Despotism and Risk of Infanticide Influence Grizzly Bear Den-Site Selection

Given documented social dominance and intraspecific predation in bear populations, the ideal despotic distribution model and sex hypothesis of sexual segregation predict adult female grizzly bears (Ursus arctos) will avoid areas occupied by adult males to reduce risk of infanticide. Under ideal despotic distribution, juveniles should similarly avoid adult males to reduce predation risk. Den-site selection and use is an important component of grizzly bear ecology and may be influenced by multiple factors, including risk from conspecifics. To test the role of predation risk and the sex hypothesis of sexual segregation, we compared adult female (n = 142), adult male (n = 36), and juvenile (n = 35) den locations in Denali National Park and Preserve, Alaska, USA. We measured elevation, aspect, slope, and dominant land cover for each den site, and used maximum entropy modeling to determine which variables best predicted den sites. We identified the global model as the best-fitting model for adult female (area under curve (AUC) = 0.926) and elevation as the best predictive variable for adult male (AUC = 0.880) den sites. The model containing land cover and elevation best-predicted juvenile (AUC = 0.841) den sites. Adult females spatially segregated from adult males, with dens characterized by higher elevations ( = 1,412 m, SE = 52) and steeper slopes ( = 21.9°, SE = 1.1) than adult male (elevation:  = 1,209 m, SE = 76; slope:  = 15.6°, SE = 1.9) den sites. Juveniles used a broad range of landscape attributes but did not avoid adult male denning areas. Observed spatial segregation by adult females supports the sex hypothesis of sexual segregation and we suggest is a mechanism to reduce risk of infanticide. Den site selection of adult males is likely related to distribution of food resources during spring

Microwave Image Processing Lab.

http://deepblue.lib.umich.edu/bitstream/2027.42/21040/2/rl0876.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/21040/1/rl0876.0001.001.tx

Above-ground biomass estimation using JERS/Radarsat SAR composites

Synthetic Aperture Radar is known to have a response that is directly related to the amount of living material with which it interacts. It is this property that our research seeks to exploit in order to better understand carbon dynamics in the Amazon. Several complicating factors include: (1)a dependency on vegetation moisture, species, and egetation density. Moisture has a profound effect on the signal, since microwave scattering properties are largely controlled by the quantity of liquid water molecules ontained in the soil and the vegetation cover. The vegetation species, or species mix, also effects the signal due to the differences in plant geometry and canopy structure. Geometry causes subtle differences in radar backscatter that can be exploited for monocultures, but in the case of the Amazon the high species diversity becomes a source of noise in the observed radar signal. Radar backscatter is proportional to vegetation density up to a saturation point that is dependent upon wavelength and polarization of the radar. Beyond this saturation point, further increases in vegetation density can, in certain cases, produce a reduction in net backscatter due to extinction of the signal within the canopy layer. This effect limits the capability of of a given radar (wavelength and polarization)to differentiate aboveground biomass levels beyond the saturation point. The saturation point can be extended somewhat through use of multifrequency and/or multipolarization data. In this study we use multifrquency composites of L-band (JERS-1)and C-band (Radarsat)data. Radar backscatter from the undisturbed forest generally falls into this saturated region, and hence radar (at L- and C-bands)cannot be used to assess the biomass of those regions, beyond classifying it as greater than or equal to the saturation value. However, areas of regrowth can have a low enough biomass during the first 10 years of regrowth to be accurately assessed using radar. It is in this area where we expect our estimates of biomass to be most useful. Our efforts involve obtaining appropriate pairs of radar mages from a number of sites within the Amazon basin and for both (wet and dry)seasons. Given that JERS-1 and Radarsat have very different viewing geometry, these data are orthorectified using a map and elevation data of the area. Once orthorectified, the data overlay one another with sufficient accuracy to allow reasonably good calibration and incidence angle correction. Without these corrections, the terrain effects would make our analysis too noisy and inaccurate to be useful. The seasonality of the data is used to deal with the moisture sensitivity of the data, and different frequency data (band JERS-1 and C-band Radarsat)is used to help classify the data into several classes for use in classspecific biomass estimates. We have chosen the following sites for our study: Manaus, Rio Branco, Tapajos, Ariquemes, and Brasilia. In order to accomplish the orthorectification step, we have obtained the highest-resolution paper maps of the areas. We have had these maps digitized, so that we have separate layers for roads, rivers, and elevation. A digital elevation map (DEM)has been generated from this data and then used as an integral part of the orthorectification process. In order to classify, as a first step to biomass estimation, we use the JERS (L-band)and RADARSAT (C-band)data at the 2 different seasons to create a 4-channel composite. We can also use several texture measures (lacunarity, entropy, etc..)to further increase the number of vectors for classification. This data is classified into simple land-cover classes (e.g. water, bare soil, short vegetation, and forest)and then biomass estimation is conducted separately for each class. In this paper we report upon progress in the classification and subsequent estimation of aboveground biomass for the study site (each approx. 200-km x 150-km in size).Pages: 170

