Protocol for phenological observations in alpine grasslands

Transcription

1 Protocol for phenological observations in alpine grasslands PhenoALP Team Corresponding authors: Edoardo Cremonese (ARPA VDA IT) Erwan Henry (CREA - FR) erwan@crea.hautesavoie.net 1 Introduction PhenoAlp ( ) is a new EU co-funded Interreg Project, under the operational program for cross-border cooperation ItalyFrance (Alps-ALCOTRA) , aiming to get a better understanding of phenological changes in the Alps. The main goals of the project are: 1. The implementation of an observation network in the involved territories (i.e. the Aosta Valley and the Savoies in the Western Alps); 2. The denition of a common observation strategy and common protocols; 3. The involvement of local community members (e.g. through schools) in the observation activities as a way to increase the awareness on the issue of the eects of climate change. Project leader is the Environmental Protection Agency of Aosta Valley (ARPA Valle d'aosta IT) and the partners are the Alpine Ecosystems Research Center (CREA FR), Mont Avic Regional Park (PNMA - IT), Massif des Bauges Natural Regional Park (PNRB - FR) and the Protected Area Service of the Autonomous Region of Aosta Valley (SAP - IT). The PhenoAlp project is composed by 8 actions: 1. PhenoPlantes (plant phenology) 2. PhenoDetect (remote sensing and webcams) 3. PhenoFlux (phenology and productivity) 1

2 4. PhenoZoo (animal phenology) 5. Inter_Pheno (plant animal mismatches) 6. Meteo_Reseau (Network of automatic stations of temperature) 7. PhenoForm (Training activities) 8. PhenoComm/Coord (Communication and coordination) 2 PhenoPlantes The aim of this activity is to develop climate change indicators from plants phenology. Regarding forest species (Picea abies, Larix decidua, Betula pubescens, Betula pendula, Fraxinus excelsior, Sorbus aucuparia, Syringa vulgaris, Corylus avellana, Primula veris, Tussilago farfara) the knowledge and the experience arising from the Phénoclim Project ( will be transferred to the Italian partners territories (Aosta Valley). Observation protocols lead to the estimation of both the beginning and the end of the growth season by the monitoring of leaf development, owering, leaf decolouration and leaf fall events. Observations are done either by specialist and volunteers. A new protocol for alpine grasslands is developed in the framework of the project. To be not dependent of the presence/absence of single species in each observation site, the protocol considers seven growth life forms: cyperaceous, poaceae (palatable and non palatable), evergreen and deciduous shrubs, forbs and leguminous. For each group quantitative variables (e.g. leaves length, plant length, phenophase,..) are monitored along the growth season. Observation sites are located along an elevation gradient from 1560 masl (PNRB) to 2580 masl (GP); observation are carried out on marked individuals located in permanent plots. 3 Alpine Grasslands phenology protocol One of the aims of the project is to study some alpine grasslands located at dierent altitudes above timberline in order to determine the impact of climate change on vegetation, analyzing the vegetative and reproductive phenology of several functional growth-life types. Each study zone is equipped with a temperature stations recording every 15 minutes soil temperature at a depth of 5 cm, surface temperature, and air temperature at 30 cm and 2m height. Study zones: 1. FR Vallorcine Loriaz - Chamonix Valley 2. FR Regional Natural Park of Massif des Bauges 3. IT Mont Avic Natural Park 4. IT ARPA Torgnon Tellinod (2160 m asl) 5. IT ZPS Mont Emilius 6. IT Gran Paradiso National Park Observation Frequency: every week between April and July 2

3 Sites environmental conditions: 1. above the top limit of forest 2. southern slope 3. no pasture or late pasture 4. homogeneous slope 5. avoid convex and concave areas (micro-topography + snow accumulation in concave zones or early snow melting in convex ones) Number and size of plots: in each study zone, 3 plots of 600m 2 (20x30m or 24x25m or 40x15m) are delimited (avoiding signicant elevation variations between plots). Three shapes are available to setup the study plot, in order to avoid microtopography eects (rocks, concave and convex micro zones...). Each plot is subdivided into 30 subplots of 4x5m (Figure 1). Figure 1: Plot and subplot shape and dimensions Growth life forms observed: seven common growth life forms (listed in Table 1) of alpine pastures are selected for phenological observations. Sampling and marking eorts: for each plot, 5 individuals of each growth life forms are monitored; this leads to 35 (5 individuals x 7 growth life form) plants per plot and 105 (35 x 3 plots) plants per study zone. Plants are localized in randomly chosen subplots up to reach the considered number of samples. 3

