| Title |
Investigators | Department | Objectives | Approach Keywords | Progress Reports | Impact Statements | Publications | |
Project * COL00530 | |
| Title | *Aspen Persistence in Multi-Aged Forest Communities on the Western Slope of Colorado |
| Investigator(s) | Smith, FW; |
| Department | Forest, Rangeland, & Watershed Sciences |
| Objectives | Aspen is a short-lived, shade-intolerant pioneering species in subalpine forests of the inter-mountain western. Disturbance was essential to maintain aspen in the historic forest landscape. Aging of the forest landscape is a probable result of fire suppression. Under these conditions, long-lived, shade tolerant conifers may be dominating stands where disturbance had maintained an aspen-dominated landscape. We will identify the areas of the landscape where aspen is at risk of being replaced by conifer dominance and identify mechanisms responsible for aspen persistence and restoration in these landscapes. |
| Approach | We will test this model of aspen replacement by shade tolerant conifers to determine if and where aspen forest may be at risk. We will seek to identify mechanisms by which aspen is maintained in multi-aged and mixed-species communities. We will stratify the Uncompaghre Plateau by forest type and determine under what conditions aspen is successfully regenerating. We will seek to identify the mechanisms responsible for aspen persistence in mixed-species communities and test the ability of subordinated aspen to respond to restoration treatment. |
| Keywords | Aspen, Mixed hardwood /conifer forest, Forest stand dynamics, Forest restoration |
| Progress Reports | |
| 1993 | The primary objective of this project is to increase understanding of factors influencing forest growth in the harsh environment of the central Rocky Mountains. Three subprojects of this project are in their final stages. The first subproject evaluated applicability of six landscape indices for use in analyzing silviculturally induced change in landscape patterns. The study was conducted in a 10,000 acre block of subalpine forest in the San Juan Mountains. The amount and timing of cutting is critical to achieving desired future conditions. The second subproject centered on 1) use of phytoliths to document past crown fires, and 2) in comparing such natural disturbance with human-caused disturbance in generating forest edge characteristics. Use of C- isotope ratios in phytoliths holds promise in dating past crown fires. Forest edges produced by natural and human factors are distinct. The differences are presently being quantified. The third sub-project explores the relation between leaf area of subalpine forests of the central Rocky Mountains and soil fertility. The purpose of this study is to determine why leaf area declines with stand age. Leaf area of older forests can be increased by fertilization. GSY=3. |
| 1994 | The objectives of this project are to develop models of Rocky Mountain forests predicting 1) forest development and resilience as related to natural and human disturbances; 2) function of these ecosystems in terms of biogeochemistry and biological productivity; and 3) the role of the community structure and spatial patterns of disturbance in maintaining biodiversity. Work this year has focused on determining biological productivity of subalpine zone coniferous forests. Experiments have been performed to determine the role of mineral nutrition and leaf area distribution on net primary productivity of mature lodgepole pine forests on soils derived from granite soil parent material. Experiments include fertilization to alter soil nutrient status and thinning and pruning to modify vertical and horizontal distribution of leaf area. The overall goal of this work is to determine factors of the physical and biological environment that regulate productivity in Rocky Mountain forests. Much of this work is aimed at above-ground fiber production. However, a portion of this study is also focused on below-ground productivity in fine roots and mycorrhizae. This work has been in progress for less than a full year to date. Field samples are being processed including the tedious sorting of roots from soil samples. But, field data are presently being tabulated for initial analysis . |
| 1995 | The objectives of this project are to develop models of Rocky Mountain forests predicting 1) forest development and resilience as related to natural and human disturbances; 2) function of these ecosystems in terms of biogeochemistry and biological productivity; and 3) the role of the community structure and spatial patterns of disturbance in maintaining biodiversity. Again , this year, work has focused on determining biological productivity of subalpine zone coniferous forests. Experiments have been performed to determine the role of mineral nutrition and leaf area distribution on net primary productivity of mature lodgepole pine forests on soils derived from granite soil parent material. Experiments include fertilization to alter soil nutrient status and thinning and pruning to modify vertical and horizontal distribution of leaf area. The overall goal of this work is to determine factors of the physical and biological environment that regulate productivity in Rocky Mountain forests. A portion of this study is focused on below-ground productivity of fine roots and mycorrhizae. This work has been in progress for less than two years. Because of high variability, sampling, sample processing, and data analysis are progressing slowly. Graduate Students = 4. |
| 1996 | The objectives of this project are to develop models of Rocky Mountain forests predicting 1) forest development and resilience as related to natural and human disturbances; 2) function of these ecosystems in terms of biogeochemistry and biological productivity; and 3) the role of the community structure and spatial patterns of disturbance in maintaining biodiversity. Experiments have been performed to determine the role of mineral nutrition and leaf area distribution on net primary productivity of mature lodgepole pine forests on soils derived from granite soil parent material. Experiments include fertilization to alter soil nutrient status and thinning and pruning to modify vertical and horizontal distribution of leaf area. The overall goal of this work is to determine factors of the physical and biological environment that regulate productivity in Rocky Mountain forests. A portion of this study is focused on below-ground productivity of fine roots and mycorrhizae. Considerable progress has been made at sorting out climatic and nutritional factors influencing productivity. Graduate Students = 4. |
