Agricultural landscape homogenization has detrimental effects on biodiversity and key ecosystem services. Increasing agricultural landscape heterogeneity by increasing seminatural cover can help to mitigate biodiversity loss. However, the amount of seminatural cover is generally low and difficult to increase in many intensively managed agricultural landscapes. We hypothesized that increasing the heterogeneity of the crop mosaic itself (hereafter "crop heterogeneity") can also have positive effects on biodiversity. In 8 contrasting regions of Europe and North America, we selected 435 landscapes along independent gradients of crop diversity and mean field size. Within each landscape, we selected 3 sampling sites in 1, 2, or 3 crop types. We sampled 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders, and birds) and calculated a synthetic index of multitrophic diversity at the landscape level. Increasing crop heterogeneity was more beneficial for multitrophic diversity than increasing seminatural cover. For instance, the effect of decreasing mean field size from 5 to 2.8 ha was as strong as the effect of increasing seminatural cover from 0.5 to 11%. Decreasing mean field size benefited multitrophic diversity even in the absence of seminatural vegetation between fields. Increasing the number of crop types sampled had a positive effect on landscape-level multitrophic diversity. However, the effect of increasing crop diversity in the landscape surrounding fields sampled depended on the amount of seminatural cover. Our study provides large-scale, multitrophic, cross-regional evidence that increasing crop heterogeneity can be an effective way to increase biodiversity in agricultural landscapes without taking land out of agricultural production. ; This research was funded by the ERA-Net BiodivERsA, with the national funders French National Research Agency (ANR-11-EBID-0004), German Ministry of Research and Education, German Research Foundation and Spanish Ministry of Economy and Competitiveness, part of the 2011 BiodivERsA call for research proposals. The UK component of this research was funded by the UK Government Department of the Environment, Food and Rural Affairs (Defra), as Project WC1034. The Canadian component of this research was funded by a Natural Sciences and Engineering Research Council of Canada Strategic Project, the Canada Foundation for Innovation, Environment Canada, and Agriculture and Agri-Food Canada. N.G. was supported by the AgreenSkills+ Fellowship programme which has received funding from the EU's Seventh Framework Programme under Grant Agreement FP7-609398 (AgreenSkills+ contract). A.G.-T. (Juan de la Cierva Fellow, JCI-2012-12089) was funded by Ministerio de Economía y Competitividad (Spain). C. Violle was supported by the European Research Council Starting Grant Project "Ecophysiological and biophysical constraints on domestication of crop plants" (Grant ERC-StG-2014-639706-CONSTRAINTS). A.R.'s position at the University of Alicante is funded by the "Vicerrectorado de Investigación y Transferencia de Conocimiento."
1. Increasing landscape heterogeneity by restoring semi-natural elements to reverse farmland biodiversity declines is not always economically feasible or acceptable to farmers due to competition for land. We hypothesized that increasing the hetero-geneity of the crop mosaic itself, hereafter referred to as crop heterogeneity, can have beneficial effects on within-field plant diversity .2. Using a unique multi-country dataset from a cross-continent collaborative project covering 1,451 agricultural fields within 432 landscapes in Europe and Canada, we assessed the relative effects of compositional and configurational crop heteroge-neity on within-field plant diversity components. We also examined how these relationships were modulated by the position within the field. 3. We found strong positive effects of configurational crop heterogeneity on within-field plant alpha and gamma diversity in field interiors. These effects were as high as the effect of semi-natural cover. In field borders, effects of crop heterogeneity were limited to alpha diversity. We suggest that a heterogeneous crop mosaic may overcome the high negative impact of management practices on plant diversity in field interiors, whereas in field borders, where plant diversity is already high, landscape effects are more limited. 4. Synthesis and applications. Our study shows that increasing configurational crop heterogeneity is beneficial to within-field plant diversity. It opens up a new effec-tive and complementary way to promote farmland biodiversity without taking land out of agricultural production. We therefore recommend adopting manipulation of crop heterogeneity as a specific, effective management option in future policy measures, perhaps adding to agri-environment schemes, to contribute to the con-servation of farmland plant diversity. ; Natural Sciences and Engineering Research Council of Canada; German Ministry of Research and Education; Agence Nationale de la Recherche, Grant/Award Number: ANR-11-EBID-0004; Canada Foundation for Innovation; German Research Foundation; Spanish Ministry of Economy and Competitiveness; Agriculture and Agri-Food Canada; French National Research Agency, Grant/Award Number: ANR-11-EBID-0004; UK Government Department of the Environment, Food and Rural Affairs; Environment Canada (EC)
Tree crops such as cocoa and oil palm are important to smallholders' livelihoods and national economies of tropical producer countries. Governments seek to expand tree-crop acreages and improve yields. Existing literature has analyzed socioeconomic and environmental effects of tree-crop expansion, but its spatial effects on the landscape are yet to be explored. This study aims to assess the effects of tree-crop farming on the composition and the extent of land-cover transitions in a mixed cocoa/oil palm landscape in Ghana. Land-cover maps of 1986 and 2015 produced through ISODATA, and maximum likelihood classification were validated with field reference, Google Earth data, and key respondent interviews. Post-classification change detection was conducted and the transition matrix analyzed using intensity analysis. Cocoa and oil palm areas have increased in extent by 8.9% and 11.2%, respectively, mainly at the expense of food-crop land and forest. The intensity of forest loss to both tree crops is at a lower intensity than the loss of food-crop land. There were transitions between cocoa and oil palm, but the gains in oil palm outweigh those of cocoa. Cocoa and oil palm have increased in area and dominance. The main cover types converted to tree-crop areas are food-crop land and off-reserve forest. This is beginning to have serious implications for food security and livelihood options that depend on ecosystem services provided by the mosaic landscape. Tree-crop policies should take account of the geographical distribution of tree-commodity production at landscape level and its implications for food production and ecosystems services.
