The worldwide leaf economics spectrum.

Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate.

Mid-season gas exchange of an alpine grassland under elevated CO2.

Ecosystem net CO2 uptake, evapotranspiration (ET) and night-time CO2 efflux were measured in an alpine grassland dominated by Carex curvula, treated with doubled ambient partial pressure of CO2 via open-top chambers. One quarter of the plots were treated with mineral nutrients to simulate the effect of lowland nitrogen deposition rates. Depending upon fertilizer supply, ecosystem net CO2 uptake per ground area in full sunlight (NCEmax) was 41-81% higher in open-top chambers supplied with doubled ambient partial pressure (p a) of CO2 than in plots receiving ambient CO2. Short-term reversals of the CO2 level suggest that the extent of downward adjustment of canopy photosynthesis under elevated CO2 was 30-40%. ET tended to decline, while water use efficiency (WUE), expressed as the NCEmax:ET ratio, increased more than twofold under elevated CO2. Night-time ecosystem CO2 efflux did not respond to changes in CO2 p a. NCEmax and night-time CO2 efflux were more responsive to mineral fertilizer than the doubling of CO2. This suggests that in these alpine plant communities, atmospheric nutrient input may induce equal or greater effects on gas exchange than increased CO2.

Delays in starting morning operating lists: an analysis of more than 20,000 cases in 22 German hospitals.

INTRODUCTION: Delays in the start of the first operation of the day often lead to conflicts among the involved physicians and nurses. Data on such delays have already been published for individual hospitals, but robust comparative data from a large number of institutions have not been available till now. METHODS: The study is based on the operating room (OR) documentation of four surgical services (general surgery, trauma/orthopedic surgery, gynecology, and ear nose throat [ENT] surgery) in 22 German hospitals over a nine-month period. Three process points ("patient arrival in OR suite," "anesthesia ready," and "incision") were analyzed for the first operation of the day in each OR. RESULTS: 21,357 operations in the first position were analyzed. The percentage of delays differed markedly for the three process points. The incision was delayed in more than 70% of the general surgical and trauma/orthopedic cases, but less often in gynecological (61 ± 24%) and ENT cases (42 ± 29%). The frequency of delays longer than 10 minutes was between 20% and 40%. The mean delay in delayed cases ranged from 14.1 ± 5.4 to 21.6 ± 8.2 minutes depending on the type of service and process point. CONCLUSION: The processes for the first operation of the day are not optimally structured in the hospitals whose cases were analyzed in this study. Delayed starts were common.

Effects of habitat fragmentation on the fitness of two common wetland species, Carex davalliana and Succisa pratensis.

Small habitat size and spatial isolation may cause plant populations to suffer from genetic drift and inbreeding, leading to a reduced fitness of individual plants. We examined the germination, establishment, growth, and reproductive capacity of two characteristic species of mown fen meadows, Carex davalliana, and Succisa pratensis, common in Switzerland. Plants were grown from seeds, which were collected in 18 habitat islands, differing in size and in degree of isolation. We used both common garden and reciprocal transplant experiments to assess effects of habitat fragmentation. In the common garden, plants of Carex originating from small habitat islands yielded 35% less biomass, 30% fewer tillers, and 45% fewer flowering tillers than plants from larger ones. In contrast, plants of Succisa originating from small habitat islands yielded 19% more biomass, 14% more flower heads and 35% more flowers per flower head than plants from larger ones. Moreover, plants of Succisa from small isolated habitats yielded 32% more rosettes than did plants from small connected islands. Reciprocally transplanted plants of Succisa originating from small habitat islands produced 7% more rosettes than plants from larger ones. There was no effect of small habitat size and isolation on germination and establishment of both species in the field. Our results document genetic differences in performance attributable to habitat fragmentation in both species. We suggest that fitness loss in Carex is caused by inbreeding depression, whereas in Succisa the differences in fitness are more likely caused by genetic differentiation. Our study implies that habitat fragmentation affects common habitat-specific species, such as Carex and Succisa, as well as rare ones.

Isozyme variability of the wetland specialist Swertia perennis (Gentianaceae) in relation to habitat size, isolation, and plant fitness.

We examined the effects of size and spatial isolation of fens on the isozyme variability of 17 populations of Swertia perennis. This long-lived perennial is a locally abundant fen specialist in Switzerland, where wetlands have been strongly fragmented. Isozyme variability was comparable to other outcrossing plants (A = 1.53, AP(p) = 2.01, P(p) = 42.5, H(o) = 0.113, H(e) = 0.139). F statistics indicated both inbreeding within and differentiation between populations (F(IS) = 0.076, F(IT) = 0.194, F(ST) = 0.128), with moderate gene flow between populations (N(e)m = 1.703). Populations in small, isolated fens had reduced genetic variability and the highest within-population inbreeding coefficients (F(IS)). Isozyme variability was significantly associated with vegetative fitness traits (MANOVA), and the magnitude of leaf herbivory decreased as the percentage of polymorphic loci increased. These data suggest that the reduced genetic variability of S. perennis in small, isolated populations may reduce plant fitness, thereby increasing susceptibility to herbivore damage. Our study also shows that habitat fragmentation can reduce the genetic variability of populations of fairly common habitat specialists, which so far have attracted less conservation attention than rare species.

Dietary shift and lowered biomass gain of a generalist herbivore in species-poor experimental plant communities.

Species loss of primary producers is likely to affect processes on other trophic levels. We studied consumption and individual performance of the generalist herbivore Parapleurus alliaceus (Orthoptera) in relation to the species richness of primary producers. Adult grasshoppers were caged and left to feed for 2 weeks on experimental grassland communities ranging in plant species richness from one, two, four, eight to 32 species. Low plant diversity had a negative effect on both plant community biomass and on biomass gain of female grasshoppers, feeding to produce eggs (male grasshoppers did not gain biomass during the feeding period). This was surprising because plots with high plant diversity had a low proportion of grass biomass and grasshoppers preferentially selected grasses, leading to a greater exploitation of grasses in experimental communities of higher diversity. Thus, the concurrent increase in non-grass species in the diet from these high-diversity communities must have been beneficial to the generalist herbivore. In addition to the positive effects of plant diversity, the presence of legumes in a mixture with grasses further enhanced the biomass gain of grasshoppers at a given level of diversity. These findings suggest that plant species loss may lead to shifts in herbivore population sizes, reducing those of generalists and benefiting specialists of the remaining plant species. Our results further suggest that generalist herbivores, by having feeding preferences, can also change the relative abundances of plant species with different functional characteristics. This may feedback on both composition and diversity of plant communities.