Introductory Chapter: Bryophytes - Why Should We Study Them?

1. Introduction

Bryophytes are indeed an amazing group! For more than 470 million years, they have advanced over terrestrial environments, being responsible for the formation of the first layers of organic soil. This allowed the installation of other terrestrial plants and was responsible for about 1/3 of the oxygen available for the breathing of all living beings that later occupied these environments [1].

They cover a very large area of the planet, generally where other plants cannot grow. If we consider mountains, much of the tundra and taiga and the bark of trees which are covered with mosses, the photosynthetic area is probably greater than that of other plants combined, even though they are so small and delicate. In boreal forests, mosses may be the smallest components in biomass, but they represent the greatest coverage and have the highest primary productivity, in addition to being faster in the accumulation of nutrients, contributing to the thermal development of the environment with consequent development of the permafrost. In this way, they positively affect nutrient cycling in these ecosystems, affecting also the vascular plants [2]

Bryophytes are of unparalleled resistance, sprouting again after hundreds of years covered by ice (from 400 to 1530 years—already detected) or even if kept for years in herbaria in conditions of extreme dehydration and darkness. There are even specific genes to resist to climate changes [3, 4, 5, 6].

2. Bryophytes and the environmental changes

Climate change is affecting the group very deeply, in particular because they are very dependent on water, including for their sexual reproduction, as they have flagellated antherozoids. Even in environments where they are the dominant flora, such as in maritime Antarctica, species may have their occurrence threatened in the face of climate change. This is also the case of boreal areas and high mountains ecosystems [7]. Bryophytes can even be used for monitoring and as an indication of the effects of climate change on living organisms. They have even been indicated as “canaries in the coal mine” with regard to their behavior in relation to the external environment [8]. As a result, they are symbols of eternity in some cultures.

This group has very simple thalli, with leaves generally formed by only one layer of cells, stems without conductive tissues and rhizoids only one cell thick, which obtain their nourishment directly from atmospheric humidity, from the soil or substrate where they are fixed. Many react quickly in the presence of pollutants and can be used to monitor and control them. Morphological and even genetic modifications in relation to the toxicity of polluting metals or even the stress caused by their presence can be followed, making them first-class bioindicators [9, 10]. Many species are extremely sensitive to pollutants, suffering some injuries or even resulting in the death of the entire thallus, while others are very resistant, even managing to retain pollutants, preventing them from affecting other species in the environment [11]. The reduction of pollutants in large urban centers is already being done using bryophytes in systems that filter and purify the atmospheric air with great efficiency.

There are even species that live submerged in water and that can collaborate in the removal of pollutants from these systems without suffering damage, as is the case of Leptodyction riparium, Fontinalis antipyretica, and Scapania undulata, among others [12, 13]. Some aquatic species are even reported as accumulating very rare chemical elements in nature such as Nd, Gd, Ho, Er, Tm, Lu, La, Ce, Sm, Eu, Tb, and Dy [14].

3. More bryologists for more knowledge and preservation

The number of specialists dedicated to the study of the group, from the most basic to the applied sciences, is very small. Finding more young people who are interested in the group is now a fundamental task in all countries, as we are losing habitat and species due to anthropic interference. In this way, this group will only be known, appreciated, and preserved if more specialist researchers will be formed. As it is one of the least studied groups, much still needs to be discovered, starting with the basic taxonomy and distribution of species, their relationships with other groups, especially with vascular plants and fungi, among others. As an example of this last topic, it can be mentioned that almost nothing is known about their pathogens and how they are relating to mosses in the face of climate changes [15, 16].

Studies for the conservation of bryophytes are also very limited, requiring work with in vitro cultivation, tissue culture, with the maintenance of spore banks, creation of lists of endangered species and location of endangered populations and maintenance cultures of the genetic diversity within species [17].

Bryophyte extracts were tested against many groups of insects as to control their populations. Test against lepidopterans, dipterans and/or coleopterans of some species have had good results for antifeedant, insecticide, or as developmental inhibitor [18].

Bryophytes are generally very fragile and delicate, offering no barriers to pathogen attack. Instead, they are rich in secondary metabolites that guarantee a strong defense not only against pathogenic agents but also against herbivores. These metabolites have wide application in medicine and pharmacy, in addition to biotechnology. They have long been used in medicine and are increasingly associated with antibacterial, antiviral, and antifungal properties. Others have been tested for their antitumor activities. Many also confer special aromas to some species, also having application in this area [19, 20].

The practical application of bryophytes in environmental monitoring, in the control and reduction of pollutants, in landscaping, and in energy generation, for example, needs to be more publicized to attract the attention of other areas to the theme. Studies in electricity generation and other practical uses are also needed to reinforce their preservation [16, 21].

In this way, gathering in a book additional information about bryophytes can attract more people to study the group and to practice their conservation. One always has in mind the creation of conservation units based mainly on arboreal components or mammals, and bryophytes always indirectly compete in these projects, but without special attention. It is necessary to organize conservation areas with a focus also on threatened bryophytes.

In vitro cultivation banks that include all species already catalogued are also needed. The species known number is so small (compared with other groups), and the area occupied by massive cultivation would also be so reduced that a worldwide effort could create an in vitro germplasm bank of all redeemable species, starting with those deposited in herbaria. The effort could start with the in vitro maintenance of newly described species, as for example. This would mean a worldwide effort in this direction, but the group still lacks enthusiasm and funding in this regard.

Even though they are increasingly associated with all these areas of knowledge (and there are many others), this is perhaps the group in which less research is being done in all areas. The group was the first to massively occupy the terrestrial environment and has since evolved, longer than any other group of photosynthetic organisms, a unique set of chemicals to survive all the biotic and abiotic stresses they have been subjected to. They are also resistance heroes for that reason and deserve a prominent place in science, something we are still far from.

Even with all these known applications, why don’t you have moss gardens spread as a healthy practice among the inhabitants of the entire planet? Why we do not have a garden of medicinal bryophytes? Why don’t we have bryophyte filters to improve the air in our living and working environments? Much of this is answered with: because no one knows all this!

Attracting interest of new enthusiasts to this spectacular group is the focus of this book. Good reading.

Acknowledgments

To the Universidade Federal do Pampa campus São Gabriel in special for the efforts of our ex-director Chariston Andre Dal Belo and to the director Luciana Borba Benetti regarding our laboratory facilities.