Global loss of floristic uniqueness

The study The global loss of floristic uniqueness, published in the Nature communications, takes an alarming retrospective

by Lorenzo Ciotti
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Global loss of floristic uniqueness

With the appearance of plants, photosynthesis began on the Earth. Plants absorb CO2 and emit O2. The accumulation of the latter in the atmosphere favored the appearance of animals, which use it to breathe, emitting CO2. Tropical forests currently occupy the equatorial region of the planet and there is a temperature difference of 50°C between the Equator and the Pole.

65 million years ago the temperature was 8°C higher than it is today and the temperature difference between the Equator and the Pole was only a few degrees. An increase in the global average temperature would lead to areas in the middle latitudes more subject to desertification phenomena, also by virtue of the prolonged absence of atmospheric precipitation due to drought phenomena and heat waves.

Recent climate changes have been analyzed in more detail only since the last fifty years, that is, since human activities have grown exponentially and observation of the upper troposphere has become possible. All the main factors to which climate change is attributed are linked to human activities.

The study The global loss of floristic uniqueness, published in the Nature communications, takes an alarming retrospective. The researchers explain: "Regional species assemblages have been shaped by colonization, speciation and extinction over millions of years.

Humans have altered biogeography by introducing species to new ranges. However, an analysis of how strongly naturalized plant species (i.e. alien plants that have established self-sustaining populations ) affect the taxonomic and phylogenetic uniqueness of regional floras globally is still missing.

Here, we present such an analysis with data from native and naturalized alien floras in 658 regions around the world.We find strong taxonomic and phylogenetic floristic homogenization overall, and that the natural decline in floristic similarity with increasing geographic distance is weakened by naturalized species.Floristic homogenization increases with climatic similarity, which emphasizes the importance of climate matching in plant naturalization.

Moreover, floristic homogenization is greater between regions with current or past administrative relationships, indicating that b eing part of the same country as well as historical colonial ties facilitate floristic exchange, most likely due to more intensive trade and transport between such regions.

Our findings show that naturalization of alien plants threatens taxonomic and phylogenetic uniqueness of regional floras globally. Unless more effective biosecurity measures are implemented, it is likely that with ongoing globalization, even the most distant regions will lose their floristic uniqueness."