A survey of leaf phosphorus fractions and leaf economic traits among 12 co-occurring woody species on phosphorus-impoverished soils

Background and Aims: The leaf economic spectrum (LES) is related to dry mass and nutrient investments towards photosynthetic processes and leaf structures, and to the duration of returns on those investments (leaf lifespan, LL). Phosphorus (P) is a key limiting nutrient for plant growth, yet it is unclear how the allocation of leaf P among different functions is coordinated with the LES. We addressed this question among 12 evergreen woody species co-occurring on P-impoverished soils in south-eastern Australia. Methods: Leaf ‘economic’ traits, including LL, leaf mass per area (LMA), light-saturated net photosynthetic rate per mass (Amass), dark respiration rate, P concentration ([Ptotal]), nitrogen concentration, and P resorption, were measured for three pioneer and nine non-pioneer species. Leaf P was separated into five functional fractions: orthophosphate P (Pi), metabolite P (PM), nucleic acid P (PN), lipid P (PL), and residual P (PR; phosphorylated proteins and unidentified compounds that contain P). Results: LL was negatively correlated with Amass and positively correlated with LMA, representing the LES. Pioneers occurred towards the short-LL end of the spectrum and exhibited higher [Ptotal] than non-pioneer species, primarily associated with higher concentrations of Pi, PN and PL. There were no significant correlations between leaf P fractions and LL or LMA, while Amass was positively correlated with the concentration of PR. Conclusions: Allocation of leaf P to different fractions varied substantially among species. This variation was partially associated with the LES, which may provide a mechanism underlying co-occurrence of species with different ecological strategies under P limitation

Recreation and hunting differentially affect deer behaviour and sapling performance

Humans are increasingly acknowledged as apex predators that shape landscapes of fear to which herbivores adapt their behaviour. Here, we investigate how humans modify deer space-use and their effects on vegetation at two spatial scales; zones with different types of human use (largescale risk factor) and, nested within that, trails (fine-scale risk factor). In zones with three contrasting types of human activities: 1) no recreation, no hunting, 2) with recreation, no hunting and 3) with recreation and hunting, we linked deer space-use (dropping counts) to browsing intensity, relative growth and survival of planted saplings. Plots were located at two distances to trails (20 versus 100 m) to test how trails affect deer space-use and sapling performance. Additionally, plots were distributed over forest and heathland as risk effects are habitat-dependent. Deer space-use was highest in the zone without recreation or hunting, resulting in higher browsing levels and lower sapling growth and survival, but only in heathland. In contrast, deer space-use and sapling performance did not differ between zones with recreation only and zones with recreation and hunting. Deer dropping counts were lower near trails used for recreation, but this was not associated with browsing impact or sapling performance. Our results show that recreational use modifies deer space-use which is associated with browsing impact on woody vegetation, while seasonal hunting activities in zones with recreation did not have additive year-round effects. Yet, effects were only observed at the larger scale of recreation zones and not near trails. Furthermore, deer space-use was only associated with sapling performance in open heathland, where high visibility presumably increases avoidance behaviour because it increases detectability and decreases escape possibilities. This suggests that recreation creates behaviourally mediated cascading effects that influence vegetation development, yet these effects are context-dependent. We advocate incorporating human-induced fear effects in conservation, management and research

High nutrient-use efficiency during early seedling growth in diverse Grevillea species (Proteaceae)

Several hypotheses have been proposed to explain the rich floristic diversity in regions characterised by nutrient-impoverished soils; however, none of these hypotheses have been able to explain the rapid diversification over a relatively short evolutionary time period of Grevillea, an Australian plant genus with 452 recognised species/subspecies and only 11 million years of evolutionary history. Here, we hypothesise that the apparent evolutionary success of Grevillea might have been triggered by the highly efficient use of key nutrients. The nutrient content in the seeds and nutrient-use efficiency during early seedling growth of 12 species of Grevillea were compared with those of 24 species of Hakea, a closely related genus. Compared with Hakea, the Grevillea species achieved similar growth rates (root and shoot length) during the early stages of seedling growth but contained only approximately half of the seed nutrient content. We conclude that the high nutrient-use efficiency observed in Grevillea might have provided a selective advantage in nutrient-poor ecosystems during evolution and that this property likely contributed to the evolutionary success in Grevillea

Floral micromorphology and nectar composition of the early evolutionary lineage Utricularia (subgenus Polypompholyx, Lentibulariaceae)

Utricularia (Lentibulariaceae) is a genus comprising around 240 species of herbaceous, carnivorous plants. Utricularia is usually viewed as an insect-pollinated genus, with the exception of a few bird-pollinated species. The bladderworts Utricularia multifida and U. tenella are interesting species because they represent an early evolutionary Utricularia branch and have some unusual morphological characters in their traps and calyx. Thus, our aims were to (i) determine whether the nectar sugar concentrations and composition in U. multifida and U. tenella are similar to those of other Utricularia species from the subgenera Polypompholyx and Utricularia, (ii) compare the nectary structure of U. multifida and U. tenella with those of other Utricularia species, and (iii) determine whether U. multifida and U. tenella use some of their floral trichomes as an alternative food reward for pollinators. We used light microscopy, histochemistry, and scanning and transmission electron microscopy to address those aims. The concentration and composition of nectar sugars were analysed using high-performance liquid chromatography. In all of the examined species, the floral nectary consisted of a spur bearing glandular trichomes. The spur produced and stored the nectar. We detected hexose-dominated (fructose + glucose) nectar in U. multifida and U. tenella as well as in U. violacea. In both U. multifida and U. tenella, there were trichomes that blocked the entrance into the throat and spur. Because these trichomes were rich in chromoplasts and contained lipid droplets, they may form an additional visual attractant. Bearing in mind the phylogenetic hypothesis for the genus, we suggest that an early ancestor of Utricularia had a nectariferous spur flower with a lower lip that formed a wide landing platform for bee pollinators

