The influence of topography and fire in controlling landscape composition and structure in Sierra de Gredos (Central Spain)

Mediterranean landscapes are dynamic systems that undergo temporal changes in composition and structure in response to disturbances, such as fire. Neither landscape patterns nor driving factors that affect them are evenly distributed in space. Accordingly, disturbances and biophysical factors interact in space through time. The aim of this paper is to assess the relative influence of topography and fire on the landscape patterns of a large forested area located in Sierra de Gredos (Central Spain) through time. A series of Landsat MSS images from 1975 to 1990, and a digital elevation model (DEM) were used to map fires, assess topographical complexity and evaluate changes in landscape composition and structure. Functional regions across the entire landscape were identified using different classification criteria (i.e., percentage burned area and topographic properties) to model topographic and fire impacts at regional scales. A canonical variance partition method, with a time series split-plot design, quantified the relative influence and co-variation of topography and fire on land cover patterns through time. Main results indicated that analyzing portions of the landscape under similar environmental conditions and fire histories, the effects of different fire regimes on the spatio-temporal dynamics of main land covers can be highlighted. However, the impact of fire on landscape patterns was high variable among regions due to the different regeneration abilities of main land covers, the topographic constraints and the fire histories of each region. Hence, broad patterns of fire related variance and co-variation with topography emerged across the entire area due to the different conditions of each landscape portion in which this large Mediterranean landscape was divided. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Indicators of success for smart law enforcement in protected areas: A case study for Russian Amur tiger (Panthera tigris altaica) reserves

Although considerable conservation resources have been committed to develop and use law enforcement monitoring and management tools such as SMART, measures of success are ill‐defined and, to date, few reports detail results post‐implementation. Here, we present 4 case studies from protected areas with Amur tigers (Panthera tigris altaica) in Russia, in which indicators of success were defined and evaluated at each. The ultimate goal was an increase in tiger numbers to 1 individual/100 km² at each site. We predicted that improvements in law enforcement effectiveness would be followed by increases in prey numbers and, subsequently, tiger numbers. We used short‐term and long‐term indicators of success, including: (i) patrol team effort and effectiveness; (ii) catch per unit effort indicators (to measure reductions in threats); and (iii) changes in target species numbers. In addition to implementing a monitoring system, we focused on improving law enforcement management using an adaptive management process. Over 4 years, we noted clear increases in patrol effort and a partial reduction in threats. Although we did not detect clear trends in ungulate numbers, tiger populations remained stable or increased, suggesting that poaching of tigers may be more limiting than prey depletion. Increased effectiveness is needed before a clear reduction in threats can be noted, and more time is needed before detecting responses in target populations. Nonetheless, delineation of concrete goals and indicators of success provide a means of evaluating progress and weaknesses. Such monitoring should be a central component of law enforcement strategies for protected areas.     

The effect of urban refuse compost and different tractors tyres on soil physical properties, soil erosion and maize yield

Application of urban refuse compost to agricultural soil could help to solve municipalities' problems related to the increasing production of waste only if soil property improvement and environmental conservation can be demonstrated. The use of low-pressure tractor tyres is another proposal in modern agriculture for reducing soil compaction. This study thus aimed to detect the effects of both compost and low-pressure tractor tyres on soil loss, runoff, aggregate stability, bulk density, penetrometer resistance and maize (Zea mays L.) yield. A 3-year field experiment was carried out on a hilly (15% slope) clay loam soil in central Italy. Twelve plots (200 m² each) were monitored with tipping-pot devices for runoff and soil erosion measurement. Treatments were: compost addition (64 Mg ha⁻¹), mineral fertilisation, use of low-pressure tyres, use of traditional tyres, with three replicates, in a fully randomised block design. Compost was applied once at the beginning of the experiment. Runoff reduction due to compost ranged between 7 and 399 m³ ha⁻¹ during seasons, while soil erosion was reduced between 0.2 and 2.4 Mg ha⁻¹. Mean weight diameter (MWD) of stable aggregates, measured on wheel tracks, increased by 2.19 mm, then progressively decreased. Compost significantly increased bulk density by 0.08 Mg m⁻³ due to its inert fraction content. This effect was less evident in the second and third year, probably due to harrowing. Maize yields were slightly, but significantly, reduced in composted plots by 1.72 Mg ha⁻¹ in the third year. Low-pressure tyres significantly reduced soil loss in the third year by 1 Mg ha⁻¹. Furthermore, they did not significantly influence runoff volumes and soil structural stability. Low-pressure tyres or compost addition were singly able to prevent an increase in penetrometer resistance due to agricultural machinery traffic. Low-pressure tyres increased the maize yield during the 3 years and the difference (0.4 Mg ha⁻¹) became significant in the third year. In conclusion, results show the positive lasting effect of compost in ameliorating soil physical properties and reducing runoff and soil erosion. Low-pressure tyres appear justifiable both for the observed increase of grain production and reduction of soil compaction. This latter effect is, nevertheless, masked by compost addition which is also able to reduce penetrometer resistance. Further research is required to explain the causes of the slight inhibition of grain yield observed when compost was compared with mineral fertilisation.     

