In-Nitro: conceptualização dos efeitos do aumento da disponibilidade de azoto num ecossistema mediterrânico

As human populations grow, so do the global impacts of reactive nitrogen (N) released into the biosphere as a result of increased

agro-industrial activity (from fertilizer use and fossil fuel emissions - Galloway et al 2008). Since the stability of many natural and

semi-natural systems depends upon low fertility, ongoing and predicted N enrichment has the potential to strongly alter natural

environments. A global assessment of N deposition effects on terrestrial plant diversity acknowledged that although ecosystems in

northern Europe and America (mostly temperate ecosystems) have received considerable scientific attention others were seriously

understudied (Bobbink et al 2010). This omission represents a significant gap in our understanding of the long-term effects of N

deposition on ecosystem diversity and function regionally and globally. Underpinning knowledge of the observed and potential

effects of changes in N availability is therefore needed across European and global ecosystems to develop predictive understanding

and mitigation-adaptation management strategies that sustain valued natural ecosystem diversity and services. In this proposed

research we will address this scientific ‘gap’ in a vulnerable and globally important Mediterranean ecosystem (ME - Phoenix et al

2006) in the south region of Portugal. Most knowledge of the effects of N deposition on ME comes from California (Ochoa-Hueso et

al 2011). Although these studies are important and interesting there is clearly a need to test ideas to develop policy within the

European Union where the influences of local economics, culture and land use are significantly different than in the USA.

The In-Nitro team gathered members and consultants that are top researchers in their areas of expertise, which will contribute to

put the response of ME to N enrichment in the ‘World Map of the N problem”. The focus on ME has already started with the

establishment of the critical levels (Pinho et al 2009) and loads (Bobbink and Hettelingh 2011) of N for this ecosystems. The

implementation of this proposal will allow that novel and important Portuguese funded research is recognized within the wider

scientific arena (papers, presentations, other outputs). This effort will also support the influence of Portuguese research in the

development and implementation of EU policy regarding N deposition and ecosystem diversity and function.

Ecosystem functions depend on biodiversity attributes, but nearly all empirical research linking biodiversity and ecosystem

functioning has focused on terrestrial systems with low structural complexity (Montès et al 2008). Mediterranean Basin ecosystems

offer an opportunity to fill in this gap, since they biodiversity hotspots (Phoenix et al 2006) with high structural complexity. The

participation of some team members in previous FCT funded projects (POCTI/39230/BSE/2001; SFRH/BD/25382/2005; PTDC/BIABEC/

0999323/2008) enabled the understanding of the advantages of approaching the responses to N in a functional group (FG)

perspective. In fact we identified groups of organisms that responded differentially to N availability, thus extending the concept of

FG also to N use strategies (Cruz et al 2008). This awareness of the importance of FG developed into the idea of establishing an

intensive multilayer approach in a representative site of the Mediterranean Basin that would allow an integrated view of the N

biotransformations above and below-ground according to FG of plants (PFG) and soil microorganisms (MFG);

The long-term high N loading affecting many contrasting ecosystems, particularly in areas such as northern Europe make it difficult

to ‘catch’ the initial response of an ecosystem formerly subjected to a low N loading but that is presently under N enrichment. Thus,

the N manipulative experiment, which started in 2007 (PTDC/BIA-BRC/099323/2008) is a unique opportunity to study the different

stages of the ecosystem response to increased N availability.