Ecology
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/44
The department's teaching and research addresses critical ecological and natural resources issues for Montana, but also tackles fundamental and applied questions around the globe.
Undergraduate programs within the department include Fish & Wildlife Management and Ecology, Conservation Biology and Ecology, Organismal Biology, and Biology Teaching. Graduate programs (M.S. and P.hD.) include Fish & Wildlife Management or Biology and Biological Sciences and an intercollege PhD in Ecology and Environmental Sciences.
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Item Comparing citizen science and professional data to evaluate extrapolated mountain goat distribution models(ESA, 2017-02) Flesch, Elizabeth; Belt, JamiCitizen science provides a prime opportunity for wildlife managers to obtain low-cost data recorded by volunteers to evaluate species distribution models and address research objectives. Using mountain goat (Oreamnos americanus) location data collected through aerial surveys by professionals, ground surveys by professionals, and ground surveys by volunteers, we evaluated two mountain goat distribution models extrapolated across Waterton-Glacier International Peace Park. In addition, we compared mountain goat location data by observer and survey type to determine whether there were differences that affected extrapolated model evaluation. We found that all dataset types compared similarly to both mountain goat models. A mountain goat occupancy model developed in the Greater Yellowstone Area (GYA) was the most informative in describing mountain goat locations. We compared Spearman-rank correlations (rs) for occupancy probability bin ranks in the GYA model extrapolation and area-adjusted frequencies of mountain goat locations, and we found that all datasets had a positive correlation, indicating the model had useful predictive ability. Aerial observations had a slightly greater Spearman-rank correlation (rs = 0.964), followed by the professional ground surveys (rs = 0.946), and volunteer ground datasets (rs = 0.898). These results suggest that with effective protocol development and volunteer training, biologists can use mountain goat location data collected by volunteers to evaluate extrapolated models. We recommend that future efforts should apply this approach to other wildlife species and explore development of wildlife distribution models using citizen science.Item Investigating old‐growth ponderosa pine physiology using tree‐rings, δ13C, δ18O, and a process‐based model(Wiley, 2019-06) Ulrich, Danielle E. M.; Still, Christopher; Brooks, J. Renée; Kim, Youngil; Meinzer, Frederick C.In dealing with predicted changes in environmental conditions outside those experienced today, forest managers and researchers rely on process‐based models to inform physiological processes and predict future forest growth responses. The carbon and oxygen isotope ratios of tree‐ring cellulose (δ13Ccell, δ18Ocell) reveal long‐term, integrated physiological responses to environmental conditions. We incorporated a submodel of δ18Ocell into the widely used Physiological Principles in Predicting Growth (3‐PG) model for the first time, to complement a recently added δ13Ccell submodel. We parameterized the model using previously reported stand characteristics and long‐term trajectories of tree‐ring growth, δ13Ccell, and δ18Ocell collected from the Metolius AmeriFlux site in central Oregon (upland trees). We then applied the parameterized model to a nearby set of riparian trees to investigate the physiological drivers of differences in observed basal area increment (BAI) and δ13Ccell trajectories between upland and riparian trees. The model showed that greater available soil water and maximum canopy conductance likely explain the greater observed BAI and lower δ13Ccell of riparian trees. Unexpectedly, both observed and simulated δ18Ocell trajectories did not differ between the upland and riparian trees, likely due to similar δ18O of source water isotope composition. The δ18Ocell submodel with a Peclet effect improved model estimates of δ18Ocell because its calculation utilizes 3‐PG growth and allocation processes. Because simulated stand‐level transpiration (E) is used in the δ18O submodel, aspects of leaf‐level anatomy such as the effective path length for transport of water from the xylem to the sites of evaporation could be estimated.Item Size-specific apparent survival rate estimates of white sharks using mark–recapture models(Canadian Science Publishing, 2019-02) Kanive, Paul E.; Rotella, Jay J.; Jorgensen, Salvador J.; Chapple, Taylor K.; HInes, James E.; Anderson, Scot D.; Block, Barbara A.Abstract: For species that exist at low abundance or are otherwise difficult to study, it is challenging to estimate vital rates such as survival and fecundity and common to assume that survival rates are constant across ages and sexes. Population assessments based on overly simplistic vital rates can lead to erroneous conclusions. We estimated sex- and length-based annual apparent survival rates for white sharks (Carcharodon carcharias). We found evidence that annual apparent survival differed over ontogeny in a system with competitive foraging aggregations, from 0.63 (standard error (SE) = 0.08) for newly recruiting subadults to 0.95 (SE = 0.02) for the largest sharks. Our results reveal a potential challenge to ontogenetic recruitment in a long-lived, highly mobile top marine predator, as survival rates for subadult white sharks