Bryophytes in a changing landscape: The hierarchical effects of habitat fragmentation on ecological and evolutionary processes

Testing the myriad predictions associated with the community, demographic and genetic impacts of habitat fragmentation remains a high conservation priority. Many bryophyte taxa are ideal model systems for experimentally testing such metapopulation-based and population genetic predictions due to their relatively fast colonisation-extinction rates, high substrate specificity, dominant haploid condition, and diminutive size. Herein, we review the community, demographic and population genetic impacts of habitat fragmentation on bryophytes, highlight the present knowledge gaps, and offer ideas on how experimental studies utilizing bryophytes may be used to address the broader conservation implications associated with fragmented ecosystems. Previous research suggests that dispersal limitation best explains observed patterns of abundance and distribution of bryophytes in some fragmented habitats. However, edge effects influence bryophyte community structure of border habitats especially where abrupt differences in micro-climatic conditions between the matrix and the forest remnant exist, or where the species pool contains members with inherently restricted ecological amplitudes. Existing studies do not agree on the relationship between basic attributes of bryophyte community structure (i.e., species richness and local density), and habitat area and degree of spatial-isolation. Demographic studies are a critical step in structuring conservation strategies, however surprisingly little empirical information exists as to the impacts of habitat fragmentation on plant population dynamics. We propose that bryophytes offer great potential for testing predictions with respect to plant population persistence in spatially-structured landscapes.     

Effects of fresh and aged copper contaminations on soil microorganisms

The aim of the investigation was to compare effects of fresh and aged amendments of copper (Cu) on the active, aerobic, heterotrophic microbial biomass by respiration and potential‐nitrification measurements and on microbial‐community structure by means of phospholipid‐fatty‐acid (PLFA) analyses. An A_p horizon (10–20 cm) of a Luvisol was used for the experiments. Fresh copper amendments were carried out by spraying a CuCl₂ solution on the soil. Aged heavy‐metal amendments were achieved by mixing the control soil with monocontaminated soil derived from an abandoned site in Denmark which has been used as a wood‐preservation plant. As expected, fresh contaminations were more effective to reduce potential nitrification and respiration than aged contaminations if the total Cu concentration (Cu_t) in soils is considered. There were no differences between aged and fresh contaminations if their effects were referred to NH₄Cl‐extractable concentrations (Cu_AN). The lowest concentration reducing cumulative substrate‐induced respiration (C_R) amounted to 0.33 mg Cu_AN (kg dm)^–1. PLFA analyses revealed Cu contaminations to decrease mainly aerobic bacteria. Effects were more pronounced using the contaminated soil as an inoculum. Apparently the duration of contamination is more important to the change of microbial‐community structure than the actual availability of the contaminant.     

Phenolic compounds and fatty acids from acorns (Quercus spp.), the main dietary constituent of free-ranged Iberian pigs

The aim of the present work was to identify and quantify the phenolic compounds and fatty acids in acorns from Quercus ilex, Quercus rotundifolia, and Quercus suber. The concentration of oleic acid was >63% of total fatty acids in all cases, followed by palmitic and linoleic acids at similar concentrations (12-20%). The concentrations of alpha-tocopherol in Q. rotundifolia, Q. ilex, and Q. suber were 19, 31, and 38 mg/kg of dry matter (DM), respectively, whereas the concentrations of gamma-tocopherol were 113, 66, and 74 mg/kg of DM, respectively. Thirty-two different phenolic compounds were distinguished. All of them were gallic acid derivatives, in the form of either galloyl esters of glucose, combinations of galloyl and hexahydroxydiphenoyl esters of glucose, tergallic O- or C-glucosides, or ellagic acid derivatives. Several tergallic acid C-glucosides were also present in the extracts obtained from Q. suber. Acorns from Q. ilex and Q. rotundifolia showed similar polyphenol patterns mainly with gallic acid-like spectra. Chromatograms of Q. suber showed mainly polyphenols with ellagic acid-like spectra. Valoneic acid dilactone was especially abundant in Q. suber skin. The contribution of skin to the total phenolics of the acorn was relatively small in Q. rotundifolia and Q. ilex but relatively high in Q. suber. Skin extracts from Q. suber, Q. rotundifolia, and Q. ilex showed 1.3, 1.4, and 1.0 antioxidant efficiencies, respectively (compared to that of butylhydroxyanisole). Endosperm extracts showed lower capacity to prevent lipid peroxidation than skin extracts.     

