Defensive adaptations of Thuja plicata to ungulate browsing: a comparative study between mainland and island populations

Forests on the Haida Gwaii (HG) archipelago (British Columbia, Canada) evolved for about 10,000 years in the absence of large-mammal browsing. The introduction of black-tailed deer (Odocoileus hemionus sitkensis) from the mainland prior to 1901 provides an opportunity to evaluate changes in the adaptive defensive responses of plants to herbivory. We compared (1) food choice by deer and (2) chemical defence (terpene concentrations) between HG and mainland red cedars (Thuja plicata) using (1) nursery-grown seedlings never exposed to deer, (2) branches from trees that grew before the introduction of deer ("old trees") and (3) saplings exposed to deer herbivory on the mainland and on HG. We used the first two plant categories to test the hypothesis that plants that evolve under low herbivory levels have lower anti-herbivore defences. We used saplings to study the consequences of the dramatic increase in browsing on HG. During food experiments, deer preferred HG seedlings and old tree branches compared to those from the mainland. Total monoterpene concentrations were much higher than diterpene concentrations in all plant categories. Within plant categories, multivariate analysis showed that terpene profiles differed significantly between HG and mainland red cedars: HG seedlings and old trees had lower monoterpene levels. These results suggest that some monoterpenes may be determinants of deer food choice and that the defences of HG plants are less effective than those of mainland plants. The deer used branches from HG and mainland saplings indiscriminately. However, terpene profiles differed significantly between HG and mainland saplings, with multivariate analysis suggesting a higher defensive response in browsed HG saplings. Monoterpene profiles were different in lightly and heavily browsed saplings from HG, suggesting that under the current browsing regime, individuals with the greatest constitutive defences, or with greatest potential for induced defences, grow better and are selected on HG.     

Altitude and woody cover control recruitment of Helleborus foetidus in a Mediterranean mountain area

This study explores how variation of macro- and micro-climatic conditions associated with changes in altitude affect early recruitment dynamics of the perennial herb Helleborus foetidus (Ranunculaceae). We also analyse the relevance of facilitation by woody vegetation on seedling recruitment along altitudinal gradient. We conducted a sowing experiment testing the effect of altitude (using three populations located at 1100, 1400 and 1650 m a.s.l.) and woody cover (open areas vs cover of woody species) on seedling emergence during two years and survival three years after sowing. Simultaneously, we characterised elevations and cover types in terms of climatic factors (surface air temperature and relative humidity) throughout a whole year, and light conditions (global site factor and red/infrared ligh ratio) using hemispheric photographs. We detected a significant effect of elevation on seedling emergence, with a higher emergence at lowest altitude. Woody cover greatly affected seedling survival and recruitment, both rates being higher under woody species than in open areas. Emergence was negatively correlated with winter stress factors, which increased with elevation. Survival and recruitment were negatively correlated with summer stress factors, which were ameliorated by woody cover and with altitude. Amelioration of climatic factors by woody cover was not influenced by altitude. Implications for species persistence in Mediterranean mountains under climate change scenarios are discussed.     

Actinophages as indicators of actinomycete taxa in marine environments

It is necessary to continue to screen for new metabolites and evaluate the potential of less known and new bacterial taxa so that new and improved compounds for future use against drug-resistant bacteria or for chemical modification may be developed. There has been considerable interest in the detection and identification of marine microorganisms since they have been reported to produce bioactive compounds ranging from antitumour to antibacterial and antiviral agents. In this study, an improved technique that involves the exploitation of marine actinophages as indicators of the marine actinomycete taxa and uses marine bacteriophages as tools to reduce the numbers of common marine bacteria, which impedes the growth of rare actinomycetes on isolation plates, has been applied. This technique reduced the numbers of colony forming units of unwanted bacteria on isolation plates and hence increased the chances of detecting novel marine actinomycete genera for isolation and subsequent screening for antiviral activity.     

Physiological and environmental control of seed germination timing in Mediterranean mountain populations of Gundelia tournefortii

Plant Growth Regulation - Fruit and seed morphology interact with embryo physiology and environmental conditions to control seed germination timing. This interaction plays a pivotal role in...     

