Some nutrient dynamics associated with litterfall and litter decomposition in hoop pine plantations of southeast Queensland, Australia     

K. A. Bubb  Z. H. Xu  J. A. Simpson  P. G. Saffigna 《Forest Ecology and Management》1998,110(1-3):343-352

Litterfall was collected over a 12-month period with littertraps in hoop pine (Araucaria cunninghamii) plantations aged 10, 14 and 62 years in southeast Queensland, Australia. The bulk of litterfall occurred during spring, mainly as hoop pine foliage with the annual litterfall ranging between 6.0 and 10.9 t ha⁻¹, respectively, for the younger stands (10 and 14 years) and the mature 62-year old stand. The amount of nitrogen (N) and phosphorous (P) recycled annually through litterfall was lower in the younger stands (28–37 kg N ha⁻¹ and 4.4–5.3 kg P ha⁻¹) compared with that of the mature stand (85 N ha⁻¹ and 6.2 kg P ha⁻¹). The N and P retranslocated during senescence varied across the three stands studied with a trend for N and P retranslocation to increase as availability of soil mineral-N decreased.

Decomposition of the hoop pine foliage component of litter was also studied in the same stands using a litterbag technique and mass-balance analysis. The estimated half-life of hoop pine foliage mass ranged between 1.5 and 1.8 years. Litter-mass loss was strongly correlated with litter substrate quality indicators of N, C, P, C/N ratio, lignin, lignin/N ratio and polyphenols. During the course of the study, there was no difference in litter-mass loss between the stands of different ages. During the 15-month period, the order of element release from the hoop pine litter was K>Na>C>Mg>P, with N, Ca and Mn generally demonstrating varying degrees of net accumulation. During the course of the study, the lignin/C ratio of the hoop pine litter increased from 0.61 to 0.96. This suggested that the litter-C was predominantly in a recalcitrant form and, therefore, the associated N was unlikely to be rapidly released in the hoop pine litter layer.  相似文献   

Failure of osmoregulation with apparent potassium intoxication in marine teleosts: A primary toxic effect of copper     

P.T. Cardeilhac  C.F. Simpson  R.L. Lovelock  S.F. Yosha  H.W. Calderwood  J.C. Gudat 《Aquaculture (Amsterdam, Netherlands)》1979,17(3):231-239

Four sheepshead, Archosargus probatocephalus, weighing 665–980 g were exposed to toxic concentrations (8.5 p.p.m.) of cupric ion (copper) in sea water. Five stages of intoxication of increasing severity, based on behavior and posture, were designated as follows: lethargy; indifference; incoordination; moribundity; death. Serum, gills, liver, and kidneys were taken from fish at different stages of intoxication for examination. Kidneys were congested and swollen, the kidney wt/body wt index increasing up to 13.5 standard deviations (S.D.) over the mean control value. Gill lamellae from copper-poisoned fish were blunt and thickened, capillaries congested, and mucous cells dilated. Livers were similar to controls. Twenty-two clinical values were examined but only serum electrolytes and uric acid levels, liver and gill copper concentrations, kidney weights, and respiratory rates increased in poisoned fish by more than 5 S.D. over mean control values and correlated with the different stages of intoxication. Increased serum potassium, inorganic phosphate, and total intracellular ion values gave highest correlations with severity of intoxication. Potassium levels reached values considered lethal for mammals, and it was concluded that the intoxication following copper poisoning was a potassium intoxication caused primarily by cell damage and failure of osmoregulation by the gills and kidneys.  相似文献   

辐射松引种栽培综述     

毕慧泉  李荣伟  颜红  吴宗兴  蔡诗民 《林业研究》2003,14(4)

辐射松(PinusradiataD.Don)原产于加利弗尼亚海岸,被引种到世界各地,现在是南半球主要的人工林造林树种。1990年以来辐射松被引种到长江上游四川省阿坝州的干旱河谷地区,幼树的成活和早期生长表现良好。本文的主要内容包括:辐射松在原产地和引种地的生长情况,种源和遗传上的差异,环境限制因子和辐射松的气候生境,病虫害,引种不成功的经验教训以及辐射松在生态恢复中的应用。文中还简述了辐射松在阿坝干旱河谷地区的早期生长情况,列举了在长江上游干旱河谷地区引种辐射松可能遇到的问题以及所需开展的研究。图4表5参90。  相似文献   

Scion-rootstock relationships with respect to height growth and foliar concentrations of nitrogen and phosphorus in reciprocal grafts of Pinus caribaea var. hondurensis     

R. J. Haines  J. A. Simpson 《New Forests》1994,8(1):71-79

Both scion and rootstock clones significantly influenced scion elongation and concentrations of nitrogen and phosphorus in the scion foliage. Scion clone was the more important determinant. Scion clone × rootstock clone interactions were not significant. The ability of a clone to elongate as a scion was not correlated with its capacity to promote or retard scion elongation when used as a rootstock. Genetic differences in foliar nutrient concentrations appeared to reflect levels of nutrient demand, rather than the ability of roots to absorb nutrients. Nutrient demand of the rootstock can also explain negative correlations between nitrogen levels in rootstock clones and levels of both nitrogen and phosphorus in the scions. There was no significant relationship between scion elongation and foliar nitrogen concentrations of either rootstock or scion. The weak relationship between scion elongation and concentration of phosphorus in the rootstock apparently resulted from tissue dilution.  相似文献   

