AimThe possible linkages between the spatial distribution of primary productivity over the north-western Hawaiian islands and trends of subpopulations of Hawaiian monk seals in the period 1956-1995 were assessed. This endangered seal is endemic to the northwestern Hawaiian islands (NWHIs), where about 1300 -1400 individuals are distributed among six main breeding subpopulations. A striking property in patterns of abundance among subpopulations is their spatial nature, a feature suggesting that these may be related to variation in the biotic marine environment. In examining linkages between trends in abundance at these subpopulations and the marine habitat of the NWHIs, an understanding of the relative importance of intrinsic or extrinsic regulatory processes to the long-term dynamics of the seal can be gained. Location The north-western Hawaiian islands (Hawaiian Archipelago).Methods Productivity of the seascape was mapped using both remotely sensed images and data collected during oceanographic cruises. Measurements included sea surface temperature (SST), vertical water column structure, integrated chlorophyll, and their respective levels of variability. The spatial structure and heterogeneity of both mean values and coefficients of variation of these variables were quantified statistically by calculating descriptive statistics for each block of a 20 ° × 10 ° grid (with 200 blocks of dimensions 1 ° ) overlain on each map, and computing spatial statistics for each variable (based on the summary statistics calculated for each block). Multivariate techniques were used to identify biogeographical regions within the pelagic landscape of the NWHIs. Monk seal trends among breeding sites within and among biogeographical regions were compared by analysing correlations among mean beach counts for each subpopulation.Results Primary productivity over the marine habitat of the Hawaiian monk seal was found to be non-uniform. A significant spatial pattern of primary productivity over the NWHIs, most apparent in a gradient along latitudinal lines, was documented. Multivariate groupings of environmental data partitioned the NWHIs into distinct biogeographical regions, and Hawaiian monk seal breeding areas can be differentiated on the basis of these. Regions with similar environments displayed synchronous variation in monk seal abundance.Main conclusions These findings suggest the local trends in monk seal abundance have ultimately been shaped by the quality of the surrounding marine environment. In assessing the dynamics of the Hawaiian monk seal as a whole, and notwithstanding the short-term and local effects of proximate mortality factors, extrinsic, ecosystem-level mechanisms appear to be important in shaping the long-term population dynamics of this endangered mammal. If that is the case, then environmental variation may also be an important determinant of the potential for recovery of these subpopulations and therefore for the entire species.

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Space use by the George River caribou herd (GRCH) changes in correspondence with migration patterns. The traditional range of this herd encompasses an area of approximately 900 000 km 2 . Range use is seasonal and includes travel to traditional calving grounds. Winter range use however, is more variable. The GRCH has grown rapidly from 5000 animals in 1954 to approximately 775 000 in 1993. Beginning in the mid 1980s, the calving and summer range habitats of the GRCH have deteriorated, resulting in a decline in physical condition and subsequent poor calf survival and low pregnancy rates. We assessed the importance of the winter range as a food source compensating for poor summer range quality through an evaluation of winter range drift and use intensity. We hypothesized that if winter ranges pro¬ vide a compensatory source of forage, then George River caribou should avoid sites heavily used during the previous win¬ ter at a population level. Winter ranges for the GRCH were calculated using 4300 caribou locations obtained 1986-2000. We found that in spite of a doubling in net range area, the size of annual winter ranges did not increase, indicating the occurrence of range drift. Further, George River caribou exhibited avoidance of wintering areas at several spatial scales. Avoidance occurred across a use threshold, where the degree of use (or density) during the previous winter determined the level of avoidance during the subsequent winter. As the spatial scale decreased, the degree of avoidance increased. Caribou significantly avoided areas used the previous winter at spatial scales below and including 245 km 2 (correspon¬ ding to a 75% use distribution). Results suggest winter foraging allows caribou suspend the effects of density-dependent summer forage limitation on herd productivity. As such, analysis of GRCH population trends should be considered in light of both summer and winter range resources.

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Understanding vegetation recovery patterns following wildfire and logging disturbance is essential for long-term planning in sustainable forestry. Plot-scale studies indicate differences in revegetation rates and postdisturbance composition in Labrador, Canada, following fire in comparison with harvest but do not necessarily capture the full range of relevant landscape variability. Using a satellite-based land cover classification that distinguishes forest, woodland, shrub, lichen, and bare ground, we applied partial least-squared regression (PLS) to derive empirical models of vegetation dynamics following fire and harvest. Forest recovery rates were found to be generally slow and sensitive to predisturbance land condition and site quality (potential productivity). We found that, although disturbance type was not specifically retained in the model, estimated rates of vegetation recovery were faster for a typical harvest compared with a typical fire (i.e., 50% recovery at 14 years versus 33 years, respectively). Indeed, the model predicts important regeneration delay following fire that appears sensitive to both site quality and area burned. Understanding factors affecting broad-scale vegetation recovery relationships can help guide future sustainable forestry and wildlife habitat initiatives in the region, in part by parameterizing landscape simulation models used for strategic decision support.