Timing of Disturbance

1. Timing of Disturbance Rebecca Doubledee Mike Limm Tasha Teutsch Andrew Amacher

2. Timing of Disturbance Mike- Timing of river flows and fish Rebecca- Timing on aquatic macrophytes Andrew- Timing of fire disturbances Tasha- Use of prescibed fires in grasslands

3. Flow regime on fishes Natural flow regime -physical characteristics -biotic impacts -example -conjecture about timing effects on fishes

4. The natural flow regime (Poff et al. 1997)

5. Flow regime examples Intermittent flashy (Arizona) Figure from Poff and Ward (1990)

6. Flow regime examples Harsh intermittent (Oklahoma) Figure from Poff and Ward (1990)

7. Flow regime examples Mesic groundwater (Missouri) Figure from Poff and Ward (1990)

8. Flow regime examples Snowmelt (Colorado) Figure from Poff and Ward (1990)

9. Flow regime examples Winter rain (Oregon) Figure from Poff and Ward (1990)

10. Poff and Ward (1990)

11. Example- Marchetti and Moyle (2001) Putah Creek, Yolo County, CA

12. Example- Marchetti and Moyle (2001) Sampled fish over 5 years

13. Example- Marchetti and Moyle (2001) Sampled fish over 5 years -Two unusually dry years (1994, 1995) -Two unusually wet years (1997, 1998)

14. Example- Marchetti and Moyle (2001) Results: 1. During wet years downstream site conditions became similar to upstream conditions.

15. Example- Marchetti and Moyle (2001) • Results: • 2. Fish community composition changed at • downstream sites (non-native ---> native). Native (solid circle) and non-native species (open triangle)

16. Timing on fish Unaware of experimental studies on how timing of peak flows influence fish. -Previous research: magnitude (e.g. Schlosser 1985, 1987) frequency (e.g. Bain et al. 1988) duration (e.g. Junk et al. 1989) rate of change ( e.g. Bradford 1997)

17. Timing on fish Erman et al. (1988) on effects of winter rains in Sagehen Creek.

19. Timing on fish Erman et al. (1988) on effects of winter rains in Sagehen Creek. -snow increased effective bank height -sheer stress on stream bottom is proportional to depth -winter rains on snow covered banks increased bed movement and YOY mortality.

20. Timing on fish (conjecture) spawning rearing Fish temperature turbidity

21. Timing on fish (conjecture) spawning -cues -habitat availability rearing Fish temperature turbidity

22. Timing on fish (conjecture) spawning rearing -habitat availability Fish temperature turbidity

23. Timing on fish (conjecture) spawning rearing Fish temperature -productivity -growth turbidity

24. Timing on fish (conjecture) spawning rearing Fish temperature turbidity -reservoir releases

25. Influence of flood timing on the recovery of aquatic plants • The rate and pattern of reestablishment following a disturbance can depend on • The time it was cleared • The morphological and reproductive traits of species that are present (Sousa 1984) Availability of propagules of the different species

26. The disturbance regime of former river channels of the Rhone River, France • Two potential flooding times • The rainy season starts in autumn and continues until mid-late December • melt-off in the Alps can cause flooding in the spring • Barrat-Segretain and Amoros (1995) studied the recolonization of aquatic plants following disturbances that occurred in July of 1991 versus December of 1991.

27. Temporal changes in (a) percent cover and (b) number of species in each plot. a b Number of species % total cover

28. Aquatic plants are highly resilient to disturbance due to their high potential for dispersal, colonization and growth • The macrophyte community was more sensitive to disturbance in summer than in winter. • Result of the phenology of the plant community. Most of the plants decrease above ground biomass during the winter.

29. 1st colonizers after spring Elodea canadensis Sparagnium emersum Hippuris vulgaris Luronium natans 1st colonizers after winter Elodea canadensis Sparagnium emersum Hippuris vulgaris Potamogeton pusillus Who were the good colonizers? How does this relate to phenology and propagule supply?

30. 1st colonizers after spring Elodea canadensis Sparagnium emersum Hippuris vulgaris Luronium natans 1st colonizers after winter Elodea canadensis Sparagnium emersum Hippuris vulgaris Potamogeton pusillus • Loses most aboveground vegetation during the winter. Only marginally affected by winter floods • Allows it to colonize bare patches in the following growing season

31. 1st colonizers after spring Elodea canadensis Sparagnium emersum Hippuris vulgaris Luronium natans 1st colonizers after winter Elodea canadensis Sparagnium emersum Hippuris vulgaris Potamogeton pusillus • Spring • Fragments predominantly produced propagules • Winter • Fragments predominantly root into the sediment

32. Effects of Timing of Fire Disturbances • General Considerations • Kapalga Example • Grasslands Example

33. General Considerations • Fire Seasonality • - When are fires possible? • - What are the ignition sources?

34. Physiological Considerations Physiological State 1. Dormant vs. growing season 2. Carbohydrate reserves 3. Reproductive state 4. Stress

35. Adaptive Considerations Physiological 1. Structural 2. Sprouting Reproductive 1. Seed banks 2. Scarification, serotinous cones 3. Timing of seedbed availability Community 1. Fire adapted 2. Invaded or suppressed communities 3. Seedbanks, advanced regeneration, historical legacies

36. Effects of fire on local environment Community architecture Dominant vegetation Competitive interactions Nutrient Availability Seedling recruitment Seed bank Litter cover Reproduction refuges Habitat availability Microclimate

37. Kapalga Research Station Example Replicated study with variation in timing (1988-1994) 1. Early dry season 2. Late dry-season 3. Fire exclusion

39. Kapalga – Fire Intensities Intensity related to timing

40. Kapalga - Vegetation

41. Kapalga – Ground Beetles

42. Kapalga – Grass-layer Beetles Early vs. Late = N.S. Unburnt vs. Burnt (3-4) = **

43. Kapalga – Brown Bandicoot Survival Cormack –Jolly-Seber model - Fire Regime most important vs. age, sex, vegetation, rainfall,

44. Kapalga – Frillneck Lizard Radio-telemetry and mark-recapture - 29% (6 of 24) killed in late season fires - late season fires = moved to larger trees or termite mounds - preference for burnt habitat

45. Kapalga – Frillneck Lizard Diet Shifts -Lizards consumed larger prey post-fire - greater stomach prey volume - Sit-and-wait predators

46. Uses of prescribed fires in grasslands • Maintain palatable species for livestock • Reduce fuel load • Prevent encroachment of shrubs and trees

47. Fire history in tallgrass prairies • Summer lightning fires • Anthropogenic fires during spring, fall and winter • Native Americans burned regularly

48. C3 C4 % individuals flowering March May July Sept Hypothesis for effect of timing on species dominance in grasslands

49. Howe’s experiments • Establish plots from different seed densities • Burn plots at different phenological stages for different flowering guilds

50. Results: lognormal seed density Howe (1994). Ecological Applications 4(1):121-133