substrats.Afin de contrôler le développement des NPP en pépinière, puis en vergers après transplantation, la lutte microbiologique à l’aide de champignons nématophages (CNP) s’avère une alternative adaptée aux pépinières (inoculation aux substrats). Ainsi, 70 souches de champignons telluriques ont été isolées, dont une grande diversité d’Orbiliaceae possédant des organes de capture (Arthrobotrys spp., Dreschlerella spp., Monacrosporium spp.) et d’Hypocreaceae toxiques (Trichoderma asperellum , T. harzianum, T. longibrachiatum, Talaromyces assiutensis). Des espèces oviparasites telles que Paecilomyces lilacinus (dominante) et Pochonia chlamydosporia étaient également présentes. Plusieurs espèces endoparasites ont aussi été observées telles que Catenaria anguilullae, Nematoctunus leiosporus et Haptoglossa heterospora. Les tests de prédation in vitro ont révélé que T. assiutensis est capable de parasiter 100% des juvéniles de M. javanica. Les souches d’Orbiliaceae induisent une mortalité de 50 à 80% des juvéniles. Des analyses multivariées (ACP, co-inertie, K-tableaux) ont permis d’identifier l’impact majeur des variables climatiques (pluviométrie et température minimale) et de l’origine des substrats de culture (habitats écologiques) sur la diversité des communautés de NPP et de CNP. Les amendements minéraux (NPK), la matière organique, l’acidité et la texture argileuse des substrats ont un impact non négligeable. Les variétés multipliées n’ont aucun effet. L’analyse des co-structures entre les communautés de NPP et de CNP a indiqué une corrélation entre les Orbiliaceae et Meloidogyne spp., ce qui confirme l’intérêt de ces CNP comme agents de lutte biologique pour la gestion de ces NPP.L’étude de la physiologie de croissance et de sporulation des souches a révélé que les souches de Trichoderma spp. ont les fitness les plus élevées alors que les Orbiliaceae ont une croissance et une sporulation faible. Les études diligentées dans le cadre de cette thèse (i) confirment que la diversité des communautés de NPP sont des indicateurs pertinents pour évaluer la santé des substrats dans les pépinières oléicoles à des fins de certification des oliviers, et (ii) ouvrent des perspectives de développement de stratégies de gestion microbiologique de ces parasites respectueuse de l’environnement. / The management of plant parasitic nematodes (PPN) is a major challenge for many agricultural operators. In Morocco, the development of an intensive agriculture in the " Morocco Green Plan" will necessarily induce the emergence of plant diseases, including nematodes. On olive tree, they imperil production in nurseries and in high-density orchards. On the other hand, nurseries are a major source of introduction of PPN in orchards by transplanting rooted plants. In this context, the study of the diversity of PPN communities was conducted in 25 olive nurseries located in the main olive producing areas in Morocco (Souss, Haouz, Guerouane, Jbala). A total of 305 soil samples were analyzed. The NPP detected belonged to the Hoplolaimidae (Helicotylenchus spp., Rotylenchus spp.), Telotylenchidae (Tylenchorhynchus spp.), Meloidogynidae (Meloidogyne spp.) and Tylenchidae (Trichotylenchus spp.) families. Although no symptom have been observed on roots, the mean abundance of these genera was very high (up to 56,640 individuals/dm3 of soil). Biochemical (PAGE) and molecular (SCARS) diagnosis was focused on root knot nematodes (Meloidogyne spp.), that are major pests of olive trees. It indicated a dominance of M. javanica (72%) on M. incognita (25.5%), while M. arenaria was detected in one nursery only. This study shows the necessity for nurse producers to provide a health guarantee seedlings through traceability of substrates.To control the development of PPN in nurseries and orchards after transplantation, microbiological control using nematophagous fungi (NF) proves a suitable alternative to nurseries (inoculation to substrates). Thus, 70 soil fungal strains were isolated, including a large diversity of Orbiliaceae with trapping organs (Arthrobotrys spp., Dreschlerella spp., Monacrosporium spp.) and of toxic Hypocreaceae (Trichoderma asperellum, T . harzianum, T. longibrachiatum, Talaromyces assiutensis). Egg-parasitic species such as Paecilomyces lilacinus (dominant) and Pochonia chlamydosporia were also present. Several endoparasitic species were also observed as Catenaria anguilullae, Nematoctunus leiosporus and Haptoglossa heterospora. In vitro predation tests revealed that T. assiutensis was able to kill 100% of the M. javanica juveniles. The Orbiliaceae strains killed 50 to 80% of the juveniles. Multivariate statistical analyses (PCA, co-inertia, K-tables) pointed