Experimental warming, not grazing, decreases rangeland quality on the Tibetan Plateau.

We investigated experimental warming and simulated grazing (clipping) effects on rangeland quality, as indicated by vegetation production and nutritive quality, in winter-grazed meadows and summer-grazed shrublands on the Tibetan Plateau, a rangeland system experiencing climatic and pastoral land use changes. Warming decreased total aboveground net primary productivity (ANPP) by 40 g x m(-2) x yr(-1) at the meadow habitats and decreased palatable ANPP (total ANPP minus non-palatable forb ANPP) by 10 g x m(-2) x yr(-1) at both habitats. The decreased production of the medicinal forb Gentiana straminea and the increased production of the non-palatable forb Stellera chamaejasme with warming also reduced rangeland quality. At the shrubland habitats, warming resulted in less digestible shrubs, whose foliage contains 25% digestible dry matter (DDM), replacing more digestible graminoids, whose foliage contains 60% DDM. This shift from graminoids to shrubs not only results in lower-quality forage, but could also have important consequences for future domestic herd composition. Although warming extended the growing season in non-clipped plots, the reduced rangeland quality due to decreased vegetative production and nutritive quality will likely overwhelm the improved rangeland quality associated with an extended growing season. Grazing maintained or improved rangeland quality by increasing total ANPP by 20-40 g x m(-2) x yr(-1) with no effect on palatable ANPP. Grazing effects on forage nutritive quality, as measured by foliar nitrogen and carbon content and by shifts in plant group ANPP, resulted in improved forage quality. Grazing extended the growing season at both habitats, and it advanced the growing season at the meadows. Synergistic interactions between warming and grazing were present, such that grazing mediated the warming-induced declines in vegetation production and nutritive quality. Moreover, combined treatment effects were nonadditive, suggesting that we cannot predict the combined effect of global changes and human activities from single-factor studies. Our findings suggest that the rangelands on the Tibetan Plateau, and the pastoralists who depend on them, may be vulnerable to future climate changes. Grazing can mitigate the negative warming effects on rangeland quality. For example, grazing management may be an important tool to keep warming-induced shrub expansion in check. Moreover, flexible and opportunistic grazing management will be required in a warmer future.     

A protein signal triggers sexual reproduction in Brachionus plicatilis (Rotifera)

The defining feature of the life cycle in monogonont rotifers such as Brachionus plicatilis (Muller) is alternation of asexual and sexual reproduction (mixis). Why sex is maintained in such life cycles is an important unsolved evolutionary question and one especially amenable to experimental analysis. Mixis is induced by a chemical signal produced by the rotifers which accumulates to threshold levels at high population densities. The chemical features of this signal were characterized using size exclusion, enzymatic degradation, protease protection assays, selective binding to anion ion exchange and C3 reversed phase HPLC columns, and the sequence of 17 N-terminal amino acids. These studies were carried out over two years beginning in 2003 using B. plicatilis Russian strain. When rotifer-conditioned medium was treated with proteinase K, its mixis-inducing ability was reduced by 70%. Proteinase K was added to medium auto-conditioned by 1 female ml⁻¹ where typically 17% of daughters became mictic and mixis was reduced to 1%. A cocktail of protease inhibitors added to conditioned medium significantly reduced degradation of the mixis signal by natural proteases. Conditioned medium subjected to ultrafiltration retained mixis-inducing activity in the >10 kDa fraction, but the <10 kDa fraction had no significant activity. The putative mixis signal bound to an anion exchange column, eluting off at 0.72 M NaCl. These fractions were further separated on a C3 reversed phase HPLC column and mixis-inducing activity was associated with a 39 kDa protein. Seventeen amino acids from the N-terminus have strong similarity to a steroidogenesis-inducing protein isolated from human ovarian follicular fluid. The 39 kDa protein is an excellent candidate for the rotifer mixis induction signal.     

