18th European Orchid Council Conference “What future for orchids?”, Paris, 24-25 March,2018
Can terrestrial orchids keep pace with a changing climate? A study case in Central Italy Sara MAGRINI1, Sergio BUONO2, Emanuele GRANSINIGH2, Massimiliano REMPICCI2 & Laura ZUCCONI1,3 ¹Tuscia Germplasm Bank, Tuscia University, Largo dell’Università, I-01100 Viterbo, Italy, e-mail:
[email protected] 2GIROS - Italian Group for Wild Orchid Research, “Etruria meridionale” Section, I-01010 Oriolo Romano (Viterbo), Italy 3Department of Ecological and Biological Sciences, Tuscia University, Largo dell’Università, I-01100 Viterbo, Italy
The study area Many natural systems are being affected by global climate change, especially by temperature increase and drought. The effects on orchid populations are difficult to predict but evidence from our studies suggests that the recent climatic trend is already affecting the distribution and reproduction of many species in Central Italy and that some orchids are likely to be more vulnerable than others. Particularly, in Northern Latium, a warming climate, together with ever more frequent and extreme droughts, is threatening with extinction some terrestrial orchids living in the so-called “depressed beech forests” which grow at a lower altitude than typical, 400-600 m a.s.l.
A changing climate The maps of the Standardized Precipitation Index (SPI) show how the precipitation trend was changed during the last 10 years in Central Italy. Particularly, in the beech forests of Oriolo Romano and Monte Venere (black dot in the maps), an increasingly dry climate was experienced in May-June. Observing the 2007-2017 series of SPI related to the study area in the graphs below, June seems to be the most critical period. Standardized Precipitation Index
Standardized Precipitation Index
Standardized Precipitation Index
May 2007-2017
June 2007-2017
July 2007-2017
3
3
2
2
2
1
1
1
0 -1
SPI
3
SPI
SPI
Beech forest Oriolo Romano (Viterbo)
0 -1
0 R² = 0,4779 -1
R² = 0,6424 -2
-2
-3
-3
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
Beech forest Mt. Venere, Caprarola (Viterbo)
Effect on terrestrial orchids
R² = 0,7749
-2 -3
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
In fact, the last years have been characterized by long periods of drought together with very high temperatures reaching 35-39°C in June.
Maps of the Standardized Precipitation Index (SPI) at a 3-month scale. This meteorological drought index is obtained through a normalization of the rainfall probability distribution, estimated from the long-term local precipitation records. Positive SPI values indicate greater than median precipitation, and negative values indicate less than median precipitation (www.isprambiente.gov.it). The black dot indicates the study area comprising the beech forests of Oriolo Romano (VT) and Monte Venere, Caprarola (VT)
Orchids are particularly sensitive to habitat fragmentation or changes due to human disturbances and their effects, so many environmental and anthropic factors determine their distribution, decline, and risk status. Especially, climate change is widely expected to drive species extinct by hampering individual survival and sexual reproduction – particularly vulnerable to global warming effects – by reducing suitable habitat, or by eliminating essential organisms, like pollinators or mycorrhizal fungi [1,2,3]. In beech forests of Northern Latium, orchids with a late-spring/summer flowering result extremely vulnerable, as unable to survive the prolonged drought periods which have characterized the last years. In fact, our monitoring has highlighted a drastic loss of reproductive success in orchids like Dactylorhiza maculata, Cephalanthera rubra and several Epipactis species (E. placentina, E. gracilis, E. helleborine, E. microphylla), more and more often unable to reach the fruiting and seed dispersal phases, which should occur in summer.
Flowers dried before pollination
Plants died before blooming after 20 days without rain and 10 days with Tmax = 30-35.7°C
Cephalanthera rubra 9th July 2016
after 40 days without rain and 3 weeks with Tmax = 30-37.2°C
Conclusion
after 20 days without rain and Tmax = 33-38.5°C
Dactylorhiza maculata 14th June 2014
after 30 days without rain and Epipactis placentina [EN] 2 weeks with 28th June 2011 Tmax = 30-35.3°C
A significant biodiversity loss is foreseeable in such beech forests through local decline and extinction of orchid populations, due to the increasing temperatures and drought.
So, what future for these orchids?
Epipactis placentina seeds (bar=100 µm) and vials for long-term conservation
When habitat preservation is not possible, ex situ conservation through seed-banking can help to respond to these challenges, providing a long-term security backup for species and their genetic diversity [4]. For this purpose, the Tuscia Germplasm Bank preserves seed-lots collected from these vulnerable populations in Central Italy [5,6].
Epipactis gracilis 17th June 2012
REFERENCES 1. Hughes L., 2000. Biological consequences of global warming: is the signal already apparent? Trends in Ecology & Evolution 15(2): 56-61. 2. Memmott J., Craze P.G., Waser N.M., Price M.V., 2007. Global warming and the disruption of plant–pollinator interactions. Ecology Letters 10: 710–717. 3. Hedhly A., Hormaza J.I., Herrero M., 2009. Global warming and sexual plant reproduction. Trends in Plant Science 14(1): 30–36. 4. Seaton P.T., Hu H., Perner H., Pritchard H.W., 2010. Ex situ conservation of orchids in a warming world. Bot. Rev. 76: 193–203. 5. Magrini S., Rempicci M., Buono S., Gransinigh E., 2012. Ex situ conservation of Epipactis placentina Bongiorni & Grünanger (Orchidaceae) in Latium (central Italy). J. Eur. Orch. 44(2): 501-510. 6. Magrini S., Buono S., De Vitis M., Haile G., Rempicci M., Gransinigh E., Scarici E., Fonck M., 2014. Conservation of endemics, rare and threatened Italian orchids in Botanical Garden and Tuscia Germplasm Bank (Viterbo, Central Italy). J. Eur. Orch. 46(1): 103-114.
