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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Assessing extinction risk across the geographic ranges of plant species in Europe

Holz, Hanna, Segar, Josiane, Valdez, Jose, Staude, Ingmar R. 11 July 2023 (has links)
Societal Impact Statement Plants play fundamental roles in ecosystems, yet merely 10% of species have an assessment of their global extinction risk. Through the integration of national Red Lists and comprehensive global plant distribution data, we identify previously unassessed plant species in Europe that are threatened throughout their geographic range and thus at risk of global extinction. Our workflow can be replicated to facilitate the integration of disparate national monitoring efforts around the world and help accelerate global plant risk assessments. Summary • A comprehensive extinction risk assessment for plant species is a global biodiversity target. However, currently, only 10% of plant diversity is assessed in the global Red List of Threatened Species. To guide conservation and restoration actions in times of accelerated species extinction, plant risk assessments must be expedited. • Here, we examine the extinction risk of vascular plant species in Europe through the integration of two data streams: (1) national Red Lists and (2) global plant distribution data from Kew's Plants of the World Online database. For each species listed on a national Red List, we create a list of countries that form part of its range and indicate the threat status in these countries, allowing us to calculate the percentage of the range in which a given species is listed as threatened. • We find that 7% to 9% of European vascular plant diversity is threatened in its entire range, the majority of which are single-country endemics. Of these globally threatened species, 84% currently have no assessment in the global Red List. • With increasing national biodiversity monitoring commitments shaping the post- 2020 policy environment, we anticipate that integrating national Red Lists with global plant distribution data is a scalable workflow that can help accelerate global risk assessments of plants.
72

The impacts of possum herbivory and possum control on threatened palatable species (Pittosporum patulum, Alepis flavida and Peraxilla tetrapetala) in the Lake Ohau Catchment, South Island, New Zealand

Head, Nicholas January 2005 (has links)
The impacts of possum herbivory were assessed on 713 individual plants of the nationally endangered Pittosporum patulum and 115 individual plants of the threatened ('Gradual Decline') mistletoes (Alepis flavida & Peraxilla tetrapetala) over three years in the Temple and Huxley river valleys in the Ohau catchment, South Island New Zealand. Statistical models were used to test the influence of several explanatory variables on the probability of survival and growth rates of these rare palatable plants. Increasing defoliation levels were the most significant predictors of mortality for both P. patulum and mistletoe, and reduced growth rates in P. patulum. Mortality of P. patulum increased with plant size although smaller plants were also affected by mortality. P. patulum mortality was greater for non-forest habitats, and growth rates were greatest on warm aspects. Mistletoe mortality increased with warm aspect, steeper slopes and at lower altitudes. Plant survival and growth increased in the Temple valley following possum control. Although indicative of a positive treatment effect, other factors may have also influenced this result. Possums are the major herbivore responsible for the widespread decline of P. patulum and beech forest mistletoes throughout New Zealand, although the autecology of P. patulum predisposes it toward extinction more so than mistletoe. Monitoring in conjunction with possum control operations provide good opportunities for understanding the impacts of possums on palatable plants and ecosystems. Assessing defoliation levels on indicator species like P. patulum and mistletoes can serve as a guide for managers to assess ecosystem stress from herbivory.
73

Διαχείριση και προστασία των ενδημικών, απειλουμένων και σπανίων φυτών του Εθνικού Δρυμού Αίνου, Κεφαλονιάς / Management and conservation of the endemic, threatened and rare plants of the National Park of Ainos, Cephalonia