Cassava was imported from Latin America some 300 years ago, and colonial governments in Africa used it as a famine-reserve crop. Over time cassava spread to over 40 countries in Sub-Sahara Africa, and Nigeria is now the largest cassava producer in the world. At Africa's independence in the 1960s, cassava mosaic disease was a major problem. In the 1970s, the cassava mealybug appeared and threatened to decimate the African cassava industry. Cassava mosaic and mealybug control programs were introduced in the 1970s to combat these two problems. The International Institute of Tropical Agriculture (IITA) drew on research on mosaic disease control in Tanzania and developed high-yielding mosaic disease resistant Tropical Manioc Selection (TMS) varieties in only six years of research, from 1971 to 1977. The TMS varieties increased cassava yields by 40 percent without fertilizer. To tackle the mealybug problem, an Africa-wide biological control center was established at the IITA in Nigeria. The IITA brought together an international group of scientists and donors who crisscrossed Central and South America and eventually found a wasp that fed off the mealybug. The wasp was imported from South America into Africa and introduced into cassava fields in over 100 locations throughout Sub-Saharan Africa. The wasp has been effective in bringing the mealybug under control and reduces yield loss by 2.5 tons per hectare. The successful control of both the cassava mosaic disease and the cassava mealybug problems has raised cassava yields and turned cassava into a cash crop that is now spreading throughout Africa. Both cassava success stories are an example of the payoff from problem-solving research that may take many decades. ; Non-PR ; IFPRI1; GRP4; 2020 ; DGO
Cucumber green mottle mosaic virus (CGMMV) is a widespread pathogen capable of infecting plants cultivated in both greenhouse and openfield conditions with equal efficiency. The host range of CGMMV is restricted to cucurbit plants whereas induced crop losses may reach 25–50 %. Despite the wide array of available antiviral techniques, CGMMV could not be completely removed from the seed/planting material. In Ukraine, Cucumber green mottle mosaic virus occurs almost exclusively on greenhouse cucumbers. However, data from other countries suggest wide spread of CGMMV on watermelons, melons, cucumbers and squashes grown in both greenhouse and open-field conditions. In this view and taking into account high pathogenicity of CGMMV, we aimed at studying spread of Cucumber green mottle mosaic virus in Ukraine on cucurbit plants in the open-field conditions. Methods: enzyme-linked immunosorbent assay, electron microscopy, statistical methods. Results : Spread of Cucumber green mottle mosaic virus (CGMMV) on cucurbit vegetable crops grown in open-field conditions was analyzed in Ukraine. It was shown that CGMMV is an extremely rare pathogen in open-field conditions in our country. Duringthelast 8 years we have confirmed only several cases of CGMMV infection on cucumbers, squash, pumpkin and melon in Kyiv and Poltava regions. Additionally, half of these cases were mixed infection of 2–3 viruses. From 250 collected samples, CGMMV was detected in 5 plants totaling to only 2,4 %. Importantly, monoinfection of CGMMV was shown exclusively on cucumbers and watermelons, whereas melons and squashes were mixed infected. Melons were typically infected with CGMMV and Watermelon mosaic virus 2 (WMV 2) or with WMV 2 and Zucchini yellow mosaic virus (ZYMV). Squash plants were infected with CGMMV and Cucumber mosaic virus (CMV).Consequently, we have checked commercially available seeds of cucumber, squash, zucchini, melon and watermelon from different producers in Ukraine for virus contamination and have confirmed the occurrence of CGMMV in some seed batches. Conclusions: Long-term observations in Ukraine showed that Cucumber green mottle mosaic virus infected mostly cucumbers cultivated in greenhouses and was only rarely found in cucurbits grown in open-field conditions. Screening of commercially available seed material indicated that 16 % of it was contaminated with CGMMV. Basing on available data, it is presumed that virus-contaminated seed material may pose a major threat of CGMMV occurrence and spread on cucurbits cultivated in open-field conditions.