| 1997 | The objectives of research in this project are to develop models of the species dynamics, structure and function of Rocky Mountain forests. Specific current objectives are: 1) to predict future forests resulting from current and proposed land management practices; 2) impact of land use practices on biogeochemistry and productivity of these forests and; 3) the role of community structure and spatial disturbance patterns in maintaining plant and animal Biodiversity. Experiments are under way to determine the role of mineral nutrition and leaf area distribution on productivity of young and mature conifer and hardwood forests growing on a variety of soil types. Of current interest is research into the potential decline of aspen stands in areas known for fall foliage viewing. The relation between elk browsing and aspen regeneration is under study. The potential impact of a major blow-down in North-central Colorado is in the planning stage at present. Productivity of lodgepole pine forests continues to be a major focus. Studies of above and below ground productivity and how they are effected by altered fertility, water status and leaf area are now into their third year of data collection. A major summary paper on the lodgepole pine study will be published in early 1998. Graduate students = 4. |
| 1998 | The objectives of research in the project are to develop understanding of species dynamics, structure and function of Rocky Mountain forests. Current objectives are to predict future forests resulting from land management practices and to determine the role of forest structure in maintaining biodiversity. Disturbance patterns of Colorado's forests have undergone dramatic change in the last century. Human-caused fires, which were extensive in the past century, have been largely excluded from Colorado's forests. Cutting was extensive during the late 19th century, but has been reduced in recent years. Large mammals such as elk have gone from near extinction to populations possibly above historic levels. Changes in forest vegetation from altered disturbance regimes are poorly understood. We studied the relationship between forest structure and disturbance history in the Sangre de Christo Mountains of southeastern Colorado. We sampled age structure, patch sizes and boundaries, and fire history in 6 valleys on the eastern side and 3 valleys on the western side of the range. Significant differences were found between subalpine and mixed conifer forests. Mean patch size was larger in subalpine forest (75 ha) than mixed conifer (28 ha) on the east side of the range, but no differences were detected on the west side. Mean patch age differed between forest types on the east side (subalpine forest averaged 234 y compared with 156 y for mixed conifer forest) but did not differ on the west side. Fire frequencies (number of fires per 100 hectares per 100 years) were 0.06 for subalpine forest and 0.37 for mixed conifer forest on the west side, and 0.44 and 2.13 for the subalpine and mixed conifer forest on the eastside. Subalpine and mixed conifer forests differed in disturbance frequency, and the landscape structure reflected the differences in disturbance histories. We used aerial photographs to identify all aspen within the elk winter range in a large area of northern Colorado. From this population, we randomly selected 57 stands for evaluation of aspen regeneration. Stands that contained stems younger than 30 years and taller than 2.5 m tall were classified as regenerating successfully. Only 20% of the aspen stands in Estes Valley (a very heavily used area) contained a cohort of regenerating aspen stems, whereas 45 to 75% of aspen stands across the larger landscape of the Front Range had regenerating cohorts of aspen. At landscape scales, all locations outside of the heavily impacted Estes Valley averaged 2 cohorts/stand that regenerated after the mid-1960s. All stands that lacked a regenerating cohort showed evidence of moderate-to-severe damage from elk browsing of stems. No regenerating stands showed evidence of severe browsing. We conclude that at landscape scales, regeneration within aspen stands is very common across the Front Range, except in local areas of the highest elk use where little regeneration has occurred in the past 30 years. GSY=4 |
| 1999 | The objectives of research in the project are to develop understanding of species dynamics, structure and function of Rocky Mountain forests. Current objectives are to predict future forests resulting from land management practices and to determine the role of forest structure in maintaining biodiversity. Disturbance patterns of Rocky Mountain forests have undergone dramatic change in the last century. Human-caused fires, which were extensive in the past century, have been largely excluded from these forests. Cutting was extensive during the late 19th century, but has been reduced in recent years. Large mammals such as elk have gone from near extinction to populations possibly above historic levels while other populations have been substantially reduced by vegetation changes. Changes in forest vegetation from altered disturbance regimes are poorly understood. We continued characterization of aspen stands in the Front Range, moving beyond pure-aspen stands to examine aspen mixed with conifers. Stands of relatively pure aspen are common between 2500m to 2700m elevation, whereas aspen within conifer stands is common from 2700m to 3100m. Aspen is rare above 3500m. About half of the cover of aspen is in pure stands, and half in mixture with conifers. Aerial photos revealed an average cover of aspen of about 4%, whereas extensive ground surveys (36 random locations covering 240ha found about 7% cover. In the surveyed areas, we found no relict evidence of dead aspen in areas currently lacking aspen, indicating no substantial death of aspen clones within the past few decades. Snags are important components of structure in ponderosa pine forests, including habitat for birds and as