VEGETATION EVA BOEHRINGER

Transcription

1 VEGETATION EVA BOEHRINGER April 2, 2014

2 WUP CONSULTATIVE COMMITTEE WUP Consultative Committee (WUP CC) recognized that riparian and wetland vegetation in the reservoir drawdown zone is valuable for fish, wildlife, aesthetics, dust control and recreation. Key objectives: Protect and maintain high quality riparian vegetation Maximize vegetation diversity and wildlife habitat 2

3 COLUMBIA RIVER WATER USE PLAN VEGETATION Maximize vegetation growth in Arrow Lakes Reservoir drawdown zone Physical Works Key Questions Monitoring Studies 3

4 COLUMBIA RIVER WATER USE PLAN VEGETATION Maximize vegetation growth in Arrow Lakes Reservoir drawdown zone Reservoir-wide revegetation program to enhance sustainable vegetation growth Physical Works Key Questions Monitoring Studies 4

5 COLUMBIA RIVER WATER USE PLAN VEGETATION Maximize vegetation growth in Arrow Lakes Reservoir drawdown zone Physical Works Key Questions Monitoring Studies How does reservoir operation affect vegetation communities at the landscape level? Is the revegetation program meeting its objectives? 5

6 COLUMBIA RIVER WATER USE PLAN VEGETATION Soft Constraint Target Maintain lower reservoir water levels during the growing season to preserve current levels of vegetation. Vegetation growing at and above an elevation of 434 metres (1,424 feet) is considered a priority. If vegetation is showing signs of stress as a result of inundation during the early growing season (May to July), target lower reservoir levels during the late growing season. 6

7 3 VEGETATION PROJECTS FOR ARROW CLBWORKS-2 Arrow Lakes Reservoir Revegetation Physical Works Ran from (5 years) CLBMON-12 Arrow Lakes Reservoir Monitoring of Revegetation Efforts and Vegetation Composition Analysis Started in 2008; running bi-annually until 2017 CLBMON-33 Arrow Lakes Reservoir Inventory of Vegetation Resources Started in 2007; running bi-annually until

8 CLBWORKS-2 ARROW LAKES RESERVOIR REVEGETATION PHYSICAL WORKS Project goal - maximize vegetation growth in the drawdown zone 1 year of preparation (2007) site selection, field verification, preparation of vegetation prescription, 4 years of implementation ( ) 8

9 PROJECT OBJECTIVES Provide benefits to aquatic and wildlife habitat through increased plant diversity; Improve shoreline stability where possible; Provide better protection to known archaeological sites, if possible; and, Increase diversity of native plants. 9

10 REVEGETATION PROGRAM - RESULTS Treated sites from Revelstoke to Renata Sedge plugs, willow & cottonwood plugs; live stakes; fertilization; seeding 108 ha planted; 50 ha fertilized Variable success some areas did great; others did poorly Need further results from monitoring studies to evaluate success overall 10

11 REVEGETATION PROGRAM - RESULTS 11

12 MONITORING PROGRAM OBJECTIVES At the landscape level (big picture) Identify and map existing vegetation communities in the drawdown zone How are communities changing over time? Are changes related to soft constraint targets? 12

13 MONITORING PROGRAM OBJECTIVES At the site level (detailed view) Are we losing existing and/or planted species? At what elevations? What conditions affect the success of the revegetation program? Is revegetation more effective than natural vegetation spread? 13

14 MONITORING PROGRAM RESULTS At the landscape level (big picture) 16 vegetation community types were identified in the Arrow Lakes Reservoir Looked at influence of operating regime (inundation), elevation, soils, topography (slope & aspect), climate (temperature & precipitation), and exposure (waves & wind) 7 thought to be influenced by the operating regime 9 others more influenced by other variables BE: Sandy beach BG: Gravelly beach CR: Cottonwood riparian PA: Redtop upland PC: Reed canary grass mesic PE: Horsetail lowland RR: Reed-rill 14

15 MONITORING PROGRAM RESULTS At the landscape level (big picture) Vegetation is being maintained no significant changes in communities between 2008 and 2012 across the reservoir Types and amount of vegetation vary by elevation band Diversity varies with soil type, climate (north to south), and elevation band Reed Canary grass in 2007 Reed Canary grass in 2010 Reed Canary grass in

16 MONITORING PROGRAM RESULTS At the landscape level (big picture) Operating regime is one variable of many that affects vegetation Observed variation mostly explained by soil type & texture, scouring (from wave action), and temperature during growing season Scouring from wave action Sheltering effect of tree roots 16

17 MONITORING PROGRAM RESULTS At the site level (detailed view) Dominant species are surviving at all elevations lenticular sedge (low elevation), grasses (mid elevation), cottonwood (high elevation) Willow has had high mortality at mid elevation since high fall/winter water levels in 2008/9 Series of lower water years allowed plant expansion into unfavorable habitat Lenticular Sedge Reed Canarygrass Willow 17

18 MONITORING PROGRAM RESULTS At the site level (detailed view) Effectiveness of revegetation monitored with control vs. treatment plots Vegetation takes time to establish o As of 2013 (2 years after program completion), no significant difference in vegetation establishment between control and treatment Planting of sedge seedlings has better establishment success than cottonwood live staking Planting site conditions impact success of treatments 18

19 MONITORING PROGRAM OBJECTIVES Question for both programs What are key drivers for change in vegetation? o Climate, soil type, water source, exposure (waves & wind), operating regime Opportunity to modify operations to maintain and increase vegetation? o No answer yet; still evaluating influence of operations relative to other factors 19

20 EFFECT OF RESERVOIR OPERATIONS At landscape and site level Operating regime varied more in the fall than in the spring for duration study period ( ) Vegetation reacted negatively to high water period in fall/winter 2008/9 Fall exposure period likely beneficial for flowering plants to set seed and gain biomass before winter dormancy 20

21 CONCLUSIONS The reservoir drawdown zone is a very complex system Many variables influence vegetation in addition to water level fluctuations Operating regime may not be primary influence on vegetation Will need multiple years of data to sort out key drivers of change Repeated high or low water period in fall would provide more clarity on influence of operating regime 21

22 Innonoaklin Road 22