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Between-site Differences (between-site + difference)
Selected AbstractsOccurrence of Heterobasidion basidiocarps on cull pieces of Norway spruce left on cutting areas and in mature spruce standsFOREST PATHOLOGY, Issue 6 2007M. M. Müller Summary Fruiting of Heterobasidion on cull pieces and stumps of Norway spruce was investigated in cutting areas and mature spruce stands located in southern Finland. Cull pieces of variable size and showing butt rot were left on three clear-cut areas and in one thinned stand. Additionally, a part of the cull pieces was transported to mature forest sites with closed canopy. During the succeeding 3,4 years the cull pieces were investigated annually for sporocarps of Heterobasidion, and the area of actively sporulating pore layer of each sporocarp was measured. Root bases of spruce stumps in the logging areas were excavated and sporocarps found on the stumps also measured. At the onset of the experiment, Heterobasidion spp. were isolated from 76% of the cull pieces showing butt rot; 85% of the isolates were identified as H. parviporum and 15% as H. annosum s.s. During the following 3,4 years sporocarps were found on 20% of the 1938 cull pieces where Heterobasidion butt rot was initially detected visually. Sporocarp formation was promoted by advancement of butt rot, increasing cull piece diameter and end-to-end ground contact, but restricted by the colonization of the cull piece by Stereum sanguinolentum. Between-site differences were significant but could not be explained by differences in tree cover. At the end of the investigation period the average sporulating area of Heterobasidion sporocarp per metre of cull piece was higher than the average sporulating area per stump at three of four logging sites. Hence, leaving cull pieces containing Heterobasidion butt rot at logging areas in southern Finland can considerably increase local production of Heterobasidion spores. [source] Diet traditions in wild orangutansAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010Meredith L. Bastian Abstract This study explores diet differences between two populations of wild Bornean orangutans (Pongo pygmaeus wurmbii) to assess whether a signal of social learning can be detected in the observed patterns. The populations live in close proximity and in similar habitats but are separated by a river barrier that is impassable to orangutans in the study region. We found a 60% between-site difference in diet at the level of plant food items (plant species,organ combinations). We also found that individuals at the same site were more likely to eat the same food items than expected by chance. These results suggest the presence of diet (food selection) traditions. Detailed tests of three predictions of three models of diet acquisition allowed us to reject a model based on exclusive social learning but could not clearly distinguish between the remaining two models: one positing individual exploration and learning of food item selection and the other one positing preferential social learning followed by individual fine tuning. We know that maturing orangutans acquire their initial diet through social learning and then supplement it by years of low-level, individual sampling. We, therefore, conclude that the preferential social learning model produces the best fit to the geographic patterns observed in this study. However, the very same taxa that socially acquire their diets as infants and show evidence for innovation-based traditions in the wild paradoxically may have diets that are not easily distinguished from those acquired exclusively through individual learning. Am J Phys Anthropol 143:175,187, 2010. © 2010 Wiley-Liss, Inc. [source] Invasions and niche width: does niche width of an introduced crayfish differ from a native crayfish?FRESHWATER BIOLOGY, Issue 8 2009KARIN OLSSON Summary 1. Human activities have promoted the spread of species worldwide. Several crayfish species have been introduced into new areas, posing a threat to native crayfish and other biota. Invader success may depend on the ability to utilise a wide variety of habitats and resources. Successful invaders are generally expected to have broader niches and to be more plastic than non-invasive species. 2. Using stable isotope ratios of carbon and nitrogen we compared the niche widths of native noble crayfish and introduced signal crayfish, a successful invader of Swedish streams. The calculation of niche width took account of between-site differences in basal resource isotope signature ranges. We also assessed whether population density, prey biomass or prey diversity affected niche width. 3. At the species level, signal crayfish had twice the niche width of noble crayfish. However, individual populations of noble crayfish and signal crayfish in Swedish streams had similar niche widths. This suggests that signal crayfish has greater plasticity with respect to habitat utilisation and feeding than noble crayfish. Niche width in both species correlated positively with benthic invertebrate biomass and diversity, indicating that animal food sources are important for crayfish. 4. We find that assessing niche width in relation to invader success can be a useful tool trying to predict the impact of invasions on different scales. The findings in this study suggest that invaders and natives will have a similar impact on the stream scale whereas the invader will have a larger impact on the regional scale due to the ability to utilise a wider range of streams. [source] On the Influence of Temporal Resolution in Mesh Bag Decomposition StudiesINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 2 2007Giorgio Mancinelli Abstract The dry mass of reed mesh bags was monitored daily for 40 days at two sites in an Italian lagoon. The original daily-collected data set was manipulated by increasing inter-sampling time intervals to assess the effect of varying the sampling lag on the detection of inter-sites differences in decomposition patterns. At daily intervals, differences between sites were significant, although non-random, short-term mass fluctuations were observed. However, for linear interval increments, there were no between-site differences for lags ,7 days; in addition, for geometrical interval increments significant differences were never observed. Our study suggests that the temporal resolution chosen for a decomposition study may affect the detection of inter-site differences, emphasizing a previously-unexplored time dependency for leaf detritus decay patterns. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Survival and growth of brown trout Salmo trutta L. embryos and the timing of hatching and emergence in two boreal lake outlet streamsJOURNAL OF FISH BIOLOGY, Issue 4 2008J. Syrjänen Survival, growth and hatching of brown trout Salmo trutta embryos were studied using in situ incubation experiments in two lake outlet streams in Finland. The experimental design in both streams included an outlet site and a reference site far downstream. The date of hatching was recorded and the Elliott,Hurley model was then used to predict the time of emergence based on water temperature. For data analyses, the incubation period was divided into ,winter' (from fertilization to mid March) and ,spring' (from mid March until the end of the experiment). Temperature of the large-lake outlet remained at 1° C through the winter, while in other sites temperature was close to 0° C. In spring, temperature increased more slowly in the large-lake outlet. The survival of embryos was overall very high, from 83 to 98%, and they were larger in the outlets than in the downstream sites. Embryos hatched at the large-lake outlet in March, and 3,5 weeks later in the other sites. Although there were considerable between-site differences in hatching intervals, difference in expected 50% emergence dates of the earliest and latest site was only 4 days. Thus, any growth advantage that the outlet embryos had in winter disappeared by the end of the alevin period. Lake outlets, however, may be important for age 0 year brown trout later during the summer when other stream habitats do not provide adequate food resources. [source] | ||||||||||