Functional rather than structural connectivity explains grassland plant diversity patterns following landscape scale habitat loss

Context

Functional connectivity is vital for plant species dispersal, but little is known about how habitat loss and the presence of green infrastructure interact to affect both functional and structural connectivity, and the impacts of each on species groups.

Objectives

We investigate how changes in the spatial configuration of species-rich grasslands and related green infrastructure such as road verges, hedgerows and forest borders in three European countries have influenced landscape connectivity, and the effects on grassland plant biodiversity.

Methods

We mapped past and present land use for 36 landscapes in Belgium, Germany and Sweden, to estimate connectivity based on simple habitat spatial configuration (structural connectivity) and accounting for effective dispersal and establishment (functional connectivity) around focal grasslands. We used the resulting measures of landscape change to interpret patterns in plant communities.

Results

Increased presence of landscape connecting elements could not compensate for large scale losses of grassland area resulting in substantial declines in structural and functional connectivity. Generalist species were negatively affected by connectivity, and responded most strongly to structural connectivity, while functional connectivity determined the occurrence of grassland specialists in focal grasslands. Restored patches had more generalist species, and a lower density of grassland specialist species than ancient patches.

Conclusions

Protecting both species rich grasslands and dispersal pathways within landscapes is essential for maintaining grassland biodiversity. Our results show that increases in green infrastructure have not been sufficient to offset loss of semi-natural habitat, and that landscape links must be functionally effective in order to contribute to grassland diversity.

     

Determination of saponins in aerial parts of barrel medic (Medicago truncatula) by liquid chromatography-electrospray ionization/mass spectrometry

Triterpene saponins from aerial parts of Medicago truncatula cv. Jemalong A-17, M. truncatula Gaertn.var. longispina Urb., and M. truncatula Gaertn. var. truncatula were profiled and quantified using reverse-phase liquid chromatography with on-line photodiode array detection and electrospray ionization mass spectrometry (LC-PDA/ESI/MS/MS). The determination was based on standard curves obtained for the 18 available saponin standards, previously isolated from Jemalong A-17. Aerial parts of all three subspecies contained 17 saponins previously identified and also a substantial amount of astragaloside VIII (3-GlcA-Xyl-Rha soyasapogenol B), not previously reported in M. truncatula. The compositions of saponin mixtures were very similar in the three subspecies with three dominant groups, recognized as zanhic acid, medicagenic acid, and soyasapogenol glycosides. Relative proportions of these three groups were also similar in the three subspecies: var. longispina had 49.5, 48.1, and 2.4%; var. truncatula, 41.5, 53.4, and 5.1%; and Jemalong A-17, 42.1, 56.6, and 1.3% of zanhic acid, medicagenic acid, and soyasapogenol glycosides, respectively. Jemalong A-17 had 30% lower total content of saponins as compared to M. truncatula var. longispina and M. truncatula var. truncatula; in relation to the dry matter, var. longispina contained 0.22%, var. truncatula, 0.22%, and Jemalong A-17, 0.15% dry matter of saponins. If one takes into consideration that this determination was performed on spring-collected samples, it can be concluded that the concentration of saponins in M. truncatula is similar to the concentration in alfalfa (Medicago sativa); the proportions of the three groups of saponins in these species are slightly different from those found in alfalfa, having a higher content of zanhic acid glycosides.     

Pleiotropic effect of phenolic compounds content increases in transgenic flax plant

The principal goal of this paper was to generate flax (Linum usitatissimum L.) plants with increased antioxidant properties. To accomplish this a vector containing a multigene construct was prepared, and transgenic plants overexpressing essential flavonoid biosynthesis pathway enzymes were generated and analyzed. The simultaneous expression of genes encoding chalcone synthase (CHS), chalcone isomerase (CHI), and dihydroflavonol reductase (DFR) resulted in a significant increase of flax antioxidant capacity. To investigate the determinants of higher antioxidant properties of transgenic plants, the phenolic acids and lignans compound contents were measured. In both green part and seed extracts from transgenic plants, the phenolic acids level was increased when compared to the control. The calculated correlation coefficient between phenolic acids content and antioxidant capacity (0.82 and 0.70 for green part and flaxseed, respectively) perfectly reflects their strong relationship. The increase in yield of transgenic plants and their higher resistance to Fusarium culmorum and Fusarium oxysporum when compared to the control plants was a characteristic feature. It was assessed a very high correlation (correlation coefficient = 0.9) between phenolic acids level in flaxseed extract and resistance to F. culmorum. The flowering date of transgenic plants was approximately 3 weeks earlier than that of the control plants. Interestingly, a significant increase in monounsaturated fatty acids and a slight increase in lignans content accompanied the increase in antioxidant properties of flaxseeds.     

