Nutrient and heavy metals in decaying harvest residue needles on drained blanket peat forests

Harvest residue decomposition can significantly contribute to nutrient and heavy metal exports to receiving water courses. This study monitors the nutrient and heavy metal dynamics in decaying Sitka spruce and lodgepole pine harvest residue needles on Atlantic blanket peat forests in the west of Ireland. Using the litterbag method, harvest residue was placed both within and between furrows in two uncut forest and two clear-cut sites. On the clear-cut sites, the litterbags were positioned outside the harvest residue piles (i.e. brash windrows). Over the 2-year monitoring period, the needles decomposed slower at the clear-cut sites than the uncut forest sites, with mass losses of 46–55 and 58–77 %, respectively. Approximately 20 % less phosphorous (P) was released from the decaying needles at the clear-cut sites, while nitrogen (N) was released only at the uncut sites. Tree species was a significant factor contributing to nutrient and heavy metal release and accumulation patterns, with higher concentrations of aluminium (Al), nickel (Ni), cadmium (Cd) and zinc (Zn) in the decaying spruce needles than in pine. Conversely, the spruce needles showed accelerated depletion of calcium (Ca) and magnesium (Mg) relative to the pine. The harvest residue needle positioning (inside furrow/between furrows) and the site soil characteristics contributed significantly to Al transformations in spruce needles and iron (Fe) in both spruce and pine needles, with more accumulation occurring inside the furrows where Al and Fe contents of the peat were high. Manganese (Mn) was released from the needles in three of the four sites with a total release of over 90 % within 2 years. In the remaining site, where the Mn content of the peat was high, an accumulation of Mn in the needles was observed. The decomposition of needles on blanket peat catchments may be a significant source of P to receiving water courses, owing to their fast release of P, but not a likely source for N export.     

Sampling saproxylic beetles: lessons from a 10-year monitoring study

We sampled saproxylic beetles using trunk window traps in two birch-dominated forests in Finland during 1990-1999. The sampling scheme, 10 traps attached to living fruiting bodies of Fomes fomentarius growing on dead birches, remained unchanged in both forests throughout the study period. Beetles belonging to 32 selected families were identified every year, whereas all species were identified during the last 4 years. Total number of identified individuals was 40,294 and number of species 583, of which 258 were saproxylic (dependent on dead wood). Species richness of rare and threatened saproxylic beetles in the samples varied a lot between the years and did not fluctuate synchronously between the forests. Variation between years was smaller when all saproxylic species were pooled together and some abundant species fluctuated synchronously in the two forests. Similarity indices and DCA-ordination did not generally suggest decreasing similarity between samples with increasing temporal isolation. Incidence-based similarities of common saproxylic species within and between forests and years were high (means 0.7-0.8), whereas those of rare saproxylics were roughly 50% smaller and much more variable. More than 75% of the common saproxylic species found during the entire 10-year period were detected already after 3 years of sampling but accumulation of rare and threatened species was much slower. Our results suggest that: (1) occurrence of rare and threatened species in samples is much less predictable than that of common species and, e.g. reserve selection based on rarities should be made cautiously; (2) estimation of total number of threatened species in a forest is very difficult, because such species accumulate slowly in the samples; (3) samples from different years can be comparable in certain cases.     

Intra‐annual changes in reproductive indices of male and female Himalayan snow trout,Schizothorax richardsonii (Gray, 1832)

Periodic changes in reproductive hormone levels, gonadal histology and gonadosomatic index (GSI) of snow trout, Schizothorax richardsonii, were examined to ascertain annual cycle of gonadal development and reproductive status in their natural habitat. In females, there were coherent changes in plasma 17β‐oestradiol and vitellogenin along with GSI, oocyte maturation and vitellogenic progression, collectively indicating two distinct maturation peaks during the months of September and February. Coinciding with this, in males, plasma 11‐keto testosterone was also noticeably higher during September and February, with highest GSI values in September. However, plasma 17α, 20β‐dihydroxyprogesterone levels in males were found to be persistently high from September to February. This observation suggests the potential presence of matured oozing males over a longer period, unlike in females. Overall, the close association between reproductive hormone levels, GSI and gonadal maturation stages in males and females (particularly, the presence of postovulatory follicle complexes) with apparent natural synchronization clearly indicates that S. richardsonii breeds twice in a year, possibly during late September to early November and late February to early April in the coldwater riverine habitats of the Indian Himalayan region.     

怀孕母猪中矿物质的转运及利用

怀孕母猪除了满足本身生理活动所需的营养物质外．还必须为胎儿生长发育提供充足的养分．胎儿产生的代谢废物．也通过母猪而排出体外。因此．怀孕母猪对某些矿物质的需要可能相当高。但是胎儿和母体胎盘的血管并没有直接连通．两者之间存在血液屏障．一切营养物质都要通过血液屏障而转运到胎儿．例如铁这种矿物质就是经转铁蛋白的转运而到达胎儿的。所以说。怀孕母猪从日粮中吸收矿物质．然后把其中的一部分或本身的一部分转运给胎儿．从而参与本身和胎儿组织中大量的新陈代谢活动．一方面保证本身的发育正常．另一方面维持妊娠．保证胎儿发…     

Use of asynchrony in flowering for easy and economical polyhaploid induction in wheat following Imperata cylindrica‐mediated chromosome elimination approach

Wheat × Imperata cylindrica‐mediated approach of doubled haploidy breeding requires hand emasculation followed by pollination with I. cylindrica pollen. The pace of this endeavour can be enhanced by utilizing asynchronous flowering of wheat spikes by direct pollination without emasculation followed by morphological marker–assisted screening of selfed and crossed seeds. The emasculated and un‐emasculated spikes of 13 spring and six winter wheat genotypes and two triticale × wheat derivatives were pollinated with I. cylindrica pollen. The response of different genotypes for production of crossed and selfed seeds with direct pollination varied significantly within and between groups for spring and winter wheats, whereas triticale × wheat derivatives responded similarly to each other but significantly different from spring and winter wheats. Although, the proportion of pseudoseed formation was lower in case of direct pollination, yet in some genotypes, it was comparable to that of pollination after emasculation. Moreover, the response for haploid embryo induction frequency was similar in both the cases. The method of direct pollination can be utilized for easy and economical induction of haploids.     

Susceptibility of Sudanese Nubian goats, Nilotic dwarf goats and Garag ewes to experimental infection with a mechanically transmitted Trypanosoma vivax stock

The present study was conducted to study the susceptibility of two different types of Sudanese goats namely: Black Nubian, the Nilotic dwarf goats and ewes of Garag type to experimental infection with Trypanosoma vivax stock isolated from cattle outside tsetse area. The infection caused parasitaemia, anaemia and pyrexia in the infected goats. However, the Nilotic dwarf goats were more tolerant to the infection than the Nubian goats, showing significantly higher values of packed cell volume, haemoglobin concentration, total red and white blood cells counts and significantly low parasitaemia and low body temperature. Garag ewes which were found to be susceptible to T. vivax infection showed different signs of anaemia and pyrexia; it is recommended that comparative studies on sensitivity of this type and other different Sudanese types of sheep to Trypanosomosis should be conducted.