Interactions between mountain birch seedlings from differentiated populations in contrasting environments of subarctic Russia

So far very few experiments have accounted for the combined effect of two phenomena co-occurring in stress gradients: local adaptation to stress and the increase in facilitation with increasing stress (predicted by the stress-gradient hypothesis, SGH). Mountain birch (Betula pubescens subsp. czerepanovii) facilitates conspecific seedlings in subarctic high stress sites and is capable of rapid evolutionary adaptation, being therefore a good model species for a study combining local ecotypes and SGH. A within-species experiment was conducted to test SGH in three stress gradients, detect potential local adaptations between low and high stress populations, and assess their effects on seedling-seedling interactions. Although no evidence for local adaptation was detected, high and low stress populations showed some differentiation, possibly explained by decreasing phenotypic plasticity in high stress conditions and/or neutral evolutionary mechanisms. Weak support for SGH was detected. While facilitation was unaffected by seedling origin, low stress populations showed better competitive ability.     

Carbon isotopes as indicators of elephant diets and African environments

Stable carbon isotope ratios have been successfully used to assess modern animal diets and to reconstruct prehistoric diets of animals and humans (Vogel & van der Merwe, 1977; van der Merwe & Vogel, 1978; Burleigh & Brothwell, 1978; Vogel, 1978a; DeNiro & Epstein, 1978; Tieszen et al., 1979; Tieszen & Imbamba, 1980; Chisholm, Nelson & Schwarcz, 1982; Tauber, 1981). We have used ¹³C/¹²C ratio measurements of bone collagen to study the diets of African elephants in twelve wildlife refuges. These represent most of the habitats in which elephants live, including such diverse plant communities as primary rain forest, savanna woodland and desert. The δ¹³C values were found to have a simple linear relationship with tree density in most cases. When translated into relative amounts of dietary browse (C₃ plants) and graze (C₄ plants), the grass content is seen to be systematically under-represented, presumably due to inefficient metabolism. This does not affect the relationship between elephant diet and tree density, which has implications for the study of elephant-woodland interactions, and for reconstructions of past African environments.     

Effects of browsing in relation to vegetation cover on common yew (<Emphasis Type="Italic">Taxus baccata</Emphasis> L.) recruitment in Mediterranean environments

Common yew (Taxus baccata L.) stands are recognized as prioritary habitats for biodiversity conservation within the European Union. The effects of browsing on the regeneration capacity and spatial dispersal of T. baccata recruits at the European southern limit of the species in the Mediterranean Basin have been herein studied. The efficacy of T. baccata recruitment has been evaluated at six localities in the Northern Sardinia mountains, which have similar altitude, climate, soil, and vegetation but have different types of uses (three were grazed by livestock and three were not). At each site, five habitats have been identified for T. baccata seed dispersal: reproductive female T. baccata canopy, reproductive female Ilex aquifolium canopy, non-fleshy-fruited tree canopy, fleshy-fruited shrubs, and open areas. The density of seedlings was found to be greater under fleshy-fruited trees (reproductive female T. baccata and I. aquifolium) than under shrubs, whereas the sapling density was higher in shrubby habitats, especially at grazed sites due to the mechanical protection afforded by the spiny shrubs against herbivores. Land use (LU) has been found to be the most important factor in determining the spatial distribution of seedlings and saplings in relation to forest habitats. Although browsers had an ephemeral but positive effect on seed germination through their trampling and the resultant scarification, this process eventually became ineffective as was shown by the occurrence of the lowest density of saplings in those habitats where the density of seedlings was the highest. The ultimate and most important effect of browsing was the sharp decrease in the density of saplings, and their almost complete extinction, in non-shrubby habitats. This study highlights the result that, in Mediterranean ecosystems, browsing constitutes the main negative factor on T. baccata seedling-sapling transition and furthermore confirms the necessity to preserve shrubby patches in the vicinity of reproductive female T. baccata and I. aquifolium to permit the regeneration of T. baccata in the presence of livestock. Moreover, at ungrazed sites, T. baccata is able to colonize non-shrubby shady habitats. The application of different management strategies to ungrazed and grazed sites should therefore be the main direction in the management and preservation of T. baccata stands in the Mediterranean region.     

Herbivory in a Mediterranean forest: browsing impact and plant compensation

The compensatory response of plants to defoliation is likely to have important effects on plant–ungulate equilibria in forested ecosystems. We investigated the responses of six species of Mediterranean bushes to defoliation by wild ungulates, comparing an index of browsing impact with the productivity of plants in both open and exclusion plots. The data revealed a great diversity of plant responses to herbivory: Rubus ulmifolius was able to over-compensate and replace the lost tissues. Phillyrea latifolia exhibited a similar, albeit less evident, pattern, while Cistus salvifolius was severely damaged by browsing. Other species, such as Quercus ilex, Juncus acutus and Erica arborea, were not attacked to a large extent and suffered little or no harm. The results strongly suggest that Mediterranean ecosystems may tolerate large stocking rates of ungulates. However, the reduction of plant biomass due to browsing was very different in the six studied species, suggesting that when herbivory becomes severe the structure of the ecosystem will change with the more tolerant plants becoming more abundant. We can apply these results to improve management and conservation of relict coastal forests in the Mediterranean basin which are usually of small size and where decision-makers have to compromise between the conservation of plants and that of large mammals.     

