Climate and species stress resistance modulate the higher survival of large seedlings in forest restorations worldwide

Abstract

Seedling planting plays a key role in active forest restoration and regeneration of managed stands. Plant attributes at outplanting can determine tree seedling survival and consequently early success of forest plantations. Although many studies show that large seedlings of the same age within a species have higher survival than small ones, others report the opposite. This may be due to differences in environmental conditions at the planting site and in the inherent functional characteristics of species. Here, we conducted a global-scale meta-analysis to evaluate the effect of seedling size on early outplanting survival. Our meta-analysis covered 86 tree species and 142 planting locations distributed worldwide. We also assessed whether planting site aridity and key plant functional traits related to abiotic and biotic stress resistance and growth capacity, namely specific leaf area and wood density, modulate this effect. Planting large seedlings within a species consistently increases survival in forest plantations worldwide. Species' functional traits modulate the magnitude of the positive seedling size-outplanting survival relationship, showing contrasting effects due to aridity and between angiosperms and gymnosperms. For angiosperms planted in arid/semiarid sites and gymnosperms in subhumid/ humid sites the magnitude of the positive effect of seedling size on survival was maximized in species with low specific leaf area and high wood density, characteristics linked to high stress resistance and slow growth. By contrast, high specific leaf area and low wood density maximized the positive effect of seedling size on survival for angiosperms planted in subhumid/humid sites. Results have key implications for implementing forest plantations globally, especially for adjusting nursery cultivation to species' functional characteristics and planting site aridity. Nursery cultivation should promote large seedlings, especially for stress sensitive angiosperms planted in humid sites and for stress-resistant species planted in dry sites.

The road to recovery: a synthesis of outcomes from ecosystem restoration in tropical and sub-tropical Asian forests

“…Risks may be mitigated, through more intense maintenance and/or appropriate seedling stocking densities to bring about rapid canopy closure in very degraded systems [ 94 , 98 ]. We found a positive effect of tree height at planting on survival in the open degraded sites, as has been found in other studies [ 100 ]. Larger seedlings are usually better equipped to withstand environmental challenges or maximize on opportunities for rapid growth, but they are also more costly to produce and plant so the cost−benefit trade-off must be carefully assessed.…”

Early Growth Responses of Larix kaempferi (Lamb.) Carr. Seedling to Short-Term Extreme Climate Events in Summer

“…The early growth performance of small or young seedlings planted in open fields can be particularly affected by extreme temperatures and precipitation [21,22]. Various adverse effects of unpredictable climate factors on seedling quality, which can be assessed by measuring numerous morphological and physiological traits, have been observed in many nursery and silvicultural operations [23].…”

Salix alba Clone Wilting Response to Heat Stress

“…Multiple traits can be useful to estimate plants' ability to tolerate and regenerate after a stress period [3,20,21]. Physiological traits are more difficult to assess, compared to morphological traits, yet the importance of morphological traits in determining survival and growth outcomes is often overlooked [22,23] Therefore, the identification of traits that can Shoot count did not have a significant effect on wilting occurrence. After the cessation of the heat-induced stress period, 11% of wilted shoots recovered and regained lost turgor.…”

“…Multiple traits can be useful to estimate plants' ability to tolerate and regenerate after a stress period [3,20,21]. Physiological traits are more difficult to assess, compared to morphological traits, yet the importance of morphological traits in determining survival and growth outcomes is often overlooked [22,23] Therefore, the identification of traits that can be easily measured, and are good predictors of drought and heat resistance, can be especially useful in nursery settings, when dealing with a large number of plants. It is known that plants can withstand drought and cold stress better during their dormant stage, but are especially sensitive to these stressors during active phase of shoot growth in spring and summer [2].…”