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in the sea annually), it is estimated that by 2050 the weight of plastics in the ocean will be greater

than the sum of the weight of all the fish in the biosphere.
4. Climate change. Approximately 14% of the relative importance of threats is related to climate
change. In addition to altering locally highly biodiverse ecosystems (such as coral reefs) it has

global effects by causing acidification of the water.
5. Invasive species. Contributing values of about 10%. Accidental or intentional, the number of
species that, once introduced into a habitat they are not part of, have high reproductive success
and colonise the environment has increased when the intensity of transport in the ocean has
increased.

SDG 15 – Life on Land

Human life depends on the land as much as on the ocean for its sustenance and survival. Plants
provide 80% of human food and agriculture represents an important economic resource and
means of development. Forests, in turn, cover 30% of the earth's surface, provide crucial habitats
for millions of species and are an important source of clean air and water. They are also
fundamental to combating climate change (Leal-Filho, 2021; United Nations, 2022; IBERDROLA,
2022).

SDG 15 focuses specifically on the sustainable management of terrestrial ecosystems, halting
and reversing the degradation of land and natural habitats and forests, successfully combating
desertification and halting biodiversity loss (Keesstra et al., 2016; Behradfar et al., 2022). It is
therefore necessary to have evaluation mechanisms in place to monitor the targets and indicators

of SDG 15 (Ansari et al. 2021).
● Forest management

Forests play a significant role in regulating the global carbon cycle, as they store gigatons of
carbon each year. It is therefore a growing concern to decrease greenhouse gas (GHG) emissions
from deforestation and forest degradation as a step towards climate change mitigation (Avtar et
al., 2020). Forest cover and condition are influenced by a number of factors: growing population
(selective logging for increased demand for food and other commodities); large forest fires;
fragmentation; pests and diseases (Sayer et al. 2019).

The total global forest area in 2020 was 4 060 million hectares (ha), corresponding to 31 percent
of the total land area (0.52 ha per person), although forests are not evenly distributed by world
population or geographic location (FAO, 2020). Tropical areas hold the largest proportion of the
world's forests (45 percent), with the remainder located in boreal, temperate and subtropical
regions. Between 1990 and 2020, 5.9 million hectares of forest were lost per year (178 million

hectares), although the rate of net loss declined over those 30 years (-7.8 percent in 1990-20,
compared to -4.7 percent in 2010-20). This has been due to a reduction in deforestation, in
addition to afforestation campaigns and natural forest expansion. Forests face many disturbances

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