Economic modelling and indicators in life cycle sustainability assessment

Purpose

Sustainability assessment in life cycle assessment (LCA) addresses societal aspects of technologies or products to evaluate whether a technology/product helps to address important challenges faced by society or whether it causes problems to society or at least selected social groups. In this paper, we analyse how this has been, and can be addressed in the context of economic assessments. We discuss the need for systemic measures applicable in the macro-economic setting.

Methods

The modelling framework of life cycle costing (LCC) is analysed as a key component of the life cycle sustainability assessment (LCSA) framework. Supply chain analysis is applied to LCC in order to understand the relationships between societal concerns of value adding and the basic cost associated with a functional unit. Methods to link LCC as a foreground economic inventory to a background economy wide inventory such as an input–output table are shown. Other modelling frameworks designed to capture consequential effects in LCSA are discussed.

Results

LCC is a useful indicator in economic assessments, but it fails to capture the full dimension of economic sustainability. It has potential contradictions in system boundary to an environmental LCA, and includes normative judgements at the equivalent of the inventory level. Further, it has an inherent contradiction between user goals (minimisation of cost) and social goals (maximisation of value adding), and has no clear application in a consequential setting. LCC is focussed on the indicator of life cycle cost, to the exclusion of many relevant indicators that can be utilised in LCSA. As such, we propose the coverage of indicators in economic assessment to include the value adding to the economy by type of input, import dependency, indicators associated with the role of capital and labour, the innovation potential, linkages and the structural impact on economic sectors.

Conclusions

If the economic dimension of LCSA is to be equivalently addressed as the other pillars, formalisation of equivalent frameworks must be undertaken. Much can be advanced from other fields that could see LCSA to take a more central role in policy formation.     

Soil property,CO2 emission and aridity index as agroecological indicators to assess the mineralization of cover crop green manure in a Mediterranean environment

In this study soil chemical and biochemical properties, cover crop biomass production and quality, and climatic factors (AI) have been taken into account in order to identify sensitive agroecological indicators suitable for an early assessment of green manuring outcomes, measured in terms of soil CO₂ emission and soil mineralization dynamics in a short term experiment in a Mediterranean environment. The field experiment was conducted over two cropping rotations during 2004–2005 in central Italy. A winter cover crop/sweet pepper sequence with the cover crop used as green manure was adopted. The cover crop treatments were common vetch (CV), rye grass (RG), and fallow soil as the control (Control). Soil enzyme activities (acid phosphatase. protease and β-glucosidase), CO₂ emission, and inorganic nitrogen concentrations were monitored from cover crop green manure incorporation to pepper harvesting in order to evaluate soil mineralization dynamics. The climatic conditions were summarized by the monthly aridity index (AI) calculated as the precipitation/temperature ratio. A group of mineralization indexes, calculated using values of available nitrogen and enzyme activities, was used to describe the soil process during crop cycle after green manure. The mineralization process dynamic results as a combined effect of climatic conditions and soil organic matter quality produced by different cover crop green manures. The common vetch green manuring was effective in lowering the soil C/N with respect to the control soil (5.7 vs. 8.3 and 8.5 vs. 12.1 in 2004 and 2005, respectively), promoting CO₂ emission (8.95 vs. 5.19 and 6.75 vs. 4.28 Mg CO₂-C ha⁻¹ in 2004 and 2005, respectively), enzyme activity, nitrogen release, and crop aboveground biomass (8.59 vs. 7.05 Mg ha⁻¹ dry matter). Among the selected agroecological indicators, the relationships between enzyme activities and the monthly aridity index may suggest a new approach for agronomists and soil scientists to understand the combined effect of temperature and precipitation on soil mineralization dynamic. The high aridity index at the time of green manuring may have caused a priming effect of SOM and promoted soil mineralization during the vegetable crop growing season in a Mediterranean environment. Finally, no evidence was found between soil CO₂ emission and the aridity index; soil respiration was mainly affected by cover crop biomass and the soil C/N ratio.     

