Modeling the long-term effects of disturbances on forest succession, Olympic Peninsula, Washington

1986 ◽  
Vol 16 (1) ◽  
pp. 56-67 ◽  
Author(s):  
Virginia H. Dale ◽  
Miles Hemstrom ◽  
Jerry Franklin
Keyword(s):  
Leaf Area ◽  
Pacific Northwest ◽  
Forest Succession ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Forest Composition ◽  
Silver Fir ◽  
Long Term Effects ◽  
Olympic Peninsula

A model of forest development has been adapted for the Pacific Northwest. The regeneration, growth, and death of individual trees are tracked for simulated 0.2 ha plots and tree attributes are aggregated to provide stand measures. The model includes the influence of temperature, soil moisture, light tolerance, and competition on tree growth. Long-term simulations for Douglas-fir dominated forests on the western Olympic Peninsula show that the stand is eventually dominated by western hemlock with silver fir being codominant. Even after 1200 years of subsequent stand development, silver fir fails to replace western hemlock indicating that this is a self-replicating and stable community. Fire, windthrows, insect disturbance, and clear-cut logging followed by replanting are incorporated into the model as single-event disturbances to a 500-year-old forest. For those cases where large Douglas-fir survive the disturbance, stand biomass and leaf area patterns are not significantly impacted until the death of the last large Douglas-fir. The projections were all carried out to the time when the forest is dominated by western hemlock and silver fir. At that time, the differential effect of the earlier disturbance is not apparent from the forest composition, biomass, or leaf area patterns except for the insect disturbance. Following the removal of all Douglas-fir by an insect, leaf area fluctuates regularly with a period of 600 years.

scholarly journals The 1912 Douglas-Fir Heredity Study: Long-Term Effects of Climatic Transfer Distance on Growth and Survival

2019 ◽  
Vol 118 (1) ◽  
pp. 1-13 ◽  
Author(s):  
J Bradley St. Clair ◽  
Glenn T Howe ◽  
Jennifer G Kling
Keyword(s):  
Pacific Northwest ◽  
Douglas Fir ◽  
Future Climate Change ◽  
Long Term Effects ◽  
Term Survival ◽  
Growth And Survival ◽  
Seed Sources ◽  
The Pacific ◽  
Near Term

Abstract The 1912 Douglas-Fir Heredity Study is one of the first studies undertaken by the US Forest Service, and one of the first forest genetics studies in North America. The study considers provenance variation of 120 parent trees from 13 seed sources planted at five test sites in the Pacific Northwest. The unique, long-term nature of the study makes it valuable to revisit and consider its biological and historical significance. This analysis considers how far climatically Douglas-fir populations may be moved without incurring unacceptable declines in growth and survival. Results indicate that Douglas-fir seed sources may be moved at least 2° C cooler or warmer and still retain good long-term survival and productivity. However, projected future climate change beyond 2° C may lead to lower survival and productivity. One option to address these concerns is assisted migration; however, if seed sources are moved beyond 2–3° C to a cooler climate in anticipation of warming, or from a more continental to a maritime climate, we are likely to see increased mortality and associated losses in productivity in the near-term. Lessons from this study include: (1) pay attention to good experimental design; we were able to overcome limitations from the design by using new statistical approaches; (2) maladaptation may take time to develop; poorer survival was not evident until more than two decades after planting; and (3) long-term studies may have value for addressing new, unforeseen issues in the future.

Browse selection by beaver: effects on riparian forest composition

1990 ◽  
Vol 20 (7) ◽  
pp. 1036-1043 ◽  
Author(s):  
Carol A. Johnston ◽  
Robert J. Naiman
Keyword(s):  
Forest Succession ◽  
Riparian Forest ◽  
Basal Area ◽  
Forest Composition ◽  
Maximum Diameter ◽  
Long Term Effects ◽  
Selective Foraging ◽  
Biomass Structure ◽  
Preferred Species

Beaver (Castorcanadensis) herbivory has both immediate and long-term effects on biomass, structure, and composition of riparian forests. Intense beaver foraging of trembling aspen (Populustremuloides Michx.) decreased tree density and basal area by as much as 43% within ~ 1-ha forage zones surrounding two beaver ponds in northern Minnesota. Maximum diameter of trees cut was 43.5 cm; average aspen stem diameter cut was 13.9 and 10.2 cm at the two ponds. Woody biomass harvested per beaver averaged 1.4 Mg•ha−1•year−1 over a 6-year foraging period. Most wood harvested was left on site or used in dam construction, rather than consumed. Selective foraging by beaver decreased the relative importance of preferred species (i.e., P. tremuloides) and increased the importance of avoided species (i.e., Alnusrugosa (Du Roi) Spreng., Piceaglauca (Moench) Voss), with long-term implications to forest succession and dynamics.

