Field Study

FIELD STUDY, OBSERVATION & COLLECTION OF LICHENS

Lichens can be best understood
only in their natural habitats. And
it is only possible through field studies.

The beginners may start the field study in their own locality by collecting and studying the commonly occuring species. They must have a keen eye and search thoroughly with a lot of patience. This will help them to collect the minute and rare species. They must exercise extreme caution while observing the Lichen colonies - they should not destroy colonies of species by over collection.

PLANNING A FIELD TRIP FOR LICHEN COLLECTION

Though lichens are not season dependent they can be best observed soon after rains
(August-September and December-February).

In these months the temperature of Tamil Nadu state ranges between 20 - 30 ˚C in plains and on the mountaintops it may be less than 10 ˚C.

During summer months (March-May) the State experiences high temperatures (40-45 ˚C) coupled with dry seasons making lichens physiologically inactive, making them less conspicuous. Thus observations on micro lichens become difficult. If you happen to go during this time to field, carry a sprayer bottle with water
- spray water over the lichen colonies and observe them.

Carrying out field study during summer season makes the researchers to exhaust rapidly.

The best time for fieldwork in a day is from 7 am to 12 noon and 2 pm to 5 pm with small breaks for snacks and lunch.

WHERE CAN WE FIND LICHENS?

Natural substrates

Tree bark

Rock

Soil

Leaves

Logs

Back of hardy insects (weevil)

Tortoise carapace

Man made substrates

Fence post

Roof top

Glass

MATERIALS REQUIRED FOR FIELD COLLECTION
	Hammer Chisel Butter paper cover Knife Writing pad Tissue paper 10x Hand lens with illumination Camera preferably with digital imaging Collection bag (Jola or Jolna bag) Pencil
OBSERVING LICHEN COLONIES USING HAND LENS The Lichen colonies have to be located and observed one by one. During field work, surveying smaller land area for a greater length of time yields more species rather than going through larger areas quickly. Search extensively for lichens on substrates such as tree bases, bark/rock crevices, twigs and canopy


DATA RECORDING PRIOR TO LICHEN COLLECTION LICHEN COLONY OBSERVATION (LEFT)

	A PAGE FROM FIELD NOTE Each Field Note should contain 100 pages - Preferable size 20x14cm Field Note should be with waterproof wrapper Use a micro tip pencil always for recording data *To be removed and placed along with specimen
DATA COLLECTION ON LICHENS
Lichen collection envelope (15 x 9.7cm) with vital data to be recorded (Left) Lichen Microplot with data (Right)

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CRUSTOSE LICHEN COLLECTION
	Crustose lichens are also known as micro-lichens. Most of the crustose lichens are closely appressed to the substrate and are, therefore, very difficult to collect, and need extreme caution during collection. These lichens need to be collected only when they contain ascomata. Characteristics like the presence or absence of prothallus, its colour, margin nature (distinct, effuse, etc.), upper surface nature (smooth or matt) and the presence or absence of features like areoles, verruca, isidia or soredia are also important in species identification. So the collector has to observe several thalli of the same species present in the vicinity and select the one that is complete in all respects.

FOLIOSE LICHEN COLLECTION
	Foliose lichens have a leaf-like structure and are often attached with the help of rhizines on the substrate. Many of them may not reproduce sexually, and they often contain asexual propagules. The lobe margins may or may not contain cilia. These characteristics are vital for species identification. These lichens, along with the substrate, can be collected with a stout knife or a chisel.

FRUTICOSE LICHEN COLLECTION
Fruticose specimens are found as pendulous or erect on the surface attached with the help of a holdfast. The cylindrical fruticose thallus may contain a central axis. The holdfast and the central axis are important factors in species identification. These specimens can be collected satisfactorily like the foliose forms.

FOLIICOLOUS LICHEN COLLECTION
	Foliicolous lichens colonize the upper surface of the leaf. The entire leaf colonized by the lichen must be collected and preserved. The leaf sample must be dried properly by changing the blotting paper regularly during drying process. Lichen species belonging to Aulaxina, Tricharia, etc. possess an erect conidiomata, a key characteristic in species identification. This structure is extremely delicate. So, during collection and subsequent drying, pressure should not be exerted to remove wrinkles. Simple spreading of the leaves under the blotting paper is sufficient. Later, the dried leaves can be wrapped in tissue paper and placed inside the herbarium folder.
Lichens inhabiting rock surfaces are known as Saxicolous lichens. Most of the rock lichens are closely appressed to the substrate and are, therefore, very difficult to collect, and need extreme caution during collection. Collect lichen thallus along with a small piece of substratum (rock). Some rocks are difficult to collect and therefore it is necessary to scrap material off with sharp knife. Rock samples should be wrapped individually to avoid being damaged by rubbing against other samples in the collection bag. Some species are restricted to particular rock type and so it is important to examine as many rock types as may be present in an area. Before making a field trip it is consequently valuable first to study a geological map of the area to be visited	SAXICOLOUS LICHEN COLLECTION

Specimen Preservation

Crustose lichens are also known as micro-lichens.

Most of the crustose lichens are closely appressed to the substrate and are, therefore, very difficult to collect, and need extreme caution during collection.

These lichens need to be collected only when they contain ascomata.

Characteristics like the presence or absence of prothallus, its colour, margin nature (distinct, effuse, etc.), upper surface nature (smooth or matt) and the presence or absence of features like areoles, verruca, isidia or soredia are also important in species identification.

Foliose lichens have a leaf-like structure and are often attached with the help of rhizines on the substrate.

Many of them may not reproduce sexually, and they often contain asexual propagules.

The lobe margins may or may not contain cilia.

Foliicolous lichens colonize the upper surface of the leaf.

The entire leaf colonized by the lichen must be collected and preserved.

The leaf sample must be dried properly by changing the blotting paper regularly during drying process.

Lichen species belonging to Aulaxina, Tricharia, etc. possess an erect conidiomata, a key characteristic in species identification. This structure is extremely delicate. So, during collection and subsequent drying, pressure should not be exerted to remove wrinkles.

Simple spreading of the leaves under the blotting paper is sufficient.

Lichens inhabiting rock surfaces are known as Saxicolous lichens.

Most of the rock lichens are closely appressed to the substrate and are, therefore, very difficult to collect, and need extreme caution during collection. Collect lichen thallus along with a small piece of substratum (rock).

Some rocks are difficult to collect and therefore it is necessary to scrap material off with sharp knife.

SAXICOLOUS LICHEN COLLECTION