Stopover behaviour and departure decision of northern wheatears, Oenanthe oenanthe, facing different onward non-stop flight distances

On the small North Sea island Helgoland (54°11' N, 07°55' E) we studied the stopover ecology of two subspecies of northern wheatear, Oenanthe oenanthe, during spring migration. Birds heading for Scandinavia (O. o. oenanthe) face only short flights across an ecological barrier (50-500 km) whereas those originating from Greenland and Iceland (O. o. leucorhoa) have to cover between 1,000 and 2,500 km in the impending flight. Colour-ringed individuals showed that 90% of Scandinavian birds left on the day of ringing while 40% (males) and 30% (females) of Greenland/Icelandic birds stayed at least 1 night. The birds who remained were thus mostly O. o. leucorhoa. They often established desirable feeding territories on the beach and had a high rate of body mass increase (1.7 g/day). However, subspecies did not differ in habitat choice and in foraging effort, but O. o. leucorhoa had a higher success rate in pecking. Departure decisions were analysed by comparing (a) conditions on the day of ringing between departing and staying birds and (b) for birds staying between the day of departure and the preceding day. The factors that were probably important in the decision to depart differed between subspecies. In O. o. leucorhoa, few birds departed with bad or deteriorating weather conditions (tailwind component, cloud cover), whereas departures of O. o. oenanthe seemed to be little affected by those factors. A few O. o. oenanthe stayed early in the spring migration season and/or had low fat reserves. Interference during foraging seemed to play a role because both subspecies tended to leave when the densities of northern wheatears were high. Other factors related to refuelling conditions (food supply, foraging effort, predation risk) failed to show differences between staying and departing individuals. In summary, almost all Scandinavian birds departed quickly and irrespective of refuelling and weather conditions, whereas many (but not all) Greenland/Icelandic birds seemed to prepare for a long-distance flight and carefully adjusted departure to weather conditions. The observed differences in stopover behaviour and departure decisions in the two subspecies of northern wheatear indicate that the distance to the next stopover site or to the goal area has to be considered when applying optimal migration models.     

Geophagy in the tropics: an appraisal of three geophagical materials

Geophagy, the deliberate consumption of soil, is a common practice amongst the world's poorer or more tribally oriented people of the tropics. An appraisal of three geophagical samples suggests that Fe is a mineral nutrient which can be supplied to humans in significant amounts via ingested soil. Geophagy provides a direct link between the geochemistry of soils and human health, but as yet this association has only a limited awareness amongst research workers.     

Agricultural soil as a potential source of input of organochlorine pesticides into a nearby pond

A study was conducted in the southeastern region of Buenos Aires province, Argentina, to assess an agricultural soil as a potential source of organochlorine (OC) pesticides for the aquatic biota of a nearby pond. We analyzed gamma-HCH (lindane), still in use, and the following banned compounds: DDT, DDE, DDD heptachlor, heptachlor epoxide, aldrin, dieldrin and endrin in soil, bulrush, grass shrimp and fish using gas chromatography with electron capture detection (GC-ECD). Among the OC pesticides, lindane was most dominant in the soil (32.6 ng/g dry wt in the upper and 173.9 ng/g dry wt in the lower horizon) and bulrush (1.9 pg/g lipid). Macrophyte also accumulated high levels of heptachlor epoxide (1.5 pg/g lipid). Heptachlor, although present in the soil, was below the detection limit in all aquatic biota studied. Its primary degradation product, heptachlor epoxide, was found in both soil and biota samples. DDT was found at low levels in the surface soil (6.8 ng/g dry wt), but at higher concentrations in fish (3.6 pg/g lipid), although levels were still below permissible levels for human consumption. Since most of the compounds were found in both soil and aquatic biota, our study suggests that agricultural soil could be an important source for OC pesticides in the nearby pond.     

The effects of light and thallus scour from<Emphasis Type="Italic"> Ecklonia radiata</Emphasis> canopy on an associated foliose algal assemblage: the importance of photoacclimation

Kelp canopies have long been recognised for their influence on the structure of algal assemblages on sublittoral reefs. In Marmion Lagoon, Western Australia, we investigated how a canopy of the small kelp Ecklonia radiata affected the associated foliose algal assemblage and what potential mechanisms were responsible for the effects we observed. Light levels and physical abrasion (thallus scour) by an E. radiata canopy were manipulated in an orthogonal fixed-factor experiment that revealed that changes in light, but not thallus scour, had a significant effect on the composition of the algal assemblage. Reduced light levels were associated with a decrease in the Shannon-Wiener diversity index and an increased dominance of the foliose algae Pterocladia lucida and Rhodymenia sonderi. Photobiological investigations of three foliose species, P. lucida, R. sonderi and Chauviniella coriifolia indicated that they were able to photoacclimate to low light levels by increasing thallus absorption by up to 11%. Photoacclimation was also evident by an increase in the maximum rate of electron transport under low-light conditions. We conclude that the E. radiata canopy in Marmion Lagoon structures the foliose algal assemblage through the modification of the light environment and that this effect may be mediated by differences in the ability of different species of foliose algae to photoacclimate.Communicated by M.S. Johnson, Crawley     

