ASSESSING INTERACTIONS BETWEEN SITE CONDITIONS AND VEGETATION CONTROL TREATMENTS FOR PNW DOUGLAS-FIR PLANTATIONS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: MCINTIRE-STENNIS
• Reporting Frequency: Annual
• Accession No.: 1009767
• Project Start Date: Jul 1, 2016
• Project End Date: Jun 30, 2021
• Program Code: [(N/A)]- (N/A)

Recipient Organization
OREGON STATE UNIVERSITY
(N/A)
CORVALLIS,OR 97331

Performing Department
Forest Engineering, Resources & Management

Non Technical Summary
Competition between newly established seedlings and competing vegetation (natural or invasive) is a major process influencing seedling survival and growth. In the Pacific Northwest (PNW) chemical vegetation control is a key management tool used by forest managers to succeed in the establishment of Douglas-fir stands.The goal of the purposed study is to investigate the influence of a common set of forest vegetation management (FVM) treatments on conifer seedling survival and growth across a range of site conditions in order to develop a vegetation management decision support system that can be applied to a broad range of sites in the PNW. The FVM treatments that will be applied in this study include a factorial combination of fall site preparation and broadcast spring release treatments.Periodic measurements of biomass growth (of both seedlings and competing vegetation) along with periodic assessments of soil moisture (and soil matric potential) across different FVM treatments will allow us to determine the threshold values of competing vegetation biomass growth and soil water depletion that will impact tree growth and survival. Estimates of soil water use by competing vegetation can also be determined.The data from all of the experimental sites will be pooled into a large database and used for region wide modelling analysis. This analysis will include the effect of vegetation control treatments, site attributes, and competing vegetation characteristics on stand survival and productivity. Examples of site characteristics that will be tested include SI, soil attributes (such as texture, bulk density, water holding capacity or Nitrogen content), climatic conditions (such as rainfall during growing season, mean annual temperature or number of frost days), elevation, and aspect. The results of this analysis will then be used to develop a decision support system.The decision support system will provide land managers with a tool to help determine the vegetation control treatments required to ensure adequate seedling survival and growth under specific site conditions. The decision support system will also allow managers to predict the growth response of young conifer stands to FVM treatments on a given type of site. To accomplish this, a replicated experiment containing a factorial combination of fall site preparation, spring release during the first growing season, and spring release during the second growing season will be installed on sites with contrasting site characteristics across the geographic range of the PNW.

Animal Health Component

100%

Research Effort Categories

Basic

0%

Applied

100%

Developmental

0%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
123	0699	1070	100%

Knowledge Area
123 - Management and Sustainability of Forest Resources;

Subject Of Investigation
0699 - Trees, forests, and forest products, general;

Field Of Science
1070 - Ecology;

Keywords

vegetation management

decision support system

ecophysiology

water use

water stress

vegetation biomass

Goals / Objectives
The main objective of the purposed study is to develop a vegetation management decision support system that can be applied to a broad range of sites in the PNW.The specific objectives are: i) investigate the influence of a factorial combination of fall site preparation and broadcast spring release treatments on conifer seedling survival and growth across a range of site conditions; ii) investigate the interactions between soil characteristics (texture, depth and water availability), weather (e.g. temperature and vapor pressure deficit regimes), and vegetation community type (e.g. herbaceous, shrubs, forbs) on the response to vegetation management treatments.

