A Hynd

The University of Sheffield, Sheffield, England, United Kingdom

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Publications (6)21.24 Total impact

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    ABSTRACT: We describe a novel method for quantifying ecosystem drivers that potentially compromise the effectiveness of agri-environment schemes. We use three sources of data that for many countries are already in the public domain: governmental agricultural statistics, which provide a quantitative assessment of farming intensity in the ‘working landscape’, data on threat status and species distribution for plants and butterflies from conservation agencies and similar bodies, and functional traits of plant species abstracted from published databases.Changes in land use alter ecosystem processes which in turn modify both biodiversity and representation of functional types at the landscape scale. We interpret functional shifts to quantify important ecological drivers of floristic and faunal change and their causal land use origins.We illustrate the power of this approach by means of a worked example. We demonstrate that, despite conservation policies to counteract them, eutrophication, identified by leaf nitrogen content, and abandonment, correlated with plant canopy height, are still causing biodiversity loss to native higher plants and butterflies in the English countryside.We use our analyses to suggest how conservation policies can be made more effective and discuss how similar approaches could be applied elsewhere. This article is protected by copyright. All rights reserved.
    Functional Ecology 10/2014; 28(5). DOI:10.1111/1365-2435.12253 · 4.86 Impact Factor
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    ABSTRACT: Specific leaf area (SLA), a key element of the 'worldwide leaf economics spectrum', is the preferred 'soft' plant trait for assessing soil fertility. SLA is a function of leaf dry matter content (LDMC) and leaf thickness (LT). The first, LDMC, defines leaf construction costs and can be used instead of SLA. However, LT identifies shade at its lowest extreme and succulence at its highest, and is not related to soil fertility. Why then is SLA more frequently used as a predictor of soil fertility than LDMC? SLA, LDMC and LT were measured and leaf density (LD) estimated for almost 2000 species, and the capacity of LD to predict LDMC was examined, as was the relative contribution of LDMC and LT to the expression of SLA. Subsequently, the relationships between SLA, LDMC and LT with respect to soil fertility and shade were described. Although LD is strongly related to LDMC, and LDMC and LT each contribute equally to the expression of SLA, the exact relationships differ between ecological groupings. LDMC predicts leaf nitrogen content and soil fertility but, because LT primarily varies with light intensity, SLA increases in response to both increased shade and increased fertility. Gradients of soil fertility are frequently also gradients of biomass accumulation with reduced irradiance lower in the canopy. Therefore, SLA, which includes both fertility and shade components, may often discriminate better between communities or treatments than LDMC. However, LDMC should always be the preferred trait for assessing gradients of soil fertility uncoupled from shade. Nevertheless, because leaves multitask, individual leaf traits do not necessarily exhibit exact functional equivalence between species. In consequence, rather than using a single stand-alone predictor, multivariate analyses using several leaf traits is recommended.
    Annals of Botany 09/2011; 108(7):1337-45. DOI:10.1093/aob/mcr225 · 3.30 Impact Factor
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    ABSTRACT: Genome size is a function, and the product, of cell volume. As such it is contingent on ecological circumstance. The nature of 'this ecological circumstance' is, however, hotly debated. Here, we investigate for angiosperms whether stomatal size may be this 'missing link': the primary determinant of genome size. Stomata are crucial for photosynthesis and their size affects functional efficiency. Stomatal and leaf characteristics were measured for 1442 species from Argentina, Iran, Spain and the UK and, using PCA, some emergent ecological and taxonomic patterns identified. Subsequently, an assessment of the relationship between genome-size values obtained from the Plant DNA C-values database and measurements of stomatal size was carried out. Stomatal size is an ecologically important attribute. It varies with life-history (woody species < herbaceous species < vernal geophytes) and contributes to ecologically and physiologically important axes of leaf specialization. Moreover, it is positively correlated with genome size across a wide range of major taxa. Stomatal size predicts genome size within angiosperms. Correlation is not, however, proof of causality and here our interpretation is hampered by unexpected deficiencies in the scientific literature. Firstly, there are discrepancies between our own observations and established ideas about the ecological significance of stomatal size; very large stomata, theoretically facilitating photosynthesis in deep shade, were, in this study (and in other studies), primarily associated with vernal geophytes of unshaded habitats. Secondly, the lower size limit at which stomata can function efficiently, and the ecological circumstances under which these minute stomata might occur, have not been satisfactorally resolved. Thus, our hypothesis, that the optimization of stomatal size for functional efficiency is a major ecological determinant of genome size, remains unproven.
