37 resultados para Seedling bank.
Resumo:
Introduced browsing animals negatively impact New Zealand's indigenous ecosystems. Eradicating introduced browsers is currently unfeasible at large scales, but culling since the 1960s has successfully reduced populations to a fraction of their earlier sizes. Here we ask whether culling of ungulates has allowed populations of woody plant species to recover across New Zealand forests. Using 73 pairs of permanent fenced exclosure and unfenced control plots, we found rapid increases in sapling densities within exclosures located in disturbed forests, particularly if a seedling bank was already present. Recovery was slower in thinning stands and hampered by dense fern cover. We inferred ungulate diet preference from species recovery rates inside exclosures to test whether culling increased abundance of preferred species across a national network of 574 unfenced permanent forest plots. Across this network, saplings were observed irrespective of their preference to ungulates in the 1970s, but preferred species were rarer within disturbed sites in the 1990s after long-term culling and despite nationwide increases in sapling densities. This indicates that preferred species are relatively heavily affected by browsing after culling, presumably because remaining animals will increase consumption of preferred species as competition is reduced. Our results clearly suggest that culling will not return preferred plants to the landscape immediately, even given suitable conditions for regeneration. Complete removal of ungulates rather than simply reducing their densities may be required for recovery in heavily browsed temperate forests, but since this is only feasible at small spatial scales, management efforts must target sites of high conservation value. © 2012 Elsevier Ltd.
Resumo:
Questions - Are the germinable seed banks of upland heath and blanket bog reduced following wildfires? Are some species at particular risk? Do the impacts of wildfires on seed banks differ between heathlands and blanket bog?
Location - Northern Ireland, United Kingdom.
Methods - Vegetation surveys and seed bank sampling were conducted in 2012 at burned and unburned areas within six upland sites where large wildfires had occurred during spring 2011. Differences in seedling abundance, species richness and Jaccard similarity indices between burned and unburned areas were compared using GLMMs. Differences in the community composition were examined using pRDA.
Results - In total, 24 of the 51 species in the vegetation were detected in the germinable seed bank. Species richness and the abundance of seedlings other than Calluna vulgaris were lower in areas where wildfires had occurred. Species composition of both germinable seed banks and vegetation differed between burned and unburned areas within sites; with negative associations between burned areas and some key indicator species including Drosera rotundifolia, Eriophorum vaginatum, Empetrum nigrum, Narthecium ossifragum and Trichophorum germanicum. We did not find any evidence of significant interactions between burning and habitat, suggesting that wildfires had similar impacts on each species regardless of the habitat in which they occurred.
Conclusions - This study differs from other UK studies in that it examines impacts of wildfires at sites that have not been previously intensively managed by burning. In particular, we highlight potential impacts on N. ossifragum and D. rotundifolia, which are key components of the upland flora and, to our knowledge, were not present in previous UK studies.
Much Ado About Nothing: The Limitation of Liability and the Market for 19th century Irish Bank Stock
Resumo:
Abstract Limited liability is widely believed to be a prerequisite for the emergence of an active and liquid securities market because the transactions costs associated with trading ownership of unlimited liability firms are viewed as prohibitive. In this article, we examine the trading of shares in an Irish bank, which limited its liability in 1883. Using this bank’s archives, we assemble a time series of trading data, which we test for structural breaks. Our results suggest that the move to limited liability had a negligible impact upon the trading of this bank’s shares.
The Trading of Unlimited Liability Bank Shares in Nineteenth Century Ireland: The Bagehot Hypothesis
Resumo:
In the mid-1820s, banks became the first businesses in Great Britain and Ireland to be allowed to form freely on an unlimited liability joint-stock basis. Walter Bagehot warned that their shares would ultimately be owned by widows, orphans, and other impecunious individuals. Another hypothesis is that the governing bodies of these banks, constrained by special legal restrictions on share trading, acted effectively to prevent such shares being transferred to the less wealthy. We test both conjectures using the archives of an Irish joint-stock bank. The results do not support Bagehot's hypothesis.
Resumo:
The joint-stock banks that established after the liberalizing legislation of 1826 were periodically criticized during the nineteenth century for their low-quality and rapidly deteriorating shareholder constituencies. The quality of a bank's shareholding constituency was of paramount importance because of unlimited shareholder liability. Using archival records, this article examines the quality of bank shareholder constituencies over the nineteenth century. The main finding is that shareholder constituencies did not deteriorate in quality until the introduction of limited liability. The non-deterioration of constituencies is attributed to bank deeds which locked in the aggregate quality of shareholder constituencies by empowering directors to vet all share transfers.
Resumo:
Is there evidence that market forces effectively discipline risk management behaviour within Chinese financial institutions? This study analyses information from a comprehensive sample of Chinese banks over the 1998-2008 period. Market discipline is captured through the impact of four sets of factors namely, market concentration, interbank deposits, information disclosure, and ownership structure. We find some evidence of a market disciplining effect in that: (i) higher (lower) levels of market concentration lead banks to operate with a lower (higher) capital buffer; (ii) joint-equity banks that disclose more information to the public maintain larger capital ratios; (iii) full state ownership reduces the sensitivity of changes in a bank's capital buffer to its level of risk;(iv) banks that release more transparent financial information hold more capital against their non-performing loans. © 2010 Springer Science+Business Media, LLC.
Resumo:
This paper introduces a new technique for palmprint recognition based on Fisher Linear Discriminant Analysis (FLDA) and Gabor filter bank. This method involves convolving a palmprint image with a bank of Gabor filters at different scales and rotations for robust palmprint features extraction. Once these features are extracted, FLDA is applied for dimensionality reduction and class separability. Since the palmprint features are derived from the principal lines, wrinkles and texture along the palm area. One should carefully consider this fact when selecting the appropriate palm region for the feature extraction process in order to enhance recognition accuracy. To address this problem, an improved region of interest (ROI) extraction algorithm is introduced. This algorithm allows for an efficient extraction of the whole palm area by ignoring all the undesirable parts, such as the fingers and background. Experiments have shown that the proposed method yields attractive performances as evidenced by an Equal Error Rate (EER) of 0.03%.