April-2-מרוות-איג-שוורץ-צחור-2008-078-aspect-ratio-x

Phenological Monitoring at Ramat Hanadiv – Changes in ‘Flowering Habits’?

Ra’aya Rodich

Throughout the world and in Israel, the question has arisen as to whether climate change and global warming are affecting the timing of growth, flowering, and fruit ripening in plants. These changes can impact the entire ecosystem, for example – the impact on sources of food for insects and birds. Since winter 2014–15, flowering has been monitored every winter at Ramat Hanadiv along a marked route including 15 sample points, in the shrubland (garrigue) areas and in the cypress grove that had been thinned. The information gathered can assist in identifying and understanding changes in the ecosystem, may assist in planning management actions such as cattle grazing, and is a source of updated information about flowering for visitors hiking along the park’s trails.

Methods

Selected route and sampling frequency:

Fifteen sampling points, separated from each other by ~150 m, were marked along a fixed route. Sampling points were relatively open spaces with high representation of ephemerals (annual and perennial herbs). Each sampling point represents a 10-m-diameter circle. Sampling takes place fortnightly, at the beginning and middle of each month, between October and May.

Sampling methods for estimating flowering abundance in herbaceous plants:*

In each sampling point, the prominent flowering species are recorded. Flowering abundance of each species is estimated according to predetermined indices:

1–5 flowering individuals – abundance rank = 1
6–10 flowering individuals – abundance rank = 2
11–50 flowering individuals – abundance rank = 3
Above 50 flowering individuals – abundance rank = 4

*In woody plants, sampling takes place within a 20-m-diameter circle, and the ‘abundance’ is based on weighting of the number of flowering individuals and an estimate of flowering strength.

Trends and main findings:

Average rainfall during the five years of flowering monitoring (2015 – 2019) was 600 mm per year. During winter 2015 a ‘record’ 735 mm were recorded while winter 2016 was the driest with 456 mm.

The amount and distribution of the rain have a marked effect on the length

and intensity of the flowering, and affect the ‘behaviour’ of different species in different ways. In a late winter (rain beginning in December) a number of ‘flowering types’ were characterised (mainly among the early-flowering plants): most of the surveyed species flowered later, for a shorter period of time and with lower intensity. This group includes, for example, eastern groundsel (Senecio vernalis), poppy anemone (Anemone coronaria), annual clary (Salvia viridis), and cornflower (Centaurea cyanus). Some of the plants flowered later (between two weeks to one and a half months later) and at an intensity similar to that in years characterised by a wet autumn, for example, bunch-flowered daffodil (Narcissus tazetta) and onion grass (Romulea rosea).

Some species ‘give up’ and their presence in the field during a dry autumn is short and meagre. Prominent among these are autumn squill (Prospero autumnale) and field marigold (Calendula arvensis).

The peak of the flowering season along the monitoring route takes place during the first half of March. Wilting and desiccation take place during the second half of March. Dwindling of the flowering along the route is affected by

the amount and distribution of the rain, and is accelerated by the introduction of the cattle into the field.

Among the red flowers there is a time series: the anemones flower from December to early March; they are replaced by buttercups (Ranunculus) from late February until early April. A similar phenomenon was observed with the yellow daisies: the season is opened by eastern groundsel, field marigold and holy hawk’s-beard (Crepis sancta); later in the season we see endive daisy (Rhagadiolus stellatus) and Picris galilaea and the season ends with the tall daisies – Crepis palaestina and tuberous hawk’s-beard (Aetheorhiza bulbosa).

Prominent among the long-flowering species along the route are cyclamens and anemones, which begin flowering in late December and flower until March! (In years with a dry autumn, Anemone begins to flower only in late January). The ‘record-holder’ who ‘overtakes’ them in flowering time is bulbous dandelion (Leontodon tuberosus), which flowers from November to March!

We note that the title ‘behaviour types’ is based on a few monitoring seasons and only continued, long-term monitoring can validate their characterisation.

Any question? We will be glad to help