A field survey was conducted during the 2018 rainy season (June – October) in three major ginger producing Local Government Areas (LGAs) of Kaduna State, Nigeria to determine the occurrence and spread of wheat streak mosaic virus (WSMV) infecting ginger. Symptomatic and asymptomatic ginger leaf samples (n=180) and weed samples (n=45) were collected from the surveyed fields and indexed against WSMV using Double Antibody Sandwich Enzyme-linked Immunosorbent Assay (DAS-ELISA). The results obtained showed that WSMV occurred in all the LGAs surveyed but with significant (P = 0.05) variation in distribution. Jaba had the highest virus incidence (22.67\,\%) followed by Kagarko (17.67\,\%) while Kachia had the lowest virus incidence of 10.00\,\%. To the best of our knowledge, this is the first report of WSMV infecting ginger in Nigeria. Rottboellia cochinchinensis (Lour.) Clayton and Setaria barbata (Lam.) Kunth tested positive against WSMV as alternative weed hosts of the virus. The incidence of WSMV even at lower percentage is significant as population build-up could lead to a disease outbreak. Awareness programs need to be organised for farmers on yield loss potential of WSMV on ginger crop and the role of cultural practices on the incidence and management of the virus.
Samples of plants showing symptoms of Turnip mosaic virus (TuMV) were collected from fields planted to Brassicaceae crops in Kyiv region and different locations in the city of Kyiv. TuMV was detected in the main brassica-crop fields, private gardens and urban locations of Ukraine, with a high overall incidence of 50%. This paper describes the effects of different cultivation approaches on the incidence rate of viral infection in susceptible crops and confirms the importance of preventive measures for disease control.
Cassava is an important staple crop for an estimated 800 million people worldwide. Cassava production in Africa is constrained by cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). Both viral diseases cause annual yield losses estimated around $2.1 billion. CMD is caused by nine distinct virus species known as cassava mosaic geminiviruses (CMGs, genus: Begomovirus family: Geminiviridae). This disease is widespread across all cassava-growing regions in Africa. CBSD is caused by Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) (genus Ipomovirus; family Potyviridae). Unlike CMD, CBSD is prevalent in low to mid altitude regions of Eastern and Central Africa. The necrotic lesions on storage roots, which make them unfit for consumption or processing, further exacerbate economic losses due to CBSD. Efforts aiming at controlling incidence of both CMD and CBSD in Africa have focused on screening for resistance in both cultivated and wild species of cassava and subsequent introgression of resistance into farmer-preferred cultivars. Three sources of resistance (CMD1, CMD2 and CMD3) have been identified for CMD and have been introgressed into local germplasm. Similarly, a number of CBSD "tolerant" varieties or clones such as "Kiroba", "Kaleso" KBH 2006/18 and MM 06/0082 have been identified. However, high heterozygosity and outcrossing in cassava and the limited diversity of these sources of resistance challenge development of durable resistance to CMD and CBSD via conventional breeding approach. The main goal of this project is to engineer broad-spectrum resistance against cassava mosaic disease (CMD) into a farmer-preferred cassava cultivar in Ghana using expertise and tools developed at the Plant Biotechnology laboratory, ETH Zürich. In the first chapter, I present results characterizing genetic diversity of cassava mosaic geminiviruses (CMGs) identified in farmers' fields in Ghana. Extending this characterization to include other CMG species identified elsewhere in Africa, highly conserved genomic regions were identified. CMGs have a high propensity for mutation and recombination that can influence their evolution. Besides, the relative contribution of natural selection in shaping genetic variation and thus evolution of geminiviruses remains poorly studied. Due to the high genetic variation present in CMGs, developing durable and broad-spectrum resistance in the field is challenging. Molecular characterization of CMG species in farmers' fields in Ghana resulted in the identification of an isolate of East African cassava mosaic virus (EACMV), closely related to the EACMV-Kenya virus (EACMKV). This is the first report showing that an EACMKV species is associated with CMD in Ghana, which warrants attention as this could have epidemiological implications for control of CMD. Using current phylogenetic approaches that infer evolutionary rate variation at individual sites along protein-coding sequences, we identified the replication-associated protein (Rep/AC1) and the coat protein (CP/AV1) of CMGS to be evolving under negative selection. Evidence of strong negative selection in the Rep and CP genes of cassava mosaic geminiviruses makes them suitable targets for engineering resistance to geminiviruses in cassava. In the second chapter, I present results on screening for CBSD in four cassava-producing regions in Ghana. Furthermore, the response of eleven selected farmer-preferred cassava cultivars to mixed infections of CBSV (TAZ-DES-01) and UCBSV (TAZ-DES-02) isolates is reported. Although CBSD has not been reported in West Africa, reports in Burundi and Democratic Republic of Congo indicate a westward drift of the disease into West Africa. In this chapter, we confirmed the absence of CBSD in farmer fields in the four cassava-producing regions in Ghana. However, susceptibility of all eleven cultivars to both CBSV and UCBSV infection is alarming. It is expected that these results will encourage extensive screening for CBSD across Ghana and West Africa. Furthermore, screening of other local cassava cultivars could lead to identification of sources of CBSD resistance. The use of complementary approaches such as transgenic technology is encouraged to speed up development of CBSD-resistant cassava for farmers. In the third chapter, I present results on the induction of friable embryogenic calli (FEC) in