Altai pika (<Emphasis Type="Italic">Ochotona alpina</Emphasis>) alarm calls: individual acoustic variation and the phenomenon of call-synchronous ear folding behavior

Non-hibernating pikas collect winter food reserves and store them in hay piles. Individualization of alarm calls might allow discrimination between colony members and conspecifics trying to steal food items from a colony pile. We investigated vocal posture, vocal tract length, and individual acoustic variation of alarm calls, emitted by wild-living Altai pikas Ochotona alpina toward a researcher. Recording started when a pika started calling and lasted as long as possible. The alarm call series of 442 individual callers from different colonies consisted of discrete short (0.073–0.157 s), high-frequency (7.31–15.46 kHz), and frequency-modulated calls separated by irregular intervals. Analysis of 442 discrete calls, the second of each series, revealed that 44.34% calls lacked nonlinear phenomena, in 7.02% nonlinear phenomena covered less than half of call duration, and in 48.64% nonlinear phenomena covered more than half of call duration. Peak frequencies varied among individuals but always fitted one of three maxima corresponding to the vocal tract resonance frequencies (formants) calculated for an estimated 45-mm oral vocal tract. Discriminant analysis using variables of 8 calls per series of 36 different callers, each from a different colony, correctly assigned over 90% of the calls to individuals. Consequently, Altai pika alarm calls are individualistic and nonlinear phenomena might further increase this acoustic individualization. Additionally, video analysis revealed a call-synchronous, very fast (0.13–0.23 s) folding, depression, and subsequent re-expansion of the pinna confirming an earlier report of this behavior that apparently contributes to protecting the hearing apparatus from damage by the self-generated high-intensity alarm calls.     

Social factors mediating human–carnivore coexistence: Understanding thematic strands influencing coexistence in Central Romania

Facilitating human–carnivore coexistence depends on the biophysical environment but also on social factors. Focusing on Central Romania, we conducted 71 semi-structured interviews to explore human–bear (Ursus arctos) coexistence. Qualitative content and discourse analysis identified three socially mediated thematic strands, which showed different ways in which perceived interactions between people, bears and the environment shape coexistence. The “landscape-bear strand” described perceptions of the way in which the landscape offers resources for the bear, while the “landscape-human strand” related to ways in which humans experience the landscape. The “management strand” related to the way bears was managed. All three strands highlight both threats and opportunities for the peaceful coexistence of people and bears. Management and policy interventions could be improved by systematically considering the possible effects of interventions on each of the three strands shaping coexistence. Future research should explore the relevance of the identified thematic strands in other settings worldwide.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-015-0760-7) contains supplementary material, which is available to authorized users.     

Disaggregated contributions of ecosystem services to human well-being: a case study from Eastern Europe

Aggregated analyses of the benefits from ecosystem services (ES) to well-being neglect important differences among beneficiaries and fail to capture the complexity of factors that mediate the ES–well-being relationship. Based on 25 group interviews, we disaggregated the ES–well-being relationships across six groups of potential beneficiaries in a farming landscape in central Romania, Eastern Europe. We explored what mediates distributional patterns of needs and benefits among beneficiaries and identified six contextual factors: (1) characteristics of the appropriated ES; (2) policies, formal institutions, and markets; (3) social and power relations, and informal institutions; (4) household decisions and individual contexts; (5) different perceptions and understandings of equity; and (6) individually held values. Based on these empirically derived factors, we developed a conceptual model of mediating factors that holistically takes into account the contextual space between ES and human beneficiaries. This model provides a framework for unpacking ES–well-being relationships that may guide ES research across varying socioeconomic cases. Notably, this model of mediating factors incorporates an equity perspective that is more refined than the dominant discourse on the relation between poverty and ES (which typically emphasizes that poor people are most dependent on ES, but neglects factors such as power relations and held values). Recognizing multiple contextual factors that shape the contribution of ES to well-being opens doors for harnessing new interdisciplinary collaborations and can help to inform more holistic policy interventions.