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Birds of two suborders, Accipitres and Falcones were the subjects of the study. The thyroids were always located asymmetrically. In Accipitridae the larger left gland was usually situated significantly more cranially than the right one. In common kestrel, the size of bilateral thyroids was similar while their mutual relationships were individually variable. The location of the parathyroid glands in common kestrel was relatively constant. Seven topographical patterns of the location of the parathyroid gland were noted in Accipitridae. In birds of both the suborders, the thyroid might be supplied by three (groups of) arteries: the cranial thyroid, the caudal thyroid and the middle thyroid arteries. The aforementioned vessels were derived from the common carotid and the oesophagotracheobronchial artery. In common kestrel, the thyroid vessels might also branch from the ascending oesophageal artery, which passes along the thyroid, while in common buzzard and other Accipitridae - from the common trunk of the comes nervi vagi and the ascending oesophageal artery. The parathyroid glands were supplied by one to three parathyroid arteries. The vessels for the cranial parathyroid gland mostly originated from the caudal thyroid artery, while for the caudal one - from the oesophagotracheobronchial artery. The average number of thyroid and parathyroid arteries in common buzzard was significantly higher than those in common kestrel. 相似文献
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Miroslav Svoboda Shawn Fraver Pavel Janda Radek Bače Jitka Zenáhlíková 《Forest Ecology and Management》2010
Montane Norway spruce forests of Central Europe have a very long tradition of use for timber production; however, recently there has been increasing concern for their role in maintaining biological diversity. This concern, coupled with recent severe windstorms that led to wide-spread bark beetle outbreaks, has brought the management of montane spruce forests to the forefront of public policy discussions in Central Europe. In order to shed light on the natural development and current structure of mature montane spruce forests, we established four 0.25 ha research plots in a semi-natural montane spruce forest in the Šumava Mountains (The Bohemian Forest), Czech Republic. We mapped all trees, extracted increment cores for age and growth-pattern analyses, and inventoried all current tree regeneration, including the substrates on which it was found. Stands were characterized by uni-modal tree diameter distributions and high basal areas (56.6 m2 ha−1 on average), indicating a natural transition from the stem exclusion phase towards the understory reinitiation phase. The stands showed largely single-cohort recruitment age structures, however, with recruitment spanning seven decades. Our analyses suggest that this cohort existed as advance regeneration prior to major disturbances in the late 1800s, which included post-bark beetle salvage logging. Spatial pattern analyses of living and dead stems combined, showed an increase in uniformity of living trees, pointing to the role of natural density-dependent mortality. However, past growth patterns and historical documentation suggest that low intensity canopy disturbances (wind and snow) also caused mortality and diversified canopy structure. Because the stands developed naturally over the past 120+ years and thus escaped thinning operations, high volumes of coarse woody debris (94 m3 ha−1) and snag densities (546 stems ha−1) have accrued. Advance spruce regeneration was quite abundant and existed primarily on deadwood substrates, even though these occupied only a small percent of stand area. Because of salvage logging in the late 1880s, these stands do not qualify, according to the traditional paradigm, as natural spruce forests. As a result, they are recently subject to active management practices including salvage logging that remove dead and dying trees. Given the importance of deadwood for forest regeneration and recovery from disturbance, as demonstrated in this study, we argue that dead wood removal may limit future natural regeneration in these stands. Thus, the purported benefits of removing dead and dying trees from semi-natural forests must be carefully weighed against the potential detrimental impacts on natural spruce forest regeneration and biodiversity. 相似文献
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Tomas Lošák Jaroslav Hlusek Jiri Martinec Johann Vollmann Jiri Peterka Radek Filipcik 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(4):313-321
Abstract Camelina (Camelina sativa (L.) Crtz., false flax) is described as a species requiring fewer inputs than other oilseed crops thus making it an interesting alternative in sustainable cropping systems. As information on the combined effects of nitrogen and sulphur on camelina yield and quality parameters is meagre, a pot fertilization experiment was carried out with nitrogen applied as NH4NO3 at three increasing rates equivalent to a range from 63 up to 127 kg ha?1. These treatments were combined with sulphur additions applied as (NH4)2SO4 to achieve a soil sulphate content of 25 or 45 mg kg?1, respectively (equivalent to 75 and 135 kg S ha?1). The medium and high nitrogen rates combined with the low sulphur fertilization level increased the number of branches per plant compared with the lowest nitrogen fertilization at the same sulphur rate. Camelina seed yield increased with increasing nitrogen doses at the same low sulphur level, whereas straw yield increased only at the highest rate of nitrogen. Thousand-seed mass increased at the highest nitrogen dose and with the low sulphur application rate. In addition, the increase in nitrogen fertilization reduced seed oil content from 39.8% to 37.1%. A highly negative correlation was observed between oil and protein content of seeds. Nitrogen fertilization increased total oil yield and total protein yield. Differences in crop parameters between the sulphur treatments were not significant statistically, although the higher sulphur treatment tended to increase seed yield as well as oil and protein content compared with the low sulphur treatment. Thus, the combined application of N and S as mineral fertilizers is only recommended when growing camelina on sulphur-deficient soils if the aim is to achieve both high oil and protein production. 相似文献
24.
