Comparing Primary and Secondary Growth of Co-Occurring Deciduous and Evergreen Conifers in an Alpine Habitat

Abstract

Investigations on primary and secondary growth in co-occurring species will aid in assessment of the physiological adaptation of species and the prediction of forest stand structure dynamics. To explore the correlation and coordination between primary and secondary growth, we monitored the leaf phenology, shoot elongation, and stem growth of co-occurring Larix principis-rupprechtii Mayr. and Picea meyeri Rehd. et Wils. in an alpine habitat, Luya Mountain (North-Central China), during the growing season of 2014. We measured bud development on terminal branches three days per week by direct observations and intra-annual stem xylem formation at weekly intervals by the microcores method. The onset sequence of three organs was the needle, shoot, and stem, without species-specific differences. Needles appeared one month earlier than stem growth in larch, while it was only one week earlier in spruce. The duration of needle growth was the shortest, followed by the shoot and stem. The timing of primary growth (i.e., onset, end, and maximum growth rate) between the two species was asynchronous, but secondary growth was synchronic with the same date of the maximum growth rate occurrence, potentially indicating species competition for resources. Unlike larch, spruce staggered growth peaks among different organs, which may effectively mitigate trees’ internal competition for resources. Soil temperature was positively correlated with both shoot and stem growth in the two species, whereas air temperature and soil water content were positively correlated with needle growth only in larch. Therefore, it can be inferred that the spruce will probably outcompete the larch at cold alpine treeline sites due to its high adaptability to acquiring and allocating resources. These results provide insight into the potential physiological correlation between primary and secondary growth and allow better prediction of future climate change effects on forest ecosystem productivity.

Severe simulated herbivory constrains Sclerocarya birrea saplings regardless of resource availability

“…However, severely clipped plants were unable to completely recover leaf dry mass and were unable to compensate at the scale of the whole plant. The fact that their shoot production increased suggests that resources were diverted to primary growth, potentially benefitting C assimilation, at the expense of secondary growth (Schiestl-Aalto et al 2015;Zhang et al 2019).…”

Characteristics and Moisture Sources of the Stable Isotopes in Precipitation at the Monsoon Marginal Region of North-Central China

“…The environmental conditions in Luya Mountain are conducive to local water recycling. The Fen River headwater catchment is supplied by a series of alpine lakes from the Quaternary remnant of the glaciations [45], and the vegetation coverage in this area is high, with a canopy density of 0.8 [46]. Therefore, water evaporation pools, including evaporation from open water bodies and soil water, and plant transpiration pools, act as secondary moisture sources [47,48].…”

Asynchrony and Time-Lag between Primary and Secondary Growth of Norway Spruce Growing in Different Elevations

“…There is considerable overlap between growth processes, so the development of one process can limit the development of others occurring simultaneously. Furthermore, the climate and its variations can modify these interactions [29]. Such findings highlight the need to know the precise timing of development of each current-year shoot component, stem radial increment and the interactions among them.…”