On August 28, the reference news network reported that the British "Nature" weekly published an article entitled "We must master forest science - it is still too late" in an issue of the British "Nature" weekly on August 18. The full text is excerpted below:
Forests are one of our biggest hopes for carbon.
How are forests responding to climate change? Humanity's understanding of this is extremely scarce. Take the phenomenon of "carbon fertilization" as an example – if the concentration of carbon dioxide in the atmosphere increases, plants will absorb more carbon dioxide. This is one of nature's main mechanisms to date to save us from the worst effects of climate change, but we know very little about its future trajectory. In fact, researchers don't fully understand the interaction of climate change with various forest change processes. Complex and unresolved questions include how warming affects forest health, how warming affects the carbon sink function of forests, and whether warming will alter the ecosystem services provided by forests. Forests are our life support system, and we should take the pulse of the forest more seriously.
Six papers in the journal Nature this week provide important insights into these issues. The papers also highlight a number of challenges that must be overcome in order to fully understand the potential of forests in addressing climate change. These challenges lie not only in the science itself, but also in how forest scientists collaborate, how to get funding (especially in data collection) and how to train them.
Learn about vegetation diversity
Forest science is a mixture of disciplines. Ecologists and plant scientists measure tree growth, soil nutrients, and other parameters in thousands of forest plots around the world. Physical scientists use remote sensing data from drones or satellites to monitor factors such as forest height and above-ground forest biomass. Experimental scientists study how forests might react in a warming world by artificially changing factors such as the temperature of the experimental plot or carbon dioxide levels. Some of the resulting data was absorbed by another group: modelers, who created dynamic global vegetation models (DGVM). These models simulate how the carbon and water cycles change with climate change, informing the broader Earth system and climate models to inform policymaking.
Different DGVMs make different predictions about the duration of forest absorption of anthropogenic carbon dioxide. One reason for the discrepancy is that the model is sensitive to assumptions about forest change processes. There are many influencing factors – including temperature, humidity, fire and nutrients – that are generally studied separately. However, they interact with each other.
For example, not all DGVM take into account the inhibitory effect of soil phosphorus deficiency on carbon fertilization. Phosphorus levels are low in much of the eastern central Amazon basin, and studies have shown that introducing phosphorus limiting factors into the DGVM reduces the carbon fertilization effect. This week, Helen Fernanda Viana Cunha of the National AmazonIan Research Institute in Manaus, Brazil, and her colleagues reported an experiment demonstrating how a lack of phosphorus in the soil limits carbon uptake in ancient Amazonian forests.
Roman Dale and his colleagues at the University of the Pacific in Alaska, anchorage, say models that simulate the northward diffusion of leaf forests as temperatures rise also lack key drivers. They reported an unexpected northward migration of a species of white spruce to the Arctic tundra. To explain this, it is necessary to take into account the winter winds (which contribute to the spread of long distances) and the deep snow and soil nutrients (which promote plant growth).
Increase model complexity
Models are typically based on a small number of "functional tree types"—for example, "evergreen broadleaf" or "evergreen conifers." These trees were chosen as representatives of more than 60,000 known tree species on Earth. However, ecologists have found that the biology of individual tree species is important to understand how a tree responds to climate change.
In May, David Bowman and his colleagues at the Institute for Environmental Change at the University of Oxford in the United Kingdom reported that tree mortality rates had doubled (halving life expectancy) on 24 humid tropical lands in northern Australia over the past 35 years, apparently as a result of increasingly dry air. But that's the average mortality rate for 81 major tree species: there is a big difference in mortality between tree species, and this difference seems to be related to the density of the forest.
Peter Reich and his colleagues at the University of Michigan's Ann Arbor Institute for Global Change Biology report that slight changes in temperature and rainfall can lead to different tree species growing and surviving different species in the southern part of the Northern Leaf Forest. Thriving tree species are rare.
The model fails to look at multiple factors at the same time, so scientists are making conclusions that challenge the model's hypothesis. For temperate forests, spring comes earlier, and most models suggest that the growing season is therefore extended, so the biomass of the wooden trunk increases. However, Christina Anderson-Teixeira of the Royal Front Smithsonian Institute for Conservation Biology in Virginia and her colleagues found no sign of this happening in temperate deciduous forests. Modelers are well aware of the need to increase the complexity of the model. But they need more data.
Ensure the continuity of funds
Getting comprehensive, valuable data for a model requires continuous, long-term observation, depending on access to long-term funding. Ensuring continuity is an issue for both remote sensing and ground operations. The former could cost hundreds of millions of dollars, but the value of its long-term dataset is enormous, as evidenced by a team led by Giovanni Foziri of the University of Florence in Italy. Using 20 years of satellite data, the team showed that nearly a quarter of the world's primary forests have reached a tipping point of sharp decline. In contrast, field-based data collection operations are low costly but financially difficult.
The Global Forest Earth Observatory (ForestGEO), an important organization engaged in ground operations, is affiliated with the Smithsonian Tropical Institute, headquartered in Washington, D.C. ForestGEO monitors 7.5 million trees around the world, and the workload is enormous. For example, ForestGEO is currently conducting an eighth (five-yearly) census of a plot in Peninsular Malaysia, which includes identifying populations of 350,000 trees (about 800 trees in the area) and measuring the circumference of each trunk. 16 technicians are required each year to measure all the trees. Similar census operations in Papua New Guinea, Viet Nam, Brunei and Ecuador have been hampered by inadequate funding from ForestGEO.
Australia has provided Bowman with 49 years of continuous data for the North Queensland parcel, which is rare, but whether it will be maintained in the future is also unknown. Since the mid-1970s, CSIRO, Australia's public research funding agency, has been monitoring – initially every two years and more recently every five years. In 2019, due to CSIRO's funding shortage, the monitoring of the relevant plots was changed to once every 50 years, and scientists had to find new sources of funding.
Without continuity of funding, institutions like ForestGEO cannot guarantee that researchers have the necessary skills or collect data outside of the funding cycle. Stewart Davis, head of ForestGEO, said: "We trained some talent, but because the job was unstable, the talent was lost."
Different forest research groups are trying to solve these problems. ForestGEO is coordinating with the Tropical Forest Science Alliance to facilitate data sharing and boost the morale of skilled workers and scientists, many of whom live in low- and middle-income countries and are responsible for much of the data collection.
But we also need more imaginative funding mechanisms. For example, space agencies that fund remote sensing satellites could work with other funding agencies to strengthen terrestrial data collection capacity. Journals can also take steps to encourage long-term data collection.
In addition, more interdisciplinary collaboration is needed. The U.S. Department of Energy is funding a project called NGEE-Tropics (Next Generation Ecosystem Experiments – The Tropics). Modelers of the project will collaborate with researchers engaged in observations and experiments to build a complete model of a tropical forest that encompasses a rich process of change. This is encouraging and can be further promoted.
We need to remember that the edifice of forest science relies on long-term data that scientists have taken from forests for decades. Our chances of overcoming climate change are slim, but if we forget to monitor the basic work of the planet, our chances of overcoming climate change are getting smaller and smaller.
Photo: Cover of an issue of the British weekly nature magazine on August 18
Source: Reference News Network