Environmental quality assessment of the drainage basin of Lake Engure using Scots pine as a bioindicator Environmental quality assessment of the Lake Engure drainage area, which is the LT(S)ER region of the Latvian National Long-term Ecological Research network (Latvia LTER), was conducted using three bioindication methods based on Scots pine Pinus sylvestris L.: unspecific bioindication by pine needle tip necrosis, ground level ozone assessment by pine needle chlorotic mottling, and chemical analysis of pine bark. Samples were collected from 40 sites of the region in November 2010. Extent of needle tip necroses did not exceed class 4 (maximum possible value 6). The highest value of index of needle damage by ozone was Idam = 1.62 (maximum possible value 6). Multiple regression analysis of variables describing bark chemistry and needle damage in relation to distance from the sea, nearest roads and villages was performed. Pine bark acidity pH(KCl) and concentration of Mg and Fe decreased significantly (βpH(KCl) = -0.672, P < 0.001; βMg = -0.676, P < 0.001; βFe = -0.514, P < 0.001) with distance of sample site from gravel roads. Electric conductivity (EC) of pine bark and the extent of ozone damage of the first year needles Idam significantly decreased with distance from the sea (βozone = -0.507, P < 0.01; βEC = -0.453, P < 0.01). PCA of the pine bark chemistry data showed dust pollution from gravel roads to be the main factor responsible for the 33% variation of data. No statistically significant correlations were found between different bioindicator characteristics, except between first and second year ozone damage (ρ = 0.589, P = 0.01).

The article discusses changes in species richness and numbers of flies (Diptera, Brachycera) in the Lake Engure Nature Park (LENP) during 1995-2012. The study was performed within the framework of the National Long Term Ecological Research (LTER) network of Latvia. During the period of study, a statistically significant increase in positive temperature sums (> 4 °C) was observed at the local meteorological station (R2 = 0.489; P < 0.01). Insects were collected three times per season (June, July, and August) by entomological sweep net from twelve sample plots, which represented a variety of habitats of the LENP - dry xerophytic, mesophytic and humid hygrophytic ones. In total 411 species from 35 families were identified. Dry sample plots showed a statistically significant increase in species richness and/or numbers of flies during the period of study. Humid sample plots did not show any statistically significant trends except for two grassland plots where large herbivores were introduced in 2005 for grassland management purpose. Pooling the data from all sample plots, except those grazed by large herbivores, yielded a statistically significant trend of increase in species richness of flies (R2 = 0.647; P < 0.01). Among the main trophic groups zoophagous species showed the largest number of statistically significant positive trends mostly within the dry sample plots. For several sample plots significant positive correlations were recorded between species richness of zoophagous flies and annual sums of positive temperatures. It was hypothesised that climate warming may have an indirect effect via interaction with other environmental factors such as moisture regime, nitrogen pollution, and vegetation structure.

During the last three centuries, people involved in natural history sciences have produced thousands of natural history collections worldwide. Specimens have been used for scientific proof of various discoveries and for gaining new knowledge in many disciplines of science not only in the area of biodiversity but also in taxonomy, species biology and ecology, parasitology, evolution, organisms' responses to climate change, nature conservation and many other biological sub-disciplines. Despite never-ending financial struggles, the world's largest collections as well as many regional midsize collections contain billions of specimens. This provides an enormous database for present and future studies. This article presents a critical description of the material of the Institute of Biology, University of Latvia collection (IBULC) containing roughly 59,000 identified arthropod individuals of about 3,700 species, including twenty-eight primary types as a part of around ninety type specimens, to illustrate the importance of midsize regional natural history collections in detail.