eleven cassava cultivars from Ghana. FEC induction in cassava is highly genotype-dependent making it difficult to achieve in several African cassava cultivars. We successfully induced quality FEC tissues in ADI 001, a farmer-preferred cultivar. Using the standard protocol for cassava transformation developed in our laboratory, we successfully transformed and regenerated plantlets of ADI 001. The application of flow cytometry for routine assessment of FEC ploidy levels was carried out to ensure that quality FEC tissues are used for genetic transformation. Furthermore, over 40% of recovered lines had a single insertion of the transgene, making them suitable for downstream molecular characterization and confined field trials. In the fourth chapter, I present results showing development and successful transfer of CMD resistance into a farmer-preferred cassava cultivar, ADI 001. Using the RNAi-based approach that has achieved some success in developing resistance against both RNA and DNA viruses, we tested the single and multiple target approach for engineering resistance against mixed CMG infections present in cassava fields. Based on the genetic diversity study of CMGs identified in farmers' fields, the replication-associated protein (AC1) and the movement protein (BC1) were selected as targets for silencing. Double targeting of AC1 and BC1 resulted in a shift in viral population in cuttings multiplied from scions inoculated with mixed CMG population. However, expression of high levels of hairpin-derived small RNAs homologous to only the AC1 gene sufficed efficient silencing of mixed CMG population. Near immunity to mixed CMG infection achieved in transgenic dsAC1 line-42 was maintained in cuttings multiplied from scions inoculated with field infected rootstocks. The work presented in this thesis demonstrates successful transfer of CMD resistance through transgenic technologies into a cassava cultivar preferred by farmers in Ghana. The identification of high levels of resistance against mixed CMG infection in this local cultivar, ADI 001 (dsAC1 line-42) encourages field screening to evaluate durability of resistance engineered. More importantly, transfer of transgenic technologies to laboratories in Africa such as the Biotechnology and Nuclear Agriculture Research Institute (BNARI) in Ghana through building of capacity is necessary to encourage and sustain adoption of transgenic technologies in Africa.
The intertwined challenges of food insecurity, deforestation, and biodiversity loss remain perennial challenges in Ethiopia, despite increasing policy interventions. This thesis investigates smallholding farmers' tree- and forest-based livelihoods and management practices, in the context of national development and conservation policies, and examines how these local management practices and policies transform the agriculture–forest mosaic landscapes of southwestern Ethiopia. The thesis is guided by a political ecology perspective, and focuses on an analytical framework of ecosystem services (ESs) and disservices (EDs). It uses a mixed research design with data from participatory field mapping, a tree 'inventory', interviews, focus group discussions, population censuses, and analysis of satellite images and aerial photos. The thesis presents four papers. Paper I investigates how smallholding farmers in an agriculture–forest mosaic landscape manage trees and forests in relation to a few selected ESs and EDs that they consider particularly beneficial or problematic. The farmers' management practices were geared towards mitigating tree- and forest-related EDs such as wild mammal crop raiders, while at the same time augmenting ESs such as shaded coffee production, resulting in a restructuring of the agriculture–forest mosaic. Paper II builds further on the EDs introduced in paper I, to assess the effects of crop raids by forest-dwelling wild mammals on farmers' livelihoods. The EDs of wild mammals and human–wildlife conflict are shown to constitute a problem that goes well beyond a narrow focus on yield loss. The paper illustrates the broader impacts of crop-raiding wild mammals on local agricultural and livelihood development (e.g. the effects on food security and children's schooling), and how state forest and wildlife control and related conservation policy undermined farmers' coping strategies. Paper III examines local forest-based livelihood sources and how smallholders' access to forests is reduced by state transfer of forestland to private companies for coffee investment. This paper highlights how relatively small land areas appropriated for investment in relatively densely inhabited areas can harm the livelihoods of many farmers, and also negatively affect forest conservation. Paper IV investigates the patterns and drivers of forest cover change from 1958 to 2010. Between 1973 and 2010, 25% of the total forest was lost, and forest cover changes varied both spatially and temporally. State development and conservation policies spanning various political economies (feudal, socialist, and 'free market-oriented') directly or indirectly affected local ecosystem use, ecosystem management practices, and migration processes. These factors (policies, local practices, and migration) have thus together shaped the spatial patterns of forest cover change in the last 50 years. The thesis concludes that national development and conservation policies and the associated power relations and inequality have often undermined local livelihood security and forest conservation efforts. It also highlights how a conceptualization of a local ecosystem as a provider of both ESs and EDs can generate an understanding of local practices and decisions that shape development and conservation trajectories in mosaic landscapes. The thesis draws attention to the need to make development and conservation policies relevant and adaptable to local conditions as a means to promote local livelihood and food security, forest and biodiversity conservation, and ESs generated by agricultural mosaic landscapes. ; At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: In press. Paper 3: Submitted. Paper 4: Manuscript.