out the main impact of climate variables (rainfall and minimum temperatures) and of the substrate origins (ecological habitats) on the diversity of both PPN and NF communities. Mineral amendments (NPK), organic matter, acidity (pH) and clayey substrates have less significant impacts. The varieties multiplied had no effect.Co-structure analyses between PPN and NF communities indicated significant correlations between Orbiliaceae and Meloidogyne spp., which confirms the interest of NF as biocontrol agents for the management of PPN.The experimental monitoring of growth and sporulation physiology of the NF strains exhibited high fitness for the Trichoderma species while the Orbiliaceae have low growth and sporulation.The studies commissioned as part of this thesis (i) confirm that the diversity of PPN communities may be relevant indicators to assess the health of substrates in olive nurseries for certification purposes, and (ii) offer future prospects for the development of microbiological management strategies of these parasites respectful of the environment.

Thesis (M. Sc. Agriculture (Soil Science)) -- University of Limpopo, 2021 / Globally and in most parts of South Africa, there is a trend of increasing shrub encroachment in savanna rangelands. A number of studies have investigated the impact of shrub encroachment on soil organic carbon content (SOC) and soil organic carbon stocks (SOCs) in savannas. So far there is no clear consensus on whether shrub encroachment increases or decreases the level of SOC and SOCs, especially in semi arid savanna grasslands. Furthermore, knowledge on the effects of shrub encroachment on SOCs is largely restricted to the topsoil, as this is the part of the profile influenced by inputs and losses of soil organic matter. How shrub encroachment affects the vertical distribution of SOCs is rarely considered in the existing literature and the edaphic factors controlling SOCs with depth are poorly understood. The objectives of this study were (i) to quantify the vertical distribution of SOC and SOCs and (ii) to identify the edaphic factors controlling the vertical distribution of SOC and SOCs in a shrub-encroached savanna grassland sited on shallow plinthic soil. To achieve the objectives, a vegetation and soil survey of the savanna grassland was conducted whereby sampling areas were demarcated and characterized into open and shrub encroached grassland plots. In each encroachment level, three pits were randomly dug to the limiting layer on plots sited on the same soil type and similar topographic position. Soil samples were collected from the pits at depth intervals of 0-10, 10-20, 20-30, 30-40, 40-50, 50-60 and 60-70 cm. The collected soil samples were analyzed for chemical and physical properties in the laboratory. Correlation analysis was carried out to determine the relationship between SOC and SOCs, which were the variables of interest in this study and related controlling soil physicochemical properties. The results showed that SOC was significantly greater (P<0.05) in the shrub-encroached grassland compared to open grassland. Furthermore, the results revealed that SOC was on average 19 and 13% greater in the topsoil (0-20 cm) and subsoil (20-70 cm) of shrub encroached grassland compared to open grassland. The greater SOC in the topsoil of the shrub-encroached grassland was mainly attributed to higher SOC inputs from plant litter and detritus derived from trees and grasses, which are the dominant plant life forms in savannas. In the topsoil, SOC and SOCs were positively correlated with extractable phosphorus (P) (r = 0.60; P < 0.05), while in the subsoil they were positively correlated ix with extractable phosphorus (r = 0.54), soil porosity (r = 0.52), extractable copper (r = 0.46), extractable zinc (r = 0.41), exchangeable calcium (r = 0.37) and negatively correlated with mean weight diameter (r = -0.43). Overall, SOC and SOCs under both shrub-encroached and open grasslands vertically decreased with soil depth. The results obtained highlighted that the factors controlling the level of SOC and SOCs differs in the topsoil and subsoil of the studied shrub encroached grassland. These findings suggest that in the shallow plinthic soil investigated in this study, SOC in the topsoil is controlled by the macronutrient P, while in the subsoil it is physically protected by soil aggregates and chemically stabilized via complexation interactions with exchangeable cations and heavy metals. In-depth understanding of the physico-chemical factors controlling SOC storage is critical to foster management practices that will improve the cycling of SOC in shrub-encroached savanna grasslands.