Καραγιάννη, Βασιλική 20 April 2011 (has links)
Αντικείμενο της παρούσας εργασίας είναι η μελέτη των ενδημικών φυτικών ειδών και ειδών ιδιαίτερου ενδιαφέροντος, τα οποία απαντώνται στον Εθνικό Δρυμό του Αίνου (περιοχή NATURA 2000: GR2220002 & SPA). Μεταξύ αυτών περιλαμβάνονται τα: Viola cephalonica, Saponaria aenesia, Ajuga orientalis subsp. aenesia, Campanula garganica subsp. cephallenica, Centaurea subciliaris, κ.ά. Συνολικά η μελέτη περιλαμβάνει 21 taxa τα οποία ανήκουν σε 13 οικογένειες. Προτείνονται in situ και ex situ δράσεις προστασίας των. Για τον σκοπό αυτό έχουν καταγραφεί και μελετηθεί όλοι οι υποπληθυσμοί των ειδών, στοιχεία από τη βιολογία τους, οι απειλές που δέχονται, οι υπάρχουσες διαχειριστικές πρακτικές και οι σημαντικότεροι αβιοτικοί παράγοντες από τις θέσεις εμφάνισής των. Μέρος της μελέτης αποτελεί, επίσης, η εύρεση επιτυχημένων πρωτοκόλλων φύτρωσης και μηχανισμών άρσης του ληθάργου ο οποίος απαντάται σε ορισμένα taxa. Η οικοφυσιολογία της φύτρωσης αποτελεί ένα πολύ σημαντικό στάδιο στο βιολογικό κύκλο των φυτικών ειδών, το οποίο μπορεί να καθορίσει ακόμα και τη διατήρησή τους. Πιθανόν να πρέπει να αξιολογείται μαζί με άλλα δεδομένα (αριθμός ατόμων, έκταση και αριθμός υποπληθυσμών κ.α.) τα οποία λαμβάνονται υπ’ όψη κατά τη διάρθρωση των κόκκινων καταλόγων των φυτικών ειδών. / The object of the present work is the study of the endemic plant species and of species with special interest, which grow in the National Park of Mount Ainos (NATURA 2000 area: GR2220002 & SPA). The following are included among them: Viola cephalonica, Saponaria aenesia, Ajuga orientalis subsp. aenesia, Campanula garganica subsp. cephallenica, Centaurea subciliaris, etc. In total, the study covers 21 taxa, belonging to 13 families. In situ and ex situ actions for their protection are being proposed. For this purpose, all the species subpopulations have been recorded and data on their biology, on the encountered threats, on the current management practices and on the most important abiotic factors which characterize the locations of occurrence have been studied. Part of the study was also the creation of successful germination protocols and the finding of mechanisms for the dormancy breakage, since the seeds of some taxa are characterized by the presence of dormancy. The ecophysiology of germination constitutes a very important stage in the biological cycle of plant species, which could even define their conservation. It might be necessary to evaluate it along with the other data (no. of individuals, subpopulation size and number etc), which are being taken under consideration, during the compilation of Red Data Books of plant species.
74

Integrando aspectos filogenéticos e funcionais na biogeografia da conservação de vertebrados

