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Grassland Network

The network currently includes 6 alpine and subalpine grassland sites: 2 sites in France and 4 in Italy. Each site is equipped with temperature measurements.

Many monitoring approaches were tested according to the common protocol on these sites to determine the best approach for long term monitoring of grassland phenology.

The localisation of sites and their main topographical data are shown in the map.

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Phenology of grassland species

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Simultaneous observations of species with different development strategies enable to study a wide range of phenological responses to climatic variations and therefore to determine the best candidate species to become indicators of the effects of climate change on phenology.Read More

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Phenological monitoring was performed at different spatial scales: from individuals level (i.e. single plants of some species) to satellite images (see PhenoDetect action). Between these two extremes, the phenological monitoring was realised at community level (sets of species that make up the meadows). The objective of this type of monitoring was to test three methods, more rapid than observations at individual level and with a higher spatial resolution than satellite images: digital pictures, visual estimate of greeness and canopy height measurement. Data were collected on 12 fixed quadrants (50 x 50 cm). with a weekly frequency. From digital images a green index (GI = Green/(Red+Blue+Green)) was computed from RGB data. The GI is a good indicator of canopy greenness. GI and and green visual estimate are directly related to the green leaf area and therefore to the vegetative phenology of the community. Both methods are similar in terms of data collection speed, but the visual estimate requires a good deal of experience in the field. The results obtained from these two methods are quite similar.

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Canopy height is related to the growth of the grassland species, but not directly to their phenology. In effect, after flowering and bearing fruit, the plants continue to grow (less rapidly) until senescence. That’s why a difference can be observed between the timing of maximum canopy height and the maximum greenness. Additionally, canopy height is strongly influenced by herbivorous (grazing and trampling) and by climatic disturbances (storms, hail, etc.) thus leading to a noisy senescence signal. Canopy height is thus a less precise phenological index with respect to greenness.

Phenological observations made on alpine grassland reveal differences between monitored sites mainly related to the effect of altitude. Altitude causes a delay in plant development because (i) temperature decreases at higher elevation slowing down plant physiology and (ii) the duration of the snow covering is prolonged hampering the onset of growth.

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Considering monitoring years (2009-2011), 2011 was the warmest year since 1900. High spring temperatures in 2011 had strong effects on all observation sites: all the reproductive and vegetative phases were strongly anticipated (20 - 40 days). The monitoring set up thus allow us to detect the response of phenology to both interannual climate variations and long term warming trend.

NEWS

Jan 2013

NEW PAPER! "Phenology and carbon dioxide source/sink strength of a subalpine grassland in response to an exceptionally short snow season" was published on Environmental Research Letters

May 2013

Watch PhenoALP presentation video!

Jun 2014

NDVI database now available

Aug 2013

Do you want to start phenological observations in your classes? Here is the experience from Torgnon primary school.

Dec 2013

Midterm Meeting took place: have a look at the contents

Jan 2013

NEW PAPER! "Phenology and carbon dioxide source/sink strength of a subalpine grassland in response to an exceptionally short snow season" was published on Environmental Research Letters

May 2013

Watch PhenoALP presentation video!

Jun 2014

NDVI database now available

Aug 2013

Do you want to start phenological observations in your classes? Here is the experience from Torgnon primary school.

Dec 2013

Midterm Meeting took place: have a look at the contents

Jan 2013

NEW PAPER! "Phenology and carbon dioxide source/sink strength of a subalpine grassland in response to an exceptionally short snow season" was published on Environmental Research Letters

May 2013

Watch PhenoALP presentation video!

Jun 2014

NDVI database now available

Aug 2013

Do you want to start phenological observations in your classes? Here is the experience from Torgnon primary school.

Dec 2013

Midterm Meeting took place: have a look at the contents

Jan 2013

NEW PAPER! "Phenology and carbon dioxide source/sink strength of a subalpine grassland in response to an exceptionally short snow season" was published on Environmental Research Letters

May 2013

Watch PhenoALP presentation video!

Jun 2014

NDVI database now available

Aug 2013

Do you want to start phenological observations in your classes? Here is the experience from Torgnon primary school.

Dec 2013

Midterm Meeting took place: have a look at the contents

Jan 2013

NEW PAPER! "Phenology and carbon dioxide source/sink strength of a subalpine grassland in response to an exceptionally short snow season" was published on Environmental Research Letters

May 2013

Watch PhenoALP presentation video!

Jun 2014

NDVI database now available

Aug 2013

Do you want to start phenological observations in your classes? Here is the experience from Torgnon primary school.

Dec 2013

Midterm Meeting took place: have a look at the contents

Jan 2013

NEW PAPER! "Phenology and carbon dioxide source/sink strength of a subalpine grassland in response to an exceptionally short snow season" was published on Environmental Research Letters

May 2013

Watch PhenoALP presentation video!

Jun 2014

NDVI database now available

Aug 2013

Do you want to start phenological observations in your classes? Here is the experience from Torgnon primary school.

Dec 2013

Midterm Meeting took place: have a look at the contents

Jan 2013

NEW PAPER! "Phenology and carbon dioxide source/sink strength of a subalpine grassland in response to an exceptionally short snow season" was published on Environmental Research Letters

May 2013

Watch PhenoALP presentation video!

Jun 2014

NDVI database now available

Aug 2013

Do you want to start phenological observations in your classes? Here is the experience from Torgnon primary school.

Dec 2013

Midterm Meeting took place: have a look at the contents

Jan 2013

NEW PAPER! "Phenology and carbon dioxide source/sink strength of a subalpine grassland in response to an exceptionally short snow season" was published on Environmental Research Letters

May 2013

Watch PhenoALP presentation video!

Jun 2014

NDVI database now available

Aug 2013

Do you want to start phenological observations in your classes? Here is the experience from Torgnon primary school.

Dec 2013

Midterm Meeting took place: have a look at the contents