Challenges of scale when examining plant-interactions in arid ecosystems: micro, local, & regional

Alessandro Filazzola

ORHow I learned to stop worrying and trust the rain

mechanisms of positive plant-interactions

Filazzola & Lortie 2014

Gómez Aparicio,‐ et al. 2005

shrubs ameliorate abiotic stress

Gómez Aparicio,‐ et al. 2005

shrubs modify soil nutrients

effects of positive interactions globally

He et al. 2013

how does scale relate to plant interactions?

the microscale

north south

soil moisturelight

temperature

soil nutrientsherbivory reduction

Hoffman et al. 2013

microscale variation in deserts

rocks can out perform shrubs as facilitators

Peters et al. 2008

Pescador et al. 2014

effect of a facilitator are not dichotomous

Schlesinger et al. 1996

compare nutrients with distance from shrub

Schlesinger et al. 1996

nitrogen is spatially correlated

Franco & Nobel 1989

compare seeds with distance from shrub

Filazzola et al., 2016

mechanisms are scale specific

sampling considerations for micro gradientsConsider topographical variation (e.g. soil depressions, rocks)

Include spatial associations of plants, such as with shrubs

Include different aspects (e.g. cardinal directions)

Sample varying distances from dominant shrub

the local scale

Keddy 1992

community composition based on filters

Cavieres et al. 2002

elevation as a local scale gradient

Panoche 1130m 960m 730m

Mojave DesertSan Joaquin Valley

Lortie et al. 2016

hill aspect as a local scale gradient

Lortie et al. 2016

Chaenactis fremontii

RII 0

-1

+1

local gradients alter microscale association among plants

-1+1

similar gradients, different outcomes

Lortie et al. 2016

Michalet et al. 2006

local gradient

mic

rosc

ale

grad

ient

local gradients alter microscale plant interactions

sampling considerations for local gradientsConsider landscape topography

Include the full length of the gradient

Multiple points along a gradient

the regional scale

positive interactions increase community richness

Cavieres and Badano 2009

Scale determines plant-interactions

Callaway et al. 2002

Sotomayor et al. 2016

beneficiaries associate with benefactors

Sotomayor et al. 2016

beneficiaries associate with benefactors

parallels among spatial scales

micro local regional

parallels among spatial scales

micro

local

regional

shrub open

west longitude

south slopenorth slope

east longitude

increasing evapotranspiration

interactions among spatial scales

micro

local

regional

spatial gradients as a response surface

further considerations

additional stressors change predictions

Crain et al. 2008

additional stressors change predictions

Smit et al. 2009

No herbivoresWith herbivores

most studies only examine one stressor

Filazzola & Lortie 2014

species specificity changes predictions

Albert et al. 2010

species specificity changes predictions

Maestre et al. 2009

temporal effects alter plant interactions

Chesson et al. 2004

temporal effects alter plant interactions

Miriti 2006

Castro et al. 2002

microscale association for restoration

Gomez-Aparicio 2009

microscale association for restoration

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

Positive plant-interactions support biodiversity across all spatial gradients

Rodriguez-Cabal et al. 2012

Thank youDr. Chris LortieDr. Sapna SharmaDr. Bridget StutchburyDr. Michael WestphalDr. Diego SotomayorThe Ecoblender LabBLM: Central Coast Field OfficeDr. Richard MichaletDr. Jim AndreDr. Tasha Le DouxTejon Ranch Conservancy

filazzola.info

@alex_filazzola

Discussion

1. How (or should we) include these micro- and local-scale gradients when conducting regional modelling?

2. What should field experiments focus on in terms of scale? Deep vs wide?

3. How do you know that you have surveyed the full length a gradient?

4. Controlling variables or measuring covariates?

5. Insights into other fields that utilize scale and further implications