Brum, Fernanda Thiesen January 2015 (has links)
Estimativas recentes mostram que as taxas atuais de extinção são muito maiores do que o indicado pelo registro fóssil, sendo as principais ameaças resultado da atividade humana. Como a crise da biodiversidade age em todas as escalas e não apresenta fronteiras políticas, a aplicação do arcabouço teórico da biogeografia da conservação e do planejamento sistemático para conservação se torna muito útil para a identificação de áreas com alto valor de conservação que sejam significativas em um contexto global, continental ou regional. Além da dimensão taxonômica, as dimensões funcional e filogenética da biodiversidade são componentes importantes para a conservação, e a sua perda implica não somente em perda de espécies, mas também na perda de funções ecossistêmicas e de trajetórias evolutivas. O objetivo desta tese foi avaliar como o impacto humano atual gerado pelo uso da terra, influencia padrões funcionais (relacionados ao risco de extinção, Capítulo 1) e filogenéticos (Capítulo 2) de distribuição, e como informações filogenéticas e de atributos podem ser utilizadas para informar priorização espacial pra conservação (Capítulo 3). Nos capítulos 1 e 2 encontrei que a influência do uso da terra sobre a biodiversidade não está restrita apenas às escalas mais locais e de paisagem, mas também já é perceptível em escalas geográficas amplas. Além disso, verifiquei que o uso da terra tem impacto não somente na dimensão taxonômica, mas também nas dimensões filogenética e funcional da diversidade de vertebrados nessa escala macrogeográfica. Isso demonstra a necessidade de um planejamento de ocupação e manejo de áreas utilizadas para atividades humana em ampla escala também, pois o impacto humano não se dá mais somente em escalas finas. O uso atual da terra representa uma ameaça real maior para algumas linhagens de anfíbios (Capítulo 1) e de primatas (Capítulo 2), como, por exemplo, Microhylidae e Atelidae, respectivamente. Isso reforça a necessidade de utilizarmos abordagens filogenéticas que identifiquem quais linhagens estão mais suscetíveis aos impactos decorrentes de atividades humanas. Ao tentar maximizar a a conservação das dimensões taxonômica, filogenética e funcional da biodiversidade de mamíferos, a congruência entre as áreas selecionadas como prioritárias foi baixa. A integração dos diferentes componentes da biodiversidade para selecionar áreas mais eficientes para a conservação das espécies ainda é um desafio. O desencontro entre as prioridades de conservação para as diferentes dimensões da biodiversidade ressalta a necessidade o desenvolvimento de abordagens mais integrativas para a conservação da biodiversidade. / Recent estimates show that current exticntion rates are much higher than the indicated by fossil records. The causes of this elevated rate are mostly result of human activities. The biodiversity crisis affects all scales and presents no political boundaries, the application of the theoretical and analytical framework of Conservation Biogeography and Systematic Conservation Planning becomes very useful to identify meaningful areas with high conservation value locally and globally. In addition to taxonomic diversity, functional and phylogenetic dimensions of biodiversity are also important components to preserve, and their loss implies not only on species number, but also loss of ecosystem services and evolutionary history. The aim of the thesis was to evaluate how impacts of human land use influences functional (related to extinction risk, Chapter 1) and phylogenetic (Chapter 2) distribution patterns, and how phylogenetic and trait information could be used to inform spatial conservation prioritization (Chapter 3). In the chapter 1 and 2 I found that the influence of land use on the biodiversity is not constrained to local and landscape scales, but has an effect at broad-scales too. Besides, I verified that land use impacts on phylogenetic and functional dimensions on macrogeographical scales. These results show a need of creating a broad scale planning for ocupation and management of areas intended to human activities. Current land use is a major threat to some lineages of amphibians (Chapter 1) and primates (Chapter 2), as for example Microhylidae and Atelidae respectively. That reinforces the need of phylogenetics approaches that identify which lineages are more exposed to human activities. We found low congruence between priority areas for maximize the conservation of taxonomic, functional and phylogenetics dimensions of biodiversity. The integration of the differnt componentes of diversity to conservation still is a chalenge. The mismatch of the conservation priorities across the different dimension highlights the necessity of an integrative approach to biodiversity conservation.
75

Integrando aspectos filogenéticos e funcionais na biogeografia da conservação de vertebrados

