Climate change impacts on salt marsh vegetation ecophysiology and dynamics

Duarte, Bernardo

http://hdl.handle.net/10451/25068

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Autores

Duarte, Bernardo

Orientador(es)

Caçador, Maria Isabel Violante, 1953-

Marques, João Carlos

Resumo(s)

Ecosystems worldwide are experiencing the effects of climate change, and estuaries and salt marshes are no exceptions. Being highly productive, the plant community will be one of the most affected elements by these climatic shifts, both in terms of structure and dynamics, with undeniable effects on its productivity. This thesis aimed to study the effects of climate change on the marsh community dynamics, structure and productivity but also on its biogeochemical cycles and implications at the ecosystem level services. Although special attention was given to primary productivity and plant physiology, a multi-disciplinary approach was undertaken using both field assessments and mesocosmos trials were conducted. The results point out that these physically connected climatic changes are not only interconnected on a physical way, but also at an ecological level. Mediterranean marshes will be more severely affected on its foundations, putting the entire ecosystem at risk and prone to climate change side effects and/or to synergistic events. The majority of the evaluated climatic changes have its more negative impacts on the marsh pioneer species, affecting inevitably the marsh establishment and expansion. Although in a smaller extent, also the upper and middle marsh halophytes will suffer from these climate-driven negative impacts. Alongside the appearance of resistant non-indigenous species (NIS) will add an increased threat to the marsh. The reduction of the pioneer zone in a large extension together with a middle marsh fragilization will open new ecological niches for the colonization of resistant NIS, imposing serious shifts in the marsh structure, dynamics and services provided to the estuarine ecosystem. This is even more evident when a holistic approach is undertaken focusing not only plant physiology but also the marsh biogeochemistry and the estuarine hydrological features. All these evidences point out to the need to adopt new management efforts, highlighting the desired marsh attributes and ecosystem services in the face of human activities that threaten salt marsh ecosystems.