Variable responses of a California grassland to the reintroduction of tule elk. Brent Johnson - National Park Service

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1 Variable responses of a California grassland to the reintroduction of tule elk Brent Johnson - National Park Service

2 large mammalian herbivores

3 effects of large herbivores consuming & trampling plants changing nutrient cycles alter competition between plants modify successional processes

4 human impacts on herbivores altered distribution and abundance 1,+ years in N. America negative impacts increased with the arrival of Europeans increased hunting and habitat loss conservation efforts species and habitat protection reintroductions are often necessary many herbivore populations are now increasing

5 human impacts bison 18: 3-6 million 1889: fewer than 1, protection & reintroduction presently 5, 6, in U.S still increasing

6 prevailing focus of reintroduction target species population size genetic diversity health of population less emphasis on recipient community

7 reintroduction into altered landscapes fragmented - movement patterns changed reduction of predator populations transformed plant communities non-native species

8 Tule Elk (Cervus elaphus nannodes) endemic to California subspecies of North American elk

9 tule elk through the years , tule elk in California 185 <1 tule elk in California s Central Valley 1873 protected species 195 reintroduction efforts began tule elk throughout CA Present 2,7 individuals in 22 sites tule elk to Tomales Point Elk Reserve

10 elk population on Tomales Point 5 Number of Elk Year

11 Tomales Point Elk Reserve Point Reyes National Seashore, Marin Co. 13 ha enclosed reserve

12 Tule Elk in an altered landscape movements restricted to the point large predators absent transformed by introduced plant species unclear consequences

13 research questions Does an invasive grass avoid elk herbivory by associating with a native shrub species? Do elk play a critical role in maintaining grasslands by slowing the colonization of shrubs? How does herbivory by reintroduced elk alter plant communities, and does this vary with habitat type?

14 experimental design large scale exclosure experiment established in 1998 by National Park Service 24 plots: 12 fenced and 12 unfenced 36 x 36 m 36 m

15 Baccharis Lupinus open N Plot Layout % Baccharis % Lupinus % Open.5.5 Kilometers experimental plots on Tomales Point

16 Baccharis Lupinus open N Baccharis grassland Plot Layout % Baccharis % Lupinus % Open.5.5 Kilometers experimental plots on Tomales Point

17 Baccharis Lupinus open N Lupinus grassland Plot Layout % Baccharis % Lupinus % Open.5.5 Kilometers experimental plots on Tomales Point

18 open grassland Baccharis Lupinus open N Plot Layout % Baccharis % Lupinus % Open.5.5 Kilometers experimental plots on Tomales Point

19 neighborhood effects Does an invasive grass avoid elk herbivory by associating with a native shrub species? Holcus lanatus (velvet grass) non-native perennial grass invasive in California s coastal grasslands Baccharis pilularis native shrub widespread

20 neighborhood effects only in Baccharis plots abundance (23) and biomass (22) of Holcus elk excluded elk present X X X X X X X X

21 neighborhood effects: abundance Holcus Abundance/m 2 /Plot shrub x elk interaction, p=.478 open shrub elk present elk excluded Association

22 neighborhood effects: biomass Holcus Biomass/Plot (g/m 2 ) shrub x elk interaction, p=.33 open shrub elk present elk excluded Association

23 neighborhood effects native shrubs provide refuge for an exotic grass by protecting it from elk herbivory

24 shrub cover Do elk play a critical role in maintaining grasslands by slowing the colonization of shrubs?

25 shrub cover Shrub Percent Cover/Plot p=.83 elk present elk excluded Baccharis Lupinus Open Habitat Type

26 community composition How does herbivory by reintroduced elk alter plant communities, and does this vary with habitat type?

27 community composition 22 harvested aboveground living and dead biomass 23 abundance (number of individuals) species richness

28 multivariate analysis complexity of community data reduce dimensionality of data set non-metric multidimensional scaling (NMS or nmds) multi-response blocked permutation procedure (MRBP)

29 multivariate analysis NMS elk present elk excluded Axis 2 stress=12.17 Axis 1 MRBP: A=.35, p<.4

30 community: statistical analysis multifactorial MANOVAs & ANOVAs elk treatment (present or absent) grassland type (Baccharis, Lupinus, open) plot pair, nested within grassland type response variables

31 plant functional groups/life forms annual dicots native and exotic annual monocots exotic perennial dicots native and exotic perennial monocots native and exotic

32 total abundance Mean Abundance/m 2 /Plot Baccharis Lupinus Open Habitat Type elk present elk excluded

33 abundance: annuals Exotic Monocot p=.2 elk present elk excluded Mean Abundance/m 2 /Plot Exotic Dicot p= Native Dicot p=.48 Baccharis Lupinus Open Baccharis Lupinus Open Habitat Type Habitat Type

34 abundance: perennials 4 3 Exotic Monocot p= Native Monocot p=.46 elk present elk excluded Mean Abundance/m 2 /Plot Exotic Dicot p= Native Dicot p=.34 Baccharis Lupinus Open Baccharis Lupinus Open Habitat Type Habitat Type

35 total species richness Mean Species Richness/Plot elk present elk excluded Baccharis Lupinus Open Habitat Type

36 species richness: annuals 1 8 Exotic Monocot p=.2 elk present elk excluded 6 Mean Species Richness/Plot Native Dicot p= Exotic Dicot p=.396 Baccharis Lupinus Open Baccharis Lupinus Open Habitat Type Habitat Type

37 species richness: perennials Mean Species Richness/Plot Exotic Monocot Exotic Dicot p=.343 p= Native Monocot p=.21 Native Dicot p=.869 elk present elk excluded 1 2 Baccharis Lupinus Open Baccharis Lupinus Open Habitat Type Habitat Type

38 biomass: annuals and perennials 3 25 A. Annual p=.256 elk present elk excluded Mean Aboveground Dry Biomass/Plot (g/m 2 ) B. Perennial p=.8 Baccharis Lupinus Open Habitat Type

39 biomass: thatch Mean thatch/plot (g/m 2 ) treatment x veg. type p=.45 elk present elk excluded Baccharis Open Habitat Type

40 making sense of responses - shrub cover - richness [native perennial dicots] - thatch biomass - living biomass [perennials] - biomass [annuals] - richness [annuals] & [native per. monocots] - abundance [annuals] X -Holcus lanatus

41 conclusions they re back! complex elk have +/- effects on natives and exotics no easy answers potential solutions manage for mosaic of states

42 acknowledgements advisor: Hall Cushman field assistants: Catherine Cumberland, Amy Nadell, Trisha Tierney National Park Staff: Natalie Gates, Michelle Coppoletta & Dave Schirokauer defense committee: Dan Crocker & David Stokes statistical advice and consoling: Karina Nielsen & Nathan Rank the Cushman lab: Michelle Cooper, Jim Coleman, Emiko Stevens, Melina Kazanitas & Jeff Amaral

44 Tomales Point Elk Reserve

Bell Ringer AP Practice

Bell Ringer AP Practice 1) The largest amount of energy available in the pyramid is the a) phytoplankton b) bass c) perch d) water flea e) both A and B Bell Ringer AP Practice 2) What food chain is represented