Brum, Fernanda Thiesen January 2015 (has links)
Estimativas recentes mostram que as taxas atuais de extinção são muito maiores do que o indicado pelo registro fóssil, sendo as principais ameaças resultado da atividade humana. Como a crise da biodiversidade age em todas as escalas e não apresenta fronteiras políticas, a aplicação do arcabouço teórico da biogeografia da conservação e do planejamento sistemático para conservação se torna muito útil para a identificação de áreas com alto valor de conservação que sejam significativas em um contexto global, continental ou regional. Além da dimensão taxonômica, as dimensões funcional e filogenética da biodiversidade são componentes importantes para a conservação, e a sua perda implica não somente em perda de espécies, mas também na perda de funções ecossistêmicas e de trajetórias evolutivas. O objetivo desta tese foi avaliar como o impacto humano atual gerado pelo uso da terra, influencia padrões funcionais (relacionados ao risco de extinção, Capítulo 1) e filogenéticos (Capítulo 2) de distribuição, e como informações filogenéticas e de atributos podem ser utilizadas para informar priorização espacial pra conservação (Capítulo 3). Nos capítulos 1 e 2 encontrei que a influência do uso da terra sobre a biodiversidade não está restrita apenas às escalas mais locais e de paisagem, mas também já é perceptível em escalas geográficas amplas. Além disso, verifiquei que o uso da terra tem impacto não somente na dimensão taxonômica, mas também nas dimensões filogenética e funcional da diversidade de vertebrados nessa escala macrogeográfica. Isso demonstra a necessidade de um planejamento de ocupação e manejo de áreas utilizadas para atividades humana em ampla escala também, pois o impacto humano não se dá mais somente em escalas finas. O uso atual da terra representa uma ameaça real maior para algumas linhagens de anfíbios (Capítulo 1) e de primatas (Capítulo 2), como, por exemplo, Microhylidae e Atelidae, respectivamente. Isso reforça a necessidade de utilizarmos abordagens filogenéticas que identifiquem quais linhagens estão mais suscetíveis aos impactos decorrentes de atividades humanas. Ao tentar maximizar a a conservação das dimensões taxonômica, filogenética e funcional da biodiversidade de mamíferos, a congruência entre as áreas selecionadas como prioritárias foi baixa. A integração dos diferentes componentes da biodiversidade para selecionar áreas mais eficientes para a conservação das espécies ainda é um desafio. O desencontro entre as prioridades de conservação para as diferentes dimensões da biodiversidade ressalta a necessidade o desenvolvimento de abordagens mais integrativas para a conservação da biodiversidade. / Recent estimates show that current exticntion rates are much higher than the indicated by fossil records. The causes of this elevated rate are mostly result of human activities. The biodiversity crisis affects all scales and presents no political boundaries, the application of the theoretical and analytical framework of Conservation Biogeography and Systematic Conservation Planning becomes very useful to identify meaningful areas with high conservation value locally and globally. In addition to taxonomic diversity, functional and phylogenetic dimensions of biodiversity are also important components to preserve, and their loss implies not only on species number, but also loss of ecosystem services and evolutionary history. The aim of the thesis was to evaluate how impacts of human land use influences functional (related to extinction risk, Chapter 1) and phylogenetic (Chapter 2) distribution patterns, and how phylogenetic and trait information could be used to inform spatial conservation prioritization (Chapter 3). In the chapter 1 and 2 I found that the influence of land use on the biodiversity is not constrained to local and landscape scales, but has an effect at broad-scales too. Besides, I verified that land use impacts on phylogenetic and functional dimensions on macrogeographical scales. These results show a need of creating a broad scale planning for ocupation and management of areas intended to human activities. Current land use is a major threat to some lineages of amphibians (Chapter 1) and primates (Chapter 2), as for example Microhylidae and Atelidae respectively. That reinforces the need of phylogenetics approaches that identify which lineages are more exposed to human activities. We found low congruence between priority areas for maximize the conservation of taxonomic, functional and phylogenetics dimensions of biodiversity. The integration of the differnt componentes of diversity to conservation still is a chalenge. The mismatch of the conservation priorities across the different dimension highlights the necessity of an integrative approach to biodiversity conservation.
76

Integrando aspectos filogenéticos e funcionais na biogeografia da conservação de vertebrados