Effects of sodium selenite on microbial activity of mull,moder and mor soils

Summary Effects of Na₂SeO₃ on microbial activity of mull, moder and mor soils were investigated with perfusion experiments under controlled laboratory conditions. Treatments with Se at 50 mg/kg reduced carbon dioxide production and dehydrogenase activity in the mor and moder soils. Se at 250 (Ah) to 1000 (L) mg/kg had to be added to the mull soil in order to affect both parameters. In contrast to the effect on respiration and dehydrogenase activity, N mineralization, especially ammonification, was stimulated by the addition of Se. This is probably due to secondary effects such as dissolution of organic matter and P desorption. The relative inhibition of arylsulfatase activity was closely correlated with a decrease in soil respiration. It was conduded that the reduction of arylsulfatase activity in Se-treated soils was the result of a reduction in enzyme synthesis.     

Wirkung von 2,2′,5,5′ Tetrachlorbiphenyl,Benzo-a-pyren,Cadmium und Kupfer in einem Rieselfeldboden und Aufnahme dieser Stoffe durch Roggen (Secale cereale)

Effect of 2,2′,5,5′-tetrachlorobiphenyl, benzo-a-pyren, cadmium and copper in an original sewage field soil and uptake of these substances by rye Rye was cultivated in pots on weakly polluted sewage field soil (R) and artificially polluted variants of this soil. The aim of the project was to study the combined effect of organic pollutants (PCB, PAH) and heavy metals (HM) to parameters of soil biology, biomass production and soil-plant transfer. R was contaminated with 2,2′,5,5′-tetrachlorobiphenyl (PCB 52), benzo-a-pyren (BaP), cadmium (Cd) or copper (Cu) as well as with combinations of these substances up to concentrations comparable with an extremely polluted sewage field soil. Rye showed significant yield reductions on all treatments enriched with copper ( > 60 ppm plant-available Cu in soil). In this context copper only produced the impairments of microbial activity in the soil and caused its phytotoxicity. The yield reductions were connected with higher copper contents and also higher cadmium contents of rye as a result of concentration effect. Added copper led to increasing mobility and availability for plants of Cd in the soil. Addition of copper in combination with organic pollutants to soil R increased also availability of Cd for plants.     

Varietal differences among the polyphenol profiles of seven table grape cultivars studied by LC-DAD-MS-MS

Polyphenols present in red table grape varieties Red Globe, Flame Seedless, Crimson Seedless, and Napoleon, and the white varieties Superior Seedless, Dominga, and Moscatel Italica were analyzed by HPLC-DAD-MS. The anthocyanins peonidin 3-glucoside, cyanidin 3-glucoside (and their corresponding p-coumaroyl derivatives), malvidin 3-glucoside, petunidin 3-glucoside, and delphinidin 3-glucoside were found. In addition, caffeoyltartaric acid, p-coumaroyltartaric acid, and the flavonols quercetin 3-glucuronide, quercetin 3-rutinoside, quercetin 3-glucoside, kaempferol 3-galactoside, kaempferol 3-glucoside, and isorhamnetin 3-glucoside were detected. Flavan-3-ols were also detected, and were identified as gallocatechin, procyanidin B1, procyanidin B2, procyanidin B4, procyanidin C1, catechin, and epigallocatechin. These phenolics were present only in the skin, as the flesh of these grape cultivars was almost devoid of these compounds. Anthocyanins were the main phenolics in red grapes ranging from 69 (Crimson Seedless) to 151 (Flame Seedless) mg/kg fresh weight of grapes, whereas flavan-3-ols were the most abundant phenolics in the white varieties ranging from 52 (Dominga) to 81 (Moscatel Italica) mg/kg fresh weight of grapes. Total phenolics ranged from 115 (Dominga) to 361 (Flame Seedless) mg/kg fresh weight of grapes. This means that a serving of unpeeled table grapes (200 g) could provide up to 72 mg of total phenolics (Flame Seedless). These results indicate that the intake of unpeeled table grapes should be recommended in dietary habits as a potential source of antioxidant and anticarcinogenic phenolic compounds.