Adams, M. A. and P. M. Attiwill (1982). "Nitrogen mineralization and
nitrate reduction in forests." Soil Biol. Biochem. 14(3): 197-202.
The mineralization of soil nitrogen was studied in four forests growing on
krasnozem soils. Soils from Silver Wattle (Acacia dealbata Link.) and
Mountain Ash (Eucalyptus regnans F. Muell.) forests showed considerable
nitrification in laboratory incubations. Messmate (Eucalyptus obliqua
L'Herit) and Monterey Pine (Pinus radiata D. Don) forest soils were
predominantly ammonifiers. Forests having significant soil nitrification
were found to have considerable nitrate reductase activity (NRA) in root or
leaf tissue or both. NRA may therefore be useful as an indication of soil
nitrification in natural ecosystems. The occurrence of nitrification in
Australian forests appears to be predominantly related to the amount of N
present and its rate of turnover rather than to inhibitory effects.
Adams, M. A. and P. M. Attiwill (1984). "Role of Acacia Spp. in nutrient
balance and cycling in regenerating Eucalyptus regnans F. Muell. Forests.
I: Temporal changes in biomass and nutrient content." Aust. J. Bot. 32(2):
205-215.
Following severe fire in high-rainfall Eucalyptus regnas F. Muell.
forests, Several Acacia species may germinate in large numbers. Large
amounts of nitrogen as well as calcium, magnesium and potassium are
immobilized in the Acacia biomass, much of which is retunrned to the soil
after canopy closure. Within 3 years of a "regeneration burn", 280 kg N ha
super(-1) was in the above-ground Acacia biomass and litter layer. The
relative abundance of nitrogen in Acacia spp. is a result of N fixation.
The probable rate of N fixation appears significant in relation to losses
of nitrogen associated with slash-burning. It is concluded that the Acacia
spp. may be important in the secondary succession through nutrient
conservation, replacement and redistribution.
Adams, M. A. and P. M. Attiwill (1984). "Patterns of nitrogen
mineralization in 23-year old pine forest following nitrogen fertilizing."
For. Ecol. Manage. 7(4): 241-248.
Application of nitrogen fertilizer to 23-year old Pinus radiata D. Don at
high rates induced considerable change in patterns of nitrogen
mineralization in the soil. Increased net mineralization, nitrification,
root Nitrate Reductase Activity, and foliar N levels were measured within
12 months of fertilizer application. Fertilizing did not, however, affect
growth significantly over the 30 months of measurement. Significant
differences in inorganic-N and patterns of mineralization between
fertilized plots and controls were not maintained and all of the fertilized
plots had levels of inorganic-N and patterns of mineralization approaching
those of the control within 30 months. N added to these young aggrading
forests of high productivity therefore appears to be quickly immobilized.
Whithin normal forest rotations, it is apparent that the C/N ratio of the
soil acts as a strong buffer to perturbation of mineralization patterns.
Adams, M. A., P. J. Polglase, et al. (1989). "In situ studies of nitrogen
mineralization and uptake in forest soils: Some comments on methodology."
Soil Biol. Biochem. 21(3): 423-429.
Aspects of the methodology of and interpretation of results from, in situ
studies of N-mineralization are discussed with reference to data collected
from 17 eucalypt forests in south-eastern Australia during a 5-year period.
Results suggest that: (i) it is possible to maintain moisture of soils
contained within corers at levels not significantly different from those of
the surrounding soil; (ii) inorganic-N is not produced linearly over time
under field conditions, nor should we expect it to be; (iii) mineralization
rates are affected by all in situ methods. In each of the forests examined,
the average rate of net N-mineralization decreased as the period of
containment increased.
Adams, M., P. Attiwill, et al. (1989). "Availability of nitrogen and
phosphorus in forest soils in northeastern Tasmania." Biology and Fertility
of Soils 8(3): 212-218.