Project Methods
VMRC Data Network and Site SelectionThe VMRC data network will consist of ten study sites and will be used to create the decision support system for Douglas-fir plantations. Two of the ten study sites will be intensely sampled and receive measurements of soil moisture dynamics, soil physical properties, understory biomass, understory nutrient content, crop tree biomass and crop tree nutrient content in addition to the standard crop tree inventories and understory vegetation surveys. These sites will be known as "Tier I" sites. The remaining eight sites will be less intensely sampled and will only receive simplified measurements of soil physical properties in addition to the standard crop tree inventories and understory vegetation surveys. These sites, "Tier II" sites, will consist of a single replication of all 8 treatments, allowing for more sites to be installed in order to more fully capture the range of conditions found throughout the region.In the absence of competing vegetation, soil water availability during growing season is controlled by the water holding capacity of the soil and the amount of rainfall during growing season that re-charge the soil. During the first year of the study one Tier I site will be installed on a site with high soil water availability. The second Tier I study site will be installed the following year on a dry site with low soil water availability. The goal of this design will be to have the Tier I sites located on sites with contrasting productivity and soil water availabilities that are representative of the conditions found throughout the region. In the third and fourth years of the study eight Tier II sites will be installed on sites with soil water availability ranging between those of the Tier I sites in order to create a gradient of soil water availability. Site characteristics such as texture, depth, aspect, elevation, and competing understory species will also be considered when selecting study sites.Study DesignAll of the experimental sites in this study will utilize a randomized complete block study design with a 2 x 2 x 2 factorial of treatments, where factor 1 corresponds to fall site preparation treatment, factor 2 corresponds to spring release during growing season 1, and factor 3 corresponds to spring release during growing season 2. Each factor will have two levels: 0 (no treatment application) and 1 (treatment application). The factorial treatment design results in eight unique combinations of treatments (Table 1). For example, treatment 000 corresponds to the no action treatment where all factors have a level of 0. On the other hand, treatment 111, where all factors have a level of 1, corresponds to the application of fall site preparation + spring release during growing season 1 + spring release during growing season 2.On Tier I sites, each of these treatments will be replicated in four blocks at each site for a total of 32 plots per site. Seedlings will be planted at a spacing of 10' x 10' and each measurement plot will consists of 8 rows of 8 trees (0.15 acre) surrounded by a 2 tree buffer on all sides. Treatments will be applied to the entire 12 row by 12 tree whole plot area (0.29 acre). The Tier I study sites will also contain two additional smaller plots per block with 6 rows of 12 trees used for destructive biomass sampling. One of these plots will receive treatment 000 (no action) and the other will receive treatment 111 (fall site preparation + spring release during growing season 1 + spring release during growing season 2). These plots will be referred to as biomass plots. For each site the total the area required will be approximately 11.9 acres for Tier I sites and 2.7 acres for Tier II sites.?Vegetation Control Prescriptions The fall site preparation and spring release vegetation control treatments will be determined on a site specific basis and will depend on the competing species composition at each individual site. The goal of all spring release treatments will be to reduce understory cover below 25%. If this threshold is not achieved by a given spring release additional actions will be taken to reduce understory cover below this level.Data CollectionTree inventory and vegetation surveysInventories of tree basal diameter, height, crown radius, height to live crown, and DBH (when available) will be conducted at planting and during the winter of growing seasons 1, 2, 3, 4, 5, 8, 10, 13, 15, 17 and 20 for each of the sites regardless of tier. Vegetation surveys will also be conducted at all study sites during the summer of the same growing seasons on five 1 m2 survey points per plot and will include assessments of vegetation cover and height by species. In addition to yearly tree inventory measurements, periodic measurements of basal diameter and height will be carried out on two selected plots per block (000 and 111) during the first three growing seasons at the Tier I sties. These measurements are required to estimate seedling biomass and nutrient content dynamics and to assess interactions with vegetation and soil moisture dynamics. BiomassBiomass samples will only be collected from biomass plots on Tier I sites. Aboveground tree biomass will be sampled on two trees per biomass plot once during the dormant season for the first five growing seasons of each study site (8 trees total per site per treatment per year). Aboveground biomass will be separated into stem, branches, and foliage. Specific needle area (SNA, cm2?g-1) will be measured on a subset of needles and used to calculate leaf area (LA, m2) of each sample tree and leaf index (LAI, m2·m2) of each plot. After the fifth growing season the tree biomass sampling frequency and sample size will be reassessed based on earlier results. Understory biomass will be measured during the first three growing seasons of each study site. Understory biomass will be measured periodically during the active growing season on three 1 m2 clip plots per biomass plot and understory biomass will be separated by growth habit (forbs, grasses, ferns, shrubs, trees, vine/shrubs). The height and cover of each understory species will be measured prior to biomass sampling in order to develop a relationship between understory cover and height and understory biomass. Similar to tree biomass sampling, after the third growing season the understory biomass sampling frequency will be reassessed based on earlier results. In addition to biomass, the concentration of carbon and nutrients will be sampled in both tree needles and understory foliage.Soil sampling and weather monitoringA soil description will be developed for each study site by digging one-1 m deep soil pit per block per study. On each plot of all the experimental sites (Tier I and Tier II), 6 soil samples will be collected from each plot to assess soil bulk density, texture, organic matter, water holding capacity, and depth. All of the experimental sites will be equipped with weather stations to measure photosynthetically active radiation, temperature, relative humidity, and precipitation (one station per study site). The meteorological data collected on each site will be used to account for annual variability in weather conditions that may cause treatment x site interactions.?Soil moistureThe Tier I sites will include measurements of soil moisture on two selected plots per block (000 and 111) in order to assess soil water availability dynamics. Soil moisture will be measured using TDR soil moisture probes connected to a datalogger. Four probes per selected plot will be installed, two at a 0-20 cm depth and two at a 30-50 cm depth. A total of 32 sensors will be required for each Tier I study site. In order to translate volumetric water content (cm3·cm-3) to soil matric potential (MPa), water release curves will be determined for each study site.