Tandem size exclusion chromatography-Polyacrylamide gel electrophoresis of humic acids

Humic acids (HAs) from four soils were fractionated by size exclusion chromatography (SEC) on Sephadex G-75. Three fractions were obtained in all humic acids, collected and assayed by Polyacrylamide gel electrophoresis (PAGE). The unfractionated HA from each soil was used as reference. Each chromatographic fraction formed one electrophoretic zone corresponding closely to one band of the reference sample with some admixture of the fractions preceding or following. The results indicate that fractionation of HAs by tandem SEC-PAGE can be successfully used for obtaining fractions of reduced polydispersity and different electrophoretic mobilities. Pyrolysis/methylation-gas chromatography-mass spectrometry of the full size preparations of HA and fractions with exactly defined molecular size and electrophoretic mobility showed a different distribution in humic components, mainly lipids, lignin derivatives and N-containing compounds.     

Size‐related oxygen consumption and ammonia excretion of Eurasian perch (Perca fluviatilis L.) reared in a recirculating system

Oxygen consumption (OC) and ammonia excretion rates (AE) of perch were measured under commercial‐like conditions (temperature 23.3 °C) in both fed (F) and feed‐deprived groups (D). Measurements were taken in triplicate in six sized batches of perch ranging from 44.8 to 336.2 g. The mean daily OC was 288.3–180.6 mg O₂ kg^?1 h^?1 for group F fish ranging in size from 44.8 to 279.4 g body weight. The mean daily AE expressed as total ammonia nitrogen (TAN) was 13.8–5.2 mg TAN kg^?1 h^?1 in the same groups. Daily peaks of OC in group F perch were observed 6 h after the onset of feeding for each size group with relatively stable values up to the end of feeding. Peaks of daily AE in group F perch were observed 10 h after the onset of feeding in each size group, with a rapid decrease up to 16 h after onset. In group D, OC was 181.1–110.5 mg O₂ kg^?1 h^?1 in the weight range 57.9–336.2 g. The daily mean AE was 1.7–0.5 TAN kg^?1 h^?1 in this group. No dramatic peaks of OC and AE were observed in group D perch.     

In Vitro Anti-Orthohantavirus Activity of the High-and Low-Molecular-Weight Fractions of Fucoidan from the Brown Alga Fucus evanescens

The Hantaan orthohantavirus (genovariant Amur–AMRV) is a rodent-borne zoonotic virus; it is the causative agent of haemorrhagic fever with renal syndrome in humans. The currently limited therapeutic options require the development of effective anti-orthohantavirus drugs. The ability of native fucoidan from Fucus evanescens (FeF) and its enzymatically prepared high-molecular-weight (FeHMP) and low-molecular-weight (FeLMP) fractions to inhibit different stages of AMRV infection in Vero cells was studied. The structures of derivatives obtained were determined using nuclear magnetic resonance (NMR) spectroscopy. We found that fucoidan and its derivatives exhibited significant antiviral activity by affecting the early stages of the AMRV lifecycle, notably virus attachment and penetration. The FeHMP and FeLMP fractions showed the highest anti-adsorption activity by inhibiting AMRV focus formation, with a selective index (SI) > 110; FeF had an SI of ~70. The FeLMP fraction showed a greater virucidal effect compared with FeF and the FeHMP fraction. It was shown by molecular docking that 2O-sulphated fucotetrasaccharide, a main component of the FeLMP fraction, is able to bind with the AMRV envelope glycoproteins Gn/Gc and with integrin β3 to prevent virus–cell interactions. The relatively small size of these sites of interactions explains the higher anti-AMRV activity of the FeLMP fraction.     

Does rainbow trout justify its high rank among alien invasive species? Insights from a nationwide survey in Greece

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Slow nitrogen release from humic substances modified with aminoorganosilanes

Purpose

The purpose of the present study is to evaluate slow-release nitrogen capabilities of soil amendments obtained by modification of humic materials from peat and lignite with alkoxyorganosilanes carrying different amine substituents.

