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AbstractClonal plants from poor habitats benefit less from morphologically plastic responses to heterogeneity than plants from more productive sites. In addition, physiological integration has been suggested to either increase or decrease the foraging efficiency of clonal plants. We tested the capacity for biomass production and morphological response in two closely related, rhizomatous species from habitats that differ in resource availability, Carex arenaria (from poor sand dunes) and C. disticha (from nutrient‐richer, moister habitats). We expected lower total biomass production and reduced morphological plasticity in C. arenaria, and that both species would produce more ramets in high nutrient patches, either in response to signals transported through physiological integration, or by locally determined responses to nutrient availability. To investigate mineral nutrient heterogeneity, plants were grown in boxes divided into two compartments with homogeneous or heterogeneous supply of high (H) or low (L) nutrient levels, resulting in four treatments, H‐H, H‐L, L‐H and L‐L. Both C. arenaria and C. disticha produced similar biomass in high nutrient treatments. C. disticha responded to high nutrients by increased biomass production and branching of the young parts and by altering root:shoot ratio and rhizome lengths, while C. arenaria showed localised responses to high nutrients in terms of local biomass and branch production in high nutrient patches. The results demonstrated that although it has a conservative morphology, C. arenaria responded to nutrient heterogeneity through morphological plasticity. An analysis of costs and benefits of integration on biomass production showed that young ramets of both species benefited significantly from physiological integration, but no corresponding costs were found. This suggests that plants from resource‐poor but dynamic habitats like sand dunes respond morphologically to high nutrient patches. The two species responded to nutrient heterogeneity in different traits, and this is discussed in terms of local and distant signalling of plant status.

This article reviews some of the major lines of recent scientific progress relevant to the choice of global climate policy targets, focusing on changes in understanding since publication of the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4). Developments are highlighted in the following major climate system components: ice sheets; sea ice; the Atlantic Meridional Overturning Circulation; tropical forests; and accelerated carbon release from permafrost and ocean hydrates. The most significant developments in each component are identified by synthesizing input from multiple experts from each field. Overall, while large uncertainties remain in all fields, some substantial progress in understanding is revealed.

Effects of anthropogenic and environmental stressors on freshwater communities can propagate to ecosystem functions and may in turn impede ecosystem services. We investigated potential shifts in ecosystem functions that provide energy for freshwater ecosystems due to pesticides and salinity in 24 sites in streams of southeast Australia. First, effects on allochthonous organic matter (AOM) breakdown using three different substrates (leaves, cotton strips, wood sticks) in coarse and fine bags were investigated. Second, we examined effects on stream metabolism that delivers information on the ecosystem functions of gross primary production and ecosystem respiration. We found up to a fourfold reduction in AOM breakdown due to exposure to pesticides and salinity, where both stressors contributed approximately equally to the reduction. The effect was additive as, no interaction or correlation between the two stressors was found. Leaf breakdown responded strongly and exclusively to exposure to pesticides and salinity, whereas cotton strip breakdown was less sensitive and responded also to other stressors such as nutrients. No functional redundancy for the effects of pesticides and salinity on leaf breakdown was observed. For wood stick breakdown, no relationship to environmental gradients was found, however, the sample size was lower. We did not detect effects of pesticides or salinity on gross primary production or ecosystem respiration. A reduction in AOM breakdown by pesticides and salinity may impair the ecosystem services of food provision and possibly water purification. Hence, future studies should examine the spatial extent of these effects.

AbstractRecently, there have been several studies using open top chambers (OTCs) or cloches to examine the response of Arctic plant communities to artificially elevated temperatures. Few, however, have investigated multitrophic systems, or the effects of both temperature and vertebrate grazing treatments on invertebrates. This study investigated trophic interactions between an herbivorous insect (Sitobion calvulum, Aphididae), a woody perennial host plant (Salix polaris) and a selective vertebrate grazer (barnacle geese,Branta leucopsis). In a factorial experiment, the responses of the insect and its host to elevated temperatures using open top chambers (OTCs) and to three levels of goose grazing pressure were assessed over two summer growing seasons (2004 and 2005).OTCs significantly enhanced the leaf phenology ofSalixin both years and there was a significantOTCby goose presence interaction in 2004.Salixleaf number was unaffected by treatments in both years, butOTCs increased leaf size and mass in 2005.Salixreproduction and the phenology of flowers were unaffected by both treatments. Aphid densities were increased byOTCs but unaffected by goose presence in both years. While goose presence had little effect on aphid density or host plant phenology in this system, theOTCeffects provide interesting insights into the possibility of phenological synchrony disruption. The advanced phenology ofSalixeffectively lengthens the growing season for the plant, but despite a close association with leaf maturity, the population dynamics of the aphid appeared to lack a similar phenological response, except for the increased population observed.

