Bird conservation in fragmented Mediterranean forests of Spain: effects of geographical location, habitat and landscape degradation     

Tomás Santos  José Luis Teller?&#x;aRoberto Carbonell 《Biological conservation》2002,105(1):113-125

The effects of habitat fragmentation on forest bird assemblages were analysed in 214 holm oak (Quercus ilex) remnants spread across the northern and southern plateaux of central Spain. Bird richness was highly dependent on fragment area for all species regardless of isolation, and barely affected by habitat traits. Geographical location was associated with high differences in richness of bird assemblages, which included 17 species exclusive to northern remnants and one exclusive to southern remnants. This supports the hypothesis that habitat suitability deteriorates sharply from north to south for forest birds in Spain. The species-area relationships of bird assemblages sampled in fragmented forests along a broad continental gradient (from Norway to southern Spain) showed that true forest birds only nest in woodlands >100 ha in southern Spain, whereas the full complement of forest species occurs in much smaller fragments in central-western Europe. Loss of species that are particularly sensitive to habitat fragmentation accounts for these differences between dry Spanish and mesic European woodlands. These results are explained by the low habitat suitability of Spanish woodlands, associated with the restrictive conditions for plant regeneration in the Mediterranean climate and long-standing human usage. There is, therefore, a particular need to develop management strategies that conserve birds, and probably other forest organisms, in Mediterranean regions by preventing habitat deterioration and decreases in fragment size, and by conserving all woods >100 ha.  相似文献   

Electrical conductivity of olivine, wadsleyite, and ringwoodite under upper-mantle conditions   总被引：1，自引：0，他引：1  

Y Xu  BT Poe  TJ Shankland  DC Rubie 《Science (New York, N.Y.)》1998,280(5368):1415-1418

Geophysical models show that electrical conductivity in Earth's mantle rises about two orders of magnitude through the transition zone in the depth range 410 to 660 kilometers. Impedance measurements obtained on Mg1.8Fe0.2SiO4 olivine, wadsleyite, and ringwoodite at up to 20 gigapascals and 1400 degreesC show that the electrical conductivities of wadsleyite and ringwoodite are similar and are almost two orders of magnitude higher than that of olivine. A conductivity-depth profile to 660 kilometers, based on these laboratory data, shows a conductivity increase of almost two orders of magnitude across the 410-kilometer discontinuity; such a profile favors a two-layer model for the upper mantle. Activation enthalpies of 1.2 to 1.7 electron volts permit appreciable lateral variations of conductivity with lateral temperature variations.  相似文献   

The substitution of soybean meal for urea: the effect on the ammonia content of the rumen fluid, the N flow in the duodenum, the nitrogen and energy balances and the milk production     

E Teller  J M Godeau 《Archives of Animal Nutrition》1984,34(4):286-294

In different experiments, the nutritive value of maize silage associated with urea was compared with that of the same forage associated with soybean meal. The ammonia concentration in the rumen fluid was measured with two dry cows fitted with a permanent rumen cannula. Urea gave rise to much higher NH3 concentrations compared with soybean meal. The duodenal N flow was measured with two dry cows fitted with a re-entrant cannula at 10 cm from the pylorus. Adding increasing amounts of either of the two N supplements to the maize silage showed that they were equivalent with low N intakes. However, clearly more N reached the intestine with soybean meal than with urea when the N intake increased. With 33 cows in the second part of lactation, the substitution of soybean meal for urea decreased the urinary N loss. At the same time, it significantly increased the mammary protein secretion and the milk production. The increase of the dietary metabolizable energy density noted under these feeding conditions corresponded to about two thirds of the increase of the milk production. Milk composition was only slightly affected.  相似文献   

Protein and energy relationships in dairy cattle. 2. Lactating cows     

E Teller  J M Godeau 《Archives of Animal Nutrition》1989,39(6):543-551

Nitrogen requirements of lactating cows were calculated by means of statistical relationships established for nitrogen excretion in faeces and urine, for nitrogen balance, and for nitrogen flow in proximal duodenum and terminal ileum. The data used for elaboration of the relationships came from simultaneous measurements of nitrogen and energy balances. It appears that an increase in dietary nitrogen solubility augments total nitrogen and apparently digestible nitrogen requirements of the animals because of higher urinary nitrogen losses. This effect can be off-set by an increased metabolizable energy intake. High proportions of concentrates in the diets cause a shift in nitrogen excretion from faeces to urine. Requirements of intestinal absorbed nitrogen and its conversion into milk protein are dependant of dietary nitrogen solubility and metabolizable energy concentration, while they are favourably influenced by energy supply. Crude protein concentration is not an adequate way for expressing optimal protein supply in lactating cows because it may vary between 11.2% and 20.0% according to dietary characteristics for the same animal.  相似文献   

Eocene Patagonia fossils of the daisy family     

Barreda VD  Palazzesi L  Tellería MC  Katinas L  Crisci JV  Bremer K  Passalia MG  Corsolini R  Rodríguez Brizuela R  Bechis F 《Science (New York, N.Y.)》2010,329(5999):1621

Fossil capitula and pollen grains of Asteraceae from the Eocene of Patagonia, southern Argentina, exhibit morphological features recognized today in taxa, such as Mutisioideae and Carduoideae, that are phylogenetically close to the root of the asteracean tree. This fossil supports the hypothesis of a South American origin of Asteraceae and an Eocene age of divergence and suggests that an ancestral stock of Asteraceae may have formed part of a geoflora developed in southern Gondwana before the establishment of effective dispersal barriers within this landmass.  相似文献   

