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Practical 1 Soil ecosystems - soil biota and food webs

Introduction

An ecosystem is made up of plants, animals (biodiversity) and abiotic factors which

work toether to capture, store and transfer enery, nutrients and water! "ore#ample plants $capture% enery via photosynthesis and enery is stored as

carbohydrates in plants or fats and proteins in animals after they have eaten the

plants! Soil oranisms break down plant and animal tissues and transfer the

enery to themselves, while returnin nutrients to the soil for uptake by plants! &he

many oranisms in an ecosystem carry out these ecosystem functions, and the

more diverse an ecosystem is, the more stable and reliable are these functions!

&he soil provides a ood, easily studied e#ample of an ecosystem!

1.1 'acrofauna accelerate the rate of oranic matter decomposition! &hey

break oranic material into smaller pieces, and mi# oranic matter with soil!

owever, the relative numbers of macrofauna to microfauna in the soil is small!

procedure

ollect a sample of the leaf litter (* ori+on) and topsoil (A ori+on no deeper

than about cm) from two different locations! hoose from lawn, native veetation,

arden bed, under different species of tree etc! or other distinctive site! Place the

sample in plastic bas, seal them and label them with your name and the collection

location! At each site, record the type of veetation at the site (e! forest, swamp,

lawn etc!) and some of the site characteristics in the table below, then use this to

compare the soil habitat of the two sites! If you do not have the e.uipment

necessary (e! p kit or soil penetrometer), skip that characteristic!

Site Characteristic Site 1 Site 2

type of veetation

level of shade

soil dryness/dampness

soil p

soil compactness

soil te#ture (sandy, heavy

clay etc)

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*n return to the lab, mi# the soil and leaf litter sample from the same location

thorouhly! Put a known volume of one sample in the &ulren funnel! 0eave it for

about days, then remove the preservin 2ar containin ethanol and screw on the

lid! Place the sample from the second location in the &ulren funnel, and remove

after about days, followin the same procedure! If you know the volume of soil

you e#amined, you will be able to directly compare the macrofauna abundancebetween the two sites!

&ulren-type funnels for the e#traction of

soil fauna

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1.2 "rom the bas, e#amine a measured volume of the leaf litter (* ori+on)

and the topsoil (A ori+on) usin a microscope or hand lense! 3emove any fauna

found to a clean 2ar or petri dish for identification! Identify all oranisms to *rder if

possible, but at least put them into different roups (ie! roup A no les worms4

roup 5 6 les spiders and mites etc!)! ount the number of individuals from

each *rder or roup! If you have lare numbers you may need to estimate the

number rather than try to count them all!

1.3

(a) larer macrofauna

Macrofauna Order

or group

number @ location 1

soil volume = ____

number @ location 2

soil volume = ____

1. 7mpty the contents of the collectin 2ar into a petri dish, and identify as

many oranisms as possible to *rder or roup! ount the number of individuals

from each *rder or roup (as far as possible)!

(b) smaller macrofauna

Macrofauna Order

or group

number @ location 1

soil volume = ____

number @ location 2

soil volume = ____

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1.! 8se the results from both counts (1.2 and 1.3) and calculate the number of

Orders or groupsper litre of soil and leaf litter, and the numbers ofindividualsfrom

each *rder or roup per litre of soil and leaf litter!

Macrofauna location 1 location 2

number of Orders or groupsper litre of soil/litter

e! no! individuals of roup 5 per litre of soil/litter19 :

no! individuals of per litre of soil/litter

no! individuals of per litre of soil/litter

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;our 3eport - 7#plainin the role of the soil biota

;our report should have a title, a brief introduction e#plainin what the prac is

about, and a brief discussion (about

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?hat roups of oranisms make up the mesofauna > ?hat roups make up the

microfauna> ?hat are the main functions of these two main roups >

"ood webs can indicate the bioloical comple#ity, and therefore the health, of

the soil! 7#plain how our land manaement practices alter soil health!

7#plain how the soil biota contribute to the functionin of the soil ecosystem!

?hat ecosystem services do they reulate >

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