Rates of N mineralization and of N uptake were measured in situ in three
eucalypt forests and a cool-temperate rainforest, and were correlated with
productivity. All of the soils had a high capacity for immobilization, and
nitrification was insignificant. Changes in both organic and inorganic P
fractions during in situ containment of soils were small. While the
concentration of inorganic available P was not related to forest
productivity, a measure of labile organic P was closely related both to
productivity and to P in the microbial biomass. Estimates of inorganic- and
organic-N availability were highly correlated with independent estimates of
organic-P availability, and the results are discussed in relation to
biological control of nutrient availability in the surface horizons of
forest soils.
Adams, M. and P. Attiwill (1991). "Nutrient balance in forests of northern
Tasmania. 2. Alteration of nutrient availability and soil-water chemistry
as a result of logging, slash-burning and fertilizer application." Forest
Ecology and Management 44(2-4): 115-131.
A 100-ha plot in dry sclerophyll forest in NE Tasmania (dominant species
Eucalyptus obliqua) was logged during summer 1983-84, slash burnt in March
1985, and fertilized (N, P or N+P) eight months later. In situ measurements
of N mineralization and nutrient mobility were compared with those from an
adjacent, undisturbed forest. Nitrification was absent in all soils.
Nitrate concentrations in soil water were low and probably not responsible
for cation movement. Cation concentrations in soil water were immediately
increased by fire and by fertilizer additions and decreased continuously
after these events. Addition of strong-acid anions in fertilizer increased
cation movement. Soil water sampled at 10 cm depth was often coloured and
contained high concentrations of oxidizable organic carbon; lower
concentrations were found in samples collected from 30 cm depth. Uptake and
mineralization of N were increased by logging and slash-burning.
N-mineralization was promoted further by the addition of fertilizer-N and
was reduced by the addition of P, or N+P. Nutrient losses were exacerbated
by fertilizer additions and restricted by lack of nitrification, by
nutrient uptake by soil microorganisms and vegetation, and probably by
formation of complexes between organic anions and cations in the soil
profile.
Adams, M. and P. Attiwill (1991). "Nutrient balance in forests of northern
Tasmania. 1. Atmospheric inputs and within-stand cycles." Forest Ecology
and Management 44(2-4): 93-113.
Six undisturbed forests were studied: dry or wet sclerophyll (dominated by
Eucalyptus obliqua, E. amygdalina, E. regnans) and cool temperate rain
forest (principal species Atherosperma moschatum, Nothofagus cunninghamii).
Forest soils were ammonifying and had low concentrations of extractable P,
inorganic N and cations, irrespective of geology. Litterfall was
proportional to productivity, could be described by a climatic index, and
nutrient return via litterfall was the dominant transfer for N, P and Ca.
However, significant amounts of N (up to 8 kg/ha per year) and other
nutrients were added via rainfall, and total nutrient input was related to
rainwater quality. Soil in the rain forest was more organic than in the
eucalypt forests, and had greater amounts of P, N etc. Litterfall in the
rain forest was rich in P, but poor in Mg, relative to the eucalypt
forests, and nutrient absorption by the root mat was more effective than
that in the eucalypt forests.
Attiwill, P. M. (1986). "Interactions between carbon and nutrients in the
forest ecosystem." COUPLING OF CARBON, WATER AND NUTRIENT INTERACTIONS IN
WOODY PLANT SOIL SYSTEMS. PROCEEDINGS OF A SYMPOSIUM OF THE INTERNATIONAL
UNION OF FORESTRY RESEARCH ORGANIZATIONS. Luxmoore, R.J. 2: 1-3.
The sustained supply of nutrients in forest ecosystems depends on
processes by which nutrients are cycled from plant (in organic
combinations) to soil and back to plant (in simple inorganic form). Studies
of the key processes of decomposition and mineralization, and of equilibria
determining nutrient availability have been hampered by lack both of
appropriate chemical methods and of methods that distinguish among
fractions of organic matter of varying nutritional quality. The root
systems of forests must also be studied more intensively. In particular,
mechanisms by which nutrients in short supply are taken up (for example,
the role of mycorrhizae and of specialized systems such as proteoid roots)
and the redistribution of nutrients associated with turnover of the fine
root system are fields for future research.
