Dr. Sharon Hermann ([email protected]) • 1st Topic: an Endangered Species taxifloria ( Torreya) – Examples disease problems – Torreya biology – Torreya decline – Ecological issues – Associated research

• Collaborator: M. Schwartz • 2nd Topic: actions & new approaches 1 • 2nd Topic: New Conservation Approaches – “New” approach because terms coined • Assisted Migration • Assisted Colonization • Managed Relocation • Re-Wilding – Consider what the following have in common • Trout • Mammoths • Torreya – Review on-going actions related to Torreya

2 Examples: Declining Eastern Tree Species

American Chestnut Chestnut (Castanea dentata) Blight

American Elm Dutch Elm (Ulmus americana) Disease

Flowering Dogwood Dogwood (Cornus sp) Anthracnose

3 Torreya taxifolia (Florida Torreya) • Also called Stinking Cedar, Stinking Yew, Gopherwood, Polecat Wood, Savin • Most endangered tree species in continental US • Currently ~ <1,000 in wild; all appear unhealthy – Almost none are reproductive adults – Currently come from botanical gardens

4 Florida Torreya

• , dioecious, (15m) • 7 extant species in – 1 in SE – 1 in California – 5 in Asia • Range of Florida Torreya: one of smallest for a tree

5 Range: Florida Torreya

• One of smallest range for any tree – Portions of 2 counties in Florida & 1 in – ~ 35 km (21 mi) stretch east side of – ~ 200-400 sq km Upland dry, open forest maintained by fire

Hardwood slope forest of beech, , oak & other mesic species, including Torreya; slopes 50-100m

7 Soils & slopes unusual ecological conditions for SE 8 History

Prior to ~ 1950 • Many adult Florida Torreya cut in ravines

• All longleaf pine clearcut in uplands

• Extensive site preparation occurred

• Planting of loblolly pine plantations attempted

9 History Prior to ~ 1950 (continue) • Most wildland fires in uplands suppressed • Apalachicola River dammed for a reservoir

10 History

1954 No obvious problems noted by Kurz

1955-60? Presumed dramatic decline; no data

1962 Species “destined for ” says Godfrey and Kurz in Science (1962);

State FL says they’ll work on problem

1970s No wild reproductive observed

1984 Federally listed as endangered

11 History 1987 Arnold initiated growing trees from cuttings (5+ yrs to grow upright) 1993 1st field data published 1998 Georgia PCA out-planting in “Safeguard Program” 2003 Botanical Garden (ABG) co-op project* 2004 “Torreya Guardians” form; considers assisted migration & re-wilding *

12 History 2004 Conservation interest grows 2008 “Re-wilding” (out-planting) by Torreya Guardians at 2 sites 2009 ABG program underway (includes research) 2010 New pathology studies by UF 2011 “Novel” disease finally identified!!

13 Work by Schwartz, Hermann & colleagues Our field research began 20+ years ago

• Determine population status pre- & post-decline – Target populations on public land

• Model possible rates of population extinction – Population decline – Individual tree decline

• Schwartz & Hermann 1993a,b; Schwartz et al 2000a,b

14 How did we estimate historic population?

• Based on relative data from Harper (1914) Torreya trees: – 7th most common slope tree – Common as American Beech – ~ ½ density American Magnolia • Survey modern forest for beech & magnolia & compare relative densities

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In historic times, Torreya always localized but not rare in area … now rare

16 How to project FUTURE rate of decline? • Often die slowly, decreasing in size and/or vigor

Torreya in the wild

Example of Torreya growing in NC garden 17 Would be best to compare size of extant trees to pre-decline… but no wild adult-sized trees now

Based on ~ 200 wild trees in N FL & S GA

18 Current apparent age distribution of wild trees

(based on branch nodes on main stems) 19 Model population changes based on various measures of survivorship and growth

20 Results: modeling population growth (decline)

21 Models suggest wild Florida Torreya around for another ~50-100 years • How to determine what causes decline? • Consider published pathogen data: biotic stress – Hypotheses valid – Reviewed previous study & determined it provided little information – All pathogens recorded were known as secondary – No recorded primary pathogens

22 Models suggest that there is time before extinction but action needed. Assumption is pathogen(s) caused decline; but use of initial data questionable. • Until recently (2009), most (all?) identified fungal pathogens associated with secondary infections

23 • Challenge tests on cuttings in shadehouse • Resulting symptoms are consistent with Pestalotiopsis sp. infections on • Not enough to collect fungus from wild trees • Schwartz & Hermann preliminary effort to fulfill requirements of Koch’s postulate

24 Koch’s Postulate 1. Pathogen must be found in all individuals suffering from disease, but not in healthy individuals. 2. Pathogen must be isolated from diseased trees & grown in culture. 3. Cultured pathogen causes disease when introduced into healthy trees. 4. Pathogen must be re-isolated from experimentally infected individuals. 25 Koch’s Postulate • Schwartz & Hermann preliminary results suggest pathogen part of decline

• ABG expanding research • UF student & professor identified 8 possible fungal species; work is on-going (Mount & Smith 2010)

26 “Novel Species Causes a Canker Disease of the Critically Endangered , Torreya taxifolia”

J.A. Smith, K. O’Donnell, L.L Mount, K. Shin, K. Peacock, A. Trulock, T. Spector, J. Cruse-Sanders, and R. Determann (2011) Now we know the pathogen but what caused trees to be susceptible? Until we rule out some causes trees may not be safe! Environmental Induction Hypotheses (Schwartz and Hermann) • Did changes in environment promote (induce) increased susceptibility to pathogens?

