Horacio Paz1, Fernando Pineda-García2 & Luisa Fernanda Pinzon-Perez1,3

Article title: Root depth and morphology in response to soil drought: comparing ecological groups along the secondary succession in a tropical dry forest

HORACIO PAZ1, FERNANDO PINEDA-GARCÍA2 & LUISA FERNANDA PINZON-

PEREZ1,3

1 Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, campus Morelia.

2 Escuela Nacional de Estudios Superiores, Universidad Nacional Autónoma de México, Unidad

Morelia, Morelia, México.

3 Centro de Investigación y Desarrollo Científico, Jardín Botánico José Celestino Mutis, Bogotá,

Colombia. e-mail. [email protected] Electronic Supplementary Material

Table S1. List of species and successional groups.

Successional group Genus Species Family

Early succesional Acacia Farnesiana Fabaceae

Lysiloma microphyllum Fabaceae

Mimosa arenosa Fabaceae

Senna atomaria Fabaceae

Mid succesional Apoplanesia paniculata Fabaceae

Caesalpinia coriaria Fabaceae

Caesalpinia eriostachys Fabaceae

Caesalpinia platyloba Fabaceae

Cordia alliodora Boraginaceae

Cordia dentata Boraginaceae

Erythrina lanceolata Fabaceae

Gliricidia sepium Fabaceae

Lonchocarpus constrictus Fabaceae

Lonchocarpus eriocarinalis Fabaceae

Lonchocarpus magallanesii Fabaceae

Piptadenia constricta Fabaceae

Old-growth forest Amphiterigium adstringens Julianaeae

Astronium graveolens Anacardiaceae

Bursera arborea Burseraceae

Ceiba aesculifolia Bombacaceae

Cieba grandiflora Malvaceae

Enterolobium cyclocarpum Fabaceae

Plumeria rubra Apocynaceae Table S2. List of morphological and physiological traits and the abbreviations used in the text with their corresponding units.

Abreviation Trait Units

MRD Maximum root depth cm

WFRD Weighted fine root depth cm

VRER Vertical root elongation rate cm∙cm-1∙day-1

FRL Total fine root length cm

MRD:LA Maximum root length: Leaf area ratio cm∙cm-2

WRD:LA Weighted root depth: Leaf area ratio cm

FRL:LA Total fine root length: Leaf area ratio cm∙cm-2

R:S Root:shoot mass ratio g∙g-1

SWC Maximum water content per unit stem mass g∙g-1 ∙100

RWC Maximum water content per unit root mass g∙g-1 ∙100

SMF Stem mass fraction g∙g-1

RMF Thick root mass fraction g∙g-1

TWS Total water storage in the plant g Table S3. PCA loadings of root depth and tissue water content traits.

Trait PCA axis 1 PCA axis 2

MRD 0.92 0.18

WRD 0.88 0.18

VRER 0.65 0.28

FRL 0.40 0.25

MRD:LA 0.77 0.34

WRD:LA 0.74 0.37

FRL:LA 0.53 0.55

RWC -0.62 0.61

SWC -0.68 0.62

TRMF -0.55 0.31

SMF -0.44 0.08

TWS -0.75 0.59

MRD = maximum root depth, WRD = weighted fine root depth, VRER = vertical root elongation rate, FRL = total fine root length, R:S = thick root:stem mass ratio, MRD:LA = maximum root length: leaf area ratio,

WRD:LA = weighted root depth: leaf area ratio, FRL:LA = fine root length: leaf area ratio, , RWC = water content per root tissue unit , SWC = water content per stem tissue unit, RMF= thick root mass ratio, SMR = stem mass fraction, TWS = total plant water storage. Note: PCA was based on trait values after discounting the effect of plant biomass (see methods). Figure S1. Vertical profile of soil water potential in the experimental pots. Symbols indicate six experimental pots belonging to three species: , Gliricidia sepium; ,

Acacia farnesiana; +, X Erythrina lanata. 25 a) b)

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W Early Mid OGF Early Mid OGF Successional group

Figure S2. Variation of seedling root traits among successional groups. Each data point represents a mean value per species. Mid lines denote the median values, boxes denote the 95% percentile, extreme lines represent the 95% confidence interval. All seedlings are 90 days old.

Early-successional species (Early), mid-successional species (Mid), old-growth forest species

(OGF). Each data point represents original mean values obtained per species.