An assessment of wheat (Triticum aestivum L.) genotypes under saline and waterlogged compacted soil conditions, I: grain yield and yield components

A pot experiment was conducted to study effects of salinity and waterlogging under soil compaction conditions on grain yield and yield components of wheat. Treatments were arranged in a factorial layout assigned to a randomized complete design with three replications. Treatment combinations included: two sets of compaction levels, i.e. non-compacted and compacted soil; four abiotic stresses, i.e. non-saline aerobic (untreated silt loam texture soil having ECe = 3 dS m-1); saline × aerobic (S) (ECe 15 dS m-1); saline × waterlogged (S×W); and waterlogged alone (W) were applied; and two Iranian wheat genotypes i.e. Kouhdasht and Tajan. Compaction was achieved by dropping a 5 kg weight, 20 times from 70 cm height on a wooden block placed on top of soil-filled pots. In non-waterlogged treatments, soil water was maintained at 70% of available water holding capacity (AWHC). Waterlogging was achieved by maintaining water up to 110% of the soil’s AWHC for 25 days during tillering stage. Compaction significantly intensified effect of all other treatments, except waterlogging, on grain yield and yield components of wheat genotypes as compared to control. S×W caused significantly higher reduction in grain yield and yield components for both genotypes than other treatments

An assessment of wheat (Triticum aestivum L.) genotypes under saline and waterlogged compacted soil conditions, II: leaf ion concentrations

A pot experiment was conducted to study effects of salinity and waterlogging under soil compaction conditions on grain yield and yield components of wheat. Treatments were arranged in a factorial layout assigned to a randomized complete design with three replications. Treatment combinations included: two sets of compaction levels, i.e. non-compacted and compacted soil; four abiotic stresses, i.e. non-saline aerobic (untreated silt loam texture soil having ECe = 3 dS m-1); saline × aerobic (S) (ECe 15 dS m-1); saline × waterlogged (S×W); and waterlogged alone (W) were applied; and two Iranian wheat genotypes i.e. Kouhdasht and Tajan. Compaction was achieved by dropping a 5 kg weight, 20 times from 70 cm height on a wooden block placed on top of soil-filled pots. In non-waterlogged treatments, soil water was maintained at 70% of available water holding capacity (AWHC). Waterlogging was achieved by maintaining water up to 110% of the soil’s AWHC for 25 days during tillering stage. S×W caused significantly higher reduction in K+ concentration for both genotypes than other treatments. S×W also resulted in higher leaf Na+ and Cl- concentrations in comparison to other treatments. Kouhdasht maintained significantly higher K + concentration and K+: Na+ ratio at S and S×W treatments than that Tajan (under both non-compacted and compacted soil conditions)

Hydrological controls of in situ preservation of waterlogged archaeological deposits

Environmental change caused by urban development, land drainage, agriculture or climate change may result in accelerated decay of in situ archaeological remains. This paper reviews research into impacts of environmental change on hydrological processes of relevance to preservation of archaeological remains in situ. It compares work at rural sites with more complex urban environments. The research demonstrates that both the quantity and quality of data on preservation status, and hydrological and chemical parameters collected during routine archaeological surveys need to be improved. The work also demonstrates the necessity for any archaeological site to be placed within its topographic and geological context. In order to understand preservation potential fully, it is necessary to move away from studying the archaeological site as an isolated unit, since factors some distance away from the site of interest can be important for determining preservation. The paper reviews what is known about the hydrological factors of importance to archaeological preservation and recommends research that needs to be conducted so that archaeological risk can be more adequately predicted and mitigated. Any activity that changes either source pathways or the dominant water input may have an impact not just because of changes to the water balance or the water table, but because of changes to water chemistry. Therefore, efforts to manage threatened waterlogged environments must consider the chemical nature of the water input into the system. Clearer methods of assessing the degree to which buried archaeological sites can withstand changing hydrological conditions are needed, in addition to research which helps us understand what triggers decay and what controls thresholds of response for different sediments and types of artefact

Effect of soil waterlogging on below-ground biomass allometric relations in Norway spruce

An increasing importance is assigned to the estimation and verification of carbon stocks in forests. Forestry practice has several long-established and reliable methods for the assessment of aboveground biomass; however we still miss accurate predictors of belowground biomass. A major windthrow event exposing the coarse root systems of Norway spruce trees allowed us to assess the effects of contrasting soil stone and water content on belowground allocation. Increasing stone content decreases root/shoot ratio, while soil waterlogging leads to an increase in this ratio. We constructed allometric relationships for belowground biomass prediction and were able to show that only soil waterlogging significantly impacts model parameters. We showed that diameter at breast height is a reliable predictor of belowground biomass and, once site-specific parameters have been developed, it is possible to accurately estimate belowground biomass in Norway spruce