Brum, Fernanda Thiesen January 2015 (has links)
Estimativas recentes mostram que as taxas atuais de extinção são muito maiores do que o indicado pelo registro fóssil, sendo as principais ameaças resultado da atividade humana. Como a crise da biodiversidade age em todas as escalas e não apresenta fronteiras políticas, a aplicação do arcabouço teórico da biogeografia da conservação e do planejamento sistemático para conservação se torna muito útil para a identificação de áreas com alto valor de conservação que sejam significativas em um contexto global, continental ou regional. Além da dimensão taxonômica, as dimensões funcional e filogenética da biodiversidade são componentes importantes para a conservação, e a sua perda implica não somente em perda de espécies, mas também na perda de funções ecossistêmicas e de trajetórias evolutivas. O objetivo desta tese foi avaliar como o impacto humano atual gerado pelo uso da terra, influencia padrões funcionais (relacionados ao risco de extinção, Capítulo 1) e filogenéticos (Capítulo 2) de distribuição, e como informações filogenéticas e de atributos podem ser utilizadas para informar priorização espacial pra conservação (Capítulo 3). Nos capítulos 1 e 2 encontrei que a influência do uso da terra sobre a biodiversidade não está restrita apenas às escalas mais locais e de paisagem, mas também já é perceptível em escalas geográficas amplas. Além disso, verifiquei que o uso da terra tem impacto não somente na dimensão taxonômica, mas também nas dimensões filogenética e funcional da diversidade de vertebrados nessa escala macrogeográfica. Isso demonstra a necessidade de um planejamento de ocupação e manejo de áreas utilizadas para atividades humana em ampla escala também, pois o impacto humano não se dá mais somente em escalas finas. O uso atual da terra representa uma ameaça real maior para algumas linhagens de anfíbios (Capítulo 1) e de primatas (Capítulo 2), como, por exemplo, Microhylidae e Atelidae, respectivamente. Isso reforça a necessidade de utilizarmos abordagens filogenéticas que identifiquem quais linhagens estão mais suscetíveis aos impactos decorrentes de atividades humanas. Ao tentar maximizar a a conservação das dimensões taxonômica, filogenética e funcional da biodiversidade de mamíferos, a congruência entre as áreas selecionadas como prioritárias foi baixa. A integração dos diferentes componentes da biodiversidade para selecionar áreas mais eficientes para a conservação das espécies ainda é um desafio. O desencontro entre as prioridades de conservação para as diferentes dimensões da biodiversidade ressalta a necessidade o desenvolvimento de abordagens mais integrativas para a conservação da biodiversidade. / Recent estimates show that current exticntion rates are much higher than the indicated by fossil records. The causes of this elevated rate are mostly result of human activities. The biodiversity crisis affects all scales and presents no political boundaries, the application of the theoretical and analytical framework of Conservation Biogeography and Systematic Conservation Planning becomes very useful to identify meaningful areas with high conservation value locally and globally. In addition to taxonomic diversity, functional and phylogenetic dimensions of biodiversity are also important components to preserve, and their loss implies not only on species number, but also loss of ecosystem services and evolutionary history. The aim of the thesis was to evaluate how impacts of human land use influences functional (related to extinction risk, Chapter 1) and phylogenetic (Chapter 2) distribution patterns, and how phylogenetic and trait information could be used to inform spatial conservation prioritization (Chapter 3). In the chapter 1 and 2 I found that the influence of land use on the biodiversity is not constrained to local and landscape scales, but has an effect at broad-scales too. Besides, I verified that land use impacts on phylogenetic and functional dimensions on macrogeographical scales. These results show a need of creating a broad scale planning for ocupation and management of areas intended to human activities. Current land use is a major threat to some lineages of amphibians (Chapter 1) and primates (Chapter 2), as for example Microhylidae and Atelidae respectively. That reinforces the need of phylogenetics approaches that identify which lineages are more exposed to human activities. We found low congruence between priority areas for maximize the conservation of taxonomic, functional and phylogenetics dimensions of biodiversity. The integration of the differnt componentes of diversity to conservation still is a chalenge. The mismatch of the conservation priorities across the different dimension highlights the necessity of an integrative approach to biodiversity conservation.
77