    Annals of Botany 04/2010; 105(4):573-84. DOI:10.1093/aob/mcq011 · 3.30 Impact Factor
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    ABSTRACT: A simple protocol is presented for a functional classification of European grassland species using attributes that can be quickly and easily measured. These attributes relate to habitat fertility, intensity of grazing and disturbance. As a surrogate for habitat fertility we use leaf nitrogen predicted by multiple regression from three leaf characters, specific leaf area, dry matter content and size. Average maximum canopy height of the component species of our vegetation, weighted by abundance, provides a rough assessment of the intensity of grazing. The percentage of annuals and vernal geophytes assesses disturbance. Functional descriptions of the CLIMB grasslands were produced and trends relating to both ecosystem and economic processes were detected. Most importantly, our estimate of habitat fertility predicts land use change. Within NW Europe the threat to grassland of conservation value from agricultural ‘improvement’ increases with fertility while in the Mediterranean increased fertility decreases the likelihood of abandonment. These mathematical relationships between an ecological attribute and a perception of economic potential can help us to routinely combine ecological and economic data. This is an important preliminary step as we attempt to reconcile practical economic concerns and conservation objectives within working landscapes.
    Basic and Applied Ecology 01/2005; 6(2):119–131. DOI:10.1016/j.baae.2005.01.006 · 2.39 Impact Factor
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    ABSTRACT: Conservation initiatives are failing to arrest the global loss of biodiversity. From our mechanistic studies of ecology and economics, we suggest that for grazing lands the root cause of this failure is a powerful economic deterrent to measures designed to protect diversity. We identify an exponential relationship between monetary returns and intensification of farming methods over an extremely wide range of grassland productivities and farm systems. At intermediate to high levels of fertility, however, this exponential increase in financial benefit from intensification is associated with a decline in biodiversity and an acceleration of the ecological processes driving species losses from grassland ecosystems.
    Biological Conservation 07/2004; 122(2):263-273. DOI:10.1016/j.biocon.2004.07.016 · 4.04 Impact Factor
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    ABSTRACT: Question: A set of easily-measured ('soft') plant traits has been identified as potentially useful predictors of ecosystem functioning in previous studies. Here we aimed to discover whether the screening techniques remain operational in widely contrasted circumstances, to test for the existence of axes of variation in the particular sets of traits, and to test for their links with 'harder' traits of proven importance to ecosystem functioning. Location: central-western Argentina, central England, north-ern upland Iran, and north-eastern Spain. Recurrent patterns of ecological specialization: Through ordination of a matrix of 640 vascular plant taxa by 12 stand-ardized traits, we detected similar patterns of specialization in the four floras. The first PCA axis was identified as an axis of resource capture, usage and release. PCA axis 2 appeared to be a size-related axis. Individual PCA for each country showed that the same traits remained valuable as predictors of resource capture and utilization in all of them, despite their major differences in climate, biogeography and land-use. The results were not significantly driven by particular taxa: the main traits determining PCA axis 1 were very similar in eudicotyledons and monocotyledons and Asteraceae, Fabaceae and Poaceae. Links between recurrent suites of 'soft' traits and 'hard' traits: The validity of PCA axis 1 as a key predictor of resource capture and utilization was tested by comparisons between this axis and values of more rigorously established predictors ('hard' traits) for the floras of Argentina and England. PCA axis 1 was correlated with variation in relative growth rate, leaf nitrogen content, and litter decomposition rate. It also coincided with palatability to model generalist herbivores. Therefore, location on PCA axis 1 can be linked to major ecosystem processes in those habitats where the plants are dominant. Conclusion: We confirm the existence at the global scale of a major axis of evolutionary specialization, previously recog-nised in several local floras. This axis reflects a fundamental trade-off between rapid acquisition of resources and conserva-tion of resources within well-protected tissues. These major trends of specialization were maintained across different envi-ronmental situations (including differences in the proximate causes of low productivity, i.e. drought or mineral nutrient deficiency). The trends were also consistent across floras and major phylogenetic groups, and were linked with traits di-rectly relevant to ecosystem processes.
    Journal of Vegetation Science 01/2004; 15:295-304. · 3.37 Impact Factor