Novel Methanotrophs of the Family Methylococcaceae from Different Geographical Regions and Habitats

Terrestrial methane seeps and rice paddy fields are important ecosystems in the methane cycle. Methanotrophic bacteria in these ecosystems play a key role in reducing methane emission into the atmosphere. Here, we describe three novel methanotrophs, designated BRS-K6, GFS-K6 and AK-K6, which were recovered from three different habitats in contrasting geographic regions and ecosystems: waterlogged rice-field soil and methane seep pond sediments from Bangladesh; and warm spring sediments from Armenia. All isolates had a temperature range for growth of 8–35 °C (optimal 25–28 °C) and a pH range of 5.0–7.5 (optimal 6.4–7.0). 16S rRNA gene sequences showed that they were new gammaproteobacterial methanotrophs, which form a separate clade in the family Methylococcaceae. They fell into a cluster with thermotolerant and mesophilic growth tendency, comprising the genera Methylocaldum-Methylococcus-Methyloparacoccus-Methylogaea. So far, growth below 15 °C of methanotrophs from this cluster has not been reported. The strains possessed type I intracytoplasmic membranes. The genes pmoA, mxaF, cbbL, nifH were detected, but no mmoX gene was found. Each strain probably represents a novel species either belonging to the same novel genus or each may even represent separate genera. These isolates extend our knowledge of methanotrophic Gammaproteobacteria and their physiology and adaptation to different ecosystems

Fir-dominated forests in Bavaria, Germany

The map of “Regional natural forest composition by main tree species” (WALENTOWSKI et al. 2001) depicts Bavaria as a region largely predominated by the European beech (Fagus sylvatica). Analyses of climatope, hygrotope and trophotope of fir-dominated regional natural units make evident that the reasons for the preponderance of the European silver fir (Abies alba) are edaphic. In terms of regeneration vigour, growth and yield the fir particularly dominates in habitats with a combination of humus cover, acid-oligotrophic topsoils and clayey or waterlogged subsoils, where the beech usually exhibits stunted and malformed growth forms. This ecological preference has the effect that Bavarian Abies alba-forests are restricted to small patches within a matrix of potential natural vegetation formed by mixed deciduous-coniferous mountain forests. Within European Natura 2000 areas Abies- forests should be recorded carefully as special habitats. Their transitional character between temperate beech forests (habitat type 9130) and boreal spruce forests (habitat type 9410), the ecological preference of Abies alba as an endangered tree species and their sensitivity against environmental stressors, including changes in forest structure, air quality, and climate, make them important objects for nature conservation

Comparative measurements of carbon dioxide fluxes from two nearby towers in a central Amazonian rainforest: the Manaus LBA site

Forests around Manaus have staged the oldest and the longest forest-atmosphere CO2 exchange studies made anywhere in the Amazon. Since July 1999 the exchange of CO2, water, and energy, as well as weather variables, have been measured almost continuously over two forests, 11 km apart, in the Cuieiras reserve near Manaus, Brazil. This paper presents the sites and climatology of the region based upon the new data sets. The landscape consists of plateaus dissected by often waterlogged valleys, and the two sites differ in terms of the relative areas of those two landscape components represented in the tower footprints. The radiation and wind climate was similar to both towers. Generally, both the long-wave and short-wave radiation input was less in the wet than in the dry season. The energy balance closure was imperfect (on average 80%) in both towers, with little variation in energy partitioning between the wet and dry seasons; likely a result of anomalously high rainfall in the 1999 dry season. Fluxes of CO2 also showed little seasonal variation except for a slightly shorter daytime uptake duration and somewhat lower respiratory fluxes in the dry season. The net effect is one of lower daily net ecosystem exchange (NEE) in the dry season. The tower, which has less waterlogged valley areas in its footprint, measured a higher overall CO2 uptake rate. We found that on first sight, NEE is underestimated during calm nights, as was observed in many other tower sites before. However, a closer inspection of the diurnal variation of CO2 storage fluxes and NEE suggests that at least part of the nighttime deficits is recovered from either lateral influx of CO2 from valleys or outgassing of soil storage. Therefore there is a high uncertainty in the magnitude of nocturnal NEE, and consequently preliminary estimates of annual carbon uptake reflecting this range from 1 to 8 T ha-1 y-1, with an even higher upper range for the less waterlogged area. The high uptake rates are clearly unsustainable and call for further investigations into the integral carbon balance of Amazon landscapes