Biogeography and conservation of Amazon palms

Valles, Carlos Mariano Alvez 22 February 2018 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2018-03-27T19:45:32Z No. of bitstreams: 1 carlosmarianoalvesvalles.pdf: 5972976 bytes, checksum: 908806a8077c5751983d6b9690d566cd (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-04-09T19:22:27Z (GMT) No. of bitstreams: 1 carlosmarianoalvesvalles.pdf: 5972976 bytes, checksum: 908806a8077c5751983d6b9690d566cd (MD5) / Made available in DSpace on 2018-04-09T19:22:27Z (GMT). No. of bitstreams: 1 carlosmarianoalvesvalles.pdf: 5972976 bytes, checksum: 908806a8077c5751983d6b9690d566cd (MD5) Previous issue date: 2018-02-22 / - / Palms are abundant in tropical forests and are recognized as effective bioindicators of hot climates. Moreover, play an important ecological and economic role for local populations. Though palms remain relatively well-conserved, they are under increasing pressure from deforestation. Therefore, endemicity is important for the delimitation of conservation areas. The purposes of the study is 1) to synthesize available information in the literature on species diversity, ecological aspects, use and conservation of Amazon palms (Chapter 1); to analyse palms species richness patterns relative to the latitudinal gradient, sample efforts, and deforestation in the Amazon region (Chapter 2); to compare richness and floristic similarities patterns among the Amazonian sub-regions (Chapter 2); to detect endemic areas for palms in the Amazon region (Chapter 3); and to determine whether the species that define these endemic areas are protected within conservation units (Chapter 3). Records of occurrences were extracted from the Global Biodiversity Information Facility (GBIF). The final dataset consisted of 17,310 records, for 177 species of Amazonian palms. The areas with the greatest richness were in the western, central and northeastern Amazon, principally at latitudes 0–5ºS. Most palms species grow in different habitats, but the highest species richness are found in terra firme forest. Palms are widely used with different category of use according to the regions and species, principally are used for human consumption, elaboration of utensils and tools, and construction of houses. Highest rates of deforestation (>2000 km2) were found in the southern and eastern brazilian Amazon, which coincide with low species richness and gaps in records. Similarity analysis resulted in two groups of sub-regions: the first included the Amazon s.s., Andes and Guiana, and the other group included the Plateau and Gurupi sub-region. The combination of PAE and NDM-VNDM analyses resulted in eight endemic palm areas in western Amazon shared with Andean sub-region. Of the species that define the endemic areas, five are threatened with extinction in one of three IUCN categories (EN, VU, NT), and they are not protected in any conservation units. In conclusion, the western Amazon, besides having high palm richness, also has palm endemic areas, especially, near the Andean sub-region and the Peruvian Amazon, and areas with low species richness, especially those areas with data deficiency, need to be further researched for a better knowledge of their diversity and richness patterns.
78

Population biology of the <em>Primula sibirica</em> group species inhabiting frequently disturbed seashore meadows: implications for management

Rautiainen, P. (Pirjo) 29 March 2006 (has links)
Abstract Many plant species inhabiting the seashore meadows of the Bothnian Bay, especially early successional ones, have become threatened. Isostatic land uplift creates virgin land for early successional species to colonise. However, at the same time it gradually elevates the habitat and eventually makes the habitat unsuitable for them. Disturbances of the waterfront may slow down succession and create new empty sites. In order to persist on the shores, pioneer species have to be able to colonise new sites by seeds, vegetative propagules or growth. In this thesis I studied the status of an endangered early successional grass species, A. fulva var. pendulina, at the Liminka Bay. According to a matrix population model based on eight years of observations (1992–1999), the population seemed not to be in immediate danger of extinction. However, simulations based on four-year field observations (2000–2003) indicated that if the current trend continues, the species will decrease considerably in area in the next 30 years. In the field studies no seedlings or viable seeds of A. fulva were found. In spite of this, high genotypic diversity was found in the A. fulva population, suggesting that sexual reproduction has taken place at some time during the history of the population. Analysis of the population structure revealed a low level of genotypic differentiation between subpopulations and significant sub-structuring within subpopulations. The overall pattern of genetic variation suggests that the population has characters of both stepping-stone and metapopulation models. The results of the study on the ability of a seashore plant Potentilla anserina ssp. egedii to change its allocation of resources to sexual and vegetative reproduction according to competitive stress implied that the species can modify the allocation of resources to different life-history traits. For a plant living in disturbance-prone environment, it may be beneficial to be able to rapidly track the competition-free space formed by disturbances by changing its reproductive pattern. Management studies on three endangered seashore plant species showed that deterioration of suitable habitats of A. fulva and Primula nutans var. jokelae could be slowed down by management, and the vegetative and/or sexual reproduction of these species was enhanced. However, in the case of Puccinellia phryganodes, no positive response to management was observed.
79