An increased incidence and severity of Orthotospovirus species has been observed in the peanut crop. The typical symptoms of the virus, usually known as ringspot in peanut and spotted wilt in other crops, include mosaic, chlorotic ring-shaped spots, necrosis, and plant stunting. This study aimed to verify the occurrence of this virus in peanut growing areas in the São Paulo State, Brazil, identify the predominant virus species, and determine losses resulting from the presence of this virus. Surveys were carried out in four peanut commercial areas sown in the municipalities of Santa Adélia and Cândido Rodrigues in the 2014/2015 season using the cultivar Granoleico. The following parameters were evaluated: plant stand, number of plants with symptoms, and severity of these symptoms through a scoring scale of visual symptoms. The results showed that the predominant virus species is Groundnut ringspot tospovirus (GRSV). Also, the lower the stand is, the higher the percentage of plants with virus symptoms. The mean incidence of GRSV in commercial peanut areas is 40%, with mean losses estimated at 38% when GRSV is present and 64% when there is the presence of virus and reduction in plant density.
This paper evaluates the impact of an emergency research for development project implemented in the Democratic Republic of Congo from 2000 to 2009 by a various actors including the International Institute of Tropical Agriculture in response to the outbreak of the Cassava Mosaic Disease that threatened the national food security. It applies methods developed in the econometric and statistical treatment effects literature on evaluation of social programs. The study evaluates impact by analyzing changes over time of outcomes of sample households in the project areas compared to neighboring non-project areas. We find that the project had statistically significant positive effects on technology adoption, area planted cassava, productivity, profitability,household food security and aggregate supply response. The effects are strongest among lower tails of distribution of outcomes mostly made up of female-headed households who grew the crop mainly for food. These findings are useful for informing agricultural and food policy debates in Africa. ; Peer Review
In Madagaskar ist ein Großteil der ländlichen Bevölkerung von Armut betroffen und ist damit auf kleinbäuerliche Landwirtschaft und die Nutzung natürlicher Ressourcen zur Grundversorgung angewiesen. Folglich sind die natürlichen und artenreichen Ökosysteme des Landes einem hohen Landnutzungsdruck ausgesetzt. Vor allem die Regenwälder im Nordosten des Landes weisen eine bemerkenswerte Vielfalt an Baumarten und eine hohe Endemismusrate auf, sind jedoch von einer raschen Umwandlung in eine von Menschen veränderte Mosaiklandschaft bedroht. In dieser Mosaiklandschaft im Nordosten Madagaskars findet sich noch ein kleiner Anteil geschützter alter Wälder, ansonsten setzt sich die Landschaft aus einem Mosaik landwirtschaftlicher Flächen, Waldfragmente und Agroforste zusammen. Diese Agroforste dienen dem kleinbäuerlichen Anbau von Gewürzvanille, die Madagaskars wichtigstes Exportprodukt darstellt. In diesen Agroforsten spielen Bäume eine entscheidende Rolle. Sie werden entweder als Schattenbäume oder als Stützbäume für die kletternde Vanille-Orchidee (Vanilla planifolia) dauerhaft in das Anbausystem integriert. Vanille-Agroforste decken bezüglich ihrer Struktur und ihrer Artenzusammensetzung ein breites Spektrum ab. Somit weisen sie vielversprechende Landnutzungsoptionen auf, um die Erhaltung der biologischen Vielfalt mit den Produktionszielen im Nordosten Madagaskars in Einklang zu bringen. Da es bisher nur wenige Belege gibt, die eine soziale und ökologische Bewertung der Vanille-Agroforstwirtschaft erlauben, befasst sich das Forschungsprojekt "Diversity Turn in Land Use Science" mit dieser Forschungslücke. Im Rahmen des Diversity Turn-Projekts befasst sich die vorliegende Doktorarbeit mit dem Naturschutzwert von Agroforsten, indem sie die Vielfalt, Bestandsstruktur und Zusammensetzung von Baumgemeinschaften in Vanille-Agroforsten untersucht und sie mit anderen baumbasierten Landnutzungstypen in der Mosaiklandschaft im Nordosten Madagaskars vergleicht. Um dies zu erreichen, entwickelt die vorliegende Doktorarbeit zunächst einen konzeptionellen Rahmen, der eine Naturschutzbewertung von Agroforstsystemen erleichtert. Anschließend werden einzelne Aspekte dieses konzeptionellen Rahmens anhand von Fallstudien untersucht. Die Fallstudien setzen unterschiedliche Schwerpunkte und decken damit ein umfassendes Spektrum ab, das von der Baumartenvielfalt und Bestandsstruktur, über die Baumartenzusammensetzung, die Vielfalt der Agroforst-Stützbäume bis zur Erfassung des oberirdischen Kohlenstoffbestands reicht. Die Fallstudien stützen sich auf Bauminventurdaten, die in Vanille-Agroforsten mit unterschiedlicher Landnutzungsgeschichte erhoben wurden, sowie in weitgehend ungestörten