sources of coarse woody debris. The purpose of this study was to determine the occurrence and persistence of snags in the Black Hills in relation to forest structure. The results are intended to provide a basis for estimating snag densities and snag replacement strategies in managed pine stand. We surveyed snag density, snag use and snag persistence at nine study sites distributed throughout the Black Hills pine forests. Study sites were unmanaged, mature pine forest. Mean snag densities were 6.9 ha-1 for all snags, 1.5 ha-1 where DBH > 25 cm, and 0.13 ha-1 for snags with DBH > 50 cm. 98% of snags over 25 cm DBH were ponderosa pine. Use was directly related to snag DBH (R2 = 0.95) where cavity use increases from 15% of snags at 25 cm DBH to 45% of snags at 50 cm DBH. Snag density was directly correlated with live tree basal area (R2 = 0.55). Snags were uniformly distributed in the study area where >60% of 0.15 ha plots had 1 - 4 snags, < 15% of plots had no snags. (GSY=4) |
| 2000 | In our continuing work on the trends in aspen stand development, we've focused on documenting the interactions of aspen and conifers on the west slope and in the Front Range of Colorado. On the west slope, we examined patterns of forest development in 2-storied, mixed stands of aspen and conifers. Here, aspen and conifers have coexisted in the same stands as canopy dominants for nearly 3 centuries. A second cohort of aspen and conifers of about 120 years old were established following large-scale fires around 1880. Subsequently, there has been nearly continuous regeneration of conifer seedlings, but no successful regeneration of aspen. Disturbances on a multiple-century time scale appear capable of sustaining aspen in mixed forest communities. In the Front Range, 25% of all aspen stands show no invasion by conifers, and 40% of the stands containing aspen are dominated by conifers (based on basal area). Where aspen are mixed with conifers, stand development does lead to increasing conifer dominance. However, we found no cases where increasing conifer dominance had led to complete removal of aspen clones; aspen clones appear to be extremely capable of remaining as minor components of conifer-dominated ecosystems. In belt transects of more than 36 1-km transects spread at random across Rocky Mountain, we did not find even a single case where a clone appeared to have been lost as a result of competition with conifers. GS=3.5 |
| 2001 | Quaking aspen (Populus tremuloides) is a critical component of western forest ecosystems. Rocky Mountain aspen regenerates from root suckers and depends on periodic disturbance to maintain a viable root system. In absence of disturbance, there is concern that aspen will be replaced by long-lived conifers. Current forest management policies, such as fire suppression and reduced logging activity, cause concern about the long-term health and persistence of aspen in the Rocky Mountains. We assessed the stand types on the Uncompahgre Plateau in order to determine whether there is a risk of losing a significant amount of aspen dominance on the landscape. Specifically, we asked 1) what portion of the forested landscape is in pure aspen and mixed aspen/conifer stands? 2) in what proportion of pure aspen and mixed aspen/conifer stands is aspen regenerating?; and 3) is aspen decreasing in dominance in mixed aspen/conifer stands? We developed a preliminary classification system with 7 categories for the risk of conifer replacement of aspen communities based on canopy cover of aspen and conifer. We assessed the vegetation of the study area in a GIS system using this classification. We selected 10 stands in each category where a vegetation description existed from inventories collected 20 to 30 years ago. We located each stand and measured current stand species composition, tree sizes and ages. We also measured ages of seedlings and saplings of aspen and conifer in each stand. We will determine the rate of change in overstory species dominance for each of our risk categories in the study area. Also, we will determine whether aspen or conifers are successfully regenerating. From this information, we will be able to assess the type and rate of change in aspen forest cover on the Uncompaghre Plateau. GS=2.3 |
| 2002 | Aspen (Populus tremuloides) is a short-lived, shade-intolerant pioneering species in subalpine forests of the inter-mountain western. Disturbance was essential to maintain aspen in the historic forest landscape. Aging of the forest landscape is a probable result of fire suppression. Under these conditions, long-lived, shade tolerant conifers may be dominating stands where disturbance had maintained an aspen-dominated landscape. We have identified stand types on the Uncompaghre Platues in western Colorado where aspen is mixed with conifers including Englemann spruce, subalpine fir and ponderosa pine. We have measured stand structure in these mixed species forests, including species composition, tree size and age of regenerating aspen and conifers. We are comparing the current stand structure with inventory data collected in the same stands during the 1980's to detect shifts in species composition and species dominance. GS=1 |
| 2003 | Long-term persistence of aspen was evaluated on the Uncompaghre Plateau in western Colorado. Distribution of aspen and aspen/conifer, conifer/aspen and conifer community types were evaluated with current aerial photography. Change in overstory composition of aspen and conifer was evaluated from repeated inventories in 53 stands taken 20 years apart. Aspen and conifer overstory trees and regeneration was measured and aged in each inventoried stand. Aspen stands occurred on 16% of the study area, mixed stands on 62% of the area and pure conifer stands were confined to 12% of the area, mainly subalpine forest. Overstory composition of pure aspen and pure conifer stands was stable over 20 years, with self-thinning dominating stand development. However, in mixed conifer/aspen stands, conifer basal area doubled over the last 20 years in stands and there was decrease in aspen basal area. Most overstory tress ranged in age from 100 to 150 years old. Aspen regeneration occurred in all stand types, but few trees were greater than 20 years old. Conifer regeneration occurred in mixed stands and ranged in age up to 60 years. Pure aspen stands appear stable on the Uncompaghre Plateau. However, substantial change is occurring in mixed conifer/aspen stands, where conifer dominance is increasing in the overstory and aspen cover is decreasing. While aspen regenerates, suckers do not persist or emerge into the overstory in mature mixed stands. Conifer regeneration occurs in mixed stands, persists and new individuals grow into the overstory. This pattern suggests accelerated change resulting in development of multi cohort conifer stands without replacement of mature aspen stems. Most stands are capable of producing aspen suckers, but it will require some level of disturbance to create a successful new cohort . GS=1 |