28 Environmental Induction Hypotheses (Schwartz and Hermann) • Explored data on: • Changes in soil chemistry • Moisture &/or temp stress –Soil moisture –Temperature –Relative humidity –Light – Fire exclusion in uplands (effect of smoke)

29 Environmental Induction Hypotheses (Schwartz and Hermann) •No distinct pattern in temporal changes … pre- and post- dam •Decline not likely related to • Soil chemistry or moisture factors • Temperature or relative humidity

30 Environmental Induction Hypotheses (Schwartz and Hermann)

•Hypotheses target: • Light (field research preliminary) • Effect of smoke

31 Preliminary indications of effect of lack of fire Experimental field treatments demonstrated that smoke could decrease the number of fungal spores on juvenile Torreya

32 33 Summary on Disease • To date, no data supports importance of to Torreya • Recent studies identified likely pathogens

• Decrease light may play a role • Past fire suppression may play role

• Reason trees not recovering unknown so torreya not safe any place

• Issue of “inertia”  once significantly compromised, might be difficult to recover

34 Lack of recovery from decline may be unrelated to what triggered decline

• May be multiple reasons that explain why Florida Torreya has yet to recover from 1950’s crash

• Stressors may prevent recovery (climate change?)

35 Lack of recovery prompted debate & 2nd topic is extreme action needed?

• New ABG-GPCA cooperative project – Some aspects have prompted debate – Assisted migration questioned by some scientists

• Debate specific to torreya related to: – View that torreya needs cooler temp – Planting torreya north of range – In other words … assisted migration for torreya

36 Assisted Migration, Assisted Colonization, Re-Wilding, • Assisted migration & assisted colonization: provide means for migration across disrupted landscape • Re-Wilding: reconstituting “natural” landscapes, including processes & food webs – What if some factors missing? – Example: top predators • New terms that initially encompassed & summarized many previous ideas • Initially major focus was often on recreating natural processes and landscape structure

37 Assisted Migration and Assisted Colonization (Traditional view: aiding species to overcome human barriers)

Fish “Ladders” Captive Bred Herp Whooping Cranes Crossings Until recently, efforts on assisted migration knew where (1937 Bonneville Dam) 38 species needed to go. Assisted Migration (new definition: Keel 2004) “For plants to survive climate change …” “ … human intervention in the form of assisted migration will be necessary to prevent extinction.”

Assumes that we know the what, where and how species would migrate if there were not anthropogenic barriers to movement.

39 Assisted Migration

• Keel (2004) formally proposed concept of assisted migration for some orchid species

• There are individuals & informal groups have carried out similar, but unofficial, assisted migration actions for favorite species – ex. Venus-flytrap – Moved to N Florida

40 Georgia Conservation Alliance Project “Safeguarding Torreya taxifolia”

• Initiative to rescue & maintain FL Torreya in Georiga • Some concerns prompting action include: – Originally probably small proportion of range in Georgia – Current natural site is public but without much protection – Belief that climate of new, far north sites more beneficial for growth and/or resistance to disease

• Recent out-planting in North Georgia – On state land, outside of recent natural range – Goal to safeguard future existence of Torreya

41 Barlow & Martin (2004) “Torreya Guardians” expanded idea

– Consider distribution of Florida Torreya in “near time” (< 15,000 YBP, human influence) as well as “deep time” (> 15,000 YBP, pre-human influence)

– Relocation becomes “repatriation of a once-native”

– Propose considering assisted migration “a form of rewilding that uses near-time or deep-time baseline for determining native range” (Barlow et al. 2004)

42 Adult tree in NC garden regularly produces fruit … used to promote idea of assisted migration for Florida Torreya

43 Reasons why conservation efforts for Florida Torreya should not include assisted migration • Need to escape disease not fully supported by data • Little support that extant plants are overly susceptible to a specific disease • Agent for original decline (pre- 1960) not determined

• Some Torreya planted in NC have died or appear unhealthy

44 Reasons why conservation efforts for Florida Torreya should not include assisted migration

• Unknown effects of new species on recipient ecosystems … all exotic species are native somewhere (need to consider if species has traits that suggest likely problems)

• Do plantings in botanical gardens have most of benefits of assisted migration without most of the potential negative side effects?

45 Reasons why conservation efforts for Florida Torreya should not include assisted migration

• Not all in situ remediation actions tried – thinning to improve light conditions – In situ planting

• Assisted Migration might be bad precedent & promote concept of re-wilding Dead juvenile Torreya planted in NC

46 Re-wilding “putting the pieces back” that are thought to have been eliminated by humans

Numerous letters & commentaries in scientific journals 47 Initially major focus on top predators

But since 2004, ideas of assisted migration and re-wilding have expanded.

48 “Ecological Wounds” (caused by all humans) • Direct killing • • Habitat fragmentation • Exotic species – including diseases • Pollution • Loss of natural processes – ecological & evolutionary

• Climate change 49 “Extreme” Re-wilding Idea of re-wilding (assisted re-introduction) dramatically expanded; suggested for some large once native to N America

Donlan et al. (2005) proposes “restoring animals that disappeared 13,000 years ago from NA”

50 Official re-wilding is happening, maybe ultimate assisted migration. Current species unlikely to create problems but, could be a precedent.

Georgia torreya one example

In preparation: Bolson to be moved to New Mexico after 13,000 yr absence (Donlan et al 2005 & 2006) 51 McLachlan, J., J. Hellmann, and M. Schwartz. 2007. A framework for debate of assisted migration in an era of climate change. Conservation Biology 21(2):297-303

• Encourage debate immediately

• Framework for debating Assisted Migration: three policy options suggested – Aggressive Assisted Migration – Avoidance of Assisted Migration – Constrained Assisted Migration

52 • On-going debate over interjecting “novel” species into existing native ecosystems • Will it be for greater good or increase destruction of native ecosystems & species?

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