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Mite (Acari) occurrence in selected substrates used for a restoration of degraded soils

Klimek A., Chachaj B., Gackowski G., Dąbrowski J.

Infrastruktura i Ekologia Terenów Wiejskich

2018

nr II/1

277--291

The number and groups of mites (Acari) and species composition of oribatid mites (Oribatida) were analysed in three different substrates used for the restoration of degraded soils: (1) pine forest litter, (2) apple orchard litter, and (3) pine chips. The study was conducted in the years 2011-2012, on microplots of the area of 1m2 , established in a belt of trees of a nursery in Białe Błota (Bydgoszcz Forest District). Average biannual mite density per 50 cm3 of the investigated substrates ranged from 14.6 to 54.43 individuals. The highest numbers of mites were found in shredded forest litter and the lowest in pine chips. The most abundant mites in the studied material were oribatid mites, accounting for 57.3 % of these arthropods. The highest number of oribatid mites was found in the forest litter (28), and the lowest (20) in pine chips. The number of species in both types of litter was similar in the first and second year of the study, but it rose three times in the pine chips substrate over the study period. Oribatid species in the litter substrates were dominated by the eurytopic Tectocepheus velatus, and the most abundant species in the pine chips substrate was Oribatula tibialis. The experiment indicated a possibility of practical use of the shredded litter in the reintroduction of soil mesofauna and soil regeneration. This may facilitate the soil inoculation process, e.g., by using seeders specially adapted for this purpose. Additionally, a quick colonization of wood chips by acarofauna may suggest the possibility of using them as an excellent substrate for soil regeneration.

Acclimation of silver fir (Abies alba Mill.) seedlings to irradiance conditions under canopies of different tree species in Sudety Mts. (Southern Poland)

Robakowski P., Wyka T.

Polish Journal of Ecology

2003

Vol. 51, nr 3

323-337

To determine the influence of tree canopy composition on growth and physiological performance of silver fir (Abies alba Mill.) in Karkonoski National Park (Sudety Mountains, Southern Poland), three-year-old fir seedling were planted in five forest stands dominated by Betula pendula, Fagus sylvatica, Larix decidua, Picea abies or Pinus sylvestris. The stands differed in canopy openness such that young fir plants experienced drastically different light environments. After three years of acclimation to site conditions, length of shoots, seasonal changes in chlorophyll a fluorescence parameters, and the contents of chlorophyll, carotenoids and nutrients in the needles were studied to evaluate the seedling performance. Growth and photosynthetic characteristics of the young seedlings responded strongly to local light conditions. The lengths of leader shoot and twigs of the upper whorl reflected variation in canopy openness during the growing season and were highest under Larix. The potential quantum yield of photosystem II (F[v]/F[m]) showed a strong depression in the spring, especially under the leafless canopies of Betula and Fagus, probably because of the occurrence of low air temperatures. Later in the season F[v]/F[m] showed substantial recovery in all stands. Effective quantum yield FI[psii] measured under actinic light also showed a growing trend throughout the season with the lowest levels noted in the spring, particularly under Fagus and Betula. Fluorescence quenching revealed complex seasonal behaviour with little obvious relationship with stand illumination, except for consistently low value of photochemical quenching, and immediate or high nonphotochemical quenching under the dark Picea canopy, probably reflecting photoprotective acclimation to sunflecks. Although needle chlorophyll content showed no relationship to ambient light, the ratio of carotenoids to chlorophyll was positively linked to canopy openness suggesting the existence of leaf photoprotection that evaded detection by quenching analysis. Nutrient contents in needles depended on site conditions. In the light-transparent Larix stand, the fir needles were strongly depleted in Mg and Ca. Overall, however, all fir plants from experimental plots had much lower needle nutrient content than nursery-raised plants. Needle chlorosis found in Betula and Pinus stands was, however, not caused by macronutrient deficiencies. Considering all variables, conditions most conductive for fir growth and good vigor were found under larch and pine canopies where light penetration was intermediate to high. In contrast, the poorest conditions were found in the Betula stand, where high light penetration in the spring was followed by shading of firs during the growing season.