Progress 07/01/16 to 06/30/21

Outputs
Target Audience:Cooperative members (from industry and state agencies), faculty from OSU and other national and international universities, and other forest professionals from private companies and federal and state agencies. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?The data was presented at: 2020 Winter Vegetation Management Seminar for Forestry, February 11, Albany, OR. 2020 Winter Vegetation Management Seminar for Forestry, February 12, Tumwater, WA. Stand Management Cooperative (SMC) Annual Meeting, October 21,Remote Meeting Via Zoom. PNW Forest Vegetation Conference Webinars, December 3,Remote Meeting Via Zoom. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? During the first growing season (2017) we measured a suite of variables in order to describe and understand the interactions of seasonal dynamics of productivity and resources use by western hemlock seedlings and competing vegetation. We developed functions to estimate vegetation biomass from cover%. We determined seasonal dynamics of soil water availability under different vegetation management treatments. We determined a water use factor of 24.7 mm of water per Mg of understory biomass per month. During years 2017-2018 we installed 1 study site planted with Douglas-fir seedlings, applied herbicide treatments and carried out all measurements programed. During the first (western hemlock site) and second (Douglas-fir site) growing seasons we measured a suite of variables in order to describe and understand the interactions of seasonal dynamics of productivity and resources use by western hemlock and Douglas-fir seedlings and competing vegetation. We developed functions to estimate vegetation biomass from cover%. We determined seasonal dynamics of soil water availability under different vegetation management treatments. We determined a model to determine water use of competing vegetation from cover percent, soil moisture and weather data. WE presented a detailed description of stress physiology of western hemlock and Douglas-fir growing under contrasting vegetation management conditions. During years 2018-2019 we continue with herbicide treatments at the Douglas-fir site and carried out all measurements programed on both study sites already installed (western hemlock, 2017; Douglas-fir, 2018). We selected a new site to be planted in winter 2020. We improved the functions to estimate vegetation biomass from cover%. We determined seasonal dynamics of soil water availability and seedling water stress under different vegetation management treatments. We presented a detailed description of stress physiology of western hemlock and Douglas-fir growing under contrasting vegetation management conditions. During years 2019-2020we continue with measurements and planted a thirdsite.The new site include both species (Dougasl-fir and western hemlock). On old study sites, during the fourth (western hemlock site) and third (Douglas-fir site) growing seasons we continued measuring a suite of variables in order to describe and understand the interactions of seasonal dynamics of productivity and resources use by western hemlock and Douglas-fir seedlings and competing vegetation. Highlights: •The CoSInE project has two contrasting Tier I sites with at least three years of intensive tree and vegetation measurements. On both study sites, vegetation management (VM) treatments significantly affected the abundance and composition of the vegetation community. • Plots with spring release treatments during the first two growing seasons had higher soil moisture than the control and fall site preparation only treatments which did not differ. There were no longer any differences in soil moisture among the treatments during the third and fourth growing seasons. • Drought stress was minimal at the coastal site planted with western hemlock (WH) due to the influence of the Pacific Ocean and low vapor pressure deficit (VPD). Survival of seedlings at the site was high regardless of treatment. • Drought stress was much higher at the dry inland site planted with Douglas-fir (DF) due to the site having less rainfall and much