Dinoflagellate cysts as indicators of water quality and productivity in British Columbia estuarine environments

Palynological analyses of 60 surface sediment samples from estuarine environments near Vancouver Island, including the Georgia Strait (GS), the Effingham (EFF) and the Seymour–Belize (SB) Inlets were performed in order to document the distribution of dinoflagellate cyst assemblages and their relationship to hydrographic conditions, productivity and nutrient concentrations. We tested transfer functions using the analogue method, and suggest that dinoflagellate cyst assemblages can be used to reconstruct primary productivity, temperature and salinity. The EFF and SB Inlets are characterized by a dominance of autotrophic taxa, particularly Operculodinium centrocarpum, whereas the Protoperidinioid and gymnodinial heterotrophic taxa such as Quinquecuspis concreta and Brigantedinium spp. dominate the assemblages of the GS. Multivariate analysis shows that this distribution is closely linked to primary productivity, sea-surface temperature (SST) and spring silica concentration. The abundance of autotrophic taxa in the EFF and SB Inlets is associated with high primary productivity and low summer SST, indicating summer upwelling of coastal British Columbia, whereas the heterotrophic taxa that characterizes the GS assemblages are related to low productivity, high summer SST and high silica concentration during spring. Multivariate analysis shows that the most important environmental parameters related to dinocyst distribution in the restricted embayment of the GS, are distance to the shore, distance to Vancouver Harbor, spring sea surface salinity (SSS), spring phosphate concentration and spring productivity. The autotrophic taxa are generally more common in coastal and shallow waters, but Spiniferites ramosus and Pentapharsodinium dalei show an opposite correlation to spring productivity and salinity. P. dalei is particularly abundant around Vancouver Harbor, near highly urbanized shores and within the Fraser River plume, where salinity is low and spring productivity and continental runoff are high. S. ramosus shows its highest abundance on the western coast of GS. Protoperidinioid and gymnodinial cysts characterize distal zones within the central and southern GS that are associated with a mixture of brackish waters coming from the Fraser River and deep upwelling waters entering the GS via Juan de Fuca Strait. The relationship between dinoflagellate cyst assemblages and primary productivity in these estuarine systems differs from that in oceanic and outer neritic zones, where the abundance of heterotrophic taxa is commonly associated with upwelling and high productivity.     

Caddisflies (Trichoptera) as good indicators of environmental stress in mountain lotic ecosystems

We analysed the influence of environmental stress (mainly deforestation of catchment due to windstorm) on taxonomic structure as well as composition of functional groups (FG) based on zonation preferences and feeding types of caddisfly species in 11 streams (12 sites) with various environmental conditions situated in the High Tatra Mts, Slovakia. Using Spearman correlation, we confirmed an expected positive association between taxonomic and functional groups richness (Ri), diversity (Shannon — Wiener Index) (Di) and equitability (Eq), but not with habitat diversity (HQA indices). By testing measured physiographical, physico-chemical and hydromorphological factors using CCA analysis we found that stream order and temperature best explained the functional and taxonomic structure of caddisfly assemblages. The occurrence of Rhyacophila glareosa decreased with increasing daily mean water temperature positively correlated with deforestation, whereas R. tristis (dominating at sites most affected by erosion) showed the opposite pattern. Composition of functional groups based on zonation preferences and feeding types distinguished well near natural sites from impacted ones, dominated by crenal/rhithral predators, and explained more of the overall variance of the species-environment relationships than taxonomic composition of caddisfly assemblages.     

Increasing intraspecific facilitation in exposed environments: consistent results from mountain birch populations in two subarctic stress gradients

The stress‐gradient hypothesis predicts that the importance of facilitation relative to competition should increase with increasing stress. The hypothesis has received support from several environments, but multi‐gradient studies on the generality of the hypothesis are exceptionally rare. A within‐species experiment with mountain birch Betula pubescens subsp. czerepanovii was conducted to test the hypothesis in the extreme ends of two subarctic stress gradients (elevation and seashore) in the Kola Peninsula, northwestern Russia. The high stress sites were characterized by strong winds, temperature extremes and potentially drought. The negative effects of abiotic stress on the study seedlings were verified from performance characteristics. Effects of adult hosts as well as seedling–seedlings interactions were studied. Positive host–seedling interactions dominated in each study site, and three out of four performance variables indicated stronger positive net effects in the high stress sites. In the seashore gradient also seedling survival gave similar interpretations. Also a temporal shift towards host–seedling competition was detected in a low stress site after two study years. In seedling–seedling interactions competition dominated, but the effects were weak, likely due to the ‘noise’ caused by genetic and environmental factors. Our results support the stress‐gradient hypothesis and its generality in subarctic environments, as the interpretations were similar for both stress gradients and several fitness‐related variables. The temporal variation in host–seedling interactions and the difference between host–seedling and seedling–seedling effects hint on size‐dependency of plant interactions: facilitation might dominate when the benefactor is substantially larger than the beneficiary, while competition may be stronger when the plants are of similar size and developmental status.     

