Characterizing stand-replacing disturbance in western Alberta grizzly bear habitat, using a satellite-derived high temporal and spatial resolution change sequence

Timely and accurate mapping of anthropogenic and natural disturbance patterns can be used to better understand the nature of wildlife habitats, distributions and movements. One common approach to map forest disturbance is by using high spatial resolution satellite imagery, such as Landsat 5 Thematic Mapper (TM) or Landsat 7 Enhanced Thematic Mapper plus (ETM+) imagery acquired at a 30 m spatial resolution. However, the low revisit times of these sensors acts to limit the capability to accurately determine dates for a sequence of disturbance events, especially in regions where cloud contamination is a frequent occurrence. As wildlife habitat use can vary significantly seasonally, annual patterns of disturbance are often insufficient in assessing relationships between disturbance and foraging behaviour or movement patterns.The Spatial Temporal Adaptive Algorithm for mapping Reflectance Change (STAARCH) allows the generation of high-spatial (30 m) and -temporal (weekly or bi-weekly) resolution disturbance sequences using fusion of Landsat TM or ETM+ and Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. The STAARCH algorithm is applied here to generate a disturbance sequence representing stand-replacing events (disturbances over 1 ha in area) for the period 2001-2008, over almost 6 million ha of grizzly bear habitat along the eastern slopes of the Rocky Mountains in Alberta. The STAARCH algorithm incorporates pairs of Landsat images to detect the spatial extent of disturbances; information from the bi-weekly MODIS composites is used in this study to assign a date of disturbance (DoD) to each detected disturbed area. Dates of estimated disturbances with areas over 5 ha are validated by comparison with a yearly Landsat-based change sequence, with producer's accuracies ranging between 15 and 85% (average overall accuracy 62%, kappa statistic of 0.54) depending on the size of the disturbance event. The spatial and temporal patterns of disturbances within the entire region and in smaller subsets, representative of the size of a grizzly bear annual home range, are then explored. Disturbance levels are shown to increase later in the growing season, with most disturbances occurring in late August and September. Individual events are generally small in area (<10 ha) except in the case of wildfires, with, on average, 0.4% of the total area disturbed each year. The application of STAARCH provides unique high temporal and spatial resolution disturbance information over an extensive area, with significant potential for improving understanding of wildlife habitat use.     

What factors influence the stem taper of <Emphasis Type="Italic">Eucalyptus</Emphasis>: growth,environmental conditions,or genetics?

• Introduction   

Stem taper equations have been widely used for volume estimation to varied top diameter limits or for biomass calculations. However, their main drawback is that specific calibration is often necessary for each species or clone, and accounting for genetic and environmental effects is often a challenge.     

Effects of forest structure and microhabitat on the distribution and flowering of a rare understory plant, Actaea elata

Knowing which environmental characteristics constrain forest understory species’ distribution and reproduction can inform conservation decisions about habitat management and locations for reintroduction efforts. Differential plant performance is common in varying environmental conditions, such as levels of canopy closure. Actaea elata (tall bugbane) is a rare, perennial, forest understory herb found from Oregon to British Columbia. Populations throughout this species’ range commonly occur in managed forests. We assessed the importance of environmental variation on the distribution and flowering of A. elata at both microhabitat and site-level scales. At four sites encompassing a variety of forest types, we measured several biotic and abiotic variables at vegetative and reproductive plants, as well as at random points. We measured these same variables at three sites where A. elata has been extirpated. Within occupied sites, reproductive plants were more likely to be located in canopy gaps than were vegetative plants. Both vegetative and reproductive plants were more likely to be found in areas of high herb cover compared to random points. These results indicate that gaps in the canopy may be critical for this species’ ability to reproduce, but survival may be possible in a broader range of forest understory conditions (similar to other co-occurring herb species). Random points at extirpated and occupied sites both tended to be located in areas of lower canopy openness and moisture availability than points in occupied sites where A. elata was present. Extirpated sites were either densely forested or clearcut, while occupied sites contained stands of intermediate density. Circaea alpina, Geranium robertianum, and Lactuca muralis were indicator species for A. elata and normally indicate moist soils, with Circaea alpina being a strong indicator of the presence of flowering A. elata. Taken together, our results suggest that maintenance of canopy gaps is important to promote flowering, and understory species that indicate moist sites, particularly Circaea alpina, can be used as aids to locate new populations of A. elata.     

Predator control for protecting kaki (Himantopus novaezelandiae)—lessons from 20 years of management

In New Zealand, the endemic kaki or black stilt (Himantopus novaezelandiae) has been the focus of intensive conservation management for the past 20 years. Threatened by predation and habitat loss, the population fell to as low as 23 birds before management was implemented to reverse the decline. Predator trapping has been one form of management intervention in the wild, yet despite 20 years of control, there is only limited evidence to suggest that predator trapping is beneficial for the survival of kaki. Lack of adequate experimental design and understanding of the predator-prey dynamics in the system in which kaki live appear to be the main reasons why the benefits of predator control are not consistently clear. An adaptive management approach would have provided more information on the efficacy of predator trapping and increased understanding of the inter-relationships between kaki survival and predator abundance.     

Motor control by sensory cortex

Classical studies of mammalian movement control define a prominent role for the primary motor cortex. Investigating the mouse whisker system, we found an additional and equally direct pathway for cortical motor control driven by the primary somatosensory cortex. Whereas activity in primary motor cortex directly evokes exploratory whisker protraction, primary somatosensory cortex directly drives whisker retraction, providing a rapid negative feedback signal for sensorimotor integration. Motor control by sensory cortex suggests the need to reevaluate the functional organization of cortical maps.     