higher VPD. Extreme heat waves (>35°C) were also more common. • There was a strong effect of VM treatment on drought stress (measured as predawn and midday water potential, ΨPD andΨMD) at the dry inland site. The Ψ of the control treatment dropped rapidly reaching minimum values of -2.2 MPa at ΨPD and -2.9 MPa at ΨMD in September of the first growing season. Drought stress of seedlings growing under the more intensive treatments (011 and 111) was minimal throughout the first two growing seasons at both sites, demonstrating the effectiveness of VM treatments. • At the end of the fourth growing season, WH seedlings growing in the 111 treatment were, on average, 49 cm taller than those in the control treatment (000), while DF seedlings in the 111 were, on average, 29 cm taller than those in the control. VM effects on seedling height became clearer during the third growing season at both sites. • Due to favorable site conditions, there was no effect of VM treatments on WH seedling survival at the costal site. There was a strong effect of VM treatment on seedling survival at the inland site, with the control reaching a minimum of 33% of survival. • There were substantial differences between the control and 111 treatment in seedling volume at the final measurement (October 2020). Differences in seedling diameter, height, and volume suggest differences in growth potential during future years.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Wightman, M.G., Gonzalez-Benecke, C.A. 2017. Competition and Site Interactions Experiment Tier II and New Study Sites. VMRC Annual Report 2016 - 2017, p. 43-50
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Gonzalez-Benecke, C.A., Wightman, M.G. 2017. Competition and Site Interactions Experiment Tier I Western hemlock. VMRC Annual Report 2016 - 2017, p. 51-62
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Guevara, C.A., Gonzalez-Benecke, C.A., Wightman, M.G. 2018. Competition and Site Interactions Experiment Tier I Western hemlock and Douglas-fir. VMRC Annual Report 2017 - 2018, p. 1-21
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Guevara, C.A., Gonzalez-Benecke, C.A., Wightman, M.G. 2019. Competition and Site Interactions Experiment Tier I Western hemlock and Douglas-fir (Vegetation Dynamics, Soil Moisture, Seedling Growth and Survival). VMRC Annual Report 2018 - 2019, p. 1-21
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Cowden, R., Gonzalez-Benecke, C.A., Wightman, M.G. 2019. Water Use and Competitiveness of Senecio sylvaticus in Young Douglas-fir Plantations. VMRC Annual Report 2018 - 2019, p. 24-50
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Wightman, M.G. , Guevara, C.A., Gonzalez-Benecke, C.A. 2019. A Comparison of Three CoSInE Tier I Sites: First Year Results. VMRC Annual Report 2019 - 2020, p. 35-56
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: CoSInE Tier I Sites: A Comparison at Year Three (Douglas-fir) and Four (western hemlock). VMRC Annual Report 2019 - 2020, p. 57-79
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: C.A. Guevara, C.A. Gonzalez-Benecke and M.G. Wightman. 2019. Modeling the effects of competing vegetation on soil moisture dynamics and planted conifer seedling water stress, growth and mortality in the U.S. Pacific Northwest. 25th IUFRO World Congress, September 29 - October 5, Curitiba, Brazil.
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: M.G. Wightman and C.A. Gonzalez-Benecke. 2019. Competition and site interactions experiment: understanding vegetation management treatment responses. 2019 Inland Empire Reforestation Council Meeting, March 5, Coeur dAlene, ID.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: M.G. Wightman and C.A. Gonzalez-Benecke. 2018. Ecophysiology and vegetation management: understanding treatment responses. PNW Forest Vegetation Management Conference, December 4-5, Wilsonville, OR.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: C.A. Guevara, M.G. Wightman and C.A. Gonzalez-Benecke. 2018. Competing vegetation effects on soil water dynamics and conifer seedling growth in PNW forest plantations. Poster. SAF Annual Convention, October 3-7, Portland, OR.