Wäldern, Waldfragmenten und holzigen Brachflächen, die alle Teil der kleinbäuerlichen Mosaiklandschaft im Nordosten Madagaskars sind. In der konzeptionellen Studie (Kapitel 1) wird zunächst dargelegt, dass sich tropische Agroforste in ihrer Landnutzungsgeschichte unterscheiden: sie können entweder im Wald oder auf Brachland angelegt werden. Jedoch wird dieser Unterschied in der Agroforstforschung und -politik bisher kaum beachtet. Auf der Grundlage von Literaturdaten und einem Beispiel aus eigenen Bauminventurdaten zeigt die Studie, dass sich Agroforste mit unterschiedlicher Landnutzungsgeschichte in Bezug auf biologische Vielfalt, Ökosystemfunktionen und Ökosystemdienstleistungen unterscheiden. Die Studie legt nahe, dass die Unterscheidung basierend auf der Landnutzungsgeschichte in verschiedenen Regionen und Agroforstsystemen anwendbar sein könnte, um lokale Naturschutzziele und Landschaftsmanagement besser aufeinander abzustimmen. Kapitel 2 analysiert die Bestandsstruktur und die Artenvielfalt von Bäumen in den verschiedenen Landnutzungstypen der kleinbäuerlichen Mosaiklandschaft. Dabei steht insbesondere im Fokus, wie sich die Landnutzungsgeschichte in Vanille-Agroforsten auf deren Bestandsstruktur und die Baumartenvielfalt auswirkt: die Studie zeigt, dass Agroforste, die im Wald etabliert wurden, wichtig für die Erhaltung der Lebensraumstruktur und der Baumvielfalt sind, während Agroforste, die auf Brachland etabliert wurden, eine Möglichkeit zur Wiederherstellung der Baumbestände auf diesen ehemals bewaldeten Brachflächen bieten. Kapitel 3 quantifiziert die Vielfältigkeit und Zusammensetzung der Baumartengemeinschaften innerhalb und zwischen verschiedenen Landnutzungstypen in der Mosaiklandschaft. Die Studie verwendet Beta-Diversitätsmaße, die Veränderungen in der Baumartenzusammensetzung und -häufigkeit in diesen verschiedenen Landnutzungstypen widerspiegeln, und zeigt, dass (bis jetzt) viele Baumarten in dieser Mosaiklandschaft überleben können. Allerdings sind die Fluktuationsraten innerhalb und zwischen den Baumgemeinschaften in den verschiedenen Landnutzungstypen hoch, was darauf hindeutet, dass sich die Baumgemeinschaften sowohl in ihrer Identität als auch in ihrem Abundanz verändern. Die Studie befürwortet die Durchführung von Maßnahmen zur Aufforstung und Renaturierung ehemals bewaldeten Brachlands, um die einzigartigen Baumartengemeinschaften in der vom Menschen veränderten Mosaiklandschaft zu erhalten, und schlägt als Einstieg die Etablierung von Agroforsten auf ehemals bewaldeten Brachflächen vor. Die Studie betont jedoch, dass die hohe Fluktuationsrate von Baumartengemeinschaften bei der Planung solcher Aktivitäten zu berücksichtigen ist. Kapitel 4 befasst sich mit der Vielfalt und Zusammensetzung von Agroforst-Stützbäumen, denen bisher wenig wissenschaftliche Aufmerksam zukam. Die Studie stützt sich auf Daten aus der Bestandsaufnahme von Agroforst-Stützbäumen in Vanille-Agroforsten mit unterschiedlicher Landnutzungsgeschichte, sowie auf Befragungen der Besitzer:innen der jeweiligen Vanille-Agroforste. Die Studie analysiert die Artenvielfalt, die Zusammensetzung und die geographische Herkunft der Stützbäume in diesen Vanille-Agroforsten und zeigt, dass Stützbäume wesentlich zur Baumvielfalt dieser Agroforste beitragen, aber abhängig von der Landnutzungsgeschichte werden deutliche Unterschiede zwischen Stützbaum-Beständen sichtbar: Stützbäume in Agroforsten, die im Wald etabliert wurden, umfassen viele einheimische und endemische Stützbaumarten und weisen einen viermal höheren Artenreichtum auf als Agroforste, die auf Brachland etabliert wurden und einen hohen Anteil an eingeführten Stützbaumarten beherbergen. Da auf Brachland etablierte Vanille-Agroforste eine wichtige Rolle bei der Aufforstung und Renaturierung ehemals bewaldeten Brachlands spielen können, empfiehlt die Studie bei deren Etablierung verstärkt auf einheimische oder endemische Baumarten als Stützbäume zurück zu greifen. Kapitel 5 quantifiziert die oberirdischen Kohlenstoffvorräte in den verschiedenen Landnutzungstypen der kleinbäuerlichen Mosaiklandschaft. Dabei wird insbesondere analysiert, wie die Landnutzungsgeschichte die oberirdischen Kohlenstoffvorräte in Agroforstsystemen beeinflusst. Die Studie zeigt, dass Agroforste als Kohlenstoffspeicher in einer multifunktionalen Landschaft fungieren können, dass es aber wichtig ist, ihre Landnutzungsgeschichte und ihre Bewirtschaftung zu berücksichtigen, um ihren Naturschutzwert zu maximieren: Agroforste, die im Wald etabliert wurden, weisen größere oberirdischen Kohlenstoffvorräten auf und haben das Potenzial, eine waldähnliche Struktur mit einheimischen und endemischen Bäumen in der Landschaft zu erhalten, während Agroforste, die auf Brachland etabliert wurden, dieses ehemalig bewaldete Brachland in dauerhaft baumdominierte Landnutzungssysteme zurückführen. Zusammenfassend tragen die Studien im Rahmen dieser Doktorarbeit dazu bei, die ökologische