Preadvies mossen en korstmossen.

Binnen het in OBN-kader uitgevoerd onderzoek was tot nu toe vaak aandacht voor de ruim 580 soorten mossen (inclusief variëteiten) en 800 soorten korstmossen die in Nederland voorkomen. Uit de Rode Lijsten blijkt dat er alle aanleiding is om meer aandacht te geven aan deze groepen. De achteruitgang van mossen en korstmossen speelt landelijk en in alle landschappen. Het Deskundigenteam Heuvellandschap heeft het preadvies begeleid namens alle deskundigenteams (droog zandlandschap, nat zandlandschap en beekdallandschap; rivierenlandschap; laagveenlandschap; zeekleilandschap; duin- en kustlandschap). Bij dit onderwerp zijn betrokken geweest: Universiteit Utrecht, Universiteit van Amsterdam, B ware (Radboud Universiteit), BLWG, Forestfun ecologisch advies en onderzoek, Alterr

Mossen en korstmossen zeggen waar het op staat

Door de directe afhankelijkheid van het substraat waarop ze groeien, zijn mossen en korstmossen goede indicatoren voor luchtkwaliteit en klimaatveranderin

Chain transfer to monomer and polymer in radical polymerisation of vinyl neo-decanoate

Molecular weight distributions of poly(vinyl neo-decanoate) produced by the bulk polymerization of the monomer to low conversions were investigated to obtain values of the rate constants for the chain transfer to monomer (C M ). The value of C M of 7.5(±0.6)x10 -4was obtained from a logarithmic plot of the number distribution at 5,25, and 50°C which suggests that the activation energy for chain transfer is on the order of 20-25 kJ mol . These plots were linear between the number and weight-average degrees of polymerization, but not over the whole molecular weight range for which a significant signal was observed in the gel permeation chromatography (GPC) trace. Modeling suggests that the deviations observed at high molecular weights can be explained by branching of the chains through chain transfer to the polymer, with a branching density as low as 10-5 , without affecting the slope at low values of the number of monomer unit, N. This deviation from the expected distribution of linear chains was used to estimate the branching densities at low conversion.ion

Diversity and ecology of lichens on churches in The Netherlands

This study presents the results of an inventory of lichen species on the walls of 344 medieval and renaissance churches in the Netherlands. In total, 194 species were recorded, of which several are more or less confined to this habitat in the country. We found several regional differences in species composition: 1. Churches in the Southwest are characterized by soft-limestone inhabiting species such as Opegrapha rupestris and Verrucaria calciseda; 2. Churches in the Rhine-Meuse-IJssel valleys are relatively species-rich and often harbour large quantities of Lecanora pannonica; and 3. Churches in the Northwest have many species that are usually found as epiphytes, like Cliostomum griffithii, Lecanora chlarotera and Lecidella elaeochroma. Multivariate analysis (PCA) shows four main ecological species groups: 1. epiphytes; 2. shaded limestone species; 3. sun-exposed limestone species; and 4. acidophilous species. The main determining factors are sun-exposition, substrate acidity and air-humidity

Korstmossen

Factsheets van de kortsmossen van het leefgebiedenbeleid

Long-tern monitoring in the Netherlands suggests that lichens respond to global warming

There is evidence to suggest that part of the recent changes in the lichen flora of the Netherlands is attributable to an increase in temperature. Changes which have occurred over the last 22 years were studied in detail, and were subjected to a statistical treatment by comparing the change of species to their latitudinal distribution and to ecological determinants. All 329 epiphytic and terrestrial lichen species occurring in the Netherlands were considered in relation to their world distribution. Arctic-alpine/boreo-montane species appear to be declining, while (sub)tropical species are invading. The proportion of increasing species is by far the largest among the wide-tropical lichens (83), and smallest among the arctic-alpine/boreo-montane lichens (14). None of the wide-tropical species was found to decrease, while 50 of the arctic-alpine/boreo-montane species show a decline. Long-term monitoring of the epiphytic lichen flora in the province of Utrecht from 1979 onwards shows that the total number of taxa present increased from 95 in 1979 to 172 in 2001, while the average number of taxa per site increased from 7.5 to 18.9. The rate of increase was greatest by far between 1989 and 1995. The majority of the species (152 taxa or 85) show a gross increase, only 17 species (10) show a decrease. :A detailed analysis of these data using multiple regression suggests global warming as an additional cause for recent changes, next to decreasing SO2 and increasing NH3. Changes appear to be correlated initially (1979-1095) only with toxitolerance and nutrient demand. Changes between 1995 and 2001, however, appear positively correlated to both temperature and nutrient demand, indicating a recent and significant shift towards species preferring warm circumstances, independent of and concurrent with changes due to nutrient availability. :This is the first paper reporting long-term floristic changes for lichens that appear to be correlated significantly with increasing temperatures. We suggest that future lichen monitoring programmes also pay attention to effects of climatic change, instead of focusing on air pollution effects only

Preadvies mossen en korstmossen

Overzicht van mossen en korstmossen per OBN landschapstype, met knelpunten, beheersmaatregelen en aanbevelingen voor onderzoek