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.     

Moss bags as indicators of trace element contamination in Pre-alpine streams

Abstract

Moss bags of the aquatic bryophyte Rhynchostegium riparioides (Hedw.) C.E.O. Jensen (=Platyhypnidium riparioides (Hedw.) Dixon) were transplanted into freshwaters of the Province of Belluno (NE Italy). This study was aimed at testing the bioaccumulation of trace elements in Pre-alpine Dolomitic streams, where this species does not grow naturally, and where analyses of water samples have never revealed trace element pollution. Mosses were collected after 13, 26 and 59 days of exposure. The concentrations of nine trace elements in the apical shoots were measured. Average concentrations reached in three control stations were adopted as background values, to calculate the contamination factor (CF). Transplants accumulated trace elements and discriminated between non- or scarcely contaminated waters (low CF) and polluted ones (high CF). Furthermore, two patterns of contamination were revealed by multivariate analysis: (I) metals (Cr, Cu, Ni) from galvanic industries, and (II) metals (Pb, Zn) from other industrial/domestic sources or mine sites.     

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.     

Parasites as indicators of host populations

The literature on parasites as indicators of populations of aquatic hosts is reviewed, with the emphasis on work published since about 1980. General guidelines are proposed for the selection of tag parasites, with a discussion of earlier criteria in the light of recent knowledge. The use of parasites for different types of population study, for different types of ecosystem and for different taxonomic groups of hosts is discussed. Some promising future application of parasites in population studies of aquatic hosts are suggested.     

Habitat and climate shape growth patterns in a mountain ungulate

Uptake and use of energy are of key importance for animals living in temperate environments that undergo strong seasonal changes in forage quality and quantity. In ungulates, energy intake strongly affects body mass gain, an important component of individual fitness. Energy allocation among life‐history traits can be affected by internal and external factors. Here, we investigate large‐scale variation in body growth patterns of Alpine chamois Rupicapra rupicapra rupicapra, in relation to sex, age, temperature, and habitat variations across 31 (sub)populations in the Central European Alps. Taking advantage of an exceptionally large dataset (n = 178,175) of chamois hunted over 27 consecutive years between 1993 and 2019 in mountain ranges with different proportions of forest cover, we found that (i) patterns of body mass growth differ between mountain ranges, with lower body mass but faster mass growth with increasing proportion of forest cover and that (ii) the effect of spring and summer temperatures on changes in body growth patterns are larger in mountain ranges with lower forest cover compared to mountain ranges with higher forest cover. Our results show that patterns of body mass growth within a species are more plastic than expected and depend on environmental and climatic conditions. The recent decline in body mass observed in Alpine chamois populations may have greater impacts on populations living above the treeline than in forests, which may buffer against the effects of increasing temperatures on life‐history traits.     

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.     

Methods of estimating ungulate populations in tropical forests

Pellet group counts, drive counts and track counts were used to estimate population abundances of one small and four large species of duiker (Cephalophus sp.) in a moist evergreen forest in northeastern Zaire. Procedures to develop estimates based on line transect counts of pellet groups are described. The Fourier Series estimator proved to be useful for estimating densities of pellet groups. Comparisons were made between population abundance in heavily and lightly hunted areas, and between small and large species. The three census methods were consistent in showing no significant difference between animal abundance in the hunted populations or between abundances of the smaller species relative to the larger species. All methods showed potential as population indices for assessing trends of rare and elusive species in forest environments. Drive counts and pellet group counts may also be useful for estimating densities.     

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.     

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.     

The value of muscular and skeletal scores in the live animal and carcass classification scores as indicators of carcass composition in cattle

The objective was to determine the relationship of muscular and skeletal scores taken on the live animal and carcass conformation and fat scores with carcass composition and value. Bulls (n = 48) and heifers (n = 37) of 0.75 to 1.0 late-maturing breed genotypes slaughtered at 16 and 20 months of age, respectively, were used. At 8 months of age (weaning) and immediately pre-slaughter, visual muscular scores were recorded for each animal and additionally skeletal scores were recorded pre-slaughter. Carcass weight, kidney and channel fat weight, carcass conformation and fat scores, fat depth over the longissimus dorsi muscle at the 12th (bulls) or 10th (heifers) rib and carcass length were recorded post-slaughter. Each carcass was subsequently dissected into meat, fat and bone using a commercial dissection procedure. Muscular scores taken pre-slaughter showed positive correlations with killing-out rate (r ≈ 0.65), carcass meat proportion (r ≈ 0.60), value (r ≈ 0.55) and conformation score (r ≈ 0.70), and negative correlations with carcass bone (r ≈ -0.60) and fat (r ≈ -0.4) proportions. Corresponding correlations with muscular scores at weaning were lower. Correlations of skeletal scores taken pre-slaughter, carcass length and carcass weight with killing-out rate and the various carcass traits were mainly not significant. Carcass fat depth and kidney and channel fat weight were negatively correlated with carcass meat proportion and value, and positively correlated with fat proportion. Correlations of carcass conformation score were positive (r = 0.50 to 0.68) with killing-out rate, carcass meat proportion and carcass value and negative with bone (r ≈ -0.56) and fat (r ≈ -0.40) proportions. Corresponding correlations with carcass fat score were mainly negative except for carcass fat proportion (r ≈ 0.79). A one-unit (scale 1 to 15) increase in carcass conformation score increased carcass meat proportion by 8.9 and 8.1 g/kg, decreased fat proportion by 4.0 and 2.9 g/kg and decreased bone proportion by 4.9 and 5.2 g/kg in bulls and heifers, respectively. Corresponding values per unit increase in carcass fat score were -11.9 and -9.7 g/kg, 12.4 and 9.9 g/kg, and -0.5 and -0.2 g/kg. Carcass conformation and fat scores explained 0.70 and 0.55 of the total variation in meat yield for bulls and heifers, respectively. It is concluded that live animal muscular scores, and carcass conformation and fat scores, are useful indicators of carcass meat proportion and value.     

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.     

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.     

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.