Living in Canada it is hard for us to realize the impact humans have had on the world’s forests and natural grasslands over that past 100 years.
While in B.C. we have been impacted by insects and wild fires in the last few decades most of the changes will start to heal in a few years but in much of the world most of the changes are permanent with more destruction to come as humans continue to dominate and displace the wild component. In most cases the amount of change is directly related to the population density with the number of people per square kilometre as follows: China 153 , India 460, Bangladesh 1253 and Canada 4.
In B.C. we have had some significant losses in old growth forests and interior grasslands which has impacted some of our native birds it has not been as severe as other parts of the world. Some recent research has shown that loss of habitat has been hard on the wild bird populations. The researchers estimated changes in the populations of 529 species using long-term bird-monitoring databases. This data showed that the number of individual birds across all of those species had decreased by 29 per cent, from around 10 billion in 1970 to just over seven billion in 2017.
Because of major size differences in many species most new research converts numbers into biomass so comparisons between species was more reliable. Initial literature reviews indicated there wasn’t a comprehensive, holistic estimate of all the different components of biomass. To solve the absence of data Prof Ron Milo, at the Weizmann Institute of Science in Israel lead a team of scientists who have shown that the world’s 7.6 billion people in 2018 represent just 0.01 per cent of all living things.
“Yet since the dawn of civilization, humanity has caused the loss of 83 per cent of all wild mammals. The new work is the first comprehensive estimate of the weight of every class of living creature and overturns some long-held assumptions. Bacteria are indeed a major life form – 13 per cent of everything – but plants overshadow everything, representing 82 per cent of all living matter. All other creatures, from insects to fungi, to fish and animals, make up just five per cent of the world’s biomass.
“Another surprise is that the teeming life revealed in the oceans by some television series turns out to represent just one per cent of all biomass. The vast majority of life is land-based and a large chunk – an eighth – is bacteria buried deep below the surface.”
The transformation of the planet by human activity has led scientists to debate declaring a new geological era (the Anthropocene) with one of the suggested markers being the huge increase and impact of the domestic chicken. As pointed out by author Milo, while we often we see huge flocks of native birds, of every kind, they found there are [far] more domesticated birds.
“Since the advent of domestication, humans have skewed the breakdown of species. Today, wild mammals account for just over four per cent of mammal biomass on Earth. In contrast, the biomass of livestock, the bulk of which are cattle and pigs, is more than 14 times the biomass of their wild cousins.”
While Canada has converted some native grasslands and forests for domesticated animal use it is minor compared to some tropical forests which are being burned to produce short term grasslands for cattle production.. The massive fires in Brazil this summer are just one example.
The implications for humans are obvious, as we lose biodiversity and create huge monocultures, the planet is much more susceptible to catastrophic losses due to plagues and diseases outbreaks.
Jim Hilton is a professional agrologist and forester who has lived and worked in the Cariboo Chilcotin for the past 40 years. Now retired, Hilton still volunteers his skills with local community forests organizations.