Plant biomass

Global Land Use

Global changes in human population and its land use (with its impacts on climate, ecosystems, biodiversity, and the functioning of the Earth’s long-term biogeochemical and biogeophysical systems) has increased over time and is now recognized as a transition into the Anthropocene. Only recently has there been a concerted effort to understand the causes and consequences of Earth’s anthropogenic transformation with the historical global mapping of human population densities, built structures and infrastructures, irrigation, crops, livestock grazing, and other patterns of human-altered vegetation cover. A first attempt to integrate global datasets into a single indicator (on a scale of 0 to 100), was The Human Footprint of 2002.^[14]

In 2020, Anthromes 12K was introduced as the first global historical anthrome maps for the 12,000-year period from 10,000 BCE to 2015 CE^[15] based on the latest HYDE 3.2 (History of the Global Environment, HYDE) database.^[16] This plots in graphic form the transition from hunter-gatherer burning land, to the emergence and spread of agriculture, accelerated during the major phase of global European colonial expansion, to the rise of large-scale urban industrial societies using the following categories of human land use (anthromes):

Plant Biomass – Historical background

The changing biomass of plants on planet Earth is a topic of great significance and interest within the realms of environmental science, ecology, and climate change. Over the course of Earth’s history, the biomass of plants has fluctuated in response to various factors such as climatic changes, geological events, and human activities. Understanding these changes is crucial for assessing ecosystem health, biodiversity, and the overall functioning of our planet.

Plant biomass refers to the total mass of plants present in a given area or ecosystem. This biomass plays a crucial role in regulating Earth’s climate, carbon cycle, and overall ecosystem stability. Plants, through the process of photosynthesis, absorb carbon dioxide from the atmosphere and convert it into organic compounds, releasing oxygen as a byproduct. This process not only fuels the growth of plants themselves but also helps regulate the levels of greenhouse gases in the atmosphere.

Throughout Earth’s history, the biomass of plants has undergone significant changes in response to various external factors. One of the most well-known examples of this is the impact of climate change on plant biomass. As global temperatures rise and weather patterns shift, plant distribution patterns and productivity levels are also affected. Some regions may experience increased plant growth due to warmer temperatures and longer growing seasons, while others may suffer from droughts, wildfires, and other extreme weather events that can decrease plant biomass.

Geological events such as volcanic eruptions, earthquakes, and shifts in tectonic plates can also have a profound effect on plant biomass. These events can alter landscapes, create new habitats, and disrupt existing plant communities, leading to changes in overall biomass. For example, a volcanic eruption can deposit nutrients into the soil, promoting plant growth in the aftermath.

Human activities, particularly deforestation, agriculture, and urbanization, have had a significant impact on the biomass of plants on Earth. Deforestation, in particular, has led to the loss of vast areas of forests, resulting in a decline in plant biomass and biodiversity. As trees are cut down for timber, agriculture, or development, the carbon stored in their biomass is released back into the atmosphere, contributing to climate change.

On the other hand, agriculture has played a role in increasing plant biomass in certain regions through the cultivation of crops and the use of fertilizers. However, intensive agricultural practices can also lead to soil degradation, nutrient runoff, and the loss of biodiversity, ultimately impacting plant biomass in the long term.

In recent years, there has been a growing concern over the impact of climate change and human activities on the biomass of plants worldwide. Studies have shown that global warming is altering plant distribution patterns, with some species moving to higher elevations or latitudes in search of suitable habitats. This shift in plant distribution can have cascading effects on ecosystems and biodiversity, as well as on the services that plants provide, such as carbon sequestration and habitat provision.

Efforts to monitor and assess changes in plant biomass on Earth are essential for understanding the consequences of these shifts. Remote sensing technologies, such as satellites and drones, allow scientists to track changes in plant cover, biomass, and productivity over large areas and long periods of time. These tools provide valuable data for studying the impacts of climate change, land use change, and other factors on plant biomass.