may be lower than previously assumed. Alternatively, younger and competitively inferior individuals may be forced to permanently emigrate from primary foraging sites. This study provides new methodology for estimating apparent survival as a function of diverse covariates by capture–recapture study, including when sex assignment is uncertain. Résumé : Pour les espèces qui existent en faible abondance ou dont l’étude présente par ailleurs un défi, il est difficile d’estimer des indices vitaux comme la survie et la fécondité et il est couramment présumé que les taux de survie ne varient pas selon le sexe et le groupe d’âge. Des évaluations de populations reposant sur des indices vitaux trop simplistes peuvent mener à des conclusions erronées. Nous avons estimé les taux de survie annuels apparents en fonction du sexe et de la longueur pour de grands requins blancs (Carcharodon carcharias). Nous avons relevé des preuves de variation du taux de survie annuel apparent au fil de l’ontogénie dans un système caractérisé par des regroupements concurrents d’individus en quête de nourriture, ce taux allant de 0,63 (l’écart-type (ÉT) = 0,08) pour les individus subadultes récemment recrutés à 0,95 (ÉT = 0,02) pour les requins les plus grands. Nos résultats révèlent une difficulté potentielle en ce qui concerne le recrutement ontogénique chez un prédateur marin de niveau trophique supérieur très mobile et longévif, puisque les taux de survie de grands requins blancs subadultes pourraient être plus faibles que présumés auparavant. Une autre explication est que les individus plus jeunes ou moins concurrentiels pourraient être forcés d’émigrer des meilleurs sites d’approvisionnement de manière permanente. L’étude présente une nou-velle méthodologie pour estimer la survie apparente en fonction de différentes variables reliées, par une approche de capture–recapture, y compris pour les cas où l’affectation du sexe est incertaine. [Traduit par la Rédaction]Item Vegetation Distribution and Production in Rocky Mountain Climates—with Emphasis on Whitebark Pine(International Workshop on Subalpine Stone Pines and Their Environment: the Status of Our Knowledge, 1992) Weaver, T.The distribution and production of vegetation on the altitudinal J gradient (grassland-forest-alpine) was plotted against climatic parameters to evaluate hypothetical controlling factors. (1) Whitebark pine (Pinus albicaulis) is likely excluded from higher zones by a cool growing season or wind-induced drought. It is probably not excluded by low temperatures occurring during its hardening, hard, or dehardening seasons. (2) While the lower physiological limit of whitebark pine is probably set by drought its lower realized limit is directly set by subalpine fir (Abies lasiocarpa) and lodgepole pine (Pinus contorta) competitors and indirectly set by factors that control their distribution. (3) The upper limits for most other dominant species are probably set by growing season temperature. The lower limits are likely set by competition down to the cedar-hemlock (Thuja plicata/Tsuga heterophylla) zone and by drought in drier areas. (4) Production is strongly correlated (r 2 = 0.86) with growing season length (soil thawed season minus dry soil days). Multiplying season length by average temperature did not improve the growing season predictor, perhaps because vegetation at each altitude is especially adapted to temperatures in its zone.Item Climates Where Stone Pines Grow, A Comparison(International Workshop on Subalpine Stone Pines and Their Environment: the Status of Our Knowledge, 1992) Weaver, T.------ Abstract-While stone pine climates are similar adapted to relatively moderate climates may be excluded from, species the ranges of congeners by more severe climates, and species with longer warm-moiBt growing seasons are probably more productive than congeners. Absolute low/summer average/absolute high temperatures for stone pines listed in order of increasing absolute low temperature are Pinus sibirica (-65/13/37 °C), P. pumila (-52.19/36 °C), P. koraiensis (-42/1s1/36 °C), P. albicaulis (-3419/29 °C), and P. cembra (-23/8/27 °C). The Walter drought index shows little stress in stone pine forests despite large differences in summer/winter precipitation: in order of increasing summer rainfall, precipitation is P. albicaulis (102.I 829mm), P. pumila (1421.264mm), P. sibirica (1871245=), P. cembra (3231616mm), P. koraieT18is (3941242mm). Estimated thawed-soil growing season increases from P. albicaulis (4.5mo), throughsP. pumila (4.6mo), P. sibirica (5.5mo), and P. cembra (6.3mo) to P. koraiensis (7.8mo); growing seasons of the first three trees could be shortened by drought.Item Distribution of Exotic Plants in the N. Rocky Mountains by Environmental Type and Disturbance Condition(Montana State Univeristy, 1989-06) Weaver, T.; Gustafson, D.; Lichthardt, J.; Woods, B.This report lists seventy-three exotic species found in a systematic sampling of major environmental zones of the Rocky Mountains between the Canadian border and central Wyoming. For each exotic it states the regional distribution, the environmental types (HTs) it occupies (% constancy), the disturbance conditions (DCs) it occupies (% constancy), and its dominance (in terms of% frequency and% cover) in each cell of the HT x DC matrix. Park managers need to develop policy with respect to legally noxious weeds, forage grasses (eg Phleum pratense, Poa pratensis, Bromus inermis, and Dactylis glomerata), and forage legumes (eg Melilotus and Trifolium spp).Item PLANTS