Geographic information analysis: An ecological approach for the management of wildlife on the forest landscape

This document is a summary of the project funded by NAGw-1460 as part of the Earth Observation Commericalization/Applications Program (EOCAP) directed by NASA's Earth Science and Applications Division. The goal was to work with several agencies to focus on forest structure and landscape characterizations for wildlife habitat applications. New analysis techniques were used in remote sensing and landscape ecology with geographic information systems (GIS). The development of GIS and the emergence of the discipline of landscape ecology provided us with an opportunity to study forest and wildlife habitat resources from a new perspective. New techniques were developed to measure forest structure across scales from the canopy to the regional level. This paper describes the project team, technical advances, and technology adoption process that was used. Reprints of related refereed journal articles are in the Appendix

Research in remote sensing of vegetation

The research topics undertaken were primarily selected to further the understanding of fundamental relationships between electromagnetic energy measured from Earth orbiting satellites and terrestrial features, principally vegetation. Vegetation is an essential component in the soil formation process and the major factor in protecting and holding soil in place. Vegetation plays key roles in hydrological and nutrient cycles. Awareness of improvement or deterioration in the capacity of vegetation and the trends that those changes may indicate are, therefore, critical detections to make. A study of the relationships requires consideration of the various portions of the electromagnetic spectrum; characteristics of detector system; synergism that may be achieved by merging data from two or more detector systems or multiple dates of data; and vegetational characteristics. The vegetation of Oregon is sufficiently diverse as to provide ample opportunity to investigate the relationships suggested above several vegetation types

Determining successional stage of temperate coniferous forests with Landsat satellite data

Thematic Mapper (TM) digital imagery was used to map forest successional stages and to evaluate spectral differences between old-growth and mature forests in the central Cascade Range of Oregon. Relative sun incidence values were incorporated into the successional stage classification to compensate for topographic induced variation. Relative sun incidence improved the classification accuracy of young successional stages, but did not improve the classification accuracy of older, closed canopy forest classes or overall accuracy. TM bands 1, 2, and 4; the normalized difference vegetation index (NDVI); and TM 4/3, 4/5, and 4/7 band ratio values for old-growth forests were found to be significantly lower than the values of mature forests (P less than or equal to 0.010). Wetness and the TM 4/5 and 4/7 band ratios all had low correlations to relative sun incidence (r(exp 2) less than or equal to 0.16). The TM 4/5 band ratio was named the 'structural index' (SI) because of its ability to distinguish between mature and old-growth forests and its simplicity

Analysis of conifer forest regeneration using Landsat Thematic Mapper data

Landsat Thematic Mapper (TM) data were used to evaluate young conifer stands in the western Cascade Mountains of Oregon. Regression and correlation analyses were used to describe the relationships between TM band values and age of young Douglas-fir stands (2 to 35 years old). Spectral data from well regenerated Douglas-fir stands were compared to those of poorly regenerated conifer stands. TM bands 1, 2, 3, 5, 6, and 7 were inversely correlated with the age (r greater than or equal to -0.80) of well regenerated Douglas-fir stands. Overall, the 'structural index' (TM 4/5 ratio) had the highest correlation to age of Douglas-fir stands (r = 0.96). Poorly regenerated stands were spectrally distinct from well regenerated Douglas-fir stands after the stands reached an age of approximately 15 years

Comparison of 7.5-minute and 1-degree digital elevation models

We compared two digital elevation models (DEM's) for the Echo Mountain SE quadrangle in the Cascade Mountains of Oregon. Comparisons were made between 7.5-minute (1:24,000-scale) and 1-degree (1:250,000-scale) images using the variables of elevation, slope aspect, and slope gradient. Both visual and statistical differences are presented

Strategic reserves in Oregon’s forests for biodiversity, water, and carbon to mitigate and adapt to climate change

Creating strategic forest reserves is essential for stemming the loss of biodiversity and contributing to climate mitigation and adaptation. Meeting preservation targets of 30% protection by 2030, and 50% by 2050 would lead to greater protection of animal taxa and tree species habitat, carbon stocks and accumulation, and forests that are important sources of drinking water. Here, we develop a regional framework to specifically identify at a fine resolution (30 m) high priority forestlands for preservation in Oregon, USA. We include a resilience metric that represents connectivity and topographic diversity, and identify areas within each ecoregion that are ranked high priority for carbon, biodiversity, resilience and drinking water. Oregon has less than 10% of its forestlands protected at the highest levels, yet its temperate forests are among those with the highest carbon densities in the world. Reserves for surface drinking water sources and forest habitat for birds, mammals, amphibians, and reptiles could increase to 50–70% protection at the highest levels by 2050. Protected aboveground biomass carbon could triple to 635 teragrams of carbon by 2050. The ownership of the high preservation priority lands for carbon and biodiversity is primarily federal (67% by 2050) followed by private (28% by 2050), with much less in the other ownerships. Forest reserves could be established on federal lands through executive action, regulation and rule-making, while private landowners could be incentivized to store more carbon, limit harvest in certain areas and transfer ownership to land trusts. Protecting mature and old forests on federal lands fulfills an urgent need for protection and provides a low-cost way to simultaneously meet national and international goals. This study provides a flexible, dynamic framework for identifying areas that are high priority to protect for climate mitigation and adaptation at regional and sub-regional scales

Relationships between grass canopy characteristics and Landsat Thematic Mapper bands