Effects of supplemental dietary vitamin C on quality of semen from Nile tilapia (Oreochromis niloticus) breeders          下载免费PDF全文

NLAF Sarmento  EFF Martins  DC Costa  WS Silva  CC Mattioli  MR Luz  RK Luz 《Reproduction in domestic animals》2017,52(1):144-152

The objective of this study was to evaluate the effects of vitamin C on growth and quality of semen from Oreochromis niloticus breeders. One hundred and sixty males were fed with different levels of vitamin C (0, 261, 599 and 942 mg/kg diet). The higher weight values were recorded for 599 (166 g) and 942 (175 g) mg of vitamin C/kg diet. Sperm motility, vigour and concentration were higher with 599 and 942 mg of vitamin C/kg diet. The semen volume, gonadosomatic index and plasma protein data from the last week showed a direct relationship with increasing levels of vitamin C. No changes were observed in the hepatosomatic index and blood glucose. The haematocrit and erythrocyte showed higher values estimated by equations derived at 850 and 638 mg vitamin C/kg diet, respectively. The leucocytes were inversely proportional to the increasing levels of vitamin C. After 100 days of feeding, animals fed the diet containing 942 mg vitamin C/kg diet had higher sperm motility, linearity, curvilinear velocity, straight line velocity and average path velocity (p < .05). Higher values of beat cross‐frequency were observed in broodfish fed diets containing 942 and 599 mg vitamin C/kg. The different vitamin C levels did not cause differences in straightness, lateral head displacement and sperm morphology. For Nile tilapia males on intensive rearing and handling conditions, vitamin C levels between 599 and 942 mg/kg may be used for a better performance and quality of semen.  相似文献   

Effect of selenium supplementation on semen characteristics of Brazil's ram          下载免费PDF全文

M Piagentini  DC Silva  CPF Dell'Aqua  CF Moya‐Araujo  VM Codognoto  AA Ramos  E Oba 《Reproduction in domestic animals》2017,52(3):355-358

The aim of this study was to investigate the effects of different concentrations of oral supplementation with selenium (Se) upon ram sperm parameters. Thirty rams managed in stall under intensive system were used and divided into five groups (six animals per group) as follows: control group (G1) mineral mixture supplementation without Se, group 2 (G2) mineral mixture supplemented with 5 mg/kg Se, group 3 (G3) supplemented with 10 mg/kg Se, group 4 (G4) supplemented with 15 mg/kg Se and group 5 (G5) supplemented with 20 mg/kg Se. For each group, there was an adjustment period of 14 days. The experimental period was 350 days. Every 56 days, the animals were weighed and semen samples were collected by electroejaculation. Semen analysis included volume, mass moviment, total motility, vigour, concentration and morphology. For plasmatic and acrosomal membrane integrity evaluation and mitochondrial membrane potential were used a combination of fluorescent probes. Differences between means values obtained by analysis of variance were verified by Tukey test with 5% probability. There was no statistical difference between treatment groups in relation to volume, mass moviment, total motility, vigour, concentration, plasma and acrosomal membrane integrity (p > .05). Sperm morphology was different between treatment groups, the G1 (0 mg of selenium) had the highest percentage of major defects (11.11 ± 1.11^a; p < .05). It was concluded that selenium decrease the percentage of sperm defects and did not directly influence on ram sperm volume, mass moviment, total motility, vigour, concentration and membrane integrity.  相似文献   

The characterisation of an influenza A virus isolated from Victorian ducks   总被引：2，自引：0，他引：2  

PW SELLECK  PT HOOPER  DC GRIX  CJ MORROW 《Australian veterinary journal》1994,71(7):222-223

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Intake of direct cut or wilted grass silage as related to chewing behavior, ruminal characteristics and site and extent of digestion by heifers   总被引：1，自引：0，他引：1  

E Teller  M Vanbelle  P Kamatali  J Wavreille 《Journal of animal science》1989,67(10):2802-2809

Six nonpregnant Friesian heifers (516 kg avg BW) with ruminal and duodenal cannulas were used to examine intake of direct cut (DC) or wilted (W) grass silage in relation to chewing behavior, ruminal characteristics and site and extent of digestion. Dry matter content of the silages was 20.3% and 40.3%, and feed intake averaged 1.88% and 2.17% of BW (P less than .01), respectively. Mean ruminal osmolality was 291 mosm/liter for the DC and 318 mosm/liter for the W silage (P less than .05), with extreme values exceeding 350 mosm/liter for the W silage at 1 h to 2 h postfeeding. There was a shift from eating to ruminating on W silage associated with a longer duration of the average rumination bolus cycle (P less than .01). Duration of chewing time per kilogram of DM intake was 103.5 min and 91.7 min (P less than .05) for the DC and W silages, respectively. Fecal mean particle length was 2.2 times greater (P less than .01), accompanied by higher spread coefficients (P less than .001), for the W silage. No differences occurred between silages in ruminal digestibility of OM and NDF. In the total digestive tract, apparent digestibilities of OM and NDF were depressed after wilting grass prior to ensiling (P less than .01), but the proportion of digestible OM apparently digested in the rumen was .74 for both silages.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Pyelonephritis, nephrolithiasis and perinephric abscessation in a dog     

DC LEWIS  DRT ADAMSON  KA JACOBS  WA LAMB 《Australian veterinary journal》1988,65(6):195-196

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