ESTABLISHING IN ROCKY MOUNTAIN ENVIRONMENTS-- a manual for choosing native species for revegetation(Montana State University, 1995) Weaver, T.; Gustafson, D; Lichthardt, JSpecies which have established naturally on a disturbed site in a given environment-- climate and disturbance level (defined below)-- are good candidates for revegetation plantings in that environment. On this basis we recommend native plants (grasses, forbs, and shrubs) for revegetation plantings, if they occur on at least half of the sites sampled in the environmental type and cover at least 1% of the ground there. We also list exotic plants establishing on once disturbed roadside sites; if these plants do not invade native vegetation they might, under some circumstances, be used for revegetation The environmental types considered include dry grasslands (BOGR/STCO and AGSP/BOGR), moist grasslands (FESC/FEID and FEID/AGCA) sagebrush (ARAR/FEID and ARTRVAS/FEID) , warm dry forests (PSME/ SYAL and PSME/PHMA), warm moist forests (POTR/CARU, THPL/OPHO, TSHE/CLUN, ABLA/CLUN), cool forests (ABLA/XETE, ABLA/ARCO, and ABLA/VACC), mountain meadows (FEID/AGCA, listed above) and alpine (DESC/CARX) . In each environment plant performance is contrasted across five disturbance types: continually disturbed types (roadshoulders and the adjacent ditch slope), once disturbed sites (roadcuts with organic matter removed and cleared right-of-way without organic matter removal), and undisturbed late seral sites.Item Changes in soils along a vegetational (altitudinal) gradient of the northern Rocky Mountains(Soil Science Society of America, 1979) Weaver, T.As one moves from the warm dry plains of eastern Montana to the cool moist peaks of the northern Rocky Mountains he might pass through a series of native vegetation types: Bouteloua gracilis, Agropyron spicatum, Featuca idahoensis, and Festuca scabrella grasslands; Pinua ponderosa, Pseudotsuga menziesii, and Abies lasiocarpa forests; and alpine tundra (Kuchler 1964, Muggler and Handl 1974, Pfister et al. 1977). It is commonly observed that when one moves up a vegetational gradient he moves up a soils gradient (e.g. Eyre 1963, Whittaker et al. 1968, Hanawalt and Whittaker 1976 and 1977). In the northern Rocky Mountains, Thorp (1931, N Wyoming) observed that organic matter increased, that pH decreased, that the depth to free lime increased and that the thickness of A- and B-horizons increased as he moved up a vegetational gradient similar to that described above. The same trends, as well as a tendency for nutrients to become most available at the grassland-forest boundary, were observed along a similar vegetation gradient in British Columbia (Spilsbury and Tisdale 1944). Such trends correlate well with broad groups in the 1938 Soil Taxonomy (Agricultural Experiment Station 1964 and Nimlos 1963) as well as in the 1977 Soil Taxonomy (Weaver 1978). The objects of this paper are I) to describe the change in soils observed along this gradient in more detail, 2) to consider their genesis briefly, and 3) to consider their importance to plants.Item Root distribution and soil water regimes in nine habitat types of the northern Rocky Mountains(Colorado State University, 1977) Weaver, T.Root distribution and the annual cycle of' soil water availability were measured in nine habitat types of the northern Rocky Mountains. Water stress periods became progressively longer under Abies lasiooarpa forests, Populus trerrruloides groves, Pseudotsuga menziesii forests, Festuoa idahoensis grasslands, Artemisia tridentata shrublands, and Agropyron spioatum grasslands. Water stress periods were longer under Pseudotsuga forests than under adjacent logged areas. Live feeder root biomass (1) was similar under grassland, shrubland, and forest types, (2) increased within a vegetation type with altitude, and (3) decreased at a site with depth. Seral grasslands had less live feeder root biomass than forests in the same habitat type, but climax grasslands and forests were similar in root biomass.Item Cone production in Pinus albicaulis Forests(Inland Mountain West Symposium, 1985-08) Weaver, T.; Forcella, FWhitebark pine cone production was estimated for a 6 to 8 year period in each of 29 stands widespread in.the northern.Rocky Mountains. 1) One-time sampling was possible since the estimate was m2de by multiplying the number of branches perm by an estimate of annual cone production made from counts' of cone lets, mature cones, or cone scars on successively older annual increments of those branches. 2) Average cone production ranged from 0.3 to 3.6 cones·m^-2 ·yr^1 and from 22-270 seeds·m^-2·year^-1 . 3) Regression analysis was used to relate the variance observed to time and place. a) Year-to-year variation in the cone yield of branches, trees, and stands in a region appears to be both internally and externally controlled. Internal control is suggested by the fact that good cone years were usually preceded by poor cone years. While external control is indicated by significant correlations between growth and weather conditions, control is not dominated by the effect of any one factor or any particular developmental stage. b) Although cone production of the average branch varied significantly within 30 percent of the trees and within 48 percent of the stands observed, it did not vary significantly among stands. c) Regressions relating stand cone production to easily measured stand characteristics such as canopy cover, fallen cones, and/or stand size explain no more than 50 percent of the variance among stands.