In conclusion, the changing biomass of plants on planet Earth is a complex and dynamic process that is influenced by a variety of factors, including climate change, geological events, and human activities. Understanding these changes is crucial for maintaining ecosystem health, biodiversity, and the overall functioning of our planet. By monitoring and studying plant biomass at a global scale, we can better assess the impacts of environmental changes and develop strategies for mitigating their effects. Only through a comprehensive understanding of these processes can we hope to protect and preserve the vital role that plants play in sustaining life on Earth.

Categories of human land use

Dense settlements: Urban and other nonagricultural dense settlements
Villages: Densely populated agricultural settlements
Croplands: Lands used mainly for annual crops
Rangelands: Lands used for pasture and livestock grazing
Seminatural lands: Inhabited lands with minor use for permanent agriculture and settlements
Wildlands: Lands without human populations or substantial land use

The first circumnavigation of the globe by Magellan’s maritime expedition of 1519 to 1522 established, by direct human physical experience, the spatial limits to a finite planet. Almost overnight, as European explorers charted the world’s continents, the map of the world drawn by Greco-Roman natural scientist and geographer Claudius Ptolemy (c. 100 – c. 170 CE) and used for well over a millennium, assumed the form of the world map that we are familiar with today.

The process of global animal and plant inventory began in earnest – a process that, for the higher plants is just beginning to draw to a close at around 350,000 species. But the amassing of kinds could not even hint at their quantity. Only in recent times has the technology of satellites and photogrammetry made it possible to estimate the quantities of organic matter on the surface of the Earth.

The MacCready Explosion

Only a few generations ago the world was considered a vast mysterious and unexplored realm. Today we are familiar with a steady inflow of information about the influence of the human population explosion that followed the industrial Revolution and the post-World War II Great Acceleration in population numbers. This greatly vamped up human demand on planetary resources affecting the Earth’s biogeochemical systems that prompted the naming of a new epoch, the Anthropocene.

One of the lesser-known phenomena is that of the MacCready explosion which relates to shifts in global biomass resulting from domesticated animals.

The ‘MacCready explosion’ claims that 10,000 years ago humans, their pets and livestock comprised around 0.1% of the terrestrial vertebrate biomass. Today this total has rocketed to 98% (MacCready 2004). Though a statistic that is difficult to substantiate, this is a stark reminder that superimposed on human demands for plant food and other resources are the demands on planetary ecosystems resulting from animal domestication.

Net primary productivity

Human appropriation of plant net primary productivity (HANPP) is a metric that tracks the percentage of global net primary production for human food, livestock production and fuel: it includes the loss of potential NPP due to human land use (Fig. 3). It is a benchmark indicator of human impact on the biosphere. From 1910 to 2005 HANPP almost doubled from 13% to 25% while population grew 2.7 times and GDP grew about 17 times (Krausmann et al., 2013; Haberl et al., 2014). The increasing harvest from forests and the additional land occupied by infrastructure has added little to HANPP. It is agriculture that dominates HANPP globally, representing 84–86% of total appropriation of plant growth over the entire period, with 42–46% on cropland and 29–33% on grazing land. We must also consider the impact of plant-energy-dependent domesticated animals. 

The pulse of plants sustaining the Earth

Plants are primary producers – food factories powered by sunlight. The Sun’s energy drives plant photosynthesis which builds up the plant matter that sustains all life on Earth – which includes our society and economy.

Gross primary production (GPP) shown here (click the link below), is the total amount of carbon dioxide ‘fixed’ by land plants per unit time.^[11]

Humans now take about a quarter of the Earth’s primary productivity which is is now generated by agricultural and horticultural crops – as food for humans.

This cartogram animation from Worldmapper uses satellite observations from NASA’s Moderate Resolution Imaging Spectroradiometer (MOD17) which detects the seasonal pulse of the Earth’s primary productivity. This is much like the pulse of a human heartbeat. The animation shows how the changing seasons determine the variability of energy production throughout the year. Production depends on land surface (e.g. desert, forest, crops) and climate/weather, the tropics being highly productive, especially in the northern hemisphere’s winter.