Partial streamflow diversion due to the siting of hydroelectric generating plants may increase the incidence and degree of water stress in riparian vegetation. This study, conducted on Bishop Creek in the eastern Sierra Nevada (California), compared the water relations of riparian vegetation on paired undiverted (natural flow) and diverted (low flow) reaches. Riparian plants on diverted reaches had reduced stomatal conductance and water potential compared to plants on undiverted reaches in a dry year, but not in a high-runoff year. Juvenile plants on diverted reaches had reduced stomatal conductance and lower midday water potentials relative to surrounding mature trees, a trend that was not observed on undiverted reaches. Predawn water potentials were uniformly high in all species and sites, but low midday water potentials (-1.2 to -1.5 MPa) were observed for most species on diverted reaches. Plants on diverted reaches possessed significantly smaller, thicker leaves and a reduced total leaf area relative to trees on streamside reaches. Reduced community leaf area and effective stomatal control of water loss may allow riparian corridors on diverted reaches to retain their canopies in low-runoff years. However, a long-term consequence of streamflow diversion may be selective mortality of juvenile plants because of the elimination of floods and high flows.

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We describe the use of a unique plant growth facility, which has as its centerpiece four 'EcoCELLs', or 5x7 m mesocosms designed as open-flow, mass-balance systems for the measurement of carbon, water and trace gas fluxes. This system is unique in that it was conceived specifically to bridge the gap between measurement scales during long-term experiments examining the function and development of model ecosystems. There are several advantages to using EcoCELLs, including (i) the same theory of operation as leaf level gas exchange systems, but with continuous operation at a much larger scale; (ii) the ability to independently evaluate canopy-level and ecosystem models; (iii) simultaneous manipulation of environmental factors and measurement of system-level responses, and (iv) maximum access to, and manipulation of, a large rooting volume. In addition to discussing the theory, construction and relative merits of EcoCELLs, we describe the calibration and use of the EcoCELLs during a 'proof of concept' experiment. This experiment involved growing soybeans under two ambient CO2 concentrations (approximately 360 and 710 micromoles mol-1). During this experiment, we asked 'How accurate is the simplest model that can be used to scale from leaf-level to canopy-level responses?' in order to illustrate the utility of the EcoCELLs in validating canopy-scale models.

Fox2-year-old, 15-kg, male Chow Chow was referred to A the Oklahoma State University Veterinary MedicalTeaching Hospital for evaluation of ataxia that had progressed to an inability to stand. Eleven weeks before referral, the dog had been examined by the referring veterinarian for unilateral epistaxis of 1 day's duration. A CBC at that time revealed severe anemia (PCV 15.3%, reference range 33-55%; mean corpuscular volume [MCV] 71 fL, reference range 60-75 fL; mean corpuscular hemoglobin concentration [MCHC] 28.8 g/dL, reference range 32-36 g/dL) and thrombocytopenia (20 X 103/pL, reference range 200-500 X 103/pL). Erythrocyte morphology did not suggest evidence of a bone marrow response, but a reticulocyte count was not obtained. The dog's serum was negative for Ehrlichia canis antibody. Treatment consisted of doxycycline (100 mg PO q24h for 5 days) and prednisone (30 mg q12h for 5 days, 20 mg q24h for 15 days, 15 mg q24h for 15 days, then 10 mg q24h for 15 days). The epistaxis and thrombocytopenia resolved within 48 hours after treatment began. Anemia persisted, but had improved (PCV 23.6%) after 6 days. The dog appeared clinically normal 6 weeks before referral and the only hematologic abnormality was a mild normocytic, normochromic anemia (PCV 27.3%, MCV 66 fL, MCHC 33 g/dL). Two days before referral, the dog presented for ataxia. Laboratory evaluation revealed severe normocytic, normochromic anemia (PCV 16%, MCV 65 fL, MCHC 3lg/dL), thrombocytopenia (37 X lOVpL), leukocytosis (23.3 X lOVpL, reference range 5-17 X 103/pL), and hyperglobulinemia (albumin 2.6 g/ dL, reference range 2.3-3.9 g/dL; globulin 6.3 g/dL, reference range 2.7-4.5 g/dL). Treatment with amoxicillin (250 mg PO q12h) was begun and the dog was referred for further evaluation.Abnormalities noted at physical examination included depressed mentation, generalized weakness, hyperreflexia of all 4 limbs, mild conscious proprioceptive deficits of the rear limbs, and evidence of cervical pain. Medicine 103/pL), and hyperproteinemia (7.8 g/dL, reference range 6.0-7.5 g/dL) resulting from hyperglobulinemia (5.5 g/dL). The dog was anesthetized for bone marrow aspiration, cerebrospinal fluid (CSF) collection, and spinal radiography. No radiographic abnormalities were observed on spinal radiographs. The bone marrow aspirate yielded numerous marrow flecks of normal cellularity. Normal numbers of megakaryocytes were present. The myeloid (M) series was prominently represented and displayed orderly maturation. Cells of the erythroid (E) series also displayed normal maturation, but appeared quantitatively decreased. The (M:E) ratio was estimated to be approximately 3:l. One to 8 plasma cells were present per 50X field in cellular areas of the smears and hemosiderin-laden macrophages were abundant. These findings were interpreted as mild erythroid hypoplasia with mild plasmacytosis and increased iron stores. The CSF was cloudy and had pleocytosis (total nucleated cell count 590/pL, reference range 0-8/yL), increased protein concentration (3,400 mg/dL, refere...