Kurzumtriebsplantagen (KUP) besitzen das Potenzial, beträchtliche Mengen Biomasse für die Versorgung mit erneuerbaren Energien und nachwachsenden Rohstoffen bereitzustellen. Es ist bekannt, dass KUP auf landwirtschaftlichen Flächen mehr Ökosystemdienstleistungen hervorbringen können als üblicherweise angebaute einjährige Ackerfrüchte oder Energiepflanzen wie Raps und Mais. Trotzdem gibt es nur wenige Informationen über den Wasserverbrauch und die Transpiration von Pappelarten und ihren Hybriden unter den spezifischen Standortsbedingungen in Deutschland. Darüber hinaus bestehen Wissenslücken für die Abschätzung langfristiger Auswirkungen von KUP auf bodenökologische Aspekte. Um diese Defizite zu minimieren wurden auf einem Standort im mittelsächsischen Löss-Hügelland Felduntersuchungen durchgeführt. Für die Untersuchung der Effekte von KUP auf die Bodenwasserbilanz wurden Saftfluss- und Bodenfeuchte-Messungen in einer 10jährigen Hybrid-Pappelplantage durchgeführt. Darüber hinaus wurden Biomasseakkumulation, Nährelementverteilung und bodenökologische Parameter erforscht. Die Daten wurden genutzt, um ein prozess-orientiertes Wasserhaushaltsmodell zu parametrisieren und zu kalibrieren. Das validierte Modell wurde danach für die Untersuchung und Bewertung des Einflusses von Pappel-KUP und Winterweizen auf die Wasserbilanz verschiedener sächsischer Standorte genutzt. Schließlich wurden die standortsspezifischen Biomasseerträge von KUP hergeleitet. Diese Informationen wurden mithilfe eines Geografischen Informationssystems (GIS) mit den Flächen verschnitten, auf denen der Anbau von KUP zu Synergien bzw. potenzielle Risiken für den Bodenschutz sowie den Natur- und Landschaftsschutz führen kann. Die Ergebnisse zeigen, dass Hybrid-Pappelplantagen deutlich mehr Wasser als Ackerkulturen und einheimische Forstbaumarten verbrauchen. Es kann daraus abgeleitet werden, dass die Anlage von KUP auf Ackerflächen den wassergebundenen Nährstoffaustrag sowie den Austrag von Schadstoffen reduziert. Auch das Erosionsrisiko würde verringert. Andererseits kann eine im vergleich zum Einzugsgebiet großflächige Anlage von KUP in Regionen mit negativer klimatischer Wasserbilanz zu einer geringeren Grundwasserneubildung führen. Eine ausreichende Wasserversorgung ist unverzichtbar, um die Wuchspotenziale von Pappel-Hochleistungssorten voll auszuschöpfen. Pappel-KUP können weitgehend ohne zusätzliche Düngung bewirtschaftet werden. Ehemals intensiv genutzte Ackerböden enthalten ausreichend Nährstoffe und Elemententzüge über die geerntete Biomasse werden durch atmosphärische Depositionen ausgeglichen. Auf lange Sicht kann der KUP-Anbau jedoch zu einer Verringerung des pH-Wertes und der Kationen-Austauschkapazität im Boden führen. Für die Vermeidung negativer Folgen für die Bodenfruchtbarkeit und das Pflanzenwachstum wären dann angepasste Konzepte für die Kalkung und Düngung notwendig. Die GIS-basierte Analyse unterstreicht, dass in Sachsen beträchtliche Flächenpotenziale für die Anlage von KUP existieren. Auf einem großen Teil würde die Anlage von KUP auch andere Ökosystemdienstleistungen aus dem Bereich Boden- und Naturschutz verbessern. Auch künftig sollte bei der Anlage von KUP-Flächen eine ökologische Begleitforschung erfolgen. Es besteht unter anderem der Bedarf, die ökologischen Aspekte von anderen schnell wachsenden Baumarten im Kurzumtrieb, zum Beispiel Robinie zu bewerten. Ein weiteres ziel könnte die Verbesserung von Anlage- und Rückumwandlungstechnologien sein, um die Stabilität von akkumulierter organischer Bodensubstanz zu erhalten. Es wird