Bewertung tropischer Agroforste zu verbessern. Die Studien liefern datengestützte Erkenntnisse aus Fallstudien in der Mosaiklandschaft im Nordosten Madagaskars, welche die ökologische Bewertung der Vanille-Agroforstwirtschaft in dieser Region ermöglichen. Die vorliegende Doktorarbeit beleuchtet die Vielfalt, die Zusammensetzung und die Bestandsstruktur von Baumgemeinschaften in der Mosaiklandschaft im Nordosten Madagaskars und liefert damit wichtige Informationen, um die Folgen von Landnutzungsänderungen in dieser tropischen Landschaft zu quantifizieren und zu verstehen. Ein solches Verständnis ist unerlässlich für die Entwicklung von regional angepassten Landnutzungsplänen und Schutzmaßnahmen, die darauf abzielen, die Artenvielfalt, Ökosystemfunktionen und Ökosystemdienstleistungen zu erhalten, und ist somit sowohl für die Forschung als auch für den angewandten Naturschutz von hohem Wert. ; In Madagascar, a large percentage of the rural human population faces multifaceted poverty and depends on agriculture and natural resources as main livelihood sources. Consequently, the country's biodiverse natural ecosystems experience high land-use pressure. Especially the north-eastern rainforests comprise a remarkable diversity of trees species with high endemism rates but face rapid transformation into a human-modified mosaic landscape. This human-modified mosaic landscape in north-eastern Madagascar still contains a small share of protected old-growth forest and is otherwise composed of smallholder agricultural land, forest fragments, and smallholder agroforests to cultivate Madagascar's major export product vanilla. In these agroforests, trees are permanently integrated into the crop cultivation system either as shade trees or as support trees for the climbing vanilla orchid (Vanilla planifolia). Vanilla agroforests cover a wide range of structural and compositional characteristics and might offer promising land use options to reconcile biodiversity conservation with production goals in north-eastern Madagascar. Since evidence on the social and environmental benefits and tradeoffs of vanilla agroforestry has been scarce so far, the research project "Diversity Turn in Land Use Science" addresses this research gap. Within the frame of the Diversity Turn project, this thesis addresses the conservation value of agroforests by examining the diversity, stand structure, and composition of tree communities in vanilla agroforests and contrasting them to other tree-based land-use types in the mosaic landscape of north-eastern Madagascar. To do so, this thesis first establishes a conceptual framework on agroforestry systems and then works through the individual aspects of this framework, using case studies on species diversity and stand structure, species composition, support tree diversity, and aboveground carbon stocks. The case studies build on tree inventory data from vanilla agroforests of contrasting land-use history, old-growth forests, forest fragments, and woody fallows after slash-and-burn shifting cultivation, which all contribute to the smallholder mosaic landscape of north-eastern Madagascar. The conceptual study (chapter 1) elaborates that tropical agroforests differ in land-use history and may be either established inside a forest or on open land but this difference is often neglected in agroforestry research and policy. Based on literature data and an example from own tree inventories, the study shows that agroforests of contrasting land-use history differ in biodiversity, ecosystem functions, and services. The study suggests that the differentiation based on land-use history might be applicable in various regions and agroforestry systems, to better align landscape management with conservation goals. Chapter 2 analyses the stand structure and species diversity of trees in the different land-use types of the smallholder mosaic landscape. Therein, the study puts a special focus on how land-use history affects stand structure and species diversity in vanilla agroforests and demonstrates that forest-derived agroforests are important for maintaining habitat structure and tree diversity, whereas fallow-derived agroforests offer tree cover rehabilitation opportunities on open but formerly forested land. Chapter 3 quantifies the variation of tree species communities within and among different land-use types in the mosaic landscape. The study uses beta-diversity metrics that reflect changes in both species composition and abundance in these different land-use types and demonstrates that (thus far) many tree species can persist in this mosaic landscape. However, turnover rates are high within and between tree communities in the land-use types, indicating that tree communities are transforming both in identity and abundance. The study endorses the implementation of conservation and restoration activities to maintain the unique tree species assemblages in the human-modified mosaic landscape and suggests