Abstract Forest managers use artificial regeneration to influence tree species composition and productivity. The selection of plant material could assume a leading role in forest planning, mainly when aiming to increase the adaptation of stands within a context of climate change. In this study, we investigated the timing of bud burst and bud set in five black spruce [Picea mariana (Mill.) B.S.P.] ecotypes growing in a common garden and originating from a latitudinal range in the boreal forest of Quebec, Canada. Bud phenology was monitored weekly during the 2015, 2017 and 2018 growing seasons. On average, the bud burst process lasted 23 days, occurring 1.2 days later for each degree Celsius of increase in mean annual temperature at the provenance site. Bud set duration was 55 days and occurred 1.8 days later for each degree Celsius of increase in mean annual temperature at the provenance site. We demonstrated that both bud burst and bud set occurred earlier in individuals from colder sites, which resulted in similar lengths of the growing season among provenances. This clinal variation in the timings of growth resumption and cessation confirms the ecotypic differentiation of black spruce populations and reflects a long-lasting adaptation to the local temperatures in the sites of origin. The findings of this study demonstrate that ecotype selection in black spruce can aim to avoid damage from either early or late frosts, but not both.

Abstract In the near future dairy enterprises will have to meet increasing environmental regulations. Therefore, we aimed to evaluate the effects on the environment of dairy buffalo farming as affected by two different heifer rearing systems, free-ranging (FR) and confinement (C) using the Life Cycle Assessment approach. The primary data were collected from 32 subjects. The analysis included all of the farming phases (i.e. birth to weaning, weaning to 7–8 months of age, 7–8 months to puberty, puberty to first calving, lactation, dry period). During the heifer phase from 7 to 8 months of age to puberty, sixteen animals were group-housed and confined in an indoor slatted floor pen (4 m2/animal) with an outdoor paddock (4 m2/animal); 16 others were FR on a Mediterranean natural pasture. When pubertal, the animals from system FR were returned to the farm and reunited with the animals from system C. We used 1 kg of fat and protein corrected buffalo milk (FPCM), with a reference milk fat and protein content of 8.3% and 4.73%, respectively, as functional unit. Impact categories investigated were Climate Change (CC), Terrestrial Acidification (TA), Marine Eutrophication (ME), Agricultural land occupation (ALO), Water depletion (WD). At category level system FR showed a reduction of the impact in terms of CC (9%), TA (10%), ME (6%) and WD (11%), whereas ALO was 7% higher as compared to system C. In conclusion, we clearly showed that the conduction of part of dairy buffalo farming (i.e. the unproductive phase from 7 to 8 months of age to puberty) on natural pasture is possible and it also allows the reduction of several sources of pollution while reducing the production costs, hence the economic sustainability. Although this system requires a greater use of land, parameters concerning the quality of land use should be included for a more accurate assessment of this aspect.

According to predicted changes in climate, waterlogging events may occur more frequently in the future during autumn and winter at high latitudes of the Northern Hemisphere. If excess soil water coincides with the process of cold acclimation for plants, winter survival may potentially be affected. The effects of waterlogging during cold acclimation on stomatal aperture, relative water content, photochemical activity of photosystem II, freezing tolerance and plant regrowth after freezing were compared for two prehardened overwintering forage grasses, Lolium perenne and Festuca pratensis. The experiment was performed to test the hypothesis that changes in photochemical activity initiated by waterlogging-triggered modifications in the stomatal aperture contribute to changes in freezing tolerance. Principal component analysis showed that waterlogging activated different adaptive strategies in the two species studied. The increased freezing tolerance of F. pratensis was associated with increased photochemical activity connected with stomatal opening, whereas freezing tolerance of L. perenne was associated with a decrease in stomatal aperture. In conclusion, waterlogging-triggered stomatal behavior contributed to the efficiency of the cold acclimation process in L. perenne and F. pratensis.