Attiwill, P. M. and M. A. Adams (1993). "Tansley Review No. 50. Nutrient
cycling in forests." New Phytol 124(4): 561-582.
Studies of nutrient cycling in forests span more than 100 yr. In earlier
years, most attention was given to the measurement of the pools of
nutrients in plants and soil and of the return of nutrients from plant to
soil in litterfall. The past 20 yr or so have seen a major concentration on
the processes of nutrient cycling, with particular emphasis on those
processes by which the supply of nutrients to the growing forest is
sustained. In the more highly productive forests, up to 10 tonnes of litter
of low nutritional quality is deposited annually on the forest floor. The
decomposition of this litter, the mineralization of the nutrients it holds,
and the uptake of nutrients by tree roots in the carbon-rich environment
which results are the themes of this review. Studies of decomposition of
litter in forests have been dominated by the role of nitrogen as a limiting
factor, a domination which reflects the preponderance of studies of
temperate forests in the Northern Hemisphere. For many forests of the world
growing on soils of considerable age, it seems more probable that growth
and nutrient cycling are limited by phosphorus (or some other element).
There is increasing evidence for a number of forests that phosphorus is
immobilized in the first stages of decomposition to a significantly greater
extent than is nitrogen. Advances in research will depend, as with studies
of soil organic matter, in defining and developing analytical techniques
for studying biologically active forms of potentially limiting nutrients,
rather than total elemental concentrations. Net nitrogen mineralization
rates approximate rates of nitrogen return in litterfall but the
contribution of nitrification is variable. Nitrification is not inhibited
by the low pH of many forest soils and there is increasing evidence of
nitrate immobilization by microorganisms and of increased diversity and
better competitiveness for NH sub(4) super(+) of nitrifying microorganisms
than has previously been accepted. Variability in rates of nitrification is
often interpreted as being due to allelopathy. Hypotheses invoking
allelopathy are more or less untestable, and it seems likely that new
techniques using super(15)N in situ will lead to a more fundamental
understanding of nitrogen transformations in forest soils. Recent studies
in coniferous forest soils have highlighted the short (< 1 d) turnover time
of NH sub(4) super(+).
Bowman, D. M. J. S., A. R. Maclean, et al. (1986). "Vegetation-soil
relations in the lowlands of south-west Tasmania." Aust. J. Ecol. 11(2):
141-153.
A geographic survey of 14 south-west Tasmanian sedgeland-heaths revealed
that soil organic matter is related to: water content; total nitrogen (N);
total and exchangeable sodium (Na), calcium (Ca) and magnesium (Mg);
exchangeable potassium (K) cation exchange capacity: and total exchangeable
bases. However, total and available phosphorus (P), total K and iron (Fe),
pH level and percentage base saturation were found to be independent of
organic content. Most of the soil nutrient capital is contained in the A
sub(0) horizon, the depth of which was found to be positively related to
the time elapsed since the last fire. There is no clear relationship
between rock type and soil fertility, but there is evidence of
soil-vegetation interaction. The sedgeland-heath species have lower
concentrations of P, Ca and Mg in their foliage and are more efficient in
the withdrawal of P and K upon tissue senescence than the surrounding scrub
and forest species. Over a vegetation transition from sedgeland-heath to
forest on uniform geology there was a change in soil type.
Campbell, E. O. (1983). "Mires of Australasia." MIRES: SWAMP, BOG, FEN AND
MOOR. REGIONAL STUDIES. Gore, A.J.P. ed.
The author reviews the wetlands of Australia, Tasmania and New Zealand;
and the effects of climate on their development and geographical
distribution. Wetland vegetation are covered and used to classify types of
wetlands as well as soil composition. The main land masses of the
Australasian region are Australia, Tasmania and New Zealand. Australia is
an island continent with an area over three-quarters that of Europe.
