Positive interactions and ecosystem function in deserts

positive interactions & ecosystem function in deserts

@cjlortie

theory time

rich & controversial dialogue in community ecology

community assemblygradients

negative versus positive interactionsplant-animal interactions

community resilienceinvasive species

foundation versus keystone speciesstress-gradient hypothesis

collapse

the sure-thing principle from the philosophy of causality

Savage (1954), Pearl (2016)

Simpson’s paradox

(x,y) <- z

Simpson (1951), Blyth (1972)

Simpson’s paradox in ecology is context dependency

Chamberlain et al 2014

150 years of competition research

grasslands

25 years of facilitation research

deserts

grasslands versus deserts

Germano et al. 2011

deserts

Germano et al. 2011

alternative ecosystem classification = different management strategies

Germano et al. 2011

alternative ecosystem classification = different ecological theories

the sure-thing in desert communities

positive plant interactions


positive plant interactions

(+, 0)

(+, +)

(+,-)

+ net outcome

facilitation


Bertness & Callaway 1994

He et al. 2013

frequency does not necessarily = importance in communities

Brooker (2010), Kikvidze et al. (2011)

facilitation theory: assembly

Lortie et al. 2004

facilitation theory: diversity

Michalet et al. 2006

facilitation theory: niche

Bulleri et al 2015

facilitation theory: function

Lortie et al. 2016

facilitation theory: ecosystem function

carbon capturewater retention

pollinatorsmoderating climate

reduced evaporation transpirationrefuges

biodiversityfood

pollinator maintenance

function research decoupled from interactions

shrubs in the San Joaquin Desert

ecological function of shrubs in San Joaquin Desert

niche theory for the San Joaquin Desert

test1. niche & ranges

Sotomayor et al. (2016)

Hypothesis: Dominant plants in deserts provide additional fundamental niches for protégé species expanding their ranges.

test1. niche & ranges for local plant species

Sotomayor et al. (2016)

field tests: two-phase model

Pescador et al. (2014)

test1I. shrub loss

Liczner, Westphal, Filazzola

test1I. shrub loss


Hypothesis: Shrubs and shrub mimics have a positive influence on the activity of Gambelia sila by providing shelter for hunting, light, or

predators.

test1I. shrub loss


test III. regional survey of shrub effects & seed addition

Filazzola, Westphal

Hypothesis: Positive shrub-annual interactions increase with abiotic stress and reduced nutrient availability along a regional gradient of

continentality.

test III. regional survey of shrub effects & seed addition

Filazzola, Westphal

test IV. regional survey of shrub effects

Lortie, Filazzola, Westphal

Hypothesis: Facilitation by desert shrubs within the San Joaquin Desert region is species specific.

20142013 2015

E. californica L. tridentata E. californica L. tridentata E. californica L. tridentata

decreasing abiotic stress decreasing abiotic stress decreasing abiotic stress



test V. shrub-animal effects in the Carrizo

Noble, Westphal, Saslaw, Germano, Butterfield

Hypothesis: Desert shrubs provide direct benefits to small animals (shelter) & indirect benefits (prey & protection).

440,000 pictures

~0.5% animal detection rate

presence of listed species



test VI. climate mediation by shrubs in the Cuyama Valley

Lortie, Filazzola, Westphal, Butterfield

Hypothesis: Shrubs directly and indirectly buffer local changes in the microenvironment thereby functioning as refuges for other species

within regions subject to dramatic global change drivers.


Lortie, Filazzola, Westphal, Butterfield

test VII. shrub-pollinator functions

Ruttan

Hypothesis: Shrub resource islands have positive, non-additive effects on pollinator communities.

test VII. shrub-pollinator functions

Ruttan

implications & opportunities

shrubs are a lucky charm for experimental structure & restorationin deserts

implications & opportunities

other taxaconnections to shared data

informed management

NSERCBLMTNC

ecoblender.org

Positive interactions and ecosystem function in deserts

Environment

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