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:Cooperative members (from industry and state agencies), faculty from OSU and other national and international universities, and other forest professionals from private companies and federal and state agencies. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?The data was presented at: 2020 Winter Vegetation Management Seminar for Forestry, February 11, Albany, OR. 2020 Winter Vegetation Management Seminar for Forestry, February 12, Tumwater, WA. Stand Management Cooperative (SMC) Annual Meeting, October 21, Remote Meeting Via Zoom. PNW Forest Vegetation Conference Webinars, December 3, Remote Meeting Via Zoom. What do you plan to do during the next reporting period to accomplish the goals?During year 2021, second year spring release treatment will be applied in order to finish treatment applications at the third study site. Measurements of soil moisture, plant water stress, vegetation and seedling biomass, and seedling growth will continue during year 2021 at the second (Douglas-fir) and third ((Douglas-fir and western hemlock) study sites.

Impacts
What was accomplished under these goals? During the first growing season (2017) we measured a suite of variables in order to describe and understand the interactions of seasonal dynamics of productivity and resources use by western hemlock seedlings and competing vegetation. We developed functions to estimate vegetation biomass from cover%. We determined seasonal dynamics of soil water availability under different vegetation management treatments. We determined a water use factor of 24.7 mm of water per Mg of understory biomass per month. During years 2017-2018 we installed 1 study site planted with Douglas-fir seedlings, applied herbicide treatments and carried out all measurements programed. During the first (western hemlock site) and second (Douglas-fir site) growing seasons we measured a suite of variables in order to describe and understand the interactions of seasonal dynamics of productivity and resources use by western hemlock and Douglas-fir seedlings and competing vegetation. We developed functions to estimate vegetation biomass from cover%. We determined seasonal dynamics of soil water availability under different vegetation management treatments. We determined a model to determine water use of competing vegetation from cover percent, soil moisture and weather data. WE presented a detailed description of stress physiology of western hemlock and Douglas-fir growing under contrasting vegetation management conditions. During years 2018-2019 we continue with herbicide treatments at the Douglas-fir site and carried out all measurements programed on both study sites already installed (western hemlock, 2017; Douglas-fir, 2018). We selected a new site to be planted in winter 2020. We improved the functions to estimate vegetation biomass from cover%. We determined seasonal dynamics of soil water availability and seedling water stress under different vegetation management treatments. We presented a detailed description of stress physiology of western hemlock and Douglas-fir growing under contrasting vegetation management conditions. During years 2019-2020 we continue with measurements and planted a third site. The new site include both species (Dougasl-fir and western hemlock). On old study sites, during the fourth (western hemlock site) and third (Douglas-fir site) growing seasons we continued measuring a suite of variables in order to describe and understand the interactions of seasonal dynamics of productivity and resources use by western hemlock and Douglas-fir seedlings and competing vegetation. Highlights: • The CoSInE project has two contrasting Tier I sites with at least three years of intensive tree and vegetation measurements. On both study sites, vegetation management (VM) treatments significantly affected the abundance and composition of the vegetation community. • Plots with spring release treatments during the first two growing seasons had higher soil moisture than the control and fall site preparation only treatments which did not differ. There were no longer any differences in soil moisture among the treatments during the third and fourth growing seasons. • Drought stress was minimal at the coastal site planted with western hemlock (WH) due to the influence of the Pacific Ocean and low vapor pressure deficit (VPD). Survival of seedlings at the site was high regardless of treatment. • Drought stress was much higher at the dry inland site planted with Douglas-fir (DF) due to the site having less rainfall and much higher VPD. Extreme heat waves (>35°C) were also more common. • There was a strong effect of VM treatment on drought stress (measured as predawn and midday water potential, ΨPD andΨMD) at the dry inland site. The Ψ of the control treatment dropped rapidly reaching minimum values of -2.2 MPa at ΨPD and -2.9 MPa at ΨMD in September of the first growing season. Drought stress of