Laboratory test for grouping tropical species for kiln drying     

A. de Souza Mendes  W. T. Simpson  S. P. Verrill 《Wood Science and Technology》1995,29(5):353-362

Summary A system was developed for grouping tropical wood species for kiln drying based on similar estimated drying times. Six tropical species were subjected to drying and water soaking tests; variables were test temperature and specimen thickness. Soaking time, specimen thickness, and test temperature were used in an empirical model to predict drying times. The capability of the model to predict drying times was considered acceptable based on an adjusted coefficient of determination equal to 0.929 and an average error of 14 percent. The overall capability of the method proposed for grouping tropical hardwoods for drying is considered promising and worthy of further investigation.  相似文献   

Effect of a single injection of gonadotropin-releasing hormone (GnRH) and human chorionic gonadotropin (hCG) on testicular blood flow measured by color doppler ultrasonography in male Shiba goats     

Haney SAMIR  Kazuaki SASAKI  Eman AHMED  Aly KAREN  Kentaro NAGAOKA  Mohamed EL SAYED  Kazuyoshi TAYA  Gen WATANABE 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(5):549-556

Although color Doppler ultrasonography has been used to evaluate testicular blood flow in many species, very little has been done in goat. Eight male Shiba goats were exposed to a single intramuscular injection of either gonadotropin-releasing hormone (GnRH group; 1 µg/kg BW) or human chorionic gonadotropin (hCG group; 25 IU/kg BW). Plasma testosterone (T), estradiol (E2) and inhibin (INH) were measured just before (0 hr) and at different intervals post injection by radioimmunoassay. Testis volume (TV) and Doppler indices, such as resistive index (RI) and pulsatility index (PI) of the supratesticular artery, were measured by B-mode and color Doppler ultrasonography, respectively. The results indicated an increase in testicular blood flow in both groups, as RI and PI decreased significantly (P<0.05), but this increase was significant higher and earlier in hCG group (1 hr) than in the GnRH group (2 hr). A high correlation was found for RI and PI with both T (RI, r= −0.862; PI, r= −0.707) and INH in the GnRH group (RI, r=0.661; PI, r=0.701). However, a significant (P<0.05) correlation was found between E2 and both RI (r= −0.610) and PI (r= −0.763) in hCG group. In addition, TV significantly increased and was highly correlated with RI in both groups (GnRH, r= −0.718; hCG, r= −0.779). In conclusion, hCG and GnRH may improve testicular blood flow and TV in Shiba goats.  相似文献   

Detection of Clinically Relevant Pain Relief in Cats with Degenerative Joint Disease Associated Pain     

M.E. Gruen  E. Griffith  A. Thomson  W. Simpson  B.D.X. Lascelles 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2014,28(2):346-350

Background

Detection of clinically relevant pain relief in cats with degenerative joint disease (DJD) is complicated by a lack of validated outcome measures and a placebo effect.

Hypothesis/Objectives

To evaluate a novel approach for detection of pain relief in cats with DJD.

Animals

Fifty‐eight client‐owned cats.

Methods

Prospective, double‐masked, placebo‐controlled, stratified, randomized, clinical study. Enrolled cats were 6–21 years of age, with owner‐observed mobility impairment, evidence of pain in at least 2 joints during orthopedic examination, and overlapping radiographic evidence of DJD, and underwent a 2‐week baseline period, 3‐week treatment period with placebo or meloxicam, and 3‐week masked washout period. Outcome measures were evaluated at days 0, 15, 36, and 57.

Results

Both groups significantly improved after the treatment period (day 36) on client‐specific outcome measures (CSOM) and feline musculoskeletal pain index (FMPI) (P < .0001 for both); there was no difference between the groups on CSOM or FMPI score improvement. After the masked washout period, more cats that received meloxicam during the treatment period had a clinically relevant decrease in CSOM score (P = .048) and FMPI score (P = .021) than cats that received placebo.

