The ecology of myxogastrids (myxomycetes).
1.Myxogastrids were shown to be common on bark of trees in the
Bristol area and a variety of species were isolated.
2.Myxogastrids were more common on old bark than young bark.
3.Myxogastrids were isolated from banana peel but not from a
variety of dung samples.
4.Myxogastrids were isolated from soil and a medium and method
for their enumeration were developed.Soil was chosen as the
habitat for further quantitative research.
5.The recor"ding unit for myxogastrids was the Plasmodium Forming
6.Myxogastrids were found to be patchily distributed in soil and
more abundant in the surface layers than from several
7.A precise and repeatable sampling system was devised
consisting of many small samples pooled to form a single
large sample. Samples from nine sites were taken at monthly
intervals for one year. These samples were assayed for
myxogastrids by a standard proceedure.
8.The biological and edaphic parameters of the series of soil
samples were also measured and weather records from the Long
Ashton recording station collected.
9.A series of soil samples was taken from Sites of Special
Scientific Interest in the Bristol area and assayed as for the
IO.A number of soil samples were obtained from various countries
and assayed for myxogastrids.
11.Myxogastrids were not abundant in typical woodland soils but
they were in many other sites, even including a Barley field.
12.Graphical analysis of some of the biological parameters and
of the soil moisture of the temporally sampled sites showed
that there was a high negative correlation between soil
bacterial numbers and P.F.U.'s in response to changes in soil
12.Populations of soil ciliates and amoebae showed a
response to soil bacteria similar to that shown by the P.F.U.'s
but not always synchronously.
13.Frost appeared to lead to increased numbers of myxogastrids
l4.Statistical analysis of the the ecological data showed a high
positive correlation between P.F.U.'s and pH and negative with
organic matter. Numbers of P.F.U.'s were highly positively
correlated with those of other soil protozoa which, with the
exception of dictyostelids, all showed similar responses to soil
physical properties •
IS. The S.S.S.I. data analysis showed similar correlations to
that of the temporal data but not as strongly.
16.The foreign samples showed myxogastrids to be widespread and
not confined to normally moist soils for some were recovered
17.Myxogastrids were amenable to experimental manipulations used
to follow their population dynamics, and were shown to possess
forms resistant to freezing. The latter appeared to stimulate
excystment of dormant P.F.U.'s.
18.Microcosm experiments showed a pronounced rhizosphere effect,
but a role for myxogastrids in the enhancement of nutrient
cycling and uptake was not conclusively shown.
19.A series of samples from Czechoslovakia showed similar
characteristics to samples from the Bristol area.
20.Most species of myxogastrids isolated from soils were of the
genus Didymium but with the exception of Didymium squamulosum
• I and D. difforme conclusive identification of most 1solates was
21. Calculations suggest myxogastrids represent a significant
biomass in some soils and that this biomass corresponds to a
similarly significant biomass of bacterial prey.