| 2004 | Aspen is declining as a component of western forests due to fire suppression and grazing of regeneration by domestic livestock and elk. Aspen clones are critical habitat for neotropical songbirds, provide high grazing value for elk and domestic livestock, and are highly valued for their visual aesthetics. Here, aspen is likely declining in dominance because of competition from ponderosa pine following a century of effective fire suppression. Reintroduction of prescribed fire for fuels treatment and restoration of natural stand conditions is being considered as a management tool in these forests. Little is known about the consequence of fire on aspen following a long period of fire exclusion. We examined the effects the fire had on aspen (Populus tremuloides Michx.) regeneration, development, and clone expansion following a large, mixed severity wildfire in ponderosa pine (Pinus ponderosa var scopulorum) dominated forests in the Black Hills, South Dakota. Without fire, unburned clones produced sprouts at a rate of 15 655 sprouts ha-1. No difference in sprout density between unburned and low severity fire was observed; however sprout density in response to high severity fire was more than double that in unburned clones averaging 31 913 sprouts ha-1. Sprout height responded positively to increases in fire severity averaging 21, 33, and 50 cm for unburned, low, and high fire severity, respectively. The high rates of herbivory by native and domestic ungulates across all fire severities limited sprout height. Overall, 58 % of all live sprouts were browsed. Among all fire severities, browsed sprouts were significantly taller than unbrowsed sprouts suggesting that herbivores selectively utilize the taller, more visible sprouts preventing the recruitment of regenerated sprouts into the overstory. Severe fire that killed nearly all overstory aspen and consumed a high proportion of surface fuels had the largest effect on aspen suckering and growth rates. |
| 2005 | Quaking aspen (Populus tremuloides Michx.) is an important component of forests of the west, but there has been concern that it is declining during the 20th century. Aspen is the primary deciduous canopy species amid expansive conifer forests and is highly valued as a critical component of ecosystem diversity. For over a century, fire suppression, increased herbivory from wildlife and livestock, and the conversion of aspen stands to conifer stands for increased timber production have altered the distribution and abundance of aspen. Aspen regeneration dynamics including sprout production, growth, and clone size were measured to determine the effects of fire on small aspen clone persistence following a mixed-severity wildfire in the Black Hills, South Dakota. Four years post fire, 10 small, isolated aspen clones per low and high fire severity classes were compared with 10 unburned clones. Regardless of severity, fire did not cause an increase in the area occupied by individual aspen clones. Clones affected by high severity fire had the greatest suckering response producing an average of 31 930 sprouts per ha more than double the sprout density in unburned clones and 67% greater than the sprout density in clones affected by low severity fire. Sprout growth in high severity clones was 135% and 60% greater than sprout growth in unburned and low severity clones. The succession of these clones to more shade-tolerant ponderosa pine was delayed in clones affected by high severity fire as high severity fire caused significant pine mortality within and surrounding the clone, whereas, without further disturbance, pine encroachment and dominance will likely continue in clones affected by low severity fire. |
| 2006 | Ponderosa pine forests across the western United States are being managed to reduce fire hazard. High stand density and multi-story canopy structures likely to support active crown fire have become common due to fire suppression and custodial management. Intensive low thinning is the most common mechanical fuel treatment intended to remove ladder fuels, reduce canopy bulk density and minimize the probability of active crown fire. However, the stand densities best suited to reduce crown fire occurrence are also the densities typically associated with promoting regeneration. Growth of prolific regeneration creates ladder fuels and increases canopy density, which in turn, reduces the longevity of treatment effects. We explore the use of prescribed fire to prolong physical effectiveness and cost effectiveness of fuel treatments. Study Design and Results Successful use of prescribed fire requires enough surface fuels to generate fire behavior sufficient to kill seedlings and small trees. Surface fuels are very low following fuel treatments, and trees become less susceptible to fire as they grow. We ask whether there is an appropriate time after fuel treatments where the combination of available fuel and tree susceptibility to fire that permits the effective use of prescribed fire. We found that it takes 8 years for a seedling to reach 45 cm in height and 16 years to reach 1.37 m tall (dbh). The median age of saplings (0.25 to 10 cm dbh) ranged between 20 and 32 years. We measured tree mortality following prescribed fire where surface fuel loads were ~12 Mg/ha with grass as the primary fire carrier. Ponderosa pine seedling mortality was over 90% for seedlings less than 45 cm tall, but decreased to 58% for seedlings 76 to 110 cm tall. No mortality in saplings (>1.37 m tall) was observed. Normally occurring surface fuel loadings are not sufficient to regulate ponderosa pine sapling densities in fuel treatment areas, and need to be augmented with activity fuels to achieve desired effects. We constructed augmented fuel beds in prescribed burn areas to simulate the effects of prescribed burning with control, low (13.5 Mg/ha), moderate (27 Mg/ha), and high (40 Mg/ha) fuel loadings. Flames were about 15 cm tall in the control fuelbeds and increased to ~ 1.5 m in the high fuelbed treatment. We expect that fire-induced mortality will increase with fuelbed loading, but the mode of death will differ among treatments. Plots were burned this fall and we will assess fire related this summer. |