High-throughput sequencing has opened up possibilities of detecting new plant pathogens, especially viruses, with relative ease. However, information about biological characteristics and relevance to plant production is usually lacking. Recently, a new strawberry cytorhabdovirus named strawberry virus 1 (StrV-1) was described and characterized at a molecular level. The virus can be transmitted by aphids and is commonly found in commercial plantations. Here, we studied the impact of a sole StrV-1 infection on production in two strawberry cultivars—Darselect and Karmen. All plants infected with StrV-1 remained symptomless during the experiment. In general, Darselect was more resilient to StrV-1 infection, and the average yield per plant was nonsignificantly lowered by 11.7% over the 2-year experiment. In contrast, StrV-1 infection in cultivar Karmen led to a significant yield loss of 31.8%, indicating that the genetic background plays a role. While the average fruit weight and diameter were relatively unaffected, lower yields in infected plants stemmed from a significantly reduced number of inflorescences, by 23.6% and 29.6% in Darselect and Karmen, respectively, which resulted in a reduction in the average number of flowers per plant (decreased by 16.5% and 27.3%, respectively), and hence the number of fruits per plant (by 14.5% and 27.6%, respectively). The StrV-1 load was higher in spring than in autumn, and generally higher in the second year after infection, which corresponded to higher losses in the second harvest, especially in cultivar Karmen. 相似文献
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A total of 101 specimens were used; they came from 89 fetuses (4th to 40th week of gestation) and 12 neonates (1 to 14 days old). The age of the fetuses was determined according to the method of Kantorova (1960). The uterine veins were filled with latex using an automatic injection apparatus of our own construction. The study showed that blood left the uterus of the examined animals through constantly present veins (Ramus uterinus venae ovaricae, V. uterina and Ramus uterinus venae vaginalis) as well as through a number of inconstant veins to which belonged the Vv. vaginales accessoriae craniales et caudales. The constant uterine veins and their branches differed from their adult counterparts by being morphologically more differentiated, especially by having more branches of which some disappeared with time. The uterine veins developed toward the end of the fetal period. They arose either from the most caudal Vv. mesonephridicae lumbales (V. ovarica and its branches), or from the segmental, visceral veins of the pelvis (V. uterina and Vv. vaginales). 相似文献
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Morphology and development of the bovine ovarian artery during the fetal and postnatal periods
Development and morphology of the ovarian artery was studied in 106, 9–40 week-old fetuses and 14, 2–14 day-old calves. Different factors were considered such as time-dependent position and mode of branching from the aorta, the course of the ovarian artery in relation to the ovarian vein, and the artery's secondary distribution. Marked developmental changes which in time disappeared, become more prominent, or were reduced, could be demonstrated. 相似文献
Development and morphology of the ovarian artery was studied in 106, 9–40 week-old fetuses and 14, 2–14 day-old calves. Different factors were considered such as time-dependent position and mode of branching from the aorta, the course of the ovarian artery in relation to the ovarian vein, and the artery's secondary distribution. Marked developmental changes which in time disappeared, become more prominent, or were reduced, could be demonstrated. 相似文献
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The response of winter wheat grain yield to four variants of treatment (two input levels, combined with either conventional or reduced tillage) was tested over six seasons at three locations. These experiments with 10 and 12 winter wheat varieties were analysed within three experimental series. The environmental (location and season) effects on grain yield were large in all combinations of input level and tillage type, and the varieties responded differentially to both season and location. However, there was no varietal response either to the tillage system used, or to the level of nitrogen (and other inputs) supplied. The high input reduced tillage system (surface stubble-ploughing to a depth of 8–10 cm) resulted in all series in significantly higher grain yields than the equivalent conventional tillage system. The reduced tillage system combined with high input level delivered a yield advantage for all of the wheat varieties tested. 相似文献
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The few studies that have assessed the long-term patterns of re-use of tree cavities by bats all concern North American bats. We studied long-term re-use of tree cavities by two species of European bat, Daubenton's bats (Myotis daubentonii) and noctules (Nyctalus noctula). Cavities were inspected during consecutive years via direct capture of bats (more than 340 positive capture events, ca 2950 captured bats), observations of emerging bats, or by listening for bats during the early evening when bats emit typical vocalization (over 160 positive checks, over 450 observed bats). Between 1968 and 2007, we found 80 tree cavities used by bats (mostly excavated by woodpeckers) in the Czech Republic. Although more than half of the cavities were occupied for ≤4 summers, 28 cavities (35%) were re-used for 5–10 years. The longest period a cavity was used was 11 and 16 years for Daubenton's and noctule bats, respectively. Sixteen tree cavities (20%) were occupied solely by Daubenton's bats and 33 cavities (41%) were occupied only by noctules. The other 31 cavities (39%) were used by both species, either at separate times or simultaneously. Our data suggest that the larger volume of a cavity, the longer duration of re-use and the greater the probability of being occupied by both species. Continuous excavation of cavities by woodpeckers prevented the overgrowth of old cavities by calluses, which keep cavities accessible to bats. We suggest that woodpeckers may be the most important providers of suitable roosts for forest bats in Central Europe. Roosts were found in both economically valuable trees (Quercus robur and Tilia cordata) and less valuable tree species (Salix fragilis and Alnus glutinuosa). Economically valuable trees in our study area were long-lived and likely provide roosting habitat for longer periods but matured at a greater age. However, less economically valuable trees reached maturity and started to decay in a relatively short time, which may provide suitable cavities at a younger age. Maintaining both types of trees within forests may help provide suitable roosting oportunities for tree-dwelling bats in the Czech Republic. 相似文献