Conclusions and Clinical Importance

Using both a client‐specific and a general clinical metrology instrument, owners of cats with DJD were able to detect evident recurrence of clinical signs after withdrawal of active medication than after withdrawal of placebo, and that this study design might be a novel and useful way to circumvent the placebo effect and detect the efficacy of pain‐relieving medications.  相似文献   

Optimization of triploidy induction in the blacklip abalone, Haliotis rubra (Leach, 1814), using 6-dimethylaminopurine     

Wenshan Liu  Michael Heasman  & Rod Simpson 《Aquaculture Research》2004,35(11):1076-1085

Optimal conditions of 6‐dimethylaminopurine (6‐DMAP) for triploidy induction in the blacklip abalone Haliotis rubra (Leach, 1814) were investigated, targeting inhibition of second polar body (PB2) formation. Two experiments were conducted at a water temperature of 17.5–18.5°C where factorial combination of (1) four dosages (DSs) of 100, 150, 200 and 250 μM 6‐DMAP, four starting times (STs) of 15, 20, 25 and 30 min post fertilization, and two treatment durations (TDs) of 20 and 30 min and (2) three DSs of 50, 100 and 150 μM 6‐DMAP, three STs of 15, 20 and 25 min post fertilization, and three TDs of 10, 20 and 30 min, were applied respectively. Day 3 larvae were sampled for triploidy and survival. Percent triploidy was verified using flow cytometry (FCM). Results show that optimal inductions that combine both high rates of triploidy and reasonable survival were those treatments commenced 15 or 20 min post fertilization and continued for 20 or 30 min, using 100 μM 6‐DMAP. These conditions induced rates of triploidy and relative survival of 80.5–93.3% and 36.5–40.2%, respectively, in the first experiment, and corresponding rates were 79.1–93.6% and 20.7–43.0% in the second experiment. High percent triploidy were also obtained in a number of treatments using 150 μM 6‐DMAP, but with overall survival rates generally lower than those using 100 μM 6‐DMAP.  相似文献   

Rapid differentiation of Artemia spp. Populations by thin layer isoelectric focusing     

C. R. Siedel  K. L. Simpson 《Aquacultural Engineering》1984,3(4):303-316

Artemia spp. of various geographic origins, yearly collection lots, developmental stages, and a binary geographic mixture were analyzed by thin layer polyacrylamide gel isoelectric focusing (IEF). IEF of geographical Artemia samples yielded unique profiles for each population in the pH range employed. Parthenogenetic populations of Artemia exhibited IEF patterns which were, generally, dominated by fewer proteins; bisexual populations exhibited more evenly distributed, complex protein patterns. There were similarities reflected in IEF profiles of geographically isolated Artemia descended from a common ancestry. Yearly collections of Artemia exhibited no apparent differences in IEF protein patterns. There were differences noted in three developmental stages of Artemia. A binary mixture of geographic populations yielded IEF patterns intermediate to those of the component pure samples.  相似文献   

Effect of active immunization against growth hormone-releasing factor on growth and onset of puberty in beef heifers.   总被引：1，自引：0，他引：1  

R B Simpson  J D Armstrong  R W Harvey  D C Miller  E P Heimer  R M Campbell 《Journal of animal science》1991,69(12):4914-4924

Angus and Charolais heifers (195 +/- 7 kg) were actively immunized against growth hormone-releasing factor (GRF) to evaluate the effect on concentrations of somatotropin (ST), insulin-like growth factor I (IGF-I), insulin (INS), growth, and onset of puberty. Primary immunizations were given at 184 +/- 7 d of age (d 0 of experiment) by injecting (s.c.) 1.5 mg of GRF-(1-29)-Gly-Gly-Cys-NH2 conjugated to 1.5 mg of human serum albumin (GRFi, n = 22) or 1.5 mg of human serum albumin (HSAi, n = 21). Booster immunizations of .5 mg of antigen were given on d 62, 92, 153, and 251. Antibody binding (percentage at 1:2,000 dilution) to [125I]GRF on d 69 was greater (P less than .01) in GRFi (53.7 +/- 4.5) than in HSAi (10.1 +/- .6) heifers. Serum concentration (ng/ml) and frequency (peaks/5 h) of ST release, respectively, on d 78 were lower (P less than .01) in GRFi than in HSAi heifers (3.3 +/- .1 vs 5.6 +/- .2 and .9 +/- .3 vs 2.3 +/- .2). Serum IGF-I (ng/ml) was lower (P less than .01) in GRFi than in HSAi heifers on d 69 (41 +/- 5 vs 112 +/- 4). Serum INS (microU/ml) on d 78 was lower (P less than .05) in GRFi (2.2 +/- .1) than in HSAi (3.8 +/- .2) heifers. Feed intake, ADG, and feed efficiency were lower (P less than .05) in GRFi than in HSAi heifers. Hip height was lower (P less than .01) and fat thickness was greater (P less than .05) in GRFi than in HSAi heifers by d 132 and 167, respectively. Percentage of heifers attaining puberty (progesterone greater than 1 ng/ml for two consecutive weeks) by d 209 and 379 (12.9 and 18.5 mo of age), respectively, was lower (P less than .05) in GRFi (40.9 and 45.5) than in HSAi (81.0 and 100). In conclusion, growing heifers were successively immunized against GRF. Active immunization against GRF resulted in decreased serum concentration of ST, IGF-I, and INS. In addition, GRF immunization led to lowered feed intake, ADG, and feed efficiency, increased fat depth, and delayed onset of puberty in heifers. We propose that ST and IGF-I are important metabolic mediators involved in the initiation of puberty in heifers.  相似文献