Influence of land use history on seed banks in European temperate forest ecosystems: a review

This study summarises European research on seed banks in temperate forest systems and analyses for differences in seed bank composition between geographically scattered forests with a different land use history. Special attention is given to seed bank characteristics of ancient forest species. Results of Detrended Correspondence Analysis suggest that historical land use is a key factor in determining the seed bank composition. Particularly seed banks of forests on former heathland sites differ from seed banks of ancient forest due to a high contribution of early successional species. The effect of former land use decreases after 50 yr, due to seed senescence. Total seed density decreases with recent forest age. Seed bank composition of eastern European forests is different from northern or western European forests, a difference which is mainly caused by species with a higher Ellenberg indicator value for continentality, temperature and reaction. In general, ancient forest species are poorly represented. Only a limited number is mentioned to have a persistent seed bank, and their densities are relatively low, which means that restoration of typical ancient forest vegetation can not rely on the seed bank. However, there is still a considerable lack of knowledge concerning seed bank and germination characteristics of forest species.     

The land use history (1278–1990) of a mixed hardwood forest in western Belgium and its relationship with chemical soil characteristics

Aim During the last decades, an increasing number of studies have stressed the importance of historical human influence on the ecology of forests and on the characteristics of forest soils. Therefore, the objectives of this study are (1) the quantification of the land use history of Ename Wood from 1278 to 1990 and (2) to find out whether the former land use of the forest has long-lasting effects on present-day chemical soil properties. Location The 62-ha present-day Ename Wood is situated in western Belgium and is the remainder of the 145-ha historical Ename Wood. Methods We disposed of eighteen land-use maps for the period between 1278 and 1990 which were digitized using a geographic information system (GIS). Transition between the different land uses and Shannon–Wiener diversity indices were calculated to quantify the history of changing land use. Mixed soil samples were taken in lots delimited on the basis of the historical data. Next, the soil properties were combined with the land-use variables using redundancy analysis and ANOVA . Results The quantification of the land use changes showed that the present Ename Wood is the result of several forest regression and progression phases, with a complete clearance in the nineteenth century. Diversity in land use was maximal between the fourteenth and the sixteenth century due a variety of transitional forms between forest and pasture. A positive correlation between the duration of arable land use since the 19th century clearance and soil pH, calcium and phosphate content was observed and a negative correlation was found with the carbon content, the total nitrogen content and the C:N ratio. These correlations are probably caused by a combination of acidification processes and the accumulation of organic matter under forest in combination with manuring practices in the twentieth century. Present-day forest lots which have been pastured for some time between 1278 and nineteenth-century clearance still had a significantly lower pH and degree of base saturation, which is probably caused by the export of nutrient rich plant material at that time. Discussion and conclusions The results demonstrate that the developed methodology is successful and confirm that historical land use, even in the distant past, can still influence present-day soil characteristics. For this reason, long-term historical land use should always be considered in forest ecological research.     

Expressing and purifying membrane transport proteins in high yield

Structural analysis of native or recombinant membrane transport proteins has been hampered by the lack of effective methodologies to purify sufficient quantities of active protein. We addressed this problem by expressing a polyhistidine tagged construct of the cardiac sodium-calcium exchanger (NCX1) in Trichoplusia ni larvae (caterpillars) from which membrane vesicles were prepared. Larvae vesicles containing recombinant NCX1-his protein supported NCX1 transport activity that was mechanistically not different from activity in native cardiac sarcolemmal vesicles although the specific activity was reduced. SDS-PAGE and Western blot analysis demonstrated the presence of both the 120 and 70 kDa forms of the NCX1 protein. Larvae vesicle proteins were solubilized in sodium cholate detergent and fractionated on a chelated Ni(2+) affinity chromatography column. After extensive washing, eluted fractions were mixed with soybean phospholipids and reconstituted. The resulting proteoliposomes contained NCX1 activity suggesting the protein retained native conformation. SDS-PAGE revealed two major bands at 120 and 70 kDa. Purification of large amounts of active NCX1 via this methodology should facilitate biophysical analysis of the protein. The larva expression system has broad-based application for membrane proteins where expression and purification of quantities required for physical analyses is problematic.