TY - JOUR

T1 - Increase in size and nitrogen concentration enhances seedling survival in Mediterranean plantations

T2 - insights from an ecophysiological conceptual model of plant survival

AU - Villar-Salvador, Pedro

AU - Puertolas Simon, Jaime

AU - Cuesta, Barbara

AU - Penuelas, Juan L.

AU - Uscola, Mercedes

AU - Heredia-Guerrero, Norberto

AU - Rey Benayas, Jose M.

PY - 2012/9

Y1 - 2012/9

N2 - Reduction in size and tissue nutrient concentration is widely considered to increase seedling drought resistance in dry and oligotrophic plantation sites. However, much evidence indicates that increase in size and tissue nutrient concentration improves seedling survival in Mediterranean forest plantations. This suggests that the ecophysiological processes and functional attributes relevant for early seedling survival in Mediterranean climate must be reconsidered. We propose a ecophysiological conceptual model for seedling survival in Mediterranean-climate plantations to provide a physiological explanation of the frequent positive relationship between outplanting performance and seedling size and nutrient concentration. The model considers the physiological processes outlined in the plantation establishment model of Burdett (Can J For Res 20:415-427, 1990), but incorporates other physiological processes that drive seedling survival, such as N remobilization, carbohydrate storage and plant hydraulics. The model considers that seedling survival in Mediterranean climates is linked to high growth capacity during the wet season. The model is for container plants and is based on three main principles, (1) Mediterranean climates are not dry the entire year but usually have two seasons of contrasting water availability; (2) summer drought is the main cause of seedling mortality; in this context, deep and large roots is a key trait for avoiding lethal water stress; (3) attainment of large root systems in the dry season is promoted when seedlings have high growth during the wet season. High growth is achieved when seedlings can divert large amount of resources to support new root and shoot growth. Functional traits that confer high photosynthesis, nutrient remobilization capacity, and non-structural carbohydrate storage promote high growth. Increases in seedling size and nutrient concentration strongly affect these physiological processes. Traits that confer high drought resistance are of low value during the wet season because hinder growth capacity. We provide specific evidence to support the model and finally we discuss its implications and the factors that may alter the frequent increase in performance with increase in seedling size and tissue nutrient concentration.

AB - Reduction in size and tissue nutrient concentration is widely considered to increase seedling drought resistance in dry and oligotrophic plantation sites. However, much evidence indicates that increase in size and tissue nutrient concentration improves seedling survival in Mediterranean forest plantations. This suggests that the ecophysiological processes and functional attributes relevant for early seedling survival in Mediterranean climate must be reconsidered. We propose a ecophysiological conceptual model for seedling survival in Mediterranean-climate plantations to provide a physiological explanation of the frequent positive relationship between outplanting performance and seedling size and nutrient concentration. The model considers the physiological processes outlined in the plantation establishment model of Burdett (Can J For Res 20:415-427, 1990), but incorporates other physiological processes that drive seedling survival, such as N remobilization, carbohydrate storage and plant hydraulics. The model considers that seedling survival in Mediterranean climates is linked to high growth capacity during the wet season. The model is for container plants and is based on three main principles, (1) Mediterranean climates are not dry the entire year but usually have two seasons of contrasting water availability; (2) summer drought is the main cause of seedling mortality; in this context, deep and large roots is a key trait for avoiding lethal water stress; (3) attainment of large root systems in the dry season is promoted when seedlings have high growth during the wet season. High growth is achieved when seedlings can divert large amount of resources to support new root and shoot growth. Functional traits that confer high photosynthesis, nutrient remobilization capacity, and non-structural carbohydrate storage promote high growth. Increases in seedling size and nutrient concentration strongly affect these physiological processes. Traits that confer high drought resistance are of low value during the wet season because hinder growth capacity. We provide specific evidence to support the model and finally we discuss its implications and the factors that may alter the frequent increase in performance with increase in seedling size and tissue nutrient concentration.

KW - SEMIARID ENVIRONMENT

KW - Forest plantation

KW - Photosynthesis

KW - CARBOHYDRATE RESERVES

KW - Nutrients

KW - PINE-SEEDLINGS

KW - WATER RELATIONS

KW - Fertilization

KW - HYDRAULIC ARCHITECTURE

KW - FIELD PERFORMANCE

KW - Root growth

KW - Drought stress

KW - DROUGHT RESISTANCE

KW - QUERCUS-SUBER L.

KW - N-15 LABELING APPROACH

KW - Carbohydrates

KW - ROOT-GROWTH

KW - Remobilization

KW - Plant quality

KW - Nitrogen

U2 - 10.1007/s11056-012-9328-6

DO - 10.1007/s11056-012-9328-6

M3 - Journal article

VL - 43

SP - 755

EP - 770

JO - New Forests

JF - New Forests

SN - 0169-4286

IS - 5-6

ER -