Global ETD Search

1	Variation Among Fish Species in the Stoichiometry of Nutrient Excretion Torres, Lisette E. 05 August 2005 (has links) No description available. ecological stoichiometry nutrient cycling species identity ecosystem functioning reservoir fish biodiversity
2	Biotic resistance in freshwater fish communities Henriksson, Anna January 2015 (has links) Invasions of non-native species cause problems in ecosystems worldwide, and despite the extensive effort that has been put into research about invasions, we still lack a good understanding for why some, but not other, communities resist these invasions. In this doctoral thesis I test hypotheses on biotic resistance using a large dataset of more than 1000 both failed and successful introductions of freshwater fish into Swedish lakes. We have found that the classic species richness hypothesis is a poor descriptor of introduction success because it fails to acknowledge that resident species contribute to the resistance in different ways. We developed a new measure of biotic resistance, the weighted species richness, which takes into account that the resident species contributes to the resistance with different strength and sign. Further, we correlated performance traits of species in their role as an invader and as a resident species to predict how the biotic resistance of these communities would develop over time. We found a positive correlation between performance traits: Some species have high introduction success, they make a large contribution to the resistance, and they cause extinctions when introduced but do not go extinct themselves when other species establishes, whereas other species are weak performers in these respects. Thus, the biotic resistance of these communities should grow stronger as non-native species accumulates. These results give us clues about what type of communities that should be most sensitive to further invasions, i.e., communities harboring species weak performers. My results show that the biotic resistance of communities is an important factor in determining invasibility of a community. They also show that methods for quantifying resistance must take into account how interactions are structured in nature. What determine the biotic resistance of a community is the type of interactions that the resident species have with the invader and not the species richness of the community. biotic resistance freshwater fish introductions invasions invasion success invasibility invasiveness species richness saturation species identity weighted species richness
3	Species identity and the functioning of ecosystems: the role of detritivore traits and trophic interactions in connecting of multiple ecosystem responses Hines, Jes, Eisenhauer, Nico 05 April 2023 (has links) Ecosystems world-wide experience changes in species composition in response to natural and anthropogenic changes in environmental conditions. Research to date has greatly improved our understanding of how species affect focal ecosystem functions. However, because measurements of multiple ecosystem functions have not been consistently justified for any given trophic group, it is unclear whether interpretations of research syntheses adequately reflect the contributions of consumers to ecosystems. Using model communities assembled in experimental microcosms, we examined the relationship between four numerically dominant detritivore species and six ecosystem functions that underpin fundamental aspects of carbon and nitrogen cycling aboveand below-ground. We tested whether ecosystem responses to changes in detritivore identity depended upon species trait dissimilarity, food web compartment (aboveground, belowground, mixed) or number of responses considered (one to six). We found little influence of detritivore species identity on brown (i.e. soil-based) processes. Only one of four detritivore species uniquely influenced decomposition, and detritivore species did not vary in their influence on soil nitrogen pools (NO3 − and NH4 +), or root biomass. However, changes in detritivore identity influenced multiple aboveground ecosystem functions. That is, by serving as prey, ecosystem engineers and occasionally also as herbivores as well as detritivores, these species altered the strength of aboveground predator–herbivore interactions and plant–shoot biomass. Yet, dissimilarity of detritivore functional traits was not associated with dissimilarity of ecosystem functioning. These results serve as an important reminder that consumers influence ecosystem processes via multiple energy channels and that food web interactions set important context for consumer-mediated effects on multiple ecosystem functions. Given that species are being lost, gained and redistributed at unprecedented rates, we can anticipate that changes in species identity will have additional ecosystem consequences beyond those predicted by species’ primary functional role. info:eu-repo/classification/ddc/570 ddc:570
4	Birds, bats and arthropods in tropical agroforestry landscapes: Functional diversity, multitrophic interactions and crop yield Maas, Bea 20 November 2013 (has links) No description available. 630 birds bats arthropods multitrophic interactions agroforestry tropical landscape forest margin landscape functional diversity crop yield exclosure experiments experimental exclusion arthropod suppression avian predation ecosystem services mist netting point counts artificial plasticine caterpillar dummy experiment biological control monitoring mapping Lemon-bellied White-eye Grosbeak Starling Zosterops chloris Scissiostrum dubium Theobroma cacao cacao agroforestry cacao diseases cacao harvest cacao pests flying vertebrates aerial insectivores volant vertebrates logging breeding colony flower herbivory mesopredator release predatory insects ants spiders aphids Lepidoptera Coleoptera Lepidopteran larvae sustainable agriculture sustainable agroforestry management implications management recommendations applied managament extensive land use management landscape management conservation biodiversity-friendly dbh distance to forest forest proximity habitat conversion herbivory Indonesia insectivorous bats insectivorous birds invertebrates Central Sulawesi Napu valley leaf gleaning leaf herbivory pests insects phytophagous insects plant productivity remnant forest trees shade tree managament South-east Asia Paleotropics tropical landscape tree height landscape gradient local shade management Cacao Pod Borer Cherelle Wilt fruit abortion Helopeltis sulawesi deforestation habitat fragmentation land use intensification forest margin species critical decline predation experiment species-specific functions Southeast Asia biodiversity conservation mesopredators food security human welfare human well-being poverty alleviation poverty reduction smallholder cacao smallholder plantation cacao farmers sustainable cacao management landscape perspective landscape scale large scale field experiment long term field experiment human wellbeing economic importance economic value valuation ecosystem services landscape matrix yield quality yield quantity fruit productivity species identity species diversity species richness ecosystem functioning pesticide use chemical compounds complex food web tritrophic interactions wildlife-friendly rural livelihoods endangered bird species endangered bat species endemic endemic birds endemic bats beneficial impact IUCN Lore Lindu National Park bioindicator indicator species forest margin agricultural habitat agroforestry systems population density predation activity species activity cacao flower cacao pod Orthoptera linear mixed effect models Tukey Post Hoc Test AICc model selection generalized least squares restricted maximum likelihood model simplification species richness estimator species accumulation linear mixed-effects models Likelihood Ratio Test Maximum Likelihood nocturnal insects diurnal arthropods nocturnal arthropods diurnal insects landscape context Land- und Forstwirtschaft (PPN621302791)

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