Den Europeiska idegranens återväxtproblematik / The regeneration issues of European Yew (Taxus baccata)

Ermalm, Sandra January 2020 (has links)
Abstract I hela Europa har idegranen problem med återväxten. Olika återväxthämmande faktorer påverkar föryngringen i olika stadier, och det är aldrig bara en anledning till att föryngringen inte lyckas. Idegranen är skuggtålig men behöver ljus. Den gynnas av lövfällande bestånd då den drar nytta av vårens öppna krontak. I bristen på ljus stannar de yngre plantorna av i utvecklingen, dessa dör eller äts upp och föryngringen uteblir. Nästan alla naturligt förekommande äldre plantor (&gt; 2 år) betas. Bete av idegran är idag ett stort problem för föryngringen då rådjurens matsmältning klarar av idegran. I Stockholms norra skärgård är det framför allt betet som hämmar plantornas utveckling. Idegranen har problem med sin återväxt och detta sägs vara ett karaktärsdrag för arten.
80

Population dynamics of the threatened staghorn coral, Acropora cervicornis, and the development of a species-specific monitoring protocol

Goergen, Elizabeth 03 May 2018 (has links)
Historically, Acropora cervicornis was found in high densities on many Caribbean, Florida, and Gulf of Mexico reefs. A disease outbreak in the late 1970s and 80s caused up to 99% loss of A. cervicornis cover at some sites, leaving populations sparsely distributed throughout its range and typically found as isolated colonies. Even though populations are depauperate causing a decrease in sexual reproduction, its fast growth rate and ability to reproduce through asexual fragmentation affords this species the potential for quick recovery and population growth. However, limited to no natural recovery has been documented. Many of these populations are poorly studied because most monitoring programs are not designed to capture A. cervicornis’ unique life history characteristics. Its patchy distribution, complex growth form, frequent fragmentation, and dislodgment present a challenge for long term tracking. Furthermore, its ability to exist from small isolated colonies to semi-continuous patches spanning hectares makes defining individuals to assess abundance, survival, health, and growth a difficult task. The aim of this dissertation was to develop a species-specific monitoring protocol to describe the abundance and cover of A. cervicornis and the effects of disease, predation, and disturbance events across space and time. The monitoring protocol was developed and used across three sub-regions of the Florida Reef Tract (Broward County, Middle Keys, and Dry Tortugas). Several permanent 3.5 m radial plots were installed across multiple sites in each sub-region. A species census, percent cover, and demographic data of a sub-set of colonies were collected three times per year (winter, summer, and fall) from 2008-2016. These results were then used to assist in designing and testing optimal outplant strategies. Outplanting occurred at seven sites in Broward County, FL between 2012- 2015. Experiments were designed to assess the effects outplant colony density, host genotype, colony size, and attachment technique had on colony survival, growth, and health. The monitoring protocol was successfully used for identifying spatial and temporal patterns and trends in cover, disease, and predation on A. cervicornis across a range of population sizes. Percent cover of living A. cervicornis declined significantly during the duration of the project. Disease prevalence and occurrence was highest during the summer. Colony size and volume increased with depth and were the largest in the Broward County sub-region. Disease caused the most mortality, however fireworms were the most prevalent cause of recent mortality. Disease and predation were more prevalent on masses (individuals larger than 1.5 m in diameter). The outplant experiments showed that colony survival and health were greatest when colonies had greater than 15 cm in total tissue and in densities less than 1 col/m2. Host genotype and outplant site had variable effects on survival and growth. Outplanted colonies quickly acclimated to their environment and increased colony abundance within sites by fragmentation. Prevalence of disease and predation were lower on outplanted colonies than wild colonies. Frequent disturbances such as tropical storms, hurricanes, and disease events caused increased, prolonged, and widespread mortality and fragmentation, however periods void of disturbances resulted in recovery and growth. Therefore, reducing the effects of climate change and determining and decreasing the causes of disease could promote species recovery. In the meantime, population enhancement by outplanting is a viable way to assist species conservation and recovery.

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