the establishment of agroforests on formerly forested degraded land as an entry point. However, the study emphasizes considering the high turnover rates of tree species communities in the planning of such activities. Chapter 4 focuses on the diversity and composition of agroforest-support trees, which have received little scientific attention so far. The study builds on support tree inventory data and farmer interviews from vanilla agroforests of contrasting land-use history. The study analyses the species diversity, composition, and geographic origin of support trees in these vanilla agroforests and shows that support trees substantially contribute to the tree diversity in these agroforests, but show clear differences based on land-use history: support trees in forest-derived agroforests encompass many native and endemic species richness and have four times higher species richness compared to fallow-derived agroforests, which harbor a high share of introduced species. Since fallow-derived vanilla agroforests can play an important role in restoration and rehabilitation, the study suggests a stronger consideration of native or endemic tree species in new to establish vanilla agroforests. Chapter 5 estimates aboveground carbon stocks across stem diameters and geographic origin of tree species in the different land-use types of the smallholder mosaic landscape. Therein, the study particularly analyses how land-use history influences aboveground carbon stocks in agroforestry systems. The study demonstrates that agroforests can act as carbon reservoirs in a multifunctional landscape, but considering their land-use history and management is important to maximize their benefits: forest-derived agroforests support higher aboveground carbon stocks than fallow-derived agroforests and have the potential to maintain a forest-like structure with native and endemic trees in the landscape, whereas fallow-derived agroforests take land out of the slash-and-burn cycle by converting it into permanent tree-dominated land-use systems. In conclusion, the studies within this thesis contribute to refining the conservation evaluation of tropical agroforests and provide data-based evidence to assess the conservation value of vanilla agroforests in the mosaic landscape of north-eastern Madagascar. The thesis sheds light on the diversity, composition, and stand structure of tree communities in the mosaic landscape of north-eastern Madagascar and thereby provides vital information to quantify and understand the consequences of land-use change in this tropical landscape. Such understanding is essential to develop land-use management schemes and conservation measures that aim to maintain species diversity, ecosystem functions, and services and is thus important for research and applied conservation alike. ; 2022-01-21
Climate changes affect the level of damage from plant diseases, because the environment has a significant impact not only on plants, but also on pathogens and their vectors. Therefore, studying of the viruses, crop yield and productivity, agroclimatic changes should be in the complex. The aim of the study was to investigate the viruses affecting winter wheat and soybean plants, their yield in conditions of infection with viruses and changes in the climatic conditions of the Poltava region. Methods: biometric; crop and its structure; DAS-ELISA, RNA extraction from plant material, RT-PCR, sequencing, phylogenetic analysis, statistical methods. Results. It is established that Wheat streak mosaic virus (WSMV) is the most widespread and harmful for wheat crop and Soybean mosaic virus (SMV) – for soybean. For the first time in Ukraine, the yield of winter wheat and soybean plants under conditions of virus damage and changes of climatic conditions in the Poltava region was studied. Correlation between the HTC (the hydrothermal coefficient of Selyaninov), the damage caused by viral diseases and the productivity of winter wheat and soybean plants is revealed. It is shown that transgenic soybean Grimo is affected with SMV, which reduce grain yield twice. The molecular genetic properties of the SMV isolate GRP-17 were studied and it is determined that it has a common origin with Iranian, American, Chinese isolates and isolate from Ukraine. It has been determined that, the amino acid substitutions in CP gene of GRP-17 are unique compared to sequences of all SMV isolates taken for the analysis. Conclusions. Analysis of the meteorological data in the agrocenosis was carried out and it was established that the yield of wheat and soybean crops is closely related to the ratio of precipitation and air temperature (HTC). From these parameters also depended the frequency of WSMV and SMV detection, because they have a direct impact on insects – vectors of the viruses. The changes in the molecular genetic level in CP gene of GRP-17 can be involved in the it's harmfulness and ability to infect transgenic soybean plants.