seedlings growing under the more intensive treatments (011 and 111) was minimal throughout the first two growing seasons at both sites, demonstrating the effectiveness of VM treatments. • At the end of the fourth growing season, WH seedlings growing in the 111 treatment were, on average, 49 cm taller than those in the control treatment (000), while DF seedlings in the 111 were, on average, 29 cm taller than those in the control. VM effects on seedling height became clearer during the third growing season at both sites. • Due to favorable site conditions, there was no effect of VM treatments on WH seedling survival at the costal site. There was a strong effect of VM treatment on seedling survival at the inland site, with the control reaching a minimum of 33% of survival. • There were substantial differences between the control and 111 treatment in seedling volume at the final measurement (October 2020). Differences in seedling diameter, height, and volume suggest differences in growth potential during future years.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Guevara, C.A., Gonzalez-Benecke, C.A., Wightman, M.G. 2018. Competition and Site Interactions Experiment Tier I Western hemlock and Douglas-fir. VMRC Annual Report 2017 - 2018, p. 1-21
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Guevara, C.A., Gonzalez-Benecke, C.A., Wightman, M.G. 2019. Competition and Site Interactions Experiment Tier I Western hemlock and Douglas-fir (Vegetation Dynamics, Soil Moisture, Seedling Growth and Survival). VMRC Annual Report 2018 - 2019, p. 1-21
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Wightman, M.G., Gonzalez-Benecke, C.A. 2017. Competition and Site Interactions Experiment Tier II and New Study Sites. VMRC Annual Report 2016 - 2017, p. 43-50
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Gonzalez-Benecke, C.A., Wightman, M.G. 2017. Competition and Site Interactions Experiment Tier I Western hemlock. VMRC Annual Report 2016 - 2017, p. 51-62
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Cowden, R., Gonzalez-Benecke, C.A., Wightman, M.G. 2019. Water Use and Competitiveness of Senecio sylvaticus in Young Douglas-fir Plantations. VMRC Annual Report 2018 - 2019, p. 24-50
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Wightman, M.G. , Guevara, C.A., Gonzalez-Benecke, C.A. 2019. A Comparison of Three CoSInE Tier I Sites: First Year Results. VMRC Annual Report 2019 - 2020, p. 35-56
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: CoSInE Tier I Sites: A Comparison at Year Three (Douglas-fir) and Four (western hemlock). VMRC Annual Report 2019 - 2020, p. 57-79
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: C.A. Guevara, C.A. Gonzalez-Benecke and M.G. Wightman. 2019. Modeling the effects of competing vegetation on soil moisture dynamics and planted conifer seedling water stress, growth and mortality in the U.S. Pacific Northwest. 25th IUFRO World Congress, September 29 - October 5, Curitiba, Brazil.
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: M.G. Wightman and C.A. Gonzalez-Benecke. 2019. Competition and site interactions experiment: understanding vegetation management treatment responses. 2019 Inland Empire Reforestation Council Meeting, March 5, Coeur dAlene, ID.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: M.G. Wightman and C.A. Gonzalez-Benecke. 2018. Ecophysiology and vegetation management: understanding treatment responses. PNW Forest Vegetation Management Conference, December 4-5, Wilsonville, OR.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: C.A. Guevara, M.G. Wightman and C.A. Gonzalez-Benecke. 2018. Competing vegetation effects on soil water dynamics and conifer seedling growth in PNW forest plantations. Poster. SAF Annual Convention, October 3-7, Portland, OR.

Progress 10/01/18 to 09/30/19

Outputs
Target Audience:Cooperative members (from industry and state agencies), faculty from OSU and other national and international universities, and other forest professionals from private companies and federal and state agencies. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?The data was presented at the 2019 Vegetation Management Research Cooperative (VMRC) annual meeting, at the Washington State Commission on Pesticide Registration, at the Oregon Society of American Foresters Annual Meeting and at the 2019 IUFRO World Congress in Curitiba. Brazil. People attending to the meetings included cooperative members, faculty from OSU and other national and international universities, and other forest professionals from private companies and federal and state agencies. What do you plan to do during the next reporting period to accomplish the goals?During years 2018-2019 we continue with herbicide treatments at the Douglas-fir site and carried out all measurements programed on both study sites already installed (western hemlock, 2017; Douglas-fir, 2018). We selected a new site to be planted in winter 2020. The new site will include both species.