Materials and methods

The humates from lignite and peat were modified using (3-aminopropyltriethoxy)-silane (APTES) and (1-aminohexamethylenene, 6-aminomethylene)-triethoxysilane (AHATES). The obtained derivatives were characterized using elemental analysis and Fourier transform infrared spectroscopy. Nitrogen release in the form of ammonia or nitrate was evaluated using dissolution tests under sterile aqueous conditions as well as long-term soil experiments. Ammonium and nitrate were determined using ion-selective electrodes. Activity index (AI) was calculated from the dissolution tests. For soil trials, arable Retisol was sampled from 0- to 5-cm layer in Yaroslavl region (Russia). The soil experiments were conducted over 78 days using (NH₄)₂SO₄ as an activator of nitrification and 3-amino-1,2,4-triazole as an inhibitor of autotrophic nitrifying bacteria.

Results and discussion

Modification of lignite and peat humates leads to an increase in nitrogen content up to 2 and 4.3 %, respectively, in case of APTES, and up to 3 and 6 %, respectively, in case of AHATES. All humic derivatives gradually released N upon dissolution in water over 6 days up to 51 % of the total N. The AI values ranged from 4 to 13 %. Amendment of soil with the modified humic materials induced an increase in nitrate content resulting from nitrification of released ammonia by soil microflora. This was confirmed by aminotriasole experiments. The nitrogen release occurred slowly: over the first week of incubation, it did not exceed 36–69 % of the total N content. The higher release rate of ammonium nitrogen was observed for CHS-AHATES versus CHS-APTES derivative, whereas no difference was seen between the two peat derivatives, which showed release rate on the level of CHS-AHATES derivative. Positive effect of all modified humic materials lasted over 78 days.

Conclusions

Modification of lignite and peat humates with two aminoorganosilanes carrying one and two nitrogen atoms in the amine substituent brought about twofold to threefold enrichment of the parent humic materials with nitrogen, which was capable of slow release upon incubation in soils. It was released in the form of ammonia and transformed to nitrates by autotrophic nitrifying soil microflora. There was no clear relationship established between structure of amine substituent of organosilane and slow-release properties of the corresponding humic derivatives. The conclusion was met that principal application of aminoorganosilane derivatives of humic substances (HS) is soil structuring, whereas nitrogen-fertilizing capabilities might be considered as beneficial added-value feature of these humic products.

     

Using humic products as amendments to restore Zn and Pb polluted soil: a case study using rapid screening phytotest endpoint

Purpose

Heavy metal contamination is a priority issue affecting millions of hectares of soil throughout the world. One of the most promising, environmentally friendly, and cost-effective approaches to restore polluted soils could be applying organic amendments. We investigated the remediation potential of three types of humic products with regard to their effect on the bioavailability of Pb and Zn, content of nutrients, and the ability to mitigate acute phytotoxicity in contaminated soil.

Materials and methods

Spodosol samples were spiked with Pb (550 mg kg^?1) and Zn (880 mg kg^?1). Then, two different commercial humic products (from peat and lignosulfonate) and natural humic acids (from brown oxidized coal) were added in two doses to reach an equal content of carbon: a 10% increment and a 30% increment of the initial total organic carbon in the soil. After 30 days, the content of metals and nutrients (S, K, Na, Ca, Mn, P) was determined by the sequential extraction (i?H₂O, ii?NH₄COOH pH 4.8, iii–CH₃COOH). The effect of humic products on heavy metals bioavailability was evaluated using the calculated partition indexes. Seed germination and root elongation of Sinapis alba were also determined. Chemical and biochemical variables were aggregated by the principal component analysis.

Results and discussion

Humic products reduced the amount of bioavailable fractions of Pb and Zn in soils. The partition index, which quantitatively describes bioavailable fractions of the Zn and Pb in the soil, was 28–49% lower than in the spiked (Pb+Zn) control. The inhibition of root elongation and seed germination of mustard by Zn and Pb was significantly mitigated by humic products; in the soil test, the root length and seed germination were up to 36–87% higher than those of the Pb+Zn control and did not differ from those in the non-amended treatments. This effect may have been associated with the structural differences (H/C and O/C ratio) and content of nutrients (Na and K) in humic products.

Conclusions

Commercial humic products used in poor multi-contaminated soils can maintain plant growth by improving nutrient status due to heavy metals immobilization and can be a promising approach to remediate the soil contaminated with heavy metals at extremely high concentrations.