Let's Explore Biomass (2): "Conifers and broad-leaved trees" are as different as "sharks and dolphins"
Updated by Tatsuhiko Yamada on August 26, 2025, 8:52 AM JST
Tatsuhiko YAMADA
Forestry and Forest Products Research Institute, National Forestry Research and Development Institute
Senior Researcher, Forestry and Forest Products Research Institute, National Institute of Forestry Research and Development (NIFF) / Scientist who promotes the development of biomass-based materials. D. in 1998 from the Department of Biomaterials Science, Graduate School of Agricultural and Life Sciences, the University of Tokyo, he is also a professor at the University of Tsukuba and a visiting professor at Tokyo University of Technology. In 2023, he will establish Lignin Laboratory, Inc. as a director and CTO, and is also active as a player.
Biomass, which lexically refers to the quantity (mass) of living organisms (bio), is a term that has come to be recognized as a "biological resource" in contrast to fossil resources such as oil and coal. In other words, the term relates to "living organisms" living today, not to fossilized resources that lived in ancient times. Speaking of living organisms, all living organisms that exist today, including us humans, are creatures that have survived by successfully adapting to their environment through "evolution. When we think of evolution, we usually think of the evolution of animals that lead to us, such as fish, amphibians, reptiles, birds, and mammals, but forest biomass is not an animal but a plant. In this article, therefore, we will explore raw biomass from the perspective of "plant evolution.
Life originated in the oceans about 3.8 billion years ago. Then, about 3 billion years ago, cyanobacteria, a type of photosynthetic organism that generates oxygen from carbon dioxide, appeared. If plants are defined as photosynthetic organisms, then the organisms that incorporated cyanobacteria into their cells and formed chloroplasts can be considered to be the first to lead to the plants that flourish today. In any case, all this evolution happened in the sea. It seems that a variety of organisms were dynamically evolving in the ancient oceans.
On the other hand, the birth of land plants is thought to have occurred about 450 million years ago. Plants that came to land seem to have faced great difficulties. They had to deal with the problem of water, as well as gravity and wind and rain on the ground. In terms of water, plants had to take in water from the soil efficiently because there was not enough water on land, whereas there was plenty of water in the water. To accomplish this, plants have created a special system for transporting water called "vascular bundles. This is believed to have enabled them to carry the water they needed to the tops of taller trees, allowing them to grow larger.
On the other hand, gravity and wind and rain are also major problems, which is very different from the environment in which plants were left to fend for themselves underwater. The gravity on the ground is strong and the wind and rain are terrible, and to withstand this, plants needed to make themselves strong and flexible. To achieve this, plants are believed to have acquired a composite material structure in which cellulose fibers are firmly supported by components known collectively as hemicellulose and lignin. This structure and vascular system is believed to have constituted a forest of plants reaching several tens of meters in length some 380 million years ago. This is the birth of forest biomass, which is said to be the largest amount of biomass on earth.
Looking at the forest today, one can see that there are two main types of forests: coniferous forests and broadleaf forests. These forests have very different atmospheres, and anyone can sense the difference between them. This sense is actually very important, but in the use of timber, both types of forests are interpreted as a single group of trees.
However, it is important to deeply understand that conifers and hardwoods are different organisms when it comes to biomass utilization. In fact, they have different lines of evolution. In plant phylogeny, conifers are gymnosperms and broadleaf trees are angiosperms. In animal terms, these lines can be thought of as being as different as fish and mammals.
Suppose you were enjoying diving in the southern ocean. Then a large fish shadow approaches from offshore. You braced yourself, thinking, "It's a big shark! You braced yourself, thinking it was a big shark, but when you looked closer, you saw that it was a charming dolphin. Sharks and dolphins are about the same size and look similar from a distance, but they are not treated in the same way. Sharks are fish and dolphins are mammals. In terms of evolutionary phylogeny, sharks and dolphins can be interpreted as different organisms that happen to be at the same level of size.
The phenomenon in which different organisms become similar in appearance through the process of adapting to a similar environment is called "convergent evolution," while those that look similar but are different are called "dissimilar in appearance. On the other hand, if we consider plants, Japanese mountains have so-called "mixed coniferous and broad-leaved forests" where coniferous trees and broad-leaved trees grow unevenly. This is the equivalent of a shark and a dolphin swimming together in the ocean. Although conifers and broadleaf trees are lumped together as trees due to convergent evolution, they are similar in appearance but different in quality.
Let us now consider the origin of gymnosperms and angiosperms. The origin of gymnosperms is ancient, about 380 million years ago, while that of angiosperms is much younger, about 140 million years ago. Angiosperms are at the forefront of evolution, and it is fair to say that most plants today are angiosperms. In fact, the number of species of angiosperms is overwhelmingly large, with approximately 220,000 species known at present. Most of the plants and flowers around us and most of the crops cultivated today are angiosperms. On the other hand, the number of gymnosperms is extremely small, with only 800 species.
Although it is believed that the angiosperms differentiated from gymnosperms, the fact is that they do not seem to be well understood. Even in phylogenetic trees, no evidence has been found to link the lineages, making them the so-called "missing link. In the case of trees, it is a mistake to assume that existing conifers directly evolved into broad-leaved trees. It is more correct to think that the lineage of the conifers that evolved to become perennial and grow large became broadleaf trees. The author sensibly understands that broadleaf trees are flowering plants that evolved to grow large and are a separate organism from conifers. In fact, broadleaf trees have much in common with herbaceous species in the components that make up broadleaf trees, and are very different from conifers.
At any rate, the ground is dominated by a wide variety of angiosperms. A characteristic feature of angiosperms is that they are plants that have their own germplasm encased in an ovule, which flowers, reproduces by seed, and produces fruit. These are strategies to have their reproduction mediated by other organisms, so they need an environment where insects and birds can carry their seeds. Conversely, it can be said that these organisms cannot survive without such rich biodiversity, and in fact, angiosperms prefer to coexist with a wide variety of organisms. This is also the reason why broadleaf forests are composed of a wide variety of plants and animals.
On the other hand, conifers, which are gymnosperms, do not require the mediation of other animals for reproduction. This may be the reason why coniferous forests prefer to be composed of a single species. Reproduction is only done by wind-driven pollen dispersal, without the mediation of other organisms. It can be said that they do not allow others to take advantage of their own reproduction. This means that if biodiversity collapses due to environmental changes, most of the angiosperms will soon become extinct, but gymnosperms will probably survive. In fact, gymnosperms survived the worst natural catastrophe in the history of the earth, which is said to have wiped out more than 90% of the species at the end of the Permian period about 250 million years ago. The conifers and other trees that survive today may be carefully selected members of gymnosperms.
We know that fish and mammals are different organisms, and in cooking, fish meat and beef are prepared differently. This is because their properties are fundamentally different. In plants, this difference is equivalent to the difference between gymnosperms and angiosperms. Biorefineries, for example, which utilize the components of biomass, are the culinary equivalent. Naturally, the cooking methods of gymnosperms and angiosperms are very different. I will discuss the differences in their ingredients and suitable cooking methods in the next article. I will discuss the differences in composition and suitable cooking methods in the next article. (Tatsuhiko Yamada, Senior Researcher, Forestry and Forest Products Research Institute, National Institute of Forestry Research and Development)
