Low impact of climate change on subalpine grasslands in the Swiss Northern Alps

While phenological shifts and migration of isolated species under climate change have already been observed on alpine summits, very few studies have focused on community composition changes in subalpine grasslands. Here we use permanent plots monitored since 1954 and precisely located phytosociological censuses from 1970 to study compositional changes of subalpine grasslands in two distinct regions of the Swiss Northern Alps. In both areas, warming trends during the monitoring period were associated with changes in land management (abandonment of goat and sheep pasturing or grazing replaced by mowing). Old and recent inventories were compared with correspondence analyses (CA). Ecological indicator values, community‐affinities and biological traits of the species were used to infer the factors responsible for triggering the observed changes. In both regions, subalpine grasslands were stable with smaller changes than have previously been observed in alpine environments. Only a few species appeared or disappeared and changes were generally limited to increasing or decreasing frequency and cover of certain taxa. At one site, grazing abandonment favored fallow species. Some of these species were located at their upper altitudinal distribution limits and may have spread because of rising temperatures. In both areas, declining species were predominantly alpine and low‐growing species; their decline was probably due to increased competition (e.g., shadow) with more vigorous subalpine taxa no longer limited by grazing. We conclude that vegetation communities can respond rapidly to warming as long as colonization is facilitated by available space or structural change. In the subalpine grasslands studies, changes were mainly driven by land management. These communities have a dense vegetation cover and newly arriving herbaceous species preferring warmer conditions may take some time to establish themselves. However, climate disturbances, such as exceptional drought, may accelerate community changes by opening gaps for new species.     

Immunolocalization of Sarcoplasmic Reticulum Proteins in Mammalian Skeletal Muscle Fibers

SYNOPSIS. The sarcoplasmic reticulum is the intracellular membranesystem in skeletal muscle fibers which regulates the Ca^2$ concentrationof the myofibril and thereby the contraction relaxation cycle. In the past the proposed explanation for the differences inthe contractile properties of fast and slow skeletal fibershas been attributed mainly to quantitative rather than qualitativedifferences in the structure, function and molecular compositionof the sarcoplasmic reticulum of these two fiber types. Recentimmunocytochemical and biochemical studies have, however, clearlydemonstrated that the Ca^2$-ATPase of the sarcoplasmic reticulumin slow skeletal fibers is structurally and thus perhaps alsofunctionally related to that of the cardiac fibers, but distinctlydifferent from that of fast skeletal fibers. Furthermore similarstudies have shown that phospholamban, a cardiac sarcoplasmicreticulum protein believed to modulate the activity of the cardiacCa^2$-ATPase, is also present in slow but not fast skeletal fibers. The availability of antibodies specific to the fast and slowisoforms of the Ca^2$-ATPase, and to phospholamban will now enableus to apply immunocytochemical labeling techniques to examinethe effect of neuronal and other physiological signals on theregulation of the gene expression of sarcoplasmic reticulumproteins at the cellular level.