Coastal Prairie Recovery in Response to Shrub Removal Method and Degree of Shrub Encroachment

Shrub encroachment into grasslands is a worldwide phenomenon with no signs of abating and numerous ecological consequences. In South Texas, honey mesquite (Prosopis glandulosa Torr.) and huisache (Vachellia farnesiana [L.] Wight & Arn.) are two shrubs encroaching into coastal prairies, reducing cover of the dominant native grass, gulf cordgrass (Spartina spartinae [Trin.] Merr. ex Hitchc.), and decreasing habitat for the endangered Aplomado Falcon (Falco femoralis), which requires grasslands or savannas for survival. To determine the best management approach for deterring shrub encroachment and restoring native grasslands, the US Fish and Wildlife Service used several shrub removal techniques within coastal prairies of the Bahía Grande Wetland Complex of the Laguna Atascosa National Wildlife Refuge, a core site for Aplomado Falcon reintroductions. Here, we assess native grass recovery over a 2-yr period in response to these shrub removal methods (mechanical plus prescribed fire and/or herbicide treatments) and degree of shrub encroachment before treatment. In general, areas with high levels of shrub encroachment before treatment had the highest amount of bare ground and lowest grass cover immediately following an initial mechanical treatment; this legacy effect persisted throughout the study irrespective of shrub removal treatment. Regardless of degree of shrub encroachment before treatment, grasses in areas treated with either mechanical or mechanical followed by herbicide methods recovered the slowest, likely due to residual woody material that hindered seed germination. Herbicide treatment following mechanical removal or mechanical removal plus fire effectively hindered shrub regrowth. Overall, mechanical treatment followed by prescribed fire and then herbicide application most effectively promoted grass recovery while hindering shrub regrowth. These findings suggest that grassland recovery following shrub encroachment into South Texas coastal prairies may be promoted through the application of shrub removal methods that combine mechanical, fire, and herbicide treatments.     

Partitioning of C-photosynthates from different current shoots neighboring with fruiting spur in later-maturing Japanese pear during the period of rapid fruit growth

To elucidate the fate of photosynthates from different current shoots and their influence on fruit growth and bud differentiation in neighboring spur complex during the period of rapid fruit growth in two late-maturing Japanese pear cultivars: ‘Atago’ and ‘Shinkou’ with contrasting fruit size, ¹³C labeling of single shoot was done to investigate of C-relations in fruit branches of eight shoot-combinations. The results showed that all of the current shoots investigated (bourse shoots of nonfruiting spur, bourse shoots of fruiting spur, extension shoot, nonfruiting spur, vegetative shoot, and water sprout) could export photosynthates to the neighboring fruit and buds. Water sprouts together with vegetative shoots, bourse shoots, and extension shoots are important source for fruit growth after shoot growth termination during the period of rapid fruit growth in production of late-maturing pears. The carbon transfer rate from the neighboring to the fruit bearing spur is depent (i) on the types of shoot which acts as C source, (ii) on the position of the fruiting spur and (iii) on the source-sink distance. Furthermore, the cultivar difference in carbon partitioning from different current shoot-combinations confirmed that the movement of photosynthates into the fruit was determined by sink strength of the fruit, and ‘Atago’ exhibited a greater relative sink strength of fruit than ‘Shinkou’. In addition, vegetative shoots are very important C sources for fruit growth in ‘Atago’ and the growth pattern of bourse shoot seriously affects C allocated to fruit in ‘Shinkou’.     

Estimation of bone mineral density and breaking strength of laying hens based on scans of computed tomography for body composition analysis

1. The objective of this study was to evaluate the prediction potential of a computer tomography (CT) data collection protocol for determining total body composition used for analysis of tibiotarsal bone quality features.

2. The CT image acquisition was performed on 54 healthy TETRA SL genotype laying hens at 90 weeks of age as well as in the 69th week of the egg production period in vivo and their tibiotarsal bones, ex vivo.

3. Breaking strengths and ash content of the tibiotarsal bones were estimated based on the calculated mineral density of skeletal and tibiotarsal bones by means of CT with an estimation accuracy R² 0.963 and 0.975, respectively.