The relationships between spectral reflectance in the Landsat Thematic Mapper (TM) bands and grass canopy variables were evaluated using in situ remote sensing techniques. Reflectance data were collected from experimental plots of annual ryegrass (Lolium multiflorum) and tall fescue (Festuca arundinacea) using a Barnes Modular Multiband Radiometer (MMR). The canopy variables used were canopy height, canopy cover, total wet biomass, total dry biomass, aboveground plant water, and leaf area index. Statistically significant relationships were found between the spectral bands and the canopy variables. Inverse relationships in the visible (TM1, TM2, TM3) and middle infrared (TM5, TM7) regions were related to spectral absorption by plant pigments (visible) and moisture within plant tissue (middle infrared). Direct relationships in the near infrared (TM4, MMR5) were attributed to enhanced reflectance resulting from spectral scattering. Overall, no one spectral band was found to be superior in all situations, but TM5 consistently showed the lowest correlations with the canopy variables. Data sets were collected during three annual ryegrass phenological stages: early stem extension (June), anthesis (July), and senescence (August). The most significant correlations between reflectance and the canopy variables were found for the June data. High levels of biomass in July and plant senescence in August adversely affected the spectral reflectance/canopy relationships. Data from the tall fescue plots were obtained from a wide range of total wet biomass levels (16.5 - 1677.9 g/m²). The asymptotic limits, or the biomass range for which the reflectance could be used to predict changes in the canopy variables, were studied. The reflection asymptotes were nearly twice as high for the near infrared (TM4) as for the visible and middle infrared bands (TM1, TM2, TM3, TM7). The use of band ratios and normalized difference transformations did not consistantly increase correlations of spectral reflectance with the grass canopy variables. Logarithmic transformations of both the spectral bands and the canopy variables were successfully used to linearize the spectral reflectance/canopy regression functions. Redundancy was found among the absorption bands (TM1, TM2, TM3, TM7) and between the near infrared bands (TM4, MMR5). Principal component transformations were utilized to eliminate these spectral band redundancies. The seven spectral bands were reduced to two principal components, while maintaining nearly all of the variability found in the original bands

Revisiting Trophic Cascades and Aspen Recovery in Northern Yellowstone

We revisit the nature and extent of trophic cascades and quaking aspen (Populus tremuloides) recovery in the northern range of Yellowstone National Park (YNP), where studies have reported on Rocky Mountain elk (Cervus canadensis) browsing and young aspen heights following the St. John, 1995-96 reintroduction of gray wolves (Canis lupus). A recent study by Brice et al. (2021) expressed concerns about methodologies employed in earlier aspen studies and that results from those studies exaggerated the extent to which a trophic cascade has benefitted aspen, concerns such as: (a) the selection of aspen stands, (b) young aspen sampling and measurements within stands, (c) the upper browse level of elk, (d) cause of increased young aspen height growth, (e) interpretation of browsing and height data, and others. We review these concerns but conclude that earlier aspen studies have provided important insights regarding the recovery of aspen that is underway in northern Yellowstone. We also found that Brice et al. (2021) misinterpreted or misrepresented various aspects of those earlier studies, while failing to address potential biases and shortcomings of their own 2007-2017 study, including: (1) sampling aspen stands from only a portion of the park\u27s northern range, (2) not randomly selecting aspen stands across their study area, but only within identified treatments, (3) varying sampling density (stands/km2) by more than an order of magnitude between treatments, and (4) not sampling all stands in most years. Regardless of the advantages or disadvantages of the sampling designs and research methodologies employed in various aspen studies, they have consistently shown that decreased browsing has resulted in greater young plant heights in YNP\u27s northern range, results supportive of an ongoing trophic cascade

Aspen Recovery in Northern Yellowstone: A Comment on Brice et al. (2021)

Aspen sapling recruitment increased as browsing by elk decreased, following the 1995–96 reintroduction of wolves in Yellowstone National Park. We address claims by Brice et al. (2021) that previous studies exaggerated recent aspen recovery. We conclude that their results actually supported previous work showing a trophic cascade benefiting aspen

Bison Alter the Northern Yellowstone Ecosystem by Breaking Aspen Saplings

The American bison (Bison bison) is a species that strongly interacts with its environment, yet the effects of this large herbivore on quaking aspen (Populus tremuloides) have received little study. We documented bison breaking the stems of aspen saplings (young aspen \u3e 2 m tall and ≤ 5 cm in diameter at breast height) and examined the extent of this effect in northern Yellowstone National Park (YNP). Low densities of Rocky Mountain elk (Cervus canadensis) after about 2004 created conditions conducive for new aspen recruitment in YNP\u27s northern ungulate winter range (northern range). We sampled aspen saplings at local and landscape scales, using random sampling plots in 87 randomly selected aspen stands. Across the YNP northern range, we found that 18% of sapling stems had been broken. The causal attribution to bison was supported by multiple lines of evidence: (1) most broken saplings were in areas of high bison and low elk density; (2) saplings were broken in summer when elk were not foraging on them; (3) we directly observed bison breaking aspen saplings; and (4) mixed-effects modeling showed a positive association between scat density of bison and the proportion of saplings broken. In a stand heavily used by bison, most aspen saplings had been broken, and portions of the stand were cleared of saplings that were present in previous sampling in 2012. Bison numbers increased more than fourfold between 2004 and 2015, and their ecosystem effects have similarly increased, limiting and in some places reversing the nascent aspen recovery. This situation is further complicated by political constraints that prevent bison from dispersing to areas outside the park. Thus, one important conservation goal, the preservation of bison, is affecting another long-term conservation goal, the recovery of aspen and other deciduous woody species in northern Yellowstone