4 Growth Form code Species example Poaceae (palatable) PP Poa alpina Poaceae (non palatable) NPP Nardus stricta Cyperaceae C Carex sempervirens Evergreen shrubs SE Rhododendron ferrugineum Deciduous shrubs SD Vaccinium myrtillus Asteraceae A Arnica montana Leguminous L Trifolium alpinum Table 1: Growth forms selected for phenological observations Consequently a minimum of 5 subplots is considered among the 30 subplots available in each plot (Figure 2). Important: if a growth life form is not found in one subplot it should be found in the next etc... If a subplot is totally covered with rocks or stones, go to the next one. The corners of each plot are indicated by the use of a wooden stick. The localization of the subplots and the marking of the plants are done only once at the beginning of the season. Each plant is marked thanks to a small wooden stick put in the ground adjacent to the plant. Moreover, a cotton or woolen band is attached to the stem or branch (Figure 3). 3.1 Phenological measurements Vegetative phenophases Palatable Poaceae (Growth life form code: PP) The longest ve leaves of the year and the plant length (from the basal sheath to the apex of stem or owers) are measured for every marked individual. Before the owering period the plant length is the leaf length mean. Possible problem: in some cases (e.g. beginning of the season, grazing, leaves rotting,...) there can be less than ve leaves. Attention: plant length is dierent from plant height (often stems are curved). measurement: length of the ve longest leaves [mm] + plant length [mm] (Fig. 4) Non palatable Poaceae (Growth life form code: NPP) The longest ve leaves of the year are measured for every marked individual. If present, ten leaves of the previous year are measured during the rst observation day. Possible problem: in some cases (e.g. beginning of the season, grazing, leaves rotting,...) there can be less than ve leaves. measurement: length of the ve longest leaves [mm] (Fig. 4) Cyperaceae (Growth life form code: C) The longest ve leaves of the year and the plant length (from the basal sheath to the apex of stem or owers) are measured for every marked individual. If present, ten leaves of the previous year are measured during the rst observation day. Before the owering period the plant length is the leaf length mean. Possible problem: in some cases (e.g. beginning of the season, grazing, leaves rotting,...) there can be less than ve leaves. Attention: plant length is dierent from plant height (often stems are curved). measurement: length of the ve longest leaves [mm] + plant length [mm] (Fig. 4) Evergreen shrubs (Growth life form code: SE) The vegetative phenophase of a marked branch is evaluated. The vegetative phases considered are: without bud (NB), foliar bud (LB), light green leaves (L). If the marked branch has many buds, the phenological phase to indicate is the most common of the whole branch. When the foliar buds of the marked ramet are open, ve of them are marked and the length from the petiole to the apex of the central leaf is measured. Attention: Do not mark branches with oral buds or ower of the previous year. 4

5 Figure 2: Selection of the number of subplot required to mark 5 individuals for each growth form (4 in the example) Figure 3: Marked plants in a subplot 5

6 Figure 4: Measurements on PP, NPP and C growth forms measurement: vegetative phenophase of a branch (NB-LB-L) + length from the petiole to the apex of 5 developing foliar buds [mm] (Fig. 5) Deciduous shrubs (Growth life form code: SD) The vegetative phenophase of a marked branch is evaluated. The vegetative phases considered are: without bud (NB), foliar bud (LB), completely burstleaf green-light leaf (L), developed dark green-dark leaf (DL), dry or yellow leaf (YL). If the marked branch has many buds, the phenological phase indicated is the most common of the whole branch. Branch length is measured from a xed reference level (base, woolen band, separation) to the apex of the highest leaf. Leaf length is not measured (NA in the data sheet) measurement: vegetative phenophase of a branch (NB-LB-L-DL-YL) + length of the marked branch [mm] (Fig. 5) Asteracee (Growth life form code: A) The longest ve leaves of the year (base to apex) and the plant length (base to ower) are measured for every marked individual. Plant length is measured when the oral stem appears. Possible problem: in some cases (e.g. beginning of the season, grazing, leaves rotting,...) there can be less than ve leaves. measurement: length of 5 leaves [mm] + plant length [mm] (Fig. 6) Leguminous (Growth life form code: L) The length of the central leaet (base to apex) of the leaves (max 5 leaves) is measured for every marked individual. Plant length is measured as well: if owers are not present plant length is measured form the base to the apex of the highest leaf, when ower are present plant length is measured from the base to the ower. Possible problem: in some cases (e.g. beginning of the season, grazing, leaves rotting,...) there can be less than ve leaves. measurement: length of the central leaet (max 5 leaves) [mm] + plant length [mm] (Fig. 6) Reproductive phenophases Reproductive phenology is observed using 5 phenophases (table 2) for all the growth forms. If a marked individual bares more than one ower (e.g. shrubs marked branch), the most common phase is the recorded 6

7 Figure 5: a) SE: measurement of the length from petiole to apex of foliar buds b) SD: length of marked branch from xed reference level to highest leaf apex one. Depending on the species and diculties to distinguish the phenological phases, more details like, receptive and withered stigmatas, dry owers, beginning of fructication, ripe fruits and intermediate phases can be noted. Possible problem: some of the chosen individuals at the beginning of the season could not reach the Reproductive phenophase Without owers, no owers Flowers in the sheats, closed spikelets, closed owers Open owers, stigmatas developed, open spikelets, stigmatas receptive Dry owers, beginning of fruit development, developed seeds, fruits Loss of fruits or seeds code NF C O F LF Table 2: Reproductive phenophases reproductive phases; in this case, only vegetative observations are done on the individual. 3.2 Greening measurements Greenness seasonal evolution is monitored using digital images and visual estimations. Observations are done weekly from the beginning of the season (may-june) till late autumn before rst snow falls (october) in order to monitor both spring development and senescence. Digital pictures are taken on the four corner of each plot (12 images in each study zone). Images are taken from xed points, in automatic mode (exposure and time) and high resolution from a xed height (e.g. 1m or 7

8 Figure 6: a) A: measurement of leaf length b) L: measurement of central leaet length c) L: measurement of plant length without owers 1.6 m). The images are elaborated computing greenness indexes (from the RGB channels) considering as region of interest the area delimited by a PVC tube (or wood sticks) frame of 50x50 cm (Figure 9). The grey color of the PVC frame or a plastic test panel is used for color calibration. Attention: avoid shadows inside the image. On the same 50x50 cm frame used for the images, a visual estimation of greenness percentage is carried out (10, 20, 30, 40%...). Canopy level (i.e. grass heigth) at the four corners and in the center of the frame, is measured as well. 8

9 Figure 7: Images of some reproductive phenophases for the growth forms NPP, C, SE, SD. 9

10 Figure 8: Images of some reproductive phenophases for the growth forms A,L. Figure 9: Example of 2009 spring greening in one corner (X1) of Vallorcine Loriaz study zone. 10