utpl ecuador 2016_carlos lara romero

Efectos directos e indirectos de la invasión de arbustos en los prados alpinos mediados por las interacciones planta-polinizador

Carlos Lara RomeroUTPL – Loja 2016

Alpine tundra occurs at high enough altitude at any latitude.

Map of arctic and antarctic tundra Map of alpine tundra

alpinetundrabiome.weebly.com; www.blueplanetbiomes.org

o Alpine tundra vulnerability to global change

Nogues-Bravo, 2007 Glob Env Chang

o Alpine tundra vulnerability to global change

Ellis, 2011 Proc Royal Soc A

o Regime shift on the roof of the world

Comte et al 2014 Nature communications


Gottfried et al 2012 Climate change, Paulí et al 2012 Science, Barrio et al 2013 MRD,

http://www.illustrationsof.com/


http://www.grida.no

The three general categories of woody plants increase including (a) infilling of existing patches, (b) increase in growth and (c) an advancing shrubline.

Myers-Smith et al. 2001. Environmetnal Research Letters

o Shrub encroachment.

Increase in the density, cover and biomass of native woody plants to the detriment of herbaceous flowering plants

o Shrub encroachment.

Myers-Smith et al. 2001. Env Reser Let; Wookey et al 2009, Glob Chang Biol

Numerous studies document the effect of shrub encroachment on the structure of tundra ecosystems

• Soil–atmosphere exchange of water, carbon and nutrients.

• Plant-plant interactions and vegetation composition.

• Energy fluxes

• Regional climate

o Shrub encroachment

We lack empirical data showing how shrub encroachment modifies plant–animal interactions at community scale.

thetechjournal.com

orkin.com

o Shrub encroachment and biotic interactions

Difficulties in quantifying changes in interactions compared with changes in biodiversity

thetechjournal.com

orkin.com

Inouye & Pyke 1988, Tylianakis et al 2008 Ecology Letters, Tylianakis et al 2010 Biological Conservation



Biotic interactions play an important role in the maintenance of biodiversity and the stability and resistance of ecosystems !!!!!!

Inouye & Pyke 1988; Tylianakis et al 2008 Ecology Letters, Tylianakis et al 2010 Biological Conservation


Images downloaded from es.dreamstime.com Inouye & Pyke 1988; Kearns & Inouye 1994; Dupont, Hansen & Olesen 2003

The harsh environmental conditions of high-mountainecosystems limit pollinator richness and pollination services for plant reproduction

Biotic interactions play an important role in the maintenance of biodiversity and the stability and resistance of ecosystems !!!!!!

o In this context of limited resources, shrub encroachment increases nutritional resources for pollinators.

o Positive feedback at both trophic levels

Van valen 1965 Amer Nat, Bolnick et al 2007 PNAS, Hegland et al 2009 Ecol Lett, Blüthgen & Klein 2011 Basic Appl Ecol

Div

ersi

ty(e

.g. p

lant

s)

Diversity(e.g. flower visitors)

Functional Biodiversity HypothesisFBH

Niche width

Niche Variation HypothesisNHV


Capítulo I Capítulo II Capítulo III Capítulo IV

o Research questions

o 1. Does higher diversity at the producer trophic level (plants) result in increased diversity at the consumers (pollinators) trophic level, as predicted by FBH?

o 2. Does shrub encroachment reduce the specific niche breadth of pollinators?

o 3. Do shared pollinators mediate competitive indirect interactions between shrubs and forbs?

We expected shrub encroachment to increase pollinator species richness and simultaneously to reduce the niche breadth of each pollinator species, ultimately affecting

plant–plant interactions through competition for shared pollinators.

o Predictions

Objetivos Capítulos Conclusiones

o Study System: Mediterranean alpine communities of Iberian Peninsula



Silene ciliata

Armeria caespitosaFestuca

curvifolia

Cytisus oromediterraneus

Laguna de los PájarosMacizo de Peñalara

Año 1.956

Año 1.976


Año 2009



Adenocarpus hispanicus Lam (DC) (Fabaceae)

Cytisus oromediterraneus Rivas Mart. & Al. (Fabaceae)


Sanz-Elorza et al 2003 Annals of Botany; Garcia-Romero et al 2010 Climatic Change

10 km

Nevero

Peñalara


o Sampling design and field survey

PA EP

100 m 60 m

11 census days for each sampling site (PA & EP)

o 10 Linear transects at each site.