Floral micromorphology of the bird-pollinated carnivorous plant species Utricularia menziesii R.Br. (Lentibulariaceae)

Made available in DSpace on 2019-10-06T16:15:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01• Background and Aims Bird pollination is rare among species in the genus Utricularia, and has evolved independently in two lineages of this genus. In Western Australia, the Western Spinebill, Acanthorhynchus superciliosus, visits flowers of Utricularia menziesii (section Pleiochasia: subgenus Polypompholyx). This study aimed to examine the micromorphology of U. menziesii flowers to assess traits that might be linked to its pollination strategy. • Methods Light microscopy, histochemistry and scanning electron microscopy were used. Nectar sugar composition was analysed using high-performance liquid chromatography. • Key Results The flowers of U. menziesii fulfil many criteria that characterize bird-pollinated flowers: red colour, a large, tough nectary spur that can withstand contact with a hard beak, lack of visual nectar guides and fragrance. Trichomes at the palate and throat may act as tactile signals. Spur nectary trichomes did not form clearly visible patches, but were more frequently distributed along vascular bundles, and were small and sessile. Each trichome comprised a single basal cell, a unicellular short pedestal cell (barrier cell) and a multicelled head. These trichomes were much smaller than those of the U. vulgaris allies. Hexose-dominated nectar was detected in flower spurs. Fructose and glucose were present in equal quantities (43 ± 3.6 and 42 ± 3.6 g L-1). Sucrose was only detected in one sample, essentially at the limit of detection for the method used. This type of nectar is common in flowers pollinated by passerine perching birds. • Conclusions The architecture of nectary trichomes in U. menziesii was similar to that of capitate trichomes of insect-pollinated species in this genus; thus, the most important specializations to bird pollination were flower colour (red), and both spur shape and size modification. Bird pollination is probably a recent innovation in the genus Utricularia, subgenus Polypompholyx, and is likely to have evolved from bee-pollinated ancestors.Department of Plant Cytology and Embryology Jagiellonian University in Kraków, 9 Gronostajowa St.Faculty of Biology University of Warsaw Botanic Garden, Al. Ujazdowskie 4Department of Animal Histology and Embryology University of Silesia in Katowice, 9 Bankowa St.School of Biological Sciences University of Western Australia (M084), 35 Stirling HighwayDepartamento de Biologia Aplicada à Agropecuária Faculdade de Ciências Agrárias E Veterinárias Universidade Estadual Paulista (Unesp)Faculty of Science School of Biological Sciences University of AdelaideUnit of Botany and Plant Physiology Institute of Plant Biology and Biotechnology University of Agriculture in Kraków, 29 Listopada 54 StreetDepartamento de Biologia Aplicada à Agropecuária Faculdade de Ciências Agrárias E Veterinárias Universidade Estadual Paulista (Unesp

Improving the Phosphorus Efficiency of Temperate Australian Pastures

Phosphorus (P) is a key input necessary for high production in many temperate, grass-legume pasture systems in Australia because the pastures are situated on P-deficient and moderate to highly P-sorbing soils. A consequence of P-sorption in these soils is that much more P must be applied as fertiliser than will be exported in animal products. The P balance efficiency (PBE=100*Pexport/Pinputs) of grazing enterprises (e.g. wool, meat, milk and live animal export) is about 10-30% and compares poorly with some other agricultural enterprises (e.g. 45-54% for grain production; McLaughlin et al. 1992; Weaver and Wong 2011). P accumulates in these soils when they are fertilised as a result of phosphate reactions with Ca and/or Al and Fe oxides, and P incorporation into resistant organic materials (McLaughlin et al. 2011). Some P in grazed fields is also accumulated in animal camps. The net rate of P accumulation in soil (and in grazed fields as a whole) is related to the concentration of plant-available P in the soil. Operating grazing systems at lower plant-available P levels should help to slow P accumulation and result in more effective use of P fertiliser (Simpson et al. 2010; Simpson et al. 2011). Because the P requirement of grass-legume pastures is usually set by the high P requirements of the legume (Hill et al. 2005), we commenced a study to quantify the P requirements of a range of legumes to determine whether productive, lower P-input grazing systems can be developed. We are also screening subterranean clover, the most widely used pasture legume in temperate Australia, for root traits related to P efficiency. Here we report early findings from the establishment year of a field experiment to determine the P requirement of several alternative temperate legumes

Confluence up to Garbage

No abstract available

Moderate dietary sodium restriction added to angiotensin converting enzyme inhibition compared with dual blockade in lowering proteinuria and blood pressure: randomised controlled trial

Objective To compare the effects on proteinuria and blood pressure of addition of dietary sodium restriction or angiotensin receptor blockade at maximum dose, or their combination, in patients with non-diabetic nephropathy receiving background treatment with angiotensin converting enzyme (ACE) inhibition at maximum dose