Canopy disturbances over the five-century lifetime of an old-growth Douglas-fir stand in the Pacific Northwest

2002 ◽  
Vol 32 (6) ◽  
pp. 1057-1070 ◽  
Author(s):  
Linda E Winter ◽  
Linda B Brubaker ◽  
Jerry F Franklin ◽  
Eric A Miller ◽  
Donald Q DeWitt
Keyword(s):  
Pacific Northwest ◽  
Variable Density ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Old Growth ◽  
The Pacific ◽  
History Of ◽  
Horizontal Heterogeneity ◽  
Restoration Strategies

The history of canopy disturbances over the lifetime of an old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stand in the western Cascade Range of southern Washington was reconstructed using tree-ring records of cross-dated samples from a 3.3-ha mapped plot. The reconstruction detected pulses in which many western hemlock (Tsuga heterophylla (Raf.) Sarg.) synchronously experienced abrupt and sustained increases in ringwidth, i.e., "growth-increases", and focused on medium-sized or larger ([Formula: see text]0.8 ha) events. The results show that the stand experienced at least three canopy disturbances that each thinned, but did not clear, the canopy over areas [Formula: see text]0.8 ha, occurring approximately in the late 1500s, the 1760s, and the 1930s. None of these promoted regeneration of the shade-intolerant Douglas-fir, all of which established 1500–1521. The disturbances may have promoted regeneration of western hemlock, but their strongest effect on tree dynamics was to elicit western hemlock growth-increases. Canopy disturbances are known to create patchiness, or horizontal heterogeneity, an important characteristic of old-growth forests. This reconstructed history provides one model for restoration strategies to create horizontal heterogeneity in young Douglas-fir stands, for example, by suggesting sizes of areas to thin in variable-density thinnings.

Low Mortality of Larval Lampreys from Electrofishing, Suction-pumping, Anesthesia, and Handling

2017 ◽  
Vol 8 (2) ◽  
pp. 640-647 ◽  
Author(s):  
Jeffrey C. Jolley ◽  
Christina T. Uh ◽  
Gregory S. Silver ◽  
Timothy A. Whitesel
Keyword(s):  
Pacific Northwest ◽  
Control Group ◽  
Long Term Effects ◽  
Negative Effects ◽  
Short Term ◽  
Important Species ◽  
Pacific Lamprey ◽  
The Pacific ◽  
Delayed Mortality

Abstract Native lamprey populations are declining worldwide. In the Pacific Northwest focus on conservation and management of these ecologically and culturally important species has increased. Concern has emerged regarding the effects of sampling and handling of lamprey, with little to no attention given to the larval lifestage. We monitored the survival of larval Pacific Lamprey Entosphenus tridentatus and Lampetra spp. after backpack electrofishing, deepwater electrofishing and suction-pumping, anesthesia, and handling. We performed survival trials on wild-caught lamprey (n = 15 larvae in each trial) collected from the Clackamas River drainage in Oregon, USA, coupled with control group trials from lamprey sourced from a hatchery (n = 10 larvae). Short-term (96 h) survival was >98% with only one observed mortality. Delayed mortality (1 wk) was observed for four individuals that had fungus; two of those were positive for the bacteria Aeromonas hyrdrophila. We recorded blood hematocrit as a secondary measure of stress. The baseline, nonstressed larvae hematocrit levels did not differ from those of fish that had undergone stress through electrofishing, suction-pumping, and handling without anesthesia. Electrofishing, suction-pumping, and anesthesia showed no short-term negative effects on larval lamprey although potential long-term effects remain unstudied. These techniques appear to provide efficient and relatively safe methods for collecting and surveying larval lamprey.

Holocene forest transformations in sandstone landscapes of the Czech Republic: Stand-scale comparison of charcoal and pollen records

The Holocene ◽  
2019 ◽  
Vol 29 (9) ◽  
pp. 1468-1479 ◽  
Author(s):  
Jan Novák ◽  
Vojtěch Abraham ◽  
Petr Šída ◽  
Petr Pokorný
Keyword(s):  
Driving Forces ◽  
Forest Succession ◽  
Environmental Gradients ◽  
Silver Fir ◽  
Pollen Record ◽  
Fire Dynamics ◽  
The Czech Republic ◽  
The Holocene ◽  
Ecosystem Changes