With recent widespread awareness of dwindling petroleum supplies, considerable attention has been directed towards plants as photosynthetic energy converters. The purpose of this 3‐year study was to investigate the bioproductivity of agronomic crops as a potential energy source in Minnesota. Experiments were conducted in the field at St. Paul on a Waukegan silt loam (Typic Hapludoll) and at Waseca on a Webster clay loam (Typic Haplaquoll). Both double‐cropping and monocropping systems were evaluated. The double‐cropping system consisted of growing fall‐planted winter rye (Secale cereale L.) at recommended seeding rates and harvesting it on 15 June, near the peak of its vegetative production and before the formation of acceptable grain. After the rye was harvested, the plots were fertilized, disked, and planted to corn (Zea mays L.). Three corn hybrids: ‘Pioneer 3780’ (full season), ‘NKPX74’ (14% more than full season), and ‘Pioneer 3030’ (28% more than full‐season) were grown at each of two populations that exceeded normal production populations by approximately 25% and 100% (75,000 plants/ha and 125,000 plants/ha). Corn was chosen to follow the rye for double‐cropping since, in a preliminary study, we determined that it produced more biomass than sorghum (Sorghum bicolor [L.] Moench) or sudangrass (Sorghum blcolor [L.] Moench) when grown on rye plots following the rye harvest. A corn‐only or monocropping system was established adjacent to the double‐cropping plots. The same three corn hybrids were grown at the same two populations, but they were planted as early in the season as possible and grew uninterrupted. Rye produced an average biomass yield (dry weight of aboveground portion) of 9.6 metric tons/ha (MT/ha) by 15 June. The largest average biomass yield from corn planted after the rye harvest (double cropped) was 16.3 MT/ha, produced by NXPX74 at 125,000 plants/ha. The rye plus corn double‐cropping yields thus averaged 25.9 MT/ha. The largest average monocropped corn yield of 18.8 MT/ha (produced by NKPX74 at 125,000 plants/ha) was 7.1 MT/ha below the double‐cropped yields. Due to interactions and yield fluctuations across environments, however, the two systems were not determined significantly different. Since costs and risks of successfully producing two crops per season would be an important consideration, we suggest that monocropped corn would be preferred over rye‐corn double cropping as a biomass production system in Minnesota.