Politically it is divided into the Australian Capital Territory, the
Northern Territory and the states of Western Australia, Queensland, New
South Wales, Victoria and South Australia. Tasmania is an island lying some
200 km to the south of Victoria. It is politically part of Australia and
has an area slightly less than that of Scotland. New Zealand lies some 1600
km to the southeast of Australia. It consists of three main islands, known
as North Island, South Island and the smaller Stewart Island, with a total
area about seven-sixths of that of Great Britain.
Chambers, D. and P. Attiwill (1994). "The ash-bed effect in Eucalyptus
regnans forest: chemical, physical and microbiological changes in soil
after heating or partial sterilisation." Australian Journal of Botany
42(6): 739-749.
The ash-bed effect (the enhanced growth of plants on soil which has been
heated) following fire in Eucalyptus regnans forest is dramatic. The
results are presented of studies of the effects of a range of heating and
partial sterilization treatments on chemical, microbiological and physical
properties in soil from a 250-year-old E. regnans forest in Victoria. Soil
treatments not involving heat (chemical sterilization, gamma-irradiation
and air-drying) and the lower temperature heat treatments (100 and 200ƒC)
had no marked effects on physical characteristics. All treatments produced
more or less similar effects on microbial populations. On the other hand,
heating the soil to 400-600ƒC produced large, significant and sustained
increases in the availability of nitrogen and phosphorus and these
increases were enhanced by a decrease in clay colloid. The results support
the hypothesis that the ash-bed effect following fire in E. regnans forest
is due to an increase in the availability of nutrients, and in the
availability of nitrogen and phosphorus in particular. A transitory
increase in the concentration of manganese caused by heating the soil may
account for initial toxicity in plants grown in soils which have been
heated. Since species within the subgenus Monocalyptus are characterized by
lower tissue concentrations of manganese than those within Symphyomyrtus,
it could be hypothesized that the potential for toxicity following bushfire
varies between the two subgenera. The literature on the effects of
soil-sterilising treatments is highly variable; the causes of variability
include soil type and moisture content, treatment (sterilizing by steam,
chemicals or heat) and the method of treatment (time, how the soil was
contained, and how the treatment was applied).
Colhoun, E. a. (1992). "Late glacial and Holocene vegetation history at
Poets Hill Lake, western Tasmania." Australia Geographer 23(1): 11-23.
Two cores (down to 3.9 m) were taken from the edge of a peaty flat by
Poets Hill Lake (600 m altitude), Tasmania, for pollen analysis to give a
record of vegetation history since the last glaciation (Margaret
Glaciation). Alpine herbfield, coniferous heath and Nothofagus gunnii scrub
developed on the moraine until 11 400 BP. Wet montane forest and heath then
developed with Phyllocladus aspleniifolius, N. cunninghamii and Eucalyptus
until about 10 000 BP. After 10 000 BP, there was a mosaic of N.
cunninghamii rain forest, Myrtaceae and Proteaceae scrub and Sprengelia
incarnata heath. The development of the vegetation from alpine communities
to temperate rain forest, which is near its limit at 600 m altitude,
occurred under the influence of improving climatic conditions with rapid
upslope migration or local expansion of taxa during the late glacial.
Temperatures were warm enough for the development of rain forest at 600 m
altitude by 10 000 BP, if not earlier. The development of a mosaic of rain
forest, scrub and heath vegetation rather than extensive rain forest after
10 000 BP reflects the influence of poor soils, poor drainage and fire.
Comparison with similar pollen diagrams from W. Tasmania suggests that the
development of pollen/vegetation associations was time transgressive with
altitude during the late glacial when climatic influences and migration
rates were important, and that the mosaic of vegetation communities became
more complex during the Holocene because of adjustment to or control by
local ecological factors.
Davidson, N. J. and J. B. Reid (1989). "Response of eucalypt species to
drought." Aust. J. Ecol no. 2: pp.