geschlussfolgert, dass die künftige praktische Bedeutung von KUP eher von den sozioökonomischen Rahmenbedingungen und der regionalen Umsetzung der gemeinsamen Agrarpolitik der Europäischen Union abhängen wird als von unzureichenden Standortsbedingungen. / Short rotation plantations and short rotation coppice (SRC) have the potential to contribute significant amounts of biomass to the sectors of green energy and of renewable raw materials. It is generally accepted that SRC may provide more ecosystem services on agricultural land than common annual arable or even energy crops like oil seed rape or maize do. However, only sparse information exists about the water demand and transpiration of poplar species and their hybrids for site conditions in Germany. Furthermore, there is a lack of knowledge about the long-term impact of short rotation plantations on soil ecology. To overcome these shortcomings, field investigations were conducted at a site in the hilly loess region of Saxony. To study effects of SRC on the soil water balance, sap flow and soil moisture measurements were conducted in a 10 years old hybrid poplar plantation. Moreover biomass accumulation, nutrient allocation and soil ecological parameters were determined. The data were used to parameterize and calibrate a process-oriented hydrological model. The validated model was subsequently used to determine and assess the impact of short rotation poplar plantations and winter wheat on the water balance of different sites in Saxony Finally, site specific yields of SRC were determined and areas with synergies and potential risks for soil protection, nature conservation at the regional scale were identified using Geographical Information Systems. The results show that hybrid poplar plantations consume significantly more water than arable crops and native tree species. Thus, it can be expected that the establishment of short rotation coppice may reduce the export of nutrients and pollutants or lower the risk of soil erosion. On the other hand, the large-scale establishment of short rotation coppice at catchments with negative climatic water balance may lead to a decrease of groundwater recharge. A sufficient water supply is indispensable in order fully to exploit the growth potential of high yielding polar clones. Short rotation plantations with poplar on arable land may be extensively managed without fertilization. Former intensively used agricultural soils provide sufficient nutrients and element exports by harvested biomass may be balanced by atmospherical deposition. However, it might be that in the long run cation exchange capacity and pH of the soils will decrease. This would require appropriated concepts for liming and fertilization. The GIS based analysis shows that there exist a substantial potential of arable land for the cultivation of SRC in Saxony. There, the establishment of SRC may improve other ecosystem services as soil protection and nature conservation too. Future research should be included into the ecological evaluation of new SRC plots. There is a need to asses ecological aspects of other fast growing tree species in SRC, in particular Black Locust. Another task could be the improvement of conversion practices to ensure the stability of accumulated soil organic matter during establishment and reconversion of SRC sites. It can be concluded that the future practical relevance of SRC is rather dependant on socio-economic framework conditions and the regional implementation of the common agricultural policy within the European Union than on insufficient site condition.