| Impact | |
| 1999 | Disturbance patterns of Rocky Mountain forests have undergone dramatic change in the last century including fire exclusion and changes in harvesting regimes. Aspen is thought to be in decline in some forest areas because of fire exclusion, reduced timber harvest and excessive browsing of young aspen because of high elk populations. Our results will be used to determine the need for increased disturbances or reduced elk numbers to maintain aspen in the forest landscape. |
| 2000 | Disturbance patterns of Rocky Mountain forests have undergone dramatic change in the last century including fire exclusion and changes in harvesting regimes. Aspen is thought to be in decline in some forest areas because of fire exclusion, reduced timber harvest and excessive browsing of young aspen because of high elk populations. Our results will be used to determine the need for increased disturbances or reduced elk numbers to maintain aspen in the forest landscape. |
| 2001 | The question of whether aspen is being lost or reduced on western Colorado landscapes is a critical question to local communities, businesses, timber industry, environmentalists, and forest managers. This research will document the status and health of aspen forests across a large landscape on the western slope. The rate and types of change in aspen forests will be quantified over a significant time period. This research will describe the condition of a large and socially important forest type of Colorado. Our understanding of the state and dynamics of the aspen and aspen/mixed conifer forests of the western slope will be significantly improved. The results of this research will inform the debate on the status and health of aspen forests in Colorado. The results will be immediately and directly applicable to management of these forests by quantifying the rate of change of aspen forests and the risk of loss of aspen on landscape. |
| 2002 | The question of whether aspen dominance is in decline in western Colorado forests is an important question to local communities and land management agencies. Fire suppression and reduced harvests may have reduced the area of aspen dominated forest. If aspen dominance is in decline, proactive management will be needed to reinitiate stands dominated by healthy aspen stems. |
| 2003 | These results suggest that pure aspen stands will persist without intervention. There is no evidence for change in composition and they are producing new suckers. However, aspen cover is declining in many stands where the overstory is a mixture of aspen and conifer. In many of these stands, conifer cover has dramatically increased in the past 20 years. While aspen can and does regenerate in these stands, it does not persist and grow into the overstory under current conditions. Conifers do regenerate under current conditions, and they do persist. These results suggest continued, and perhaps accelerating, change in the mixed species stand type. The likely outcome of stand development is decreasing aspen cover, and the development of multi cohort stands dominated by conifers. Disturbance is necessary to change this process. Aspen can successfully regenerate in these stands, but disturbance is required to promote more regeneration and to permit the growth of new aspen stems into the overstory. Mixed aspen/ conifer stands would be high priority for silvicultural treatments to maintain or increase the amount of aspen cover on the Uncompahgre Plateau. |
| 2004 | Our results indicate that fire can be an effective tool to preserve and enhance aspen in landscapes where it is a rare and declining in dominance. Prescribed fire, especially in combination with mechanical treatments to remove ponderosa pine, are likely to be effective in rejuvenating and increasing the size of aspen clones. |
| 2005 | Aspen provides pockets of diversity in an otherwise homogenous landscape. Therefore, maintaining and expanding the presence of aspen is often a management objective, and fire is increasingly becoming the preferred tool to carry out this objective. This work will inform foresters and landowners about appropriate and cost-effective management techniques for conserving and increasing aspen dominance. Logistical problems arise when prescribing a high severity fire in aspen, however. It is difficult under acceptable weather conditions to get fire of any intensity to burn though an entire clone. Combinations of mechanical pretreatment followed by moderate to high intensity prescribed fire can then be used to remove the aspen overstory and stimulate suckering . Results from this study indicate that successful regeneration of small aspen clones will require high severity fire, removal of invading pine within and surrounding the clone, and steps to control herbivory at the time of treatment. These steps will create conditions favorable to the long-term development and maintenance of small aspen clones. |
| 2006 | Our results will be immediately useful for fire and vegetation managers to design and maintain effective treatments to reduce fire hazard in ponderosa pine forests. Further, our results will promote the use of prescribed fire as an ecologically appropriate and cost effective alternative compared mechanical treatments to sustain fire resistant stand structures over time. |
| Publications | |
| 1993 |