The response of three eucalypt species (Eucalyptus pulchella, Eucalyptus
coccifera and Eucalyptus delegatensis ) to a severe drought in the summer
of 1982/83 was examined at Snug Plains, south-eastern Tasmania. Few large
differences in leaf water potential ( psi sub(l)) or stomatal conductance
(gs) were apparent even at the height of the drought when both psi sub(l)
and soil water potentials ( psi sub(s)) reached ca. -4.5MPa.
Duncan, F. and Kiernan K (1989). "Drought damage in a Tasmanian forest on
limestone." Helictite 27(2): 83-86.
Widespread but patchily distributed drought death of forest trees (both
overstorey and understorey species) occurred in early 1988 on a limestone
ridge at Mole Creek, Tasmania. Moderate to severe symptoms of drought
stress were observed in Eucalyptus viminalis, E. delegatensis, E. obliqua,
Pomaderris apetala, Olearia argophylla, O. lirata, Cassinia aculeata,
Pultenaea juniperina and Senecio linearifolius while Bursaria spinosa
showed no drought symptoms and Acacia melanoxylon was only partly affected.
The close occurrence of damaged and undamaged vegetation (e.g.
juxtaposition of severely damaged specimens of the xerophytic species
Pultenaea juniperina with healthy specimens of the wet sclerophyllous
species Pomaderris apetala) is thought to reflect differences in the speed
of soil moisture decline down the length of individual soil-filled solution
tubes in which the trees were rooted. Possible palaeoecological,
geomorphological and silvicultural implications are briefly discussed.
Ellis, R. C. and A. M. Graley (1987). "Soil chemical properties as related
to forest succession in a highland area in north-east Tasmania." Aust. J.
Ecol. 12(3): 307-317.
The relationship between vegetational type and a number of soil chemical
factors was examined in secondary successions from fire-maintained
eucalypt/grass to climax rainforest communities growing on uniform granitic
soil parent material. Canonical variates analysis, which utilized the
following variables: pH; loss on ignition; total N, P, Ca, and Mg; cation
exchange capacity and exchangeable Ca, K, and Mg; and potentially
mineralizable N, revealed close overall similarity between surface soils of
adjacent types, and significant differences among those of types distant
from each other in the successional sequences. Differences among soils in
chemical composition and rates of mineralization of N were due to
differences in species composition of the vegetational types that they
carried for the time being.
Ellis, R. C. and P. I. Pennington (1989). "Nitrification in soils of
secondary vegetational successions from Eucalyptus forest and grassland to
cool temperate rainforest in Tasmania." Plant Soil 115(1): 59-73.
Rates of nitrification in well drained granitic soils from forest stands
and grassland of differing successional status and from beneath isolated
individuals of several tree species were compared in a series of laboratory
experiments. Nitrification was absent or occurred at only a low rate in
many soils; it generally increased as succession proceeded from mature
grassland or eucalypt forest towards climax temperate rainforest, but
decreased in mature climax forests. However, the influence of individual
tree species was often paramount. Nitrification was stimulated by
disturbance of a stand by disease. A possible inhibitor of nitrification in
a rainforest soil could not be removed by leaching with water, nor
transferred via the leachate to a nitrifying soil. Addition of P was
without effect on either total amount of nitrate produced or on net
mineralisation of soil N, but sometimes increased the rate of nitrification
of added ammonium.
Ellis, R. C. and P. I. Pennington (1992). "Factors affecting the growth of
Eucalyptus delegatensis seedlings in inhibitory forest and grassland
soils." Plant Soil no. 1: pp.
In many highland forests of Eucalyptus delegatensis in Tasmania the
establishment and healthy growth of eucalypts is promoted and maintained by
fire. In the absence of fire, secondary succession from eucalypt forest to
rainforest occurs, during which the eucalypts decline and die prematurely.