Life history parameters as indicators of growth rate in three salp populations

A strong correlation exists between individual growth rate andfive life history parameters in the fast growing salp Thaliademocratica. The five parameters are number of aggregate budsper chain; body size of reproductive solitaries; the ratio ofaggregate offspring to their solitary parents; the solitaryto aggregate ratio; and the relative proportions of juvenilesand adults in the solitary generation. Correlation coefficientsaveraging 0.68 and ranging up to 0.85 were found between theestimates of these parameters in 37 samples of salp blooms takenover 15 years in the western Pacific and eastern Indian oceans.Growth rate, estimated previously in 12 of these samples, alsocorrelated strongly with each of the five parameters with coefficientsranging from 0.88 to 0.96. After analysis of partial correlationswe selected parameters to form regression equations with growth.These equations are excellent indicators of growth in the sequentiallysampled salp populations. Because of the significant correlationbetween the parameters in a wider range of samples, they arealso likely to be indicators of growth in general salp populations.     

Challenges and science-based implications for modern management and conservation of European ungulate populations

Wildlife management systems face growing challenges to cope with increasingly complex interactions between wildlife populations, the environment and human activities. In this position statement, we address the most important issues characterising current ungulate conservation and management in Europe. We present some key points arising from ecological research that may be critical for a reassessment of ungulate management in the future.     

Learning from the past: Diatoms as palaeoecological indicators of changes in marine environments

The North Sea is seriously threatened by a variety of pollution sources. Terrestrially derived effluents are causing extensive environmental damage and changes to ecosystems of both the offshore and coastal waters. Coastal and estuarine communities are being lost to reclamation projects, and there is the future threat of rising sea level associaed with global warming. The spatial and temporal extent of recent anthropogenic changes are largely unknown due to the paucity of background information. The possible role of palaeoecological methodology in providing ‘reference levels’ against which current status can be compared, and their importance for restoration and policy decisions, are presented. The usefulness of diatoms as environmental indicators is illustrated. The extent of natural and anthropogenic changes on coastal habitats are demonstrated by reference to the Holocene evolution of the coastline of The Netherlands. Possible profitable areas for further research are outlined,e.g. a diatom nutrient calibration data set for shallow marine embayments.     

Terrestrial birds as indicators of agricultural-induced changes and associated loss in conservation value of Mediterranean wetlands

During the last decades, agricultural intensification has modified the hydrology of Mediterranean wetlands, as has occurred in the Mar Menor coastal lagoon (SE Spain). Salt-steppe dominated wetlands, characteristic of transitional areas surrounding this lagoon and rich in biodiversity values, are threatened by changes in their water regime originated by land-use changes in the watershed. Traditional dryland cultures have also been replaced by irrigated ones. We assess the direct and indirect changes induced by agriculture on a terrestrial vertebrate community (steppe birds) especially sensitive to these ecosystem changes. This is made on the basis of several surveys of terrestrial birds (excluding aerial feeders and raptors) carried out between 1984 and 2008 in a representative wetland of the lagoon's continental margin (Marina del Carmolí). The changes in this bird assemblage reflect the hydrological modifications induced by agriculture at the watershed scale, which have significant effects on the relative representation of wetland habitats. Bird metrics and indices (species abundance, taxonomic composition, conservation value) describe these community changes as the combination of early declines in some species and families, and transient or late increases in other. In the long term, the family Alaudidae (and particularly species like Melanocorypha calandra) have lost importance to the benefit of Turdidae and Fringillidae. The area of salt-steppe explains a large part of the variation in the abundance of Alaudidae, while most variation of Turdidae and Fringillidae respond to the area of saltmarsh. Some Alaudidae seem to take advantage of the intermediate stages of saltmarsh expansion (Calandrella rufescens), or from the marginal irrigated crops fringing the wetland (Calandrella brachydactyla) that could compensate the loss of original agricultural habitats. Habitat changes in the wetland have occurred in three differentiated stages, and modify the steppe bird community towards a more heterogeneous assemblage including scrubland and palustrine species. Among three indices of ornithological value, only that based on the EU Bird's Directive Annex I species was negatively affected, but since the wetland has been designated a Specially Protected Area under this regulation, this represents a management failure. There exists some chance, however, to manage peripheral cropland in favour of biodiversity. The importance of monitoring in conservation evaluation and management is also stressed, since the terrestrial bird community of this wetland has not been regularly surveyed. In fact, its evaluation against the Bird's Directive criteria was made in a period of quick departure from the original, good ecological state of the wetland.