ADELHARDT, L. 1993. Effects of the spatial distribution of silvicultural activities on landscape pattern. M.S. Thesis. CSU. 32 p. BINKLEY, D. and BROWN, T. 1993. A synopsis of the impacts of forest practices on water quality in North America. Water Res. Bull. 29(5):1-12. BINKLEY, D. and BROWN, T. 1993. Impacts of forest practices on water quality. USDA F.S. Gen. Tech. Rpt. BROWN, T., BROWN, D., and BINKLEY, D. 1993. Laws and programs for controlling nonpoint source pollution in forest areas. Water Res. Bull. 29(1):1-13. ROBERTS, S.D., LONG, J.N., and SMITH, F.W. 1993. Canopy stratification and leaf area efficiency: a conceptualization. For. Ecol. Mgmt. 60:143-156. SAMPSON, D.A. and SMITH, F.W. 1993. Light interception in response to changes in stand structure in lodgepole pine forests. Forest and Agricultural Meteorlogy 64:63-79. SMITH, J.K., LAVEN, R.D., and OMI, P.N. 1993. Macroplotsampling on Populus tremuloides stands in north-central Colorado. Int. J. Wildland Fire 3(2):85-94. STUMP, L.M. and BINKLEY, D. 1993. Relationships between litter quality and nitrogen availability in Rocky Mountain forests. Canadian J. For. Res. 23:492-502. ZOU, X. 1993. Species effects on earthworm density in tropical tree plantations in Hawaii. Biology and Fertility of Soils 15:35-38. ZOU, X., BINKLEY, D., and DOXTADER, K. 1993. A new method for estimating gross phosphorus mineralization and immobilization rates in soils. Plant and Soil 147:243-250. |
| 1994 |
BINKLEY,D. and BROWN,T. 1993. Management impacts on water quality of forest and rangelands. USDA FS GTR RM-239. 114 p. BINKLEY,D. and MacDONALD,L. 1994. Forests as non-point sources of pollution, and effectiveness of best mgmt. practices. Tech. Bull. #672, NCASI, NY. BINKLEY,D., CARTER,R., and ALLEN,H. 1994. Nitrogen fixation practices in forestry. pp. 421-441 in Bacon, P. (ed.) Nitrogen Fertiliz. and the Environ. Marcel Dekker, NY. BINKLEY,D., CROMACK,K.,JR., and BAKER,D. 1994. Nitrogen fixation by red alder: Biology, reates , and controls. pp. 5-72 in Hibbs, D.(ed.) The Biol. and Mgmt. of Red Alder. OSU Press BINKLEY,D., SON,Y., and KIM,Z. 1994. Impacts of air pollution on forests: A summary of current situations. J. of Korean For. Soc. 83:229-238. BINKLEY,D., STOTTLEMEYER,R., SUAREZ,F., and CORTINA,J. 1994. Soil nitrogen avail.in some arctic ecosystems in northwest AK: Responses to temperature and moisture. Ecoscience 1:64-70. BROWN,T. and BINKLEY,D. 1994. Effect of management on water quality in North America. RPA Series, USDA GTR RM-248. CZAPLEWSKI,R., REICH,R., and BECHTOLD,W. 1994. Spatial autocorrelation of undisturbed natural pine stands across Georgia. For. Sci. 30:314-328. REICH, R. 1994. Influence of spatial autocorrelation on a fixed-effect model used to evaluate treatment of oil spills. Final Rpt. CSU. USEPA Contract No. 4G0742-NATT. 81p. REMINGTON,K., BONHAM,C., and REICH,R. 1994. Estimation of biomass and heights of Agropyron cristatum: A Weibull dist. J. Japan. Grassl. 40:190-197. -- SHAFROTH, P.B., SCOTT, M.L., FRIEDMAN, J.M., AND LAVEN, R.D. 1994. Establishment, sex structure, and breeding system of an exotic ripairian willow, Salix x. rubens. Amer. Midl. Nat . 132:159-172 |
| 1995 |
BINKLEY, D. 1995. Ecosystems--an ecology primer. pp.41-47 IN: Eco. Mgmt.: Beyond the Rhetoric, Symp. Proc. CSU, Ft. Collins BINKLEY, D., SMITH, F., SON, Y. 1995. Nutrient supply & limitation in an age-sequence of lodgepole pine in SE Wyo. Can. J. For. Res. 25:621-628 GIARDINA, C., HUFFMAN, S., BINKLEY, D., CALDWELL, B. 1995. Alders increase phosphorus sup. in a Douglas-fir plant. Can. J. For. Res. 25:1652-1657 JOHNSON, D., BINKLEY, D., CONKLIN, P. 1995. Simulated effects of atmospheric deposition, harv. , & species change on nutr. cycling in a loblolly pine for. For. Eco. & Mgmt. 76:29-45 KALKHAN, M.A., REICH, R.M., and CZAPLEWSKI, R.L. 1994. Statistical properties of Pielou's index of segregation and Kappa statistic in assessing accuracy of remotely sensed data using simple random sampling. pp 251-258. In: ISPRS Commission IV Symposium on Mapping and Geographic Information Systems, Vol. 30, Part 4, May 31-June 3, 1994. Athens, GA KALKHAN, M.A., REICH, R.M., and CZAPLEWSKI, R.L. 1995. Statistical properties of five indices in assessing the accuracy of remotely sensed data using simple random sampling. pp 246-257. In: 1995 ACSM/ASPRS Conv. and Exposition Tech. Papers, Vol. 2, ASPRS, Charlotte, NC, Feb .27-March 2, 1995 KALKHAN, M.A., REICH, R.M., and CZAPLEWSKI, R.L. 1995. Evaluation of the statistical properties of the inverse estimator for remotely sensed areal estimates using simple random sampling. pp 258-270. In: 1995 ACSM/ASPRS Conv. and Exposition Tech. Papers, Vol. 2, ASPRS, Charlotte, NC, Feb. 27-March 2, 1995 NUCKOLS, J.R., REICH, R.M., WINDESHIEM, E., and STALLONES, L. 1995. Use of spatial autocorrelation analysis in health risk assessments for hazardous waste sites. pp 185-190. In: Proc. 1993 IUFRO S4.11 Conference on Stochastic Spatial Models in Forestry, May 18-21, 1993. Thessaloniki, Greece REICH, R., ARVANITIS, L. 1995. Spatial analysis and assoc. of slash pine ...pitch canker. pp 191-202. In: Proc., 1993 IUFRO S4.11 Conf. on Stoch. Spatial Mod. in For., 5/18-5/21/93, Thessaloniki, Greece REICH, R., BONHAM, C., REMINGTON, K. 1994. Comparison of classical vs inverse sampling for est . cover using Monte Carlo simulations. J.Appl.Math. & Comp. 64:171-190 REICH, R., CZAPLEWSKI, R., BECHTOLD, W. 1994. Spatial cross-correlation in growth of undisturbed nat. shortleaf pine stands in No. Georgia. J. Environ. & Ecol. Stat. 1:201-217 REICH, R.M. and CZAPLEWSKI, R.L. 1995. Bivariate spatial autocorrelation: A new technique for assessing spatial patterns. pp 91-100. In: Proc., 1993 IUFRO S4.11 Conf. on Stochastic Spatial Models in Forestry, May 18-21, 1993, Thessaloniki, Greece STOHLGREN, T., BINKLEY, D., VEBLEN, T., BAKER, W. 1995. Attributes of reliable long-term landscape-scale studies: Malpractice insur. for landscape ecologists. Environ. Monitoring & Assessmt 38:1-25. ZOU, X., BINKLEY, D., CALDWELL, B. 1995. Effects of dinitrogen-fixing trees on phosphorus biogeochemical cycl. in contrasting forests. Soil Sci.Soc.of Am. J. 59:1452-1458. -- |
| 1996 |