Stand-scale palaeoecology in sandstone landscapes provides insight into contrasting Holocene forest succession trajectories. Sharp geomorphological gradients in this investigated area, which in addition have never been deforested during the Holocene, provide a good model for upscaling the local vegetation histories to the wider territory of Central Europe. In three sandstone areas – Bohemian Paradise, Polemené hory and Broumov – we compare (1) anthracological records from archaeological stratigraphies under rockshelters with (2) pedoanthracological sequences from nearby locations in valleys, rocks and plateaus; and with (3) pollen analyses carried out in nearby peat accumulations. Taphonomical vectors discriminate the source vegetation of each proxy, however thanks to proximity of all sampling sites pollen record and charcoals from rockshelters integrate the signal from pedoanthracology. The results show that past distribution of individual arboreal taxa is clearly related to the position within local environmental gradients. All basic habitats – valleys, rocky edges and plateaus – started with the dominance of pine forest in the early Holocene. Middle Holocene witnessed expansion of spruce inside valleys and oak on plateaus. Pine has maintained its dominance on rocky edges. In the late Holocene, silver fir and beech expanded into valleys, while oak stands remained dominant on plateaus. In the High Medieval and Modern Ages, human impact triggered general spread of fir. Records indicate site-specific local histories connected to various human activities, fire dynamics and erosion. Against the background of these immediate driving forces, the long-term process of ecosystem changes has been influenced by climate of the Holocene.

Long-Term Effects of Tillage, Nitrogen, and Rainfall on Winter Wheat Yields in the Pacific Northwest

2003 ◽  
Vol 95 (4) ◽  
pp. 828-835 ◽  
Author(s):  
K. M. Camara ◽  
W. A. Payne ◽  
P. E. Rasmussen
Keyword(s):  
Winter Wheat ◽  
Pacific Northwest ◽  
Long Term Effects ◽  
The Pacific

Comparing productivity of pure and mixed Douglas-fir and western hemlock plantations in the Pacific Northwest

2006 ◽  
Vol 36 (6) ◽  
pp. 1484-1496 ◽  
Author(s):  
M M Amoroso ◽  
E C Turnblom
Keyword(s):  
Pacific Northwest ◽  
Stand Density ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Mixed Stand ◽  
Mixed Stands ◽  
Individual Tree ◽  
The Pacific ◽  
Increase In Productivity

We studied pure and 50/50 mixtures of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) plantations to compare attained total yields between mixed-species stands as opposed to monocultures of equal densities. Whether overall stand density influences this outcome has not been adequately investigated, and to address this we included three density levels (494, 1111, and 1729 trees/ha) in the analysis. At age 12, as components of the mixed stands, Douglas-fir exhibited greater height, diameter, and individual-tree volume than western hemlock at all densities. At 494 and 1111 trees/ha the monocultures had a higher volume per hectare than the mixed stand, but at 1729 trees/ha the mixed stand appeared to be just as productive as the pure stands. The increase in productivity by the mixture at high densities seems to have resulted from the partial stratification observed and most likely also from better use of the site resources. Because of this, less interspecific competition was probably experienced in the mixed stand than intraspecific competition in the pure stands. This study shows the important role density plays in the productivity of mixed stands and thus in comparing mixed and pure stands.

Crown structure in western hemlock, Douglas-fir, and grand fir in western Washington: horizontal distribution of foliage within branches

1996 ◽  
Vol 26 (1) ◽  
pp. 128-142 ◽  
Author(s):  
John A. Kershaw Jr. ◽  
Douglas A. Maguire
Keyword(s):  
Pacific Northwest ◽  
Horizontal Distribution ◽  
Relative Increase ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Prediction Equations ◽  
Parameter Recovery ◽  
Empirical Distributions ◽  
Individual Branch ◽  
Parameter Prediction

Horizontal distribution of foliage within individual branches was explored for three major tree species (western hemlock (Tsugaheterophylla (Raf.) Sarg.), Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), and grand fir (Abiesgrandis (Dougl. ex D. Don) Lindl.)) in the Pacific Northwest. Weibull, β, normal, and Johnson's SB distributions were assessed for their ability to conform to the empirical foliage distributions. Moment-based parameter recovery and parameter prediction methodologies were applied. On the basis of the rank of individual branch χ2-values, the β distribution performed best under parameter recovery, while Johnson's SB distribution was best in terms of total sum of χ2-values. Overall, few differences between the four distributions were observed. A system of moment-based parameter prediction equations was developed from branch dimensional and positional measures. The prediction equations showed that the ratio of relative distance from the stem to mean foliage density increased with increasing branch size. This relative increase was enhanced with increasing depth into crown for western hemlock, but not for Douglas-fir or grand fir. Again, the β distribution, based on predicted moments, followed most closely the empirical distributions on the basis of the ranks of χ2-values. The normal distribution was the best in terms of total sum of χ2-values. As expected, moment-based parameter recovery produced smoothed distributions that followed more closely the observed empirical distributions; however, parameter prediction provides a methodology for predicting distributions when empirical moments are not available. No significant (p > 0.05) differences in horizontal foliage distribution were found between sites or fertilization treatments.

Sign in / Sign up

Export Citation Format

Share Document