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Response of artificial acid irrigation, liming, and N-fertilisation on elemental concentrations in needles, litter fluxes, volume increment, and crown transparency of a N saturated Norway spruce stand

The response of N-fertilisation, irrigation, acid irrigation, and liming on concentrations of elements in needles, fluxes of elements in litter, volume increment, and crown density on a full stocked, healthy, and vigorously growing mature spruce stand was investigated. The plots of the Höglwald site in Southern Bavaria exhibited a high volume increment with regularly more than 20 m³ ha⁻¹ per year, despite the high age of the stand (77 years at the beginning of the experiment in 1984). Neither a distinct growth reduction of the stand due to acid irrigation, or N oversaturation, nor an enhancement of growth due to N-fertilisation, irrigation, or liming of the stand could be detected. For the years 1984 and 1985 a marked decrease in crown density was detected for all plots. This was followed by a stagnation for 2 years. Afterwards the crown density improved until the end of the investigation for all plots. Neither acid irrigation, nor liming altered the amount of litter fall. Ca fluxes in litter, and concentrations in needles were enhanced on most of the limed plots five to six years after liming. Acid irrigation reduced Ca content in litter, but other elements were not or only slightly influenced. The nutritional status of all plots as shown by the concentrations of elements in needles indicates that for most of the years a sufficient to high supply of N, P, Ca, and Mg for all investigated plots, whereas K concentration in needles exhibited wide year to year variations. Most of the elemental concentrations in needles and fluxes in litter were not influenced by any of the treatments. Also, N-fertilisation did not enhance the N concentrations in needles significantly.     

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Simple purification (desalting) procedure to facilitate structural analysis of an alkali-solubilized/neutralized starch solution by intermediate-pressure size-exclusion chromatography

A technique was established to remove impurities (e.g., salts) from starch dissolved in strong alkali and neutralized with acid to accommodate starch structural analysis via intermediate-pressure size-exclusion chromatography (IPSEC). Starch (corn and wheat) subjected to an alkaline-microwave dissolution scheme (35 s microwave heating in a mixture of 6 M urea and 1 M KOH) was either treated with ion-exchange resin or passed through a desalting column to remove salt/urea contaminants. Control (untreated) starch solution analyzed by IPSEC displayed a significant interfering peak (attributable to salt/urea), which coeluted with the starch amylose peak. The interfering peak was most efficiently eliminated by first passing the starch solution through a desalting column, which process effectively removed impurities (e.g., salts/urea) without appearing to adversely impact the starch structural analysis. This simple technique coupled with the rapid alkaline-microwave starch dissolution procedure greatly expedites structural investigation of starch by facilitating analysis by IPSEC.     

Late frost sensitivity of juvenile <Emphasis Type="Italic">Fagus sylvatica</Emphasis> L. differs between southern Germany and Bulgaria and depends on preceding air temperature

Fagus sylvatica, the dominant native forest tree species of Central Europe, is sensitive to late frost events. Advanced leaf flushing due to climate warming may lead to more frequent frost damage in the future. Here, we explore local adaptation to late frost events at both continental and regional scales and test how moderate climate warming (+1.5°C) affects late frost sensitivity. Short-term leaf injury and height growth after a late frost event were quantified in a common garden experiment with 2-year-old F. sylvatica seedlings. The fully crossed three-factorial design consisted of a late frost manipulation, a continuous warming manipulation and selected provenances (three provenances from western Bulgaria and three from southern Germany). Late frost led to leaf injury and reduced height growth (−7%). Provenances differed in their late frost sensitivity at the regional scale, and local adaptation was detected. At the larger scale, the Bulgarian provenances showed reduced height growth (−17%), while the German provenances did not exhibit growth reduction. The warming treatment prevented late frost damage, while height growth declined by 19% in the reference temperature treatment. This surprising finding was attributed to advanced leaf maturity in the warming treatment. The impact of late frost events on F. sylvatica in a warmer world will depend on timing. An event that damages leaves immediately after leaf flushing appears negligible a few days earlier or later, thereby complicating projections. Local adaptation to late frost is evident at a regional scale. Management strategies should aim at maximizing genetic diversity to adapt to climate change.