BINKLEY, D. 1995. The influence of tree species on forest soils--processes and patterns. pp. 1-33 in: Proc. of Tree and Soil Wkshop. Agronomy Soc. of NZ Spec. Publ. 10, Lincoln U. Press, Canterbury BINKLEY, D. et al. 1995. Parent material depth controls ecosystem composition and function on a riverside terrace in NW AK. Ecoscience 2:377-381 BONHAM, C. et al. 1995. Spatial relationship of Bouteloua gracilis with site characteristics. Japanese Soc. of Grasslands Sci. 41:196-201 EWERS, B. et al. 1996. Influence of adjacent stand on spatial patterns of carbon and nitrogen in Eucalyptus and Albizia plantations. Canadian Jrnl. of For. Res. 26:1501-1503 HUANG, J. et al. 1996. The contribution of wetlands to stream nitrogen load in Loch Vale Watershed, CO, USA. Acta Phytoecologica Sinica 20:289-302 KALKHAN, M. et al. 1996. Investigation of statistical properties of inverse...sampling. pp 331-340. In:1996 ACSM/ASPRS An. Conv. and Expo. Tech. Papers, Vol. 1 ASPRS, Baltimore 4/22-4/25/96 KALKHAN, M. et al. 1996. Statistical properties of Pielous index of segregation...sampling. pp 583-592. In: 1996 ACSM/ASPRS An. Conv. and Expo. Tech. Pap., Vol. 1 ASPRS, Baltimore 4/22-4/25/96 RHOADES, C. et al. 1996. Factors influencing decline in soil pH in Hawaiian Eucalyptus and Albizia plantations. Forest Ecology and Mgmt. 80:47-56 WILLIAMS, M. et al. 1996. The extent of bias caused by substitution points in forest survey: A simulation study. Res. Pap. RM-RP-327. Ft. Collins, CO:USDA FS, RMF & RES, 7p. -- |
| 1997 |
BINKLEY, D. 1996. Bioassays of the Influence of Eucalyptus Saligna and Albizia Falcataria on Soil Nutrient Supply and Limitation. Forest Ecology and Management 91:229-234 BINKLEY, D. AND GIARDINA, C. 1996. Biological Nitrogen Fixation in Plantations. Chapter 9 In: Management of Soil, Water, and Nutrients in Tropical Plantation Forests (E.K.S. Nambiar and A. Brown, eds). CSIRO/CIFOR 297-337 BINKLEY, D. AND HOBERG, P. 1997. Does Atmospheric Deposition of Acidity and Nitrogen Threaten Swedish Forests? Forest Ecology and Management 92:119-152 BINKLEY, D., GIARDINA, C., DOCKERSMITH, I., MORSE, D., SCRUGGS, M., AND TONNESSEN, K. 1997. Status of Air Quality and Related Values in Class I National Parks and Monuments of the Colorado Plateau. National Park Service, Air Resources Division, Report. 290 p BINKLEY, D., O'CONNELL, A. M. AND SANKARAN, K. V. 1996. Stand Growth: Patterns and Controls. Chapter 12 In: Management of Soil, Water, and Nutrients in Tropical Plantation Forests (E.K.S. Nambiar and A. Brown, eds). CSIRO/CIFOR 419-442 BINKLEY, D., SUAREZ, F., STOTTLEMYER, R., AND CALDWELL, B. 1997. Ecosystem Development on Terraces along the Kugururok River, Northwest Alaska. Ecoscience 4:311-318 HART, S.C., BINKLEY, D. AND PERRY, D. 1997. Influence of Red Alder on Soil Nitrogen Transformations in Conifer Forests of Contrasting Productivity. Soil Biology and Biochemistry 29:1111-1123 KALKHAN, M. A., REICH, R. M. AND CZAPLEWSKI, R. L. 1996. Statistical Properties of Measures of Association and the Kappa Statistic for Assessing the Accuracy of Remotely Sensed Data Using Double Sampling. Pp 467-476. In: 1996 Spatial Accuracy Assessment in Natural Resources and Environmental Sciences: Second International Symposium, May 21-23, 1996 (H. Todd Mowrer, Raymond L. Czaplewski, R. H. Hamre, tech. coords.). General Technical Report RM-GTR-277. Fort Collins, CO: USDA, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. 728p KALKHAN, M. A., REICH, R. M., AND CZAPLEWSKI, R. L. 1996. Statistical Properties of Pielou's Index of Segregation and Measures of Association for Assessing the Accuracy of Remotely Sensed Data Using Stratified Random Sampling. Pp 583-592. In: 1996 ACSM/ASPRS Annual Convention and Exposition Technical Papers, Vol. 1 ASPRS, Baltimore, Maryland, April 22-25, 1996 KALKHAN, M. A., REICH, R. M., AND CZAPLEWSKI, R. L. 1996. Investigation of the Statistical Properties of the Inverse Estimator for Remotely Sensed Areal Estimates Using Stratified Random Sampling. Pp 331-340. In: 1996 ACSM/ASPRS Annual Convention and Exposition Technical Papers, Vol. 1 ASPRS, Baltimore, Maryland, April 22-25, 1996. KALKHAN, M., REICH, R. M., CZAPLEWSKI, R. 1997. Variance Estimates and Confidence Intervals for the Kappa Measure of Classification Accuracy. Canadian Journal of Remote Sensing 23:246-252 KALLAS, M. A., REICH, R. M., AND JACOBI, W. R. 1996. A Hazard Rating Model for Armillaria Root Disease in the Black Hills National Forest. Proceedings of the 44th Annual Western International Forest Disease Work Conference, Hood River, Oregon, Sept. 16-20, 1996. (Abstract) REICH, R. M., BONHAM, C.D., AND METZGER, K. 1997. Modeling Small-scale Spatial Interaction of Shortgrass Prairie Species. Ecological Modeling 101:163-174 REICH, R. M., METZGER, K. L., AND BONHAM, C. D. 1997. Application of Permutation Procedures for Comparing Multi-species Point Patterns of Grassland Plants. Grasslands Science 43:189-195 RYAN, M.G., BINKLEY, D. and FOWNES, J.H. 1997. Age-related Decline in Forest Productivity: Pattern and Process. Advances in Ecological Research 27:213-262 SCOTT, N., AND BINKLEY, D. 1997. Litter Quality and Annual Net N Mineralization: Comparisons Across Sites and Species. Oecologia 111(2):151-159 STOHLGREN, T. J., COUGHENOUR, M. B., CHONG, G.W., BINKLEY, D., KALKHAN, M. A., SCHELL, L. D., BUCKLEY, D. J. AND BERRY, J. K. 1997. Landscape Analysis of Plant Diversity. Landscape Ecology 12:155-170 WILLIAMS, M. AND REICH, R. M. 1997. Modeling the Variance Error Structure of a Stem Profile Model. Forest Science 43:378-386 |
| 1998 |
Alington, C.A. 1998. Fire History and Landscape Pattern in the Sangre de Christo Mountains, Colorado. Ph.D. Dissertation. Department of Forest Sciences. Colorado State University, Fort Collins. 55pp Alington, C.A. 1998. Pattern and Process. Landscape Review 4:48-61 Hunner, G., Reich, R. M., and Mower, H.T. 1998. Modeling Forest Stand Structure Using Spatial Statistics. In: Proceedings of the 2nd Southern Forestry GIS Conference, October 28-19, 1998, Athens, Georgia. Pages 103-120 Kalkhan, M.A., Reich, R.M., and Stohlgren, T.J. 1998. Assessing the Accuracy of Landsat Thematic Mapper Classification Using Double Sampling. International Journal of Remote Sensing 19:2049-2060 Olsson, U., Binkley, D., and Smith, F.W. 1998. Nitrogen Supply, Nitrogen Use, and Production in an Age Sequence of Lodgepole Pine. Forest Science 44:454:457 |
| 1999 |