Impacts
What was accomplished under these goals? During years 2018-2019 we continue with herbicide treatments at the Douglas-fir site and carried out all measurements programed on both study sites already installed (western hemlock, 2017; Douglas-fir, 2018). We selected a new site to be planted in winter 2020. The new site will include both species. During the third (western hemlock site) and second (Douglas-fir site) growing seasons we continued measuring a suite of variables in order to describe and understand the interactions of seasonal dynamics of productivity and resources use by western hemlock and Douglas-fir seedlings and competing vegetation. We improved the functions to estimate vegetation biomass from cover%. We determined seasonal dynamics of soil water availability and seedling water stress under different vegetation management treatments. We presented a detailed description of stress physiology of western hemlock and Douglas-fir growing under contrasting vegetation management conditions.

Publications

Progress 10/01/17 to 09/30/18

Outputs
Target Audience:Forest industry members of the vegetation Management Research Cooperative (VMRC), as well as faculty from OSU and other national universities, and other forest professionals from private companies and federal and state agencies. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?The data was presented at the 2018 vegetation management research cooperative (VMRC) annual meeting and the 2018 Society of American Foresters (SAF) annual convention in Portland. People attending to the meetings included cooperative members, faculty from OSU and other national universities, and other forest professionals from private companies and federal and state agencies. What do you plan to do during the next reporting period to accomplish the goals?The study treatments were applied in fall 2016, spring 2017 and spring 2018 at the western hemlock site, and during fall 2017 and spring 2018 at the Douglas-fir site. During year 2019, second year spring release treatment will be applied in order to finish treatment applications at the Douglas-fir site. Measurements of soil moisture, plant water stress, vegetation and seedling biomass, and seedling growth will continue during year 2019.

Impacts
What was accomplished under these goals? During the first (western hemlock site) and second (Douglas-fir site) growing seasons we measured a suite of variables in order to describe and understand the interactions of seasonal dynamics of productivity and resources use by western hemlock and Douglas-fir seedlings and competing vegetation. We developed functions to estimate vegetation biomass from cover%. We determined seasonal dynamics of soil water availability under different vegetation management treatments. We determined a model to determine water use of competing vegetation from cover percent, soil moisture and weather data. We presented a detailed description of stress physiology of western hemlock and Douglas-fir growing under contrasting vegetation management conditions.

Publications

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:OSU faculty and forest managers members of the Vegetation Management Research Cooperative. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?The data of the first year of measurements were presented at the 2017 VMRC Annual Meeting. More than 30 people attended to the meeting, including VMRC members, OSU faculty, and other forest professionals from private companies and state agencies. What do you plan to do during the next reporting period to accomplish the goals?The study treatments were applied in fall 2016 and spring 2017 o. During year 2018, second year spring release treatment will be applied in order to finish treatment applications. Measurements of soil moisture, plant water stress, vegetation and seedling biomass, and seedling growth will continue during year 2018.

Impacts
What was accomplished under these goals? During the first growing season (2017) we measured a suite of variables in order to describe and understand the interactions of seasonal dynamics of productivity and resources use by western hemlock seedlings and competing vegetation. We developed functions to estimate vegetation biomass from cover%. We determined seasonal dynamics of soil water availability under different vegetation management treatments. We determined a water use factor of 24.7 mm of water per Mg of understory biomass per month.

Publications

Progress 07/01/16 to 09/30/16

Outputs
Target Audience:The target audience are the members of the Vegetation Management Research Cooperative, who are state (ODF, WDNR), private, and federal (BMLM) organizations Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?Plant seelings (February), finish plots monumentation and apply spring release treatment on plots with treatmentsT2, T4, T7 and T8. Install automatic weather station.

Impacts
What was accomplished under these goals? Two Tier II study sites selected. Fall site prep herbicide application on plots that incude treatments T5, T6, T7 and T8

Publications