TY - JOUR

T1 - Why do large, nitrogen rich seedlings better resist stressful transplanting conditions? A physiological analysis in two functionally contrasting Mediterranean forest species

AU - Cuesta, Barbara

AU - Villar-Salvador, Pedro

AU - Puertolas Simon, Jaime

AU - Jacobs, Douglass F.

AU - Rey Benayas, Jose M.

PY - 2010/6/15

Y1 - 2010/6/15

N2 - We analysed the physiological bases that explain why large and high nitrogen (N) concentration seedlings frequently have improved survival and growth relative to small seedlings in Mediterranean woodland plantations. Large seedlings of Aleppo pine (Pinus halepensis Mill.) and holm oak (Quercus ilex L) with high N concentration (L+), and small seedlings with either high (S+) or low (S-) N concentration, were planted on two sites of different weed competition intensity that created contrasting stress conditions. Seedling survival, growth, gas exchange, N remobilization (N(R)) and uptake (N(U)), and water potential were assessed through the first growing season. Weeds reduced survival and growth, but seedling response to weed competition varied among phenotypes and between species. At the end of the first growing season, L+ Aleppo pine seedlings had higher survival than both small seedling types in presence of weeds but no differences were observed in absence of weeds. Mortality differences among phenotypes occurred in spring but not in summer. L+ Aleppo pines grew more than small Aleppo pines independently of weed competition. No holm oak seedling type survived in presence of weeds and no mortality differences among phenotypes where observed in absence of weeds, although L+ holm oak seedlings grew more than small seedlings. Mortality and growth differences in Aleppo pine were linked to marked physiological differences among phenotypes while physiological differences were small among holm oak phenotypes. L+ Aleppo pines had greater root growth, gas exchange. N(R), and N(U) than small seedlings, irrespective of their N concentration. Seedling size in Aleppo pine had a greater role in the performance of transplanted seedlings than N concentration. The functional differences among oak phenotypes were small whereas they were large in pine seedlings, which led to smaller differences in transplanting performance in holm oak than in pine. This suggests that the nursery seedling quality improvement for planting in dry sites could depend on the species-specific phenotypic plasticity and functional strategy. Improved transplanting performance in large Aleppo pine seedlings relative to small seedlings was linked to greater gas exchange, root growth and N cycling. (C) 2010 Elsevier B.V. All rights reserved.

AB - We analysed the physiological bases that explain why large and high nitrogen (N) concentration seedlings frequently have improved survival and growth relative to small seedlings in Mediterranean woodland plantations. Large seedlings of Aleppo pine (Pinus halepensis Mill.) and holm oak (Quercus ilex L) with high N concentration (L+), and small seedlings with either high (S+) or low (S-) N concentration, were planted on two sites of different weed competition intensity that created contrasting stress conditions. Seedling survival, growth, gas exchange, N remobilization (N(R)) and uptake (N(U)), and water potential were assessed through the first growing season. Weeds reduced survival and growth, but seedling response to weed competition varied among phenotypes and between species. At the end of the first growing season, L+ Aleppo pine seedlings had higher survival than both small seedling types in presence of weeds but no differences were observed in absence of weeds. Mortality differences among phenotypes occurred in spring but not in summer. L+ Aleppo pines grew more than small Aleppo pines independently of weed competition. No holm oak seedling type survived in presence of weeds and no mortality differences among phenotypes where observed in absence of weeds, although L+ holm oak seedlings grew more than small seedlings. Mortality and growth differences in Aleppo pine were linked to marked physiological differences among phenotypes while physiological differences were small among holm oak phenotypes. L+ Aleppo pines had greater root growth, gas exchange. N(R), and N(U) than small seedlings, irrespective of their N concentration. Seedling size in Aleppo pine had a greater role in the performance of transplanted seedlings than N concentration. The functional differences among oak phenotypes were small whereas they were large in pine seedlings, which led to smaller differences in transplanting performance in holm oak than in pine. This suggests that the nursery seedling quality improvement for planting in dry sites could depend on the species-specific phenotypic plasticity and functional strategy. Improved transplanting performance in large Aleppo pine seedlings relative to small seedlings was linked to greater gas exchange, root growth and N cycling. (C) 2010 Elsevier B.V. All rights reserved.

KW - QUERCUS-ILEX

KW - Photosynthesis

KW - Water potential

KW - Survival

KW - Pinus halepensis

KW - Stomatal conductance

KW - HERBACEOUS VEGETATION

KW - Quercus ilex

KW - CARBON-DIOXIDE CONCENTRATION

KW - WATER RELATIONS

KW - PINUS-HALEPENSIS

KW - PLANTATION ESTABLISHMENT

KW - Root growth

KW - FIELD PERFORMANCE

KW - Nitrogen remobilization

KW - STOMATAL CONDUCTANCE

KW - LOBLOLLY-PINE

KW - ROOT-GROWTH

KW - Competition

U2 - 10.1016/j.foreco.2010.04.002

DO - 10.1016/j.foreco.2010.04.002

M3 - Journal article

VL - 260

SP - 71

EP - 78

JO - Forest Ecology and Management

JF - Forest Ecology and Management

SN - 0378-1127

IS - 1

ER -