esa 2016 filazzola - water limitation and consumer pressure in the desert

The effect of consumer pressure and abiotic stress on positive plant-interactions is mediated by droughtAlessandro Filazzola, Amanda Liczner, Michael Westphal, & Christopher J. Lortie

mechanisms of positive plant-interactions

Filazzola & Lortie 2014

Gómez Aparicio,‐ et al. 2005

shrubs ameliorate abiotic stress

shrubs reduce consumer pressure

Barbosa et al. 2009

insect abundance mammalian herbivory

most studies only examine one stressor

Filazzola & Lortie 2014

additional stressors change predictions

Smit et al. 2009

No herbivoresWith herbivores

additional stressors change predictions

Crain et al. 2008

RII 0

-1

+1

local gradients alter microscale association among plants

-1+1

Shrubs facilitate the annual community by concurrently reducing consumer pressure through associational resistance and ameliorate abiotic stress by increasing soil moisture

hypothesis and predictions

RII 0

-1

+1

-1+1

?

study site and extreme drought

2014 2016

1 - 6X 15

Design Water level

1 - 6X 5

Replication

Experimental design for 2014

Plots/sample size (N/n)

60 / 5

180 / 15

0/1X 15

Design Water level

0/1X 15

Replication

Experimental design for 2016

Plots/sample size (N/n)

60 / 15

60 / 15

E. californica ameliorates abiotic stress

Effect Biomass 2014 Biomass 2016

Soil moisture + +Microsite + +

Consumer pressure -Microsite * soil moisture

Microsite * consumer pressure +Microsite * consumer pressure *

soil moisture

E. californica reduces consumer pressure

facilitation had a greater effect than water addition or consumer pressure

an invasive species was facilitated more strongly than subordinates

RII 0

-1

+1

-1+1

E. californica facilitates regardless of soil moisture or consumer pressure

precipitation can increase phytophagous insects and attract non-resident herbivores

Patten 1998; Augustine & McNaughton 2006; Retzer & Miehe 2005

precipitation mediates mechanism of facilitation

drought above average rainfall

precipitation increases relative difference among shrub and open microsites

Augustine & McNaughton 2006

herbivory does not affect productivity when rainfall and soil fertility are high

species specificity changes predictions

Maestre et al. 2009

dominant-mediated distribution of invasives

Survival of experimentally planted seedlings of Taraxacum officinale within and outside Azorella monantha cushions at 3200 m a.s.l.

Cavieres et al. 2007

invasive beneficiaries negative affect benefactors

Rodrıguez-Buritica & Miriti 2009

loss of invasive and native species

implications

Interacting stressors alter predictions on positive plant interactions

Precipitation mediates stressors and mechanisms of facilitation in desert environments

The life strategy of beneficiary species relates to the facilitation effects

Shrubs in arid environments may be support non-native invasion

Thank youDr. Chris LortieDr. Sapna SharmaDr. Bridget StutchburyDr. Michael WestphalDr. Diego SotomayorThe Ecoblender LabBLM: Central Coast Field Office

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