Advantages of using non-isothermal bioreactors in agricultural waste water treatment by means of immobilized urease. Study on the influence of spacer length and immobilization method

The behavior of three different catalytic membranes, obtained by immobilizing urease on nylon sheets chemically grafted with methyl methacrylate, was studied in a bioreactor operating under isothermal and non-isothermal conditions. Membrane activation was carried out by condensation or acyl azide reaction, and spacers of different lengths, such as hexamethylendiamine or hydrazine, were used. Under isothermal conditions, the activities of the catalytic membranes and soluble urease were characterized as a function of pH, temperature, and urea concentration. Both enzyme forms showed the same optimum pH, whereas the optimum temperature was lower for the immobilized enzymes. The spacer length appeared to determine broader pH- and temperature-activity profiles for the urease derivatives. The apparent K(m) values of the insoluble urease were dependent on membrane type and were higher than those of the soluble counterpart, thus indicating an affinity loss for urea. Under non-isothermal conditions, all membranes exhibited an increase of percentage activity proportional to the applied temperature difference and decreasing with the increase of urea concentrations. A decrease of the apparent K(m) was also observed. These results suggest that substrate diffusion limitations due to the immobilization process can be overcome in the presence of temperature gradients. In addition, the remarkable reduction of the production times supports the use of non-isothermal bioreactors for the treatment of urea-polluted waste waters.     

Comparison of fast and conventional GC analysis for citrus essential oils

This investigation concerns the application of fast GC in the analysis of essential oils. These are complex matrixes that usually undergo GC separation with conventional methods involving long columns, slow programmed temperature rates, and consequently, a high cost in terms of time. Fast GC techniques are based on the use of narrow bore capillary columns that allow the achievement of high-speed separations on complex samples while maintaining excellent resolution. This work saw the application of two methods on five different citrus essential oils and the comparison of all the results obtained.     

Effect of cadmium on life-history parameters in Dendrobaena octaedra (Lumbricidae: Oligochaeta) populations originating from forests differently polluted with heavy metals

This study examined whether earthworm (Dendrobaena octaedra) populations originating from three differently polluted mixed oak-pine forests differ in life history parameters, and whether any observed differences are adaptive. Three forests were chosen: the most polluted forest, near Olkusz, affected by a zinc smelter and on soil containing metal ore; the Niepo?omice Forest, moderately polluted by industry; and the relatively unpolluted Kampinoska Forest. Parent animals (P generation) were collected from each forest and thereafter cultured in the laboratory. From cocoons laid in the laboratory the F1 generation was reared and observed to determine whether it inherited features observed in the parent generation. To distinguish the effect of the metal studied (Cd) from that of soil edaphic conditions, individuals collected in the field were divided into two groups: one cultured in unpolluted medium, the other in medium spiked with cadmium. Earthworms originating from polluted forests (parent generation) exhibited higher cadmium storage capacity, and a higher cadmium concentration factor (cadmium in animal/cadmium in soil). No interpopulation differences in cadmium accumulation were found in their offspring (F1 generation), meaning that the cadmium accumulation ability was acclimatory and not adaptive. Cadmium in low doses negatively affected reproduction parameters: cocoon production, mass of produced cocoons, and reproductive allocation (weight of offspring divided by the weight of adults). The effect of cadmium was stronger in animals originating from the unpolluted forest than in those from the heavily polluted forest. F1 animals originating from the heavily polluted forest exhibited the highest cadmium tolerance (higher mean survival time and median survival time, lower hazard rate probability per time unit that an individual surviving to the beginning of a given interval will die within that interval). The observed tolerance to cadmium (higher reproduction, better survival) in the population from the heavily polluted forest apparently was heritable, suggesting adaptation of D. octaedra to life in a polluted environment.     

Determination of biological stability in compost: A comparison of methodologies

Biological [dynamic respiration index (DRI); chemical humification indexes: humification index (HI), degree of humification (DH) and humification rate (HR); and thermoanalytical (thermostability index, R₁ and a labile fraction)] indexes were used to assess compost stability of 15 end products. By use of these three techniques independent assessment of compost stability was made possible. Evidence of unstable materials was found where labile, easily biodegradable, and non-humified organic fractions were present. The DRI was used as a reference index for biological stability, and no significant correlation was observed between DRI and the humification indices (HI, DH, HR) and the thermogravimetry index (R₁). On the other hand, significant correlation was observed for DRI vs. non-humified carbon (NHC), which was determined using the chemical method and the labile fraction determined by thermogravimetry, as well as for NHC vs. “labile fraction”. These fractions represent labile, easily biodegradable, and non-humified organic matter. Significant correlations were also observed between the three above mentioned measurements and TEC, suggesting that this fraction is mainly formed of the easily degradable organic fraction. These results suggest that the integrated use of biological, chemical, and thermoanalytical methods could represent a useful tool in differentiating stabilized composts from non-stabilized ones, and it could provide more reliable information for both managerial and sanitary health aspects involved in good agricultural practice.     

