The pivotal role of palaeoenvironmental studies for understanding Earth System dynamics has been highlighted in international forums in many occasions, particularly those dealing with the rapid and abrupt fluctuations that our planet is experiencing under the current Global Change. Understanding the effects of these climate oscillations on the Earth systems needs a long-term perspective only provided by precise and detailed environmental reconstructions that may improve existing predictive models of climate, environmental and societal change, as well as it may help to the definition of more accurate policies for the Earth system conservation.
Some of the questions that have been itching my curiosity lately and the funding or outputs associated to them are these:
1) Can changing fire-regimes affect irreversibly landscape dynamics?
Increasing fire intensities and frequencies over the past 50 years in the Iberian Peninsula have raised the public concern on the importance of climate change and human actions in fire dynamics, how the ecosystems can cope with changing fire regimes, and the economic and social problems related to fire-forest dynamics. Thus I have lately focused my research on the long-term fire ecology in Mediterranean (Gil-Romera et al., 2010) and alpine environments (Gil-Romera et al., 2014). I am interested on analysing fire as an Earth System process, testing hypothesis linked to biomass, climate, and human activity on changing fire regimes and its effect on landscape post-fire response in Mediterranean and alpine ecosystems, under the threat of intenser fires.
In connection with this I have obtained funding from two projects ARAFIRE and PYROS in which I am the PI.
2) How resilient are drylands when stressed by climate or human disturbances ?
The arid regions of the world are key to understand past environmental dynamics and long-term climate processes. Climate variation in these regions may trigger ecosystem threshold responses, however, suitable archives preserving biological proxies are scarce. This is especially the case of the Namib and Kalahari Deserts or the semi-arid savanna fringe of East Africa. Given the paucity of appropriate basins containing palaeoenvironmental records, I have contributed to the development of the use of hyrax middens – organically-rich fossil biogenic accumulations formed by the animal pellets and urine – that are able to store pollen and charcoal that eventually get fossilized. From there, I have reconstruct past rianfall patterns in the Namib desert (Gil-Romera et al., 2007) and the long-term biotic interactions of fire, pastoralism and vegetation (Gil-Romera et al., 2010)
In this slideshow showing some arid areas in Namibian and Southwestern Ethiopian locations where I have developed my research on palaeoenvironmental reconstructions using hyrax middens.
Despite not extremely arid, many areas of the Iberian Peninsula are lacking suitable basins preserving records of environmental change. Inspired by the success of African palaeoenvironmental reconstructions using hyrax middens (Chase et al., 2012, Scott and Vogel, 2000 amongst many others of Prof. Louis Scott and Dr Brian Chase) in 2010 I obtained funding to study fossil biogenic accumulations at the Pre-Pyrenees area (Huesca, Spain) with the project PALEOLETRINA.
3) Can we reconstruct past landcover from fossil pollen spectra?
It is well known that pollen-vegetation relationships are not linear, so from fossil pollen abundances it is not possible to infer accurately past vegetation cover. This is however a truly important parameter, from simply interpreting vegetation dynamics more accurately to defining land cover feedbacks into climate dynamics, establishing species palaeo-distribution models or determining biotic and abiotic interactions in vegetation. There has been in recent years a great development on the definition of robust quantitative pollen-vegetation relationships (Sugita, 2007a, 2007b)
Since 2010 we have been monitoring pollen rain in different locations in North Eastern Spain and through vegetation surveys we have obtained the first results on pollen productivity estimates (PPEs) which are necessary to produce precise past land cover reconstructions (Gil-Romera et al., in prep).
4) Can we deduce past ecosystem functioning from proxy records?
Looking to current ecosystem processes as bush encroachment in savannas, I have tried to define resilience patterns in semi arid savannas as those of South Western Ethiopia. Using theoretical concepts of equilibrium systems, I have identified hysteresis loops in savanna ecosystems (Gil-Romera et al., 2010) from the use of multivariate methods applied to the pollen and charcoal records.