Impacts of climate warming on reindeer herding require new land-use strategies

Climate in the Arctic has warmed at a more rapid pace than the global average over the past few decades leading to weather, snow, and ice situations previously unencountered. Reindeer herding is one of the primary livelihoods for Indigenous peoples throughout the Arctic. To understand how the new climate state forces societal adaptation, including new management strategies and needs for preserved, interconnected, undisturbed grazing areas, we coupled changes in temperature, precipitation, and snow depth recorded by automatic weather stations to herder observations of reindeer behaviour in grazing areas of the Laevas Sámi reindeer herding community, northern Sweden. Results show that weather and snow conditions strongly determine grazing opportunities and therefore reindeer response. We conclude that together with the cumulative effects of increased pressures from alternative land use activities, the non-predictable environmental conditions that are uniquely part of the warming climate seriously challenge future reindeer herding in northern Sweden.     

Spatial variability of soil gas concentration and methane oxidation capacity in landfill covers

In order to devise design criteria for biocovers intended to enhance the microbial oxidation of landfill methane it is critical to understand the factors influencing gas migration and methane oxidation in landfill cover soils. On an old municipal solid waste landfill in north-western Germany soil gas concentrations (10, 40, 90 cm depth), topsoil methane oxidation capacity and soil properties were surveyed at 40 locations along a 16 m grid. As soil properties determine gas flow patterns it was hypothesized that the variability in soil gas composition and the subsequent methanotrophic activity would correspond to the variability of soil properties. Methanotrophic activity was found to be subject to high spatial variability, with values ranging between 0.17 and 9.80 g CH₄ m⁻² h⁻¹_. Considering the current gas production rate of 0.03 g CH₄ m⁻² h⁻¹, the oxidation capacity at all sampled locations clearly exceeded the flux to the cover, and can be regarded as an effective instrument for mitigating methane fluxes. The methane concentration in the cover showed a high spatial heterogeneity with values between 0.01 and 0.32 vol.% (10 cm depth), 22.52 vol.% (40 cm), and 36.85 vol.% (90 cm). The exposure to methane raised the oxidation capacity, suggested by a statistical correlation to an increase in methane concentration at 90 cm depth. Methane oxidation capacity was further affected by the methanotroph bacteria pH optimum and nutrient availability, and increased with decreasing pH towards neutrality, and increased with soluble ion concentration). Soil methane and carbon dioxide concentration increased with lower flow resistance of the cover, as represented by the soil properties of a reduced bulk density, increase in air capacity and in relative ground level.     

Status, diversity and distribution patterns of mangrove vegetation in the Segara Anakan lagoon, Java, Indonesia

In the Segara Anakan lagoon, Java, 21 tree species and 5 understorey genera have been identified. Average tree density is 0.80 ± 0.99 Ind./m2 with 48.71% seedlings and an average basal area of 9.86 ± 10.54 cm2/m2. Tree density and diversity are high in the eastern part of the lagoon, located near the city of Cilacap. There, the dominant tree species are Aegiceras corniculatum, Nypa fruticans and Rhizophora apiculata, of which the two latter are characteristic for mature forests. By contrast, understorey species and the pioneer species (Avicennia alba, Aegiceras corniculatum and Sonneratia caseolaris) dominate the central lagoon where several rivers discharge. Compared to former studies, seedling density and tree diameter in the central lagoon has declined considerably and tree species dominance has changed. The high sedimentation rates and deforestation are likely to prevent the formation of a mature forest there. Tree communities are more equilibrated in the eastern lagoon which points to a more stable and less disturbed mangrove forest.     

Water stress alters aphid-induced glucosinolate response in Brassica oleracea var. italica differently

Glucosinolates (GS) are the main secondary metabolites in brassicaceous plants that play an important role in plant defense and plant–insect communication. GS biosynthesis in plants and their accumulation may be influenced by biotic and abiotic stressors from the environment. In the present study, GS levels in broccoli plants, Brassica oleracea var. italica Plenck, grown under different water status conditions of soil—well-watered, drought and waterlogged—were determined after two aphid species, the specialist Brevicoryne brassicae (L.) and the generalist Myzus persicae (Sulzer), had fed on them for 7 days. High-performance liquid chromatography analysis revealed that GS levels were significantly induced after B. brassicae had fed on B. italica plants grown for 2 weeks under the various water status conditions. No significant differences were determined between GS induction in the three treatments. In contrast, the induction of GS after M. persicae had fed on the plants depended greatly on water stress levels. GS content in well-watered plants increased more significantly than in plants grown under drought conditions. Feeding by M. persicae did not increase GS levels when plants were grown under waterlogged conditions. The lowest plant growth were found in M. persicae-infested plants for all three water treatments, and measurements of GS showed that the induction of GS by M. persicae decreased in line with the reduction in infested plant growth. GS induction by B. brassicae did not alter remarkably following change in plant growth under water stress. Only one of the five glucosinolates detected, the aliphatic GS 4-methylsulfinylbutyl, remained unchanged after feeding of both, M. persicae and B. brassicae, on plants under water stress. Variation in GS levels was mainly observed for the induction of indolyl GS due to aphid herbivory, but changes in indol-3-ylmethyl GS were not always consistent with the induction of other indolyl GS.