Liming induces growth of a diverse flora of ammonia-oxidising bacteria in acid spruce forest soil as determined by SSCP and DGGE

The autotrophic ammonia-oxidising bacterial (AOB) community composition was studied in acid coniferous forest soil profiles at a site in southwestern Sweden 6 years after liming. Liming caused a significant increase in pH in the organic horizons, while the mineral soil was unaffected. The AOB communities were studied by single-strand conformation polymorphism (SSCP) in parallel with denaturing gradient gel electrophoresis (DGGE) analysis of partial 16S rRNA genes amplified by PCR using primers reported to be specific for β-Proteobacteria AOB, followed by nucleotide sequencing. High genetic diversity of Nitrosospira-like sequences was found in the limed soil profiles, whereas no AOB-like sequences were detected in the control soil at any depth, according to both the SSCP and DGGE analyses. This clearly showed that liming induced growth of a diverse flora of AOB at this forest site. Both Nitrosospira cluster 2 and cluster 4 sequences were present in the limed soil profiles, regardless of soil pH, but we found a higher number of sequences affiliated with cluster 4. The high lime dose seemed to affect the AOB community more than the low dose, and its effects reached deeper into the soil profile. Seven different Nitrosospira-like sequences were found 10 cm under the litter layer in the soil limed with the high dose, but only two in the soil amended with the low lime dose.     

Eating at fast-food restaurants is associated with dietary intake, demographic, psychosocial and behavioural factors among African Americans in North Carolina

OBJECTIVE: To examine associations of the frequency of eating at fast-food restaurants with demographic, behavioural and psychosocial factors and dietary intake in African American adults. METHODS: Self-reported data from a population-based cross-sectional survey of 658 African Americans, aged 20-70 years, in North Carolina. An 11-page questionnaire assessed eating at fast-food restaurants, demographic, behavioural and diet-related psychosocial factors, and dietary intake (fruit, vegetable, total fat and saturated fat intakes, and fat-related dietary behaviours). RESULTS: The participants were aged 43.9+/-11.6 years (mean+/-standard deviation), 41% were male, 37% were college graduates and 75% were overweight or obese. Seventy-six per cent reported eating at fast-food restaurants during the previous 3 months: 4% usually, 22% often and 50% sometimes. Frequency of eating at fast-food restaurants was positively associated with total fat and saturated fat intakes and fat-related dietary behaviours (P<0.0001) and inversely associated with vegetable intake (P<0.05). For example, mean daily fat intake was 39.0 g for usually/often respondents and 28.3 g for those reporting rare/never eating at fast-food restaurants. Participants who reported usual/often eating at fast-food restaurants were younger, never married, obese, physically inactive and multivitamin non-users (all P<0.01). Frequency of eating at fast-food restaurants was positively associated with fair/poor self-rated health, weak belief in a diet-cancer relationship, low self-efficacy for healthy eating, weight dissatisfaction, and perceived difficulties of preparing healthy meals and ordering healthy foods in restaurants (all P<0.05). Frequency of eating at fast-food restaurants did not differ significantly by sex, education, smoking, ability to purchase healthy foods or knowledge of the Food Guide Pyramid. CONCLUSIONS: Eating at fast-food restaurants is associated with higher fat and lower vegetable intakes in African Americans. Interventions to reduce fast-food consumption and obesity in African Americans should consider demographic and behavioural characteristics and address attitudes about diet-disease relationships and convenience barriers to healthy eating.     

Study on the elemental composition of marine particulate matter collected on different filter material

The chemical composition of marine particulate matter from the Southern Baltic has been studied using ICP atomic emission spectrometry. The samples were collected on polycarbonate 0.4 µm, cellulose acetate and glass fiber 0.45 µm filters, and on polycarbonate filters of 0.2, 0.4, 0.6, and 1.0 µum pore size. The suspensions were analyzed for the major elements Ca, Mg, Al, Fe, and P, and for the minor and trace constituents: Mn, Mo, Zn, Cu, Co, Cd, Cr, As, Se, Sb, Ag, and S. The concentrations of metals calculated on dry weight basis were higher when polycarbonate filters were used while the values for cellulose acetate and glass fiber filter were comparable. The determination of net mass particulate matter was the main reason for these differences. A comparative study of the chemical composition of suspensions from the Southern Baltic and from other areas showed a similar range of concentrations of particulate elements in coastal waters.