Moss-dominated peat bogs store approximately 30% of global soil carbon. A climate induced shift from current moss-dominated conditions to tree-dominated states is expected to strongly affect their functioning and carbon sequestration capacity. Consequently, unraveling the mechanisms that may explain successful tree seedling establishment in these ecosystems is highly relevant. To assess the role of drought on early tree seedling establishment and the relative importance of plant traits in tree seedling survival, we conducted a factorial glasshouse experiment with seven conifer species. Our results show that drought inhibits moss growth, thereby increasing survival of tree seedlings. Survival success was higher in Pinus than in Picea species, ranking Pinus banksiana > Pinus sylvestris > Pinus nigra > Picea mariana > Picea glauca, Picea sitchensis > Picea rubens. We found that those species most successful under dry and wet conditions combined a fast shoot growth with high seed mass. We conclude that plant traits contribute to explaining successful early tree seedling establishment in bogs.
Seedlingtraitdataexperiment2
Experiment 2
Morphological traits were assessed independently of Experiment 1. We grew tree seedlings under optimal conditions by planting pre-grown 4 weeks old tree seedlings ( see plant material) into the center of a (10 cm wide) pot, using a density of one seedling per pot. The pots were filled with sterilized organic soil, watered daily and kept under the same glasshouse light and humidity conditions as Experiment 1. Pots were arranged in five replicated blocks. Both the blocks and the pots within a block were randomly moved once a week.
For more information on columnheadings see Table 1 in the associated MS
Motherfile.xls
Traitsandsurvival
Traits assessed in Experiment 2 were used to relate to seedling survival in Experiment 1. This file contains trait data from experiment 2 and seedling survival of seven conifer species in experiment 1 kept under contrasting moisture conditions (Dry, Wet)
traitsandsurvival.xlsx
Traitplasticityseedlingsmosssoil
To assess the plasticity of the morphological traits, we compared the morphological traits based on seedlings from Experiment 2 (grown on soil) with values measured on seedlings in Experiment 1 under contrasting moisture conditions
Traitflexibilitymosssoil.xlsx
germination
To assess germination, we introduced seeds to Experiment 1 in the third week, corresponding to the time when pot water contents had stabilized. Three seeds were placed around the seedling of the same species, on the capitulum of a moss individual, using 3 x 140 = 420 seeds in total. Germination was checked twice a week until harvest, 5 weeks later. We considered a seed germinated when the integument had broken and a ‘shoot’ of at least 1 mm had emerged from the seed.
Mossgrowth and seedling performance
The file contains growth and survival of seedlings grown on moss in experiment 1 as well as the moss growth itself
Relatie tussen mosgroei en seedling performance.xlsx