Mating types ofExserohilum turcicum in Israel

Fifty-one single conidial isolates ofExserohilum turcicum were collected from seven locations in Israel and three in the USA and tested for mating type and aggressiveness. Sixteen isolates mated were mating type a; 29 were mating type A; and six failed to mate with either the A or the a mating type. Isolates differed significantly in their ability to cause lesions of different sizes, and in their ability to produce conidia on the susceptible corn hybrid Jubilee. They also differed in their rate of growth on lactose casein agar. No significant difference in lesion size or conidial production was noted between mating types. Conidial production and radial growth were significantly lower for isolates with no mating capacity as compared with conidial production of defined mating types. Pseudothecia were produced after 14–16 and 21 days when mating occurred onSorghum halepense straw or barley straw, respectively. The average number of pseudothecia produced on 10 cm² of straw was 17 and 8 forS. halepense and barley, respectively. Pseudothecia were not produced on corn straw.     

Comparison of 3 techniques for ureteroneocystostomy in cats

OBJECTIVE: To compare 3 techniques for ureteroneocystostomy in cats. STUDY DESIGN: Experimental surgical study. ANIMALS: Fifteen adult cats. METHODS: Cats (15) had ureteroneocystostomy with ureteronephrectomy of the contralateral kidney: 5 cats had an intravesical mucosal apposition technique (modified Leadbetter-Politano; intravesical-MA group), 5 cats had extravesical ureteroneocystostomy (modified Lich Gregoir) using a simple continuous suture pattern (extravesical-SC group) and 5 cats had an extravesical technique using a simple interrupted suture pattern (extravesical-SI group). Renal function was evaluated by measuring serum creatinine concentration. Ultrasonographic assessment of the kidney and ureteroneocystostomy site was performed the day after surgery, twice weekly for 3 weeks and once weekly for the remainder of the study. Cats were euthanatized 50 days after surgery. The kidney and ureter removed at surgery, the remaining kidney, ureter, ureteroneocystostomy site, and bladder were examined histologically. RESULTS: Two extravesical-SC cats were euthanatized because of azotemia and uroabdomen, and 1 died acutely at day 4 for unknown reasons. In the intravesical-MA and extravesical-SI cats, the serum creatinine concentration increased after surgery, peaking at a mean (+/-SD) of 9.4+/-2.4 mg/dL and 4.9+/-3.3 mg/dL on day 3, and decreasing to 3.4+/-5.7 mg/dL and 1.5+/-0.4 mg/dL on day 7, respectively. The extravesical-SI technique was associated with consistently lower serum creatinine concentrations for the first week after surgery compared with the other techniques. The mean serum creatinine concentration was within the reference range in cats in the intravesical-MA and extravesical-SI groups by days 10 and 5, respectively. Renal pelvic dilatation occurred in all cats but resolved more rapidly in cats after extravesical techniques. There was no significant difference in serum creatinine concentrations or renal pelvic dilation between the intravesical-MA and extravesical-SI techniques. Bladder mass height at the anastomosis site was significantly larger and persisted for longer with intravesical-MA technique. CONCLUSION: An extravesical-SI technique is seemingly the choice for ureteroneocystostomy in cats with undilated ureters. Renal pelvic dilation on ultrasound examination should be expected after ureteroneocystostomy in cats. CLINICAL RELEVANCE: An extravesical ureteroneocystostomy technique using a simple interrupted pattern for anastomosis should be considered in cats undergoing renal transplantation.     

Effect of glyphosate on the tripartite symbiosis formed by Glomus intraradices,Bradyrhizobium japonicum,and genetically modified soybean

Most soybeans grown in North America are genetically modified (GM) to tolerate applications of the broad-spectrum herbicide glyphosate; as a result, glyphosate is now extensively used in soybean cropping systems. Soybean roots form both arbuscular mycorrhizal (AM) and rhizobial symbioses. In addition to individually improving host plant fitness, these symbioses also interact to influence the functioning of each symbiosis, thereby establishing a tripartite symbiosis. The objectives of this study were to (1) estimate the effects of glyphosate on the establishment and functioning of AM and rhizobial symbioses with GM soybean, and (2) to estimate the interdependence of the symbioses in determining the response of each symbiosis to glyphosate. These objectives were addressed in two experiments; the first investigated the importance of the timing of glyphosate application in determining the responses of the symbionts and the second varied the rate of glyphosate application. Glyphosate applied at recommended field rates had no effect on Glomus intraradices or Bradyrhizobium japonicum colonization of soybean roots, or on soybean foliar tissue [P]. N₂-fixation was greater for glyphosate-treated soybean plants than for untreated-plants in both experiments, but only when glyphosate was applied at the first trifoliate soybean growth stage. These data deviate from previous studies estimating the effect of glyphosate on the rhizobial symbiosis, some of which observed negative effects on rhizobial colonization and/or N₂-fixation. We did observe evidence of the response of one symbiont (stimulation of N₂-fixation following glyphosate) being dependent on co-inoculation with the other; however, this interactive response appeared to be contextually dependent as it was not consistent between experiments. Future research needs to consider the role of environmental factors and other biota when evaluating rhizobial responses to herbicide applications.