o Number flowering plant of each species

o Identity and number of contacts between plants and flower visitors

o Sites simultaneously surveyed

Animal

Planta

A B C D

A 7 2 12 2

B 0 8 34 8

C 4 9 4 0

D 2 0 23 0

Quantitative bipartite networks for full-season data for each habitat type.

o Sampling design and field survey

Jordano 1987 Amer Nat

MetricsEffect of shrubs on

metricsNetwork-level metricsNumber of plants (P)Number of animals (A)Number of interactions (I)Number of visits (V)Connectance (C)Weighted Linkage (lw)

Modularity (Q)Species-level metricsLinkage (L)Species Specialization (d’)

Species strength (S)

MetricsEffect of shrubs on

metricsNetwork-level metricsNumber of plants (P) +Number of animals (A) +Number of interactions (I) +Number of visits (V) +Connectance (C) -Weighted Linkage (lw) -Modularity (Q) +Species-level metricsLinkage (L) -Species Specialization (d’) +

Species strength (S) +


o Results & discussion: species assemblages and visitation patterns



Blüthgen & Klein 2011 Basic Appl Ecol

o Flower visitor richness was higher in EP than in PA in all functional groups of pollinators

o Result confirmed by sample-based rarefied estimates




Mixed lineal models (LMMs) fitted for flower visitors

Number of interactions

Number of visits

F value Pr(>|F|)

F value

Pr(>|F|)

Intercept 1109.51 <0.001 773.7

4 <0.001

Habitat type 20.75 <0.001 14.16 <0.00

1

Functional group 34.96 <0.001 25.40 <0.001

Plants abundance 0.07 0.78 0.10 0.76Habitat type: F. group 1.42 0.17 1.34 0.21

Increased number of interactions and visits for each functional group of flower visitors



Div

ersi

ty(e

.g. p

lant

s)

Diversity(e.g. flower visitors)

FBH


The integration of shrubs into the network increased richness and visitation rates of all functional groups of flower visitors.

Flower visitors did not vary their niche breadth (d’a , La, Lwa)

Niche width

Increased generalization at EP (H’2)

Bolnick et al 2007 PNAS, Blüthgen & Klein 2011 Basic Appl Ecol, Seifan et al 2014, J Ecol

Both habitat types displayed a similar modular structure (Q)

o Results & discussion: specific niche breadth of pollinators

Number of interactions Number of

visits Visits per flowering plant

F

value Pr(>|F|) F value

Pr(>|F|) F

value Pr(>|F|)

a) Species that occurred at encroached pastures

Intercept 356.87 <0.001 423.69 <0.001 140.6

9 <0.001

Life form 3.91 0.05 1.12 0.29 12.26 <0.001 Plants abundance 10.88 <0.01 19.46 <0.001 53.28 < 0.001

b) Species that occurred at both habitat types

Intercept 580.23 <0.001 645.22 <0.001 359.1

6 <0.001

Habitat type 0.019 0.89 0.12 0.73 25.40 <0.001 Plant species 4.64 <0.001 4.70 <0.001 22.00 <0.001 Plants abundance 26.98 <0.001 37.84 <0.001 47.71 <0.001

H. Type:P. Species 0.52 0.87 0.45 0.92 2.36 0.01

o Results & discussion: plant-plant interactions mediated by shared pollinators

LMMs fitted for plants

o Shrubs had more interactions with flower visitors and recevied more visits per plant than forb species.

o Forb species received fewer visits per plant in EP than in PA


Shrub encroachment increased plant linkage (Lp y Lwp) while reducing the number of visits per plant of forb species without affecting their specialization (d’p).

Bolnick et al 2007 PNAS, Morales & Traveset 2009 Ecol Lett, Seifan et al 2014, J Ecol

o Results & discussion: plant-plant interactions mediated by shared pollinators

Niche width

These findings suggest the existence of competition

among plant species mediated by pollinator sharing

o Research questions and conclusions

o 1. Does higher diversity at the producer trophic level (plants) result in increased diversity at the consumers (pollinators) trophic level, as predicted by FBH?

o 2. Does shrub encroachment reduce the specific niche breadth of pollinators?

o 3. Do shared pollinators mediate competitive indirect interactions between shrubs and forbs?

Introducción Objetivos o Acknowledgements