Binkley, D. 1999. Disturbance in temperate forests. Pp. 469-482 in: Ecosystems of Disturbed Group (L. Walker, ed.). Elsevier Science, Amsterdam Binkley, D., and Resh, S. 1999. Rapid changes in soils following Eucalyptus afforestation in Hawaii. Soil Science Society of America Journal 63:222-225 Binkley, D., and Ryan, M. 1998. Net primary production and nutrient cycling in replicated stands of Eucalyptus saligna and Albizia facaltaria. Forest Ecology and Management 112:79-85 Binkley, D., Burnham, H., and Allen, H L. 1999. Water quality impacts of forest fertilization. NCASI Technical Bulletin #782, 53 p Binkley, D., Burnham, H., and Allen, H.L. 1999. Water quality impacts of forest fertilization. Forest Ecology and Management 121:191-213 Fornwalt, P. 1999. Production in below-ground carbon allocation in young and old apsen forests . M.S. Thesis, Department of Forest Sciences, Colorado State University, Fort Collins Pastor, J. and Binkley, D. 1998. Nitrogen fixation and the mass balance of nitrogen in ecosystems. Biogeochemistry 43:63-78 Reich, R.M. and Bonham, C.D. 1999. Influence of spatial autocorrelation on a fixed-effect model used to evaluate treatment of oil spills. Journal of Applied Mathematics and Computations 106:149-162 Schreuder, H.T., Williams, M.S., and Reich, R.M. 1999. Estimating the number of tree species in a forest community using survey data. Environmental Monitoring and Assessment 56:293-303 Smith, F. W. and Resh, S. 1999. Age-related changes in production and below-ground carbon allocation in Pinus contorta forests. Forest Science 45:333-341 Stohlgren, T., Binkley, D., Chong, G., Kalkhan, M. A., Schell, L.D., Bull, K.A., Otsuki, Y., Newman, G., Bashkin, M., and Son, Y. 1999. Exotic plant species invade hotspots of native plant diversity. Ecological Monographs 69:25-46 |
| 2000 |
Binkley, D., Son, Y., and Valentine, D. 2000. Do forests receive occult inputs of nitrogen? Ecosystems 3:321-331. Binkley, D., Giardina, C., and Bashkin, M. 2000. Soil phosphorous pools and supply under the influence of Eucalyptus saligna and nitrogen fixing Albizia facaltaria. Forest Ecology and Management 128:241-247. Fisher, R.F., and Binkley, D. 2000. Ecology and management of forest soils. Wiley, New York. 489 p. Kaye, J.P., Resh, S.C., Kaye, M.W., and Chimner, R.A. 2000. Nutrient and carbon dynamics in a replacement series of Eucalyptus and Albizia trees. Ecology 81:3267-3273. Knight, R.L., Smith, F.W., Buskirk, S.W., Romme, W.H., and Baker, W.L., eds. 2000. Forest fragmentation in the southern Rocky Mountains. Univ. of Colorado Press. 474 pp. Long, J.N. and Smith, F.W. 2000. Restructuring the forest: Goshawks and the restoration of southwestern ponderosa pine. Journal of Forestry 98:25-31. Reich, R.M., Lundquist, J., and Bravo, V.A. 2000. Spatial relationship of resident and migratory birds and canopy openings in diseased ponderosa pine forests. Journal of Environmental Modelling and Software 15:189-197. Stohlgren, T., Bachand, R.R., Onami, Y., and Binkley, D. 1998. Species-environment relationships and vegetation patterns: Effects of spatial scale and tree life-stages. Plant Ecology 135:215-228. Suarez, F., Binkley, D., Kaye, M.W., and Stottlemyer, R. 1999. Expansion of forest stands into tundra in the Noatak National Preserve, Northwest Alaska. Icoscience 6:465-470. |
| 2001 |
Binkley, D. 2001. Patterns and processes of variation in nitrogen and phosphorus concentrations in forested streams. NCASI Technical Bulletin #836, 147 pp. Research Triangle Park, NC. Chong, G. W., Reich, R.M., Kalkhan, M.A., and Stohlgren, T.J. 2001. New approaches for sampling and modeling native and exotic plant species richness. Western North American Naturalist 61:328-335. Giardina, C., Ryan, M., Hubbard, R., and Binkley, D. 2001. Tree species effects on carbon and nitrogen mineralization in Rocky Mountain soils. Soil Science Society of America Journal 65:1272-1279. Kaye, J. 2001. Recalcitrant nitrogen pool dynamics in forest and grassland soils. Ph.D. Dissertation. Department of Forest Sciences, Colorado State University. 84 pp. Kaye, M.W., Suzuki, K., Binkley, D. and Stohlgren, T. J. 2001. Landscape-scale dynamics of aspen in Rocky Mountain National Park, Colorado. In: Sustaining Aspen in Western Landscapes: Symposium Proceedings (W.D. Shepperd, D. Binkley, D. Bartos, T.J. Stohlgren, and L.G. Eskew, eds.), 13-15 June 2000, Grand Junction, CO. Proceedings RMRS-P-18. Fort Collins, CO: USDA Forest Service, Rocky Mountain Research Station. Pp. 39-46. Manier, D.J. and Laven, R.D. 2001. Changes in landscape patterns and associated forest succession on the Western Slope of the Rocky Mountains, Colorado. In: Sustaining Aspen in Western Landscapes: Symposium Proceedings (W.D. Shepperd, D. Binkley, D. Bartos, T.J. Stohlgren, and L.G. Eskew, eds.), 13-15 June 2000, Grand Junction, CO. Proceedings RMRS-P-18. Fort Collins, CO: USDA Forest Service, Rocky Mountain Research Station. Pp. 15-25. Reich, R.M. and Bonham,C.D. 2001. Spatial analysis of grazed white birsage in the Lake Mead National Recreational Area, Nevada, USA. Journal of Grasslands Science 47:128-133. Rothe, A., and Binkley, D. 2001. Nutritional interactions in mixed species forests. Canadian Journal of Forest Research 31:1855-1870. Shepperd, W.D., Binkley, D., Bartos, D., Stohlgren, T.J., and Eskew, L.G. (eds.). 2001. Sustaining Aspen in Western Landcapes: Symposium Proceedings; 13-15 June 2000; Grand Junction, CO. Proceedings RMRS-P-18. Fort Collins, CO: USDA Foret Service, Rocky Mountain Research Station. 460 p. |
| 2004 |
Smith, A. 2004. Aspen and conifer interaction over a twenty-year period on the Uncompahgre Plateau, Colorado. M.S. Thesis, Colorado State University. Fort Collins CO. 34 p. |
| 2005 |
Amy E. Smith and Frederick W. Smith. 2005. Twenty-year change in aspen dominance in pure aspen and mixed aspen/conifer stands on the Uncompahgre Plateau, Colorado, USA. Forest Ecology and Management 213:338-348. Keyser, T.L. 2005. Aspen (Populus tremuloides Michx.) response to a mixed-severity wildfire in the Black Hills, SD, USA. M.S. Thesis. Colorado State University, Fort Collins, CO. Leigh B. Lentile, Frederick W. Smith, and Wayne D. Shepperd. 2005. Patch structure, fire-scar formation, and tree regeneration in a large mixed-severity fire in the South Dakota Black Hills, USA. Canadian Journal of Forest Research 35: 2875-2885. Tara L. Keyser, Frederick W. Smith, and Wayne D. Shepperd. 2005. Trembling aspen response to a mixed-severity wildfire in the Black Hills, South Dakota, USA. Canadian Journal of Forest Research 35:2 679-2684. |
| 2006 |
Keyser, T.L., Smith, F.W., Lentile, L.B., and Shepperd, W.D. 2006. Modeling postfire mortality of ponderosa pine following a mixed-severity wildfire in the Black Hills: The role of tree morphology and direct fire effects. Forest Science 11: 530-539. |