On sites that are prone to radiation frost severe reduction or removal of a
tree canopy allows a sward of tussock grasses to develop, in competition
with which seedlings of eucalypts decline in growth and a high proportion
dies. Factors of the soil that could contribute to these phenomena were
investigated by means of pot experiments that used soils from: a secondary
succession of vegetative types from recently burned healthy eucalypt forest
to unburned mature rainforest: this encompassed a sequence of decline and
death of the eucalypt trees; soil from old grassland in which eucalypt
seedlings were exhibiting severe growth check and mortality; from beneath
individual trees of several species growing on old grassland.
Fensham, R. J. (1989). "The pre-European vegetation of the Midlands,
Tasmania: A floristic and historical analysis of vegetation patterns." J.
Biogeogr. 16(1): 29-45.
83% of the area of native vegetation of the Midlands has been replaced
after 170 years of agricultural exploitation. However, scattered remnants
of the native vegetation still exist today in most Midlands environments,
and these were surveyed. The floristic variation within and between these
remnants was most closely related to soil moisture, as affected by texture
and topography. A classification produced thirteen groups that comprised
subdivisions of grassy communities dominated by Eucalyptus amygdalina
Labill. forest, E. viminalis Lag., E. pauciflora Sieber ex Spreng., E.
ovata Labill. woodlands, and treeless communities.
Fensham, R. and J. Kirkpatrick (1992). "The eucalypt
forest-grassland/grassy woodland boundary in central Tasmania." Australian
Journal of Botany 40(2): 123-138.
Downslope boundaries of forest with grassland and grassy woodland occur
over a wide altitudinal range in central Tasmania. Observations were made
and a series of experiments were carried out at 3 sites to study the causes
of these boundaries at low, medium and high altitudes (500, 800 and 1000 m,
respectively). Open vegetation was generally associated with moister and
less rocky soils and more subdued topography than the adjacent forest.
Frost incidence and intensity, soil moisture and waterlogging varied
markedly among the 3 open areas. Direct sowing trials were attempted at
different times using various ground treatments and species mixtures of
woodland eucalypts (Eucalyptus ovata, E. rodwayi and E. gunnii) and forest
eucalypts (E. tenuiramis, E. pauciflora and E. coccifera ). Seedlings
survived 4 years in the open at all sites, and seedlings established in the
open both naturally, and after sowing, where grass competition was reduced
by herbicide application, scarification or root competition from adult
eucalypts. Grazing had no detectable effect on seedling establishment. A
pot experiment demonstrated a suppressive effect of native grass (Poa
labillardieri) swards on establishment and growth of E. rodwayi seedlings;
this effect was largely independent of available moisture and nutrients.
While frost, waterlogging, fire and drought may play a role in inhibiting
eucalypt establishment and increasing eucalypt mortality at some or all of
the sites, the dense grass swards found in all the open areas are
considered to be the most likely primary agent of tree exclusion.
Frey, W. and P. Dalton (1996). "Hypnodendron comosum-community in
Tasmania." Nova Hedwigia 62(1-2): 215-220.
Hypnodendron comosum var. comosum var. sieberi and H. vitiense subsp.
australe (endemic in SE Australia, Tasmania and New Zealand and thought to
be archaic taxa) form a typical dendroid community. The dendroid taxa reach
high cover values and characterize the feature of the community ("miniature
forest"), which is described for the first time from Tasmania. Surveys were
made in western Tasmania, in rain forests characterized by Nothofagus
cunninghamii, Atherosperma moschatum and Eucryphia lucida and the conifers
Phyllocladus, Lagarostrobus [Lagarostrobos] and Athrotaxis. On loamy and
humic soil the number of species of the community is low, increasing on
decaying wood. The community is a complementary one to those described from
New Zealand. It is assumed that such dendroid bryophyte communities from
forests which today are temperate rain forests of the southern hemisphere
represent a relict vegetation of the forest floor of former Gondwanaland
forests.
Gibson, N. and J. B. Kirkpatrick (1985). "Vegetation and flora associated
with localized snow accumulation at Mount Field West, Tasmania." Aust. J.