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O estudo de indicadores biológicos da qualidade do solo em áreas com araucária é muito importante para entender os processos ecológicos que ocorrem nestes sistemas, já que a fauna edáfica atua na decomposição e mineralização da matéria orgânica e, também, nas propriedades e processos físicos, químicos e biológicos do solo. O objetivo deste estudo foi verificar a possibilidade de utilizar alguns grupos da fauna edáfica e das variáveis ambientais como indicadores da qualidade do solo em áreas com araucária natural e reflorestada, impactadas ou não pela queima acidental, por meio de técnicas de análise multivariada. As áreas estudadas incluem: 1. floresta nativa com araucária (NF); 2. reflorestamento de araucária (R); 3. reflorestamento de araucária submetido a incêndio acidental (RF); e 4. pastagem natural com araucárias nativas e ocorrência de incêndio (NPF). Em cada área, amostras de solo para avaliação da comunidade da fauna edáfica e das variáveis ambientais foram coletadas em 0,3 ha, perto de dez árvores de araucária selecionadas ao acaso, em três épocas contrastantes, usando diferentes métodos de coleta (monólitos e armadilhas). As análises de componentes principais (ACP), canônica discriminante (ACD) e de correlação canônica (ACC) foram aplicadas às variáveis ambientais [carbono da biomassa microbiana (CBM), respiração basal (C-CO2) e quociente metabólico (qCO2), estoques de serapilheira, umidade do solo, pH (CaCl2), matéria orgânica (MO) e teores de P, K, Ca, Mg, H+Al] e atributos da fauna edáfica. Foram encontradas cinco espécies de minhocas (2 famílias), 20 famílias de aranhas e oito famílias de colêmbolos nestas áreas. A diversidade da fauna, CBM, C-CO2, estoques de serapilheira e MO foram sempre superiores na área NF e inferiores na NPF. A comunidade de fauna do solo e as variáveis ambientais apresentaram potencial para serem usadas como indicadores da qualidade do solo. Houve alta correlação canônica entre as variáveis ambientais e a fauna edáfica. Os grupos Collembola, Diplopoda, Chilopoda, Isoptera, Araneae, Oligochaeta, biomassa da macrofauna, índice de diversidade de Shannon (H), estoques de serapilheira, P, CBM e C-CO2 foram responsáveis por praticamente toda a separação entre as áreas, sendo bons indicadores das modificações que ocorrem nos ecossistemas com araucária. A ACD demonstrou que a contribuição de cada atributo para separar as áreas sofreu efeito de sazonalidade. As técnicas de análise multivariada (especialmente ACC e ACD) são importantes ferramentas no estudo de indicadores biológicos de qualidade do solo. / The study of biological soil quality indicators in areas with Araucaria is very important to understand ecological processes in these systems, since groups of the soil fauna are major factors in the decomposition and mineralization of organic matter, as well as modifiers of soil physical, chemical and biological properties and processes. The objective of this study was to evaluate the use of soil fauna and environmental variables as quality indicators in natural and reforested Araucaria areas, impacted or not by fire, by means of multivariate analysis techniques. Four study areas included: native forest with Araucaria (NF); Araucaria reforestation (R); Araucaria reforestation submitted to an accidental fire (RF); and native grass pasture with native Araucaria , submitted to an intense accidental fire (NPF). Soil samples containing the soil fauna community and environmental variables were taken in a 0.3 ha area in each area, close to ten Araucaria trees selected at random, in three contrasting seasons, using different collection methods (soil monolith, Pitfall traps). Canonical discriminant analysis (CDA) and canonical correlation analysis (CCA) were applied to the environmental variables [(carbon of the microbial biomass (CMB), basal respiration (C-CO2) and metabolic quotient (qCO2), litter stocks, soil humidity, pH (CaCl2), organic matter (OM), P, K, Ca, Mg, H+Al] and soil fauna attributes. Five earthworm species (two families), 20 spider families and eight springtail families were found in these areas. Soil fauna diversity, CMB, C-CO2, litter stocks and OM were always higher for the NF area and lower for the NPF. The canonical correlation between environmental variables and soil fauna was highly significant. Soil fauna and environmental variables have a great potential as indicators of soil quality. The groups Collembola, Diplopoda, Chilopoda, Isoptera, Araneae, Oligochaeta, biomass of macrofauna, Shannon's diversity index (H), litter stocks, P, CMB and C-CO2 were mostly responsible for the separation between areas, and are therefore good indicators of the changes that occur in the Araucaria ecosystems. CDA identified that the contribution of each attribute for the separation of the areas varied according to the seasonal variation. Multivariate analyses (such as CDA and CCA) are important auxiliary tools in the study of soil quality indicators.