114° Congresso della Società Botanica Italiana
VI International Plant Science Conference (IPSC)
11° Congresso Annuale della Società Italiana di Biologia Vegetale
Padova, Orto Botanico 4-7 September 2019
SNOW COVER INFLUENCE ON PHENOLOGY AND PRIMARY GROWTH OF Juniperus communis L.
Elisabetta Candeago1*, Martina Pollastrini1, Marco Carrer2
1 Department of Agriculture, Food, Environment and Forestry, University of Florence, Piazzale delle Cascine 18, (FI - Italy) 2 Department of Land, Environment, Agriculture and Forestry, University of Padua, Viale dell’Università 16, (PD - Italy)
*email: elisabetta.candeago@gmail.com
Introduction
During the past decades the average temperatures has progressively increased and extreme climatic events have become more frequent and intense, affecting plants communities, especially those in the treeline ecotones.
Aims of the study
The purpose of this study is to evaluate the phenology and primary growth of the shoots of common juniper (Juniperus communis L.) in response to changes in period and duration of snow cover.
Material and methods
A snow manipulation experiment was carried out to study the effects due to the alterations of environmental conditions (duration of snow cover, air, soil, and bark temperatures, soil, water availability) on common juniper at a treeline area in the Eastern Italian Alps near to Passo Giau (San Vito di Cadore, Belluno) (Figs. 1, 2, 3).
Discussion and conclusion
The air temperatures registrated during this study at the Alpine treeline confirm the global warming phenomenon. There is a considerable difference of the average, maximum and minimum air temperatures between the decade 1996-2016 and the years 2017 and 2018. The highest temperatures recorded are from April 2018 to June 2018 (Figs. 7, 8, 9, 10).
From this study we observed that the manipulation of the snow cover affects:
1. the shoot length in junipers grown covered by snow (S) with anticipated and longer branches;
2. in S plots the snow cover influences the plant phenology with a delay in maturation of the reproductive structures;
3. in uncovered plants (U) the stress due to extreme temperatures and frost have compromised the development of the buds.
This research is the first step of a long-term experiment in alpine treeline to evaluate changes in plant communities driven by the current and future environmental changes.
b) Phenology and primary growth:
Length of the shoot of the year in (Fig. 9) C: ranges from 1,80 to 20,20 mm
U: ranges from 3 to 30,60 mm S: ranges from 0 to 31,20 mm
Presence and development of buds, new leaves, male and female sporophylls:
Period Control Plots (C) Uncovered Plots (U) Covered Plots (S) October 2017 Winter 2017 – 2018 (Nov. - Feb.) March 2018 April 2018 May 2018 June 2018 Legend Covered by snow Uncovered by snow 0,00 0,00 2,20 6,60 10,00 13,40 16,80 20,40 28,80 31,20 3,00 4,40 6,00 10,60 14,80 17,60 23,00 27,00 30,40 30,60 1,80 3,80 6,60 8,80 11,00 14,40 17,00 19,20 18,20 20,20 0,00 5,00 10,00 15,00 20,00 25,00 30,00 35,00 15 th o f J un 22 nd o f J un 29 th o f J un 4t h of Ju ly 13 th o f J ul 19 th o f J ul 26 th o f J ul 2n d of A ug 17 th o f A ug 27 th o f A ug LE N G H T (m m ) DATE
Lenght of the shoot of the year
S U C
Fig. 1 - Localization of the study site Fig. 2 - Study site on 5th of
December 2017
Fig. 3 - Study site on 7th of September 2017
Fig. 4 - Fine knit grids placed over U plots (30th of October 2017)
Fig. 5 - S plot covered with thermic blankets (March 2018)
Chart 1 - Plot design grid
-10 -5 0 5 10 15 20 25
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dic
T
(°
C)
MONTH
1996-2016 2017 2018
Comparison of T average between 1996-2016, 2017 and 2018
-10 -5 0 5 10 15 20 25
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dic
T
(°
C)
MONTH
1996-2016 2017 2018
Comparison of T max between 1996-2016, 2017 and 2018
-10 -5 0 5 10 15 20 25
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dic
T
(°
C)
MONTH 1996-2016 2017
Comparison of T min between 1996-2016, 2017 and 2018
Figs. 6, 7, 8 - Meteorological data
Fig. 7 - Female cones development
Fig. 8 - Green female cones (29th of June 2018)
Fig. 9 - Male cones development Fig. 10 - Male cones (29th of June 2018)
- cones: data recorded from 15th of June 2018-27th of August 2018 (Figs. 10, 11, 12, 13); - buds: data recorded from 15th of June 2018 -13th of July 2018;
- new leaves on the shoot of the year: grade of divergence (distance between needles and branch) during all the month of August 2018.
Fig. 9 -
b) phenology and primary growth:
length of the shoot of the year (mm);
presence and development of buds, new leaves, male and female sporophylls.
Results
a) Meteorological data:
Comparison of monthly maximum, minimum and average air temperature between the period of time 1996-2006 and 2017 and 2018 (Figs 6, 7, 8).
Has been collecting data about:
a) meteorological data:
air temperature (min. max average) took twice every 15 minutes by two weather stations located 3 km between each other, respectively one in the center of study area (data collected from September 2017 to December 2018) and one in Cinque Torri (data collected since 1996);
The experiment setup included 15 plants of common juniper, grown in 3 plots (54 m2) with 3 different treatments (5 plants in each plot):
- S: covered by snow - U: uncovered by snow - C: control plots
For U plots a series of a metal nets have been placed in oder to do not damage the plants during the snow removal operations started on March 2018 (Fig. 4).
Instead, for S plots, has been collected snow from the areas around the site and placed it over the plants and protected them using two different thermic blankets in order to postpone the beginning of vegetative growth as long as possible (Fig. 5).