Electronic Compass Option: An Analysis of Calibration Techniques

http://deepblue.lib.umich.edu/bitstream/2027.42/21570/2/rl2549.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/21570/1/rl2549.0001.001.tx

GPS Measurements for SIR-C/X-SAR and TOPSAR Forest Test Stands at Raco, Michigan Site

http://deepblue.lib.umich.edu/bitstream/2027.42/21084/2/rl0945.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/21084/1/rl0945.0001.001.tx

Detection of selective logging and regrowth by SAR and Landsat

The effects of tropical deforestation on the carbon budget are known to depend upon the land-use history of a given parcel of forest. A patch of primary forest may be clearcut in preparation for land-use conversion to agriculture or pasture or it may be selectively logged in order to remove merchantable timber. The selective logging may or may not be followed by subsequent clearcutting and land-use conversion. In all cases, logged areas may be subject to 'abandonment' with consequent regrowth and potentially leading to forest regeneration. Each pathway has different consequences with respect to the ultimate quantity of carbon removed/sequestered over time and the fate of the carbon thus exchanged. Remote sensing techniques have been championed as a viable means to estimate the location and extent of tropical deforestation, to potentially quantify the amount of carbon removed, and to use the observed time-history to predict the nature and fate of the carbon exchange. The determination of clearcut areas by use of optical and radar techniques is fairly straightforward when provided with adequate spatial resolution relative to the patch size of the forest disturbance. Identification and quantification of selective logging is more problematic because of more stringent spatial resolution requirements and because the detectable 'signal' (tone and textural changes)may itself be faint or degrade rapidly with time as a response to rapid regeneration in tropical environments. The spatial resolution requirements are determined by the size distribution of 'patios' used for the collection and processing of logs or are even more stringent if one seeks to identify the 'gaps' in the crown related to the felling of individual trees. Signal degradation is related to velocity of regrowth after disturbance and seems to range from 1 to 4 years depending upon the nature of disturbance and local factors (e.g. soil, climate and floristic composition)that control regrowth processes. This paper examines the use of Landsat data and repeat-pass interferometric SAR for detection of selective logging in the Mato Grosso province of Brazil. The study uses JERS-1 SAR data obtained over a 44- day period in 1994 (October and December)that brackets a November Landsat scene previously analyzed by INPE as part of a study to quantify selective logging history (1989 to 1998)over a number of study sites in the Amazon basin. This study tracks the time history of selective logging for 238 polygons that experienced some selective logging over the 10- year period as identified on Landsat data by INPE. The polygons are stratified into five general groups on the basis of their histories: (1)not logged, (2)those with selective logging commencing in 1994, (3)selectively logged continuously prior to SAR observation, (4)selectively logged followed by regrowth, and (5)selectively logged followed by clearcutting. We examine the SAR amplitude and multi-pass coherence as an alternative (or synergistic)method to detect selective logging. The probability density functions of optical and near-IR reflectance and radar backscatter and coherence are analyzed to test hypotheses that selective logging and the subsequent land-use pathways produce detectable signal response functions in the mean and variance. The pdfs are used to develop a machine classifier that first identifies nonforest classes, then identifies selective logging patios in the forested areas using a texture-based technique. The patios are buffered to account for the 'zone of collection' and a composite map of land use is generated. The results of the machine classification are compared to that obtained by manual interpretation of the Landsat imagery.Pages: 158

SIR-C/X-SAR Mission: Ancillary Data Report

http://deepblue.lib.umich.edu/bitstream/2027.42/21434/2/rl2411.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/21434/1/rl2411.0001.001.tx

SIR-C/X-SAR Mission: Ancillary Data Report

http://deepblue.lib.umich.edu/bitstream/2027.42/21433/2/rl2410.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/21433/1/rl2410.0001.001.tx

Role of the Peroneal Tendons in the Production of the Deformed Foot with Posterior Tibial Tendon Deficiency

Ten patients were identified with traumatic, complete common peroneal nerve palsy, with no previous foot or ankle surgery or trauma distal to the knee, who had undergone anterior transfer of the posterior tibial tendon to the midfoot. Six of these patients had a transfer to the midfoot and four had a Bridle procedure with tenodesis of half of the posterior tibial tendon to the peroneus longus tendon. Average follow-up was 74.9 months (range, 18–351 months). All patients] feet were compared assessing residual muscle strength, the longitudinal arch, and motion at the ankle, subtalar, and Chopart's joint. Weightbearing lateral X-rays and Harris mat studies were done on both feet. In no case was any valgus hindfoot deformity associated with posterior tibial tendon rupture found. It seems that the pathologic condition associated with a posterior tibial tendon deficient foot will not manifest itself if peroneus brevis function is absent