Regeneration patterns in boreal Scots pine glades linked to cold-induced photoinhibition

Abstract

Regeneration patterns of Pinus sylvestris L. juveniles in central Siberian glades were studied in relation to cold-induced photoinhibition. Spatial distribution of seedlings in different height classes revealed higher seedling densities beneath the canopy than beyond the canopy, and significantly higher densities of seedlings < 50 cm tall on the north side of the trees. These patterns coincided with differences in light conditions. Compared with plants on the north side of canopy trees (north-exposed), photosynthetic photon flux (PPF) received by plants on the south side of canopy trees (south-exposed) was always higher, making south-exposed plants more susceptible to photoinhibition, especially on cool mornings. Chlorophyll fluorescence data revealed lower photochemical efficiency and increased non-photochemical quenching of small (20-50 cm in height), south-exposed seedlings from spring to early autumn, indicating increased excitation pressure on photosynthesis. Maximum rate of oxygen evolution was less in south-exposed plants than in north-exposed plants. Increased pools of xanthophyll cycle pigments and formation of the photoprotective zeaxanthin provided further evidence for the higher susceptibility to photoinhibition of south-exposed seedlings. A linear mixed model analysis explained many of the physiological differences observed in seedlings according to height class and aspect with early morning temperature and PPF as predictors. The link between photoinhibition and differential distribution of seedlings by height class suggests that photoinhibition, together with other environmental stresses, decreases the survival of small, south-exposed P. sylvestris seedlings, thereby significantly affecting the regeneration pattern of central Siberian pine glades.

Seasonal Photoprotective Responses in Needles of Korean Fir (Abies koreana) Over an Altitudinal Gradient on Mount Halla, Jeju Island, Korea

“…Whereas this study reports the first xanthophyll cycle data on higher plants in the Arctic that we are aware of, previous studies on Antarctic mosses at 66°S (Lovelock and Robinson, 2002;Robinson et al, 2005), Antarctic angiosperms in maritime Antarctica (Bascuñan-Godoy et al, 2012) and subarctic pine forests at 66°N (Louis et al, 2005;Slot et al, 2005) also reported high xanthophyll cycle pool sizes and zeaxanthin retention, although in most cases not as high as those observed in S. pulchra in this study. Although it is difficult to compare xanthophyll interconversion rates among studies, our (Z+A) dark-retention data (Figs.…”

Early performance of planted Nothofagus dombeyi and Nothofagus alpina in response to light availability and gap size in a high-graded forest in the south-central Andes of Chile

“…; Donoso et al 2007, Soto et al 2009 or in the west of England and Wales have had severe mortality or damage. Considering that partial shade from forest canopies can protect seedlings from frosts (Slot et al 2005) and changes the intensity of direct and diffuse incident light (Norman et al 1971), it might be possible to successfully plant N. dombeyi and N. alpina in high-graded forests. However, considering that the species are of low shade tolerance, the challenge is to find the proper combination of canopy protection and light availability for optimum performance of planted seedlings of Nothofagus species.…”

Treeline (Pinus sylvestris) landscape evolution in the Swedish Scandes – a 40-year demographic effort viewed in a broader temporal context

“…Reasonably, the old mother pines and their current offspring may be functionally important as dispersal nodes if preconditions for landscape-scale pine expansion should occur (cf. Slot et al 2005;Trant et al 2011). To some extent, this option has been sustained since the early 1990s, when scattered young pine saplings started to appear sparsely but quite regularly in the alpine tundra, 600-700 m above the permanent plots (Kullman 2007b;2007c).…”