4. In conclusion, the current investigation demonstrated that the acquisition protocol of CT for total-body composition analysis has a good potential for measuring the mineral status and breaking strength of the reference bone in laying hen.     

狗牙根和三叶草的根系特征及对荒坡紫色土抗剪性能的影响

为探讨草类根系对荒坡紫色土的固土性能及其影响因素,以该环境的紫色土为研究对象,设置了空白对照、盆栽狗牙根(Cynodon dactylon)和盆栽三叶草(Trifolium repens)3个处理,8个月后分别取样用常规方法测定土壤基本理化性质、Win RHIZO(Pro.2004c)根系分析系统测定根系指标、ZJ型应变控制式直剪仪测定根-土复合体抗剪强度。结果表明,狗牙根的根系指标优于三叶草,且在根系直径(d)≤0.2 mm径级范围内更为突出;较之三叶草,狗牙根更能有效改善土壤的理化性质;两种草类均能有效提高根-土复合体的抗剪性能。较之空白对照,狗牙根的内摩擦角(φ)和粘聚力(c)分别增加了10.37%和66.36%,三叶草的分别增加了1.14%和34.22%,其中狗牙根处理的土壤抗剪性能最优;影响根-土复合体抗剪性能的关键性指标有土壤容重、总孔隙度、毛管孔隙度和根长密度,根系直径≤0.2 mm是影响根-土复合体抗剪性能的关键性径级。     

Acute polyneuromyopathy with respiratory failure secondary to monensin intoxication in a dog

Objective

To describe a successfully managed case of polyneuropathy and respiratory failure secondary to presumed monensin intoxication.

Case Summary

A 9‐month‐old Australian Shepherd was evaluated for progressive generalized weakness and respiratory distress. Several days preceding presentation, the dog was seen playing with a monensin capsule, and had free access to a barn where the product was stored and where chewed capsules were subsequently found. The dog was presented with flaccid tetraparesis, hyperthermia, and severe respiratory distress. Bloodwork and urinalysis revealed marked increase in serum creatine kinase concentration and presumed myoglobinuria. Cardiac troponin I level was markedly increased. Management included mechanical ventilation for 5 days, fluid‐therapy, active cooling, antimicrobial therapy, analgesia, gastroprotectants, antiemetics, enteral feedings, continuous nursing care, and physiotherapy. Intravenous lipid rescue therapy was administered with lack of improvement in respiratory function and muscle strength. The patient completely recovered and was discharged after 12 days of hospitalization.

New or Unique Information Provided

Monensin intoxication should be considered in the differential diagnosis of acute polyneuromyopathy and respiratory failure in dogs with access to this compound. Respiratory failure secondary to monensin intoxication does not necessarily carry a poor prognosis if mechanical ventilation can be provided as a bridge until return of respiratory function is achieved.     

辽宁省农机服务体系存在的问题及发展建议

在介绍发展农机服务体系重要意义的基础上,根据辽宁省农机服务体系的实际情况,从管理体制、技术力量、服务范围、资金投入等方面,分析其发展过程中存在的主要问题,提出相应的解决措施,为完善辽宁省农机服务体系提供参考及借鉴。     

川西北高寒沙地不同恢复年限对土壤机械组成的影响

采用时空替代法,即在立地条件一致或相近的条件下,在一定的空间尺度内,选择不同地点上不同治理年限的流动沙地来代替同一生长地点上的不同恢复年限的流动沙地。以若尔盖县高寒沙地示范区内未治理流动沙地、生态恢复年限分别为3年、5年、10年的高寒沙地作为研究对象。结果表明,高寒流动沙地与草地土壤颗粒含量差异明显,随着治理时间的递增,流动沙地土壤黏粒、粉砂等细颗粒物质含量逐渐增加,不同深度的土壤颗粒逐渐演变为表层较下层细,可能是受植被恢复地表植被影响所致,通过10年的沙化治理,流动沙地的土壤得到一定的改善,但从本试验看出土过程在川西北高寒地区是一个缓慢的过程,防大于治。因此,应继续加强对脆弱区生态系统的保护和管理,避免荒漠化导致土壤生态环境的难以恢复。