Ecol. 10(2): 91-99.
The vegetation associated with a snow patch at Mt Field in Tasmania is
described and mapped. Seven distinct vegetation types were found to be
related directly to topography and hence to the patterns of snow
accumulation, snow melt and soil drainage. The fjaeldmark found where snow
lies longest in unusual for Tasmania and may be the product of past
climatic events and a peculiar parent material. At the generic level there
exists a high similarity with the snow patch flora of the Australian Alps.
Gibson, N. (1990). "The environments and primary production of cushion
species at Mt Field and Mt Wellington, Tasmania." Aust. J. Bot no. 3: pp.
Primary production of four species of alpine cushion plants were studied
over a 2-year period. The climate of these areas was found to be severe but
with a high degree of variability on a seasonal and yearly basis. The
growing season at the higher altitude sites generally exceeded 6 months.
Net above ground primary production of the four cushion species ranged from
282 to 709 g m super(-2) year super(-1). Reproductive effort fluctuated
between species and years, ranging from 0 to 30% of net above ground
production. Patterns in dry matter accumulation suggest no individual
species would show consistently superior growth rates under present
climatic conditions. Soil moisture and soil nutrient status was found to be
similar between all sites. Altitude of the sites (830-1400 m) was found to
be strongly correlated with the timing of flowering and/or seed set but
appeared to have little effect on net primary production.
Gibson, N., Brown Mj, et al. (1992). "Flora and vegetation of ultramafic
areas in Tasmania." Australian Journal of Ecology 17(3): 297-303.
The flora and plant communities were surveyed of 15 areas of ultramafic
(serpentine) rock in Tasmania. Dry sclerophyll communities on ultramafic
rock were restricted to 2 areas in the north of Tasmania. In the wetter
western and southern areas the ultramafic land supported heathlands, wet
scrubs, and a wet sclerophyll/mixed forest community dominated by
Eucalyptus obliqua, E. nitida or E. delegatensis. One of the most striking
features of the ultramafic areas in Tasmania is the variable degree of
physiognomic differentiation between adjacent ultramafic and non-ultramafic
substrates at the different sites. Physiognomic differentiation is less on
non-lateritic soil types or where accumulation of colluvial material has
occurred. Only 3 ultramafic endemic taxa were recorded.
Grant, J., Laffan M, et al. (1995). "Mapping State Forest soilsin Tasmania." ACLEP Newsletter 4(2): 16-19.
Methods of soil mapping and characterization for the Tasmanian State
Forest at scales of between 1:50 000 and 1:100 000 are outlined. The
results are entered in a database and digitized soil boundaries in a
geographical information system. This information can be used to produce
soil/vegetation/forest productivity models for projection onto the
landscape.
Grant, J., Laffan Md, et al. (1995). "Forest soils of Tasmania: a handbook
for identification and management." 189(5).
This book describes a range of forest soils commonly found in Tasmania in
terms of their site and profile characteristics. It provides interpretation
of potential degradation hazards for each soil and recommendations for
management. Colour photographs of typical soil profiles together with
associated native vegetation are included as an aid for identification. A
glossary of soil terms is included, as well as many annexes giving detailed
information and analysis of the soils, and listing the plant species
mentioned in the site descriptions.
Grierson, P. and P. Attiwill (1989). "Chemical characteristics of the
proteoid root mat of Banksia integrifolia L." Australian Journal of Botany
37(2): 137-143.
The proteoid roots of B. integrifolia are concentrated in the topsoil,
forming a dense mat beneath the litter layer. Water extracts of the
proteoid root mat of a mature B. integrifolia var. cunninghamii stand in
Victoria contained a significantly greater amount of hydrogen ions,
reducing agents and an unidentified chelating agent than water extracts of
soil beneath the root mat, of the litter layer or of soil from beyond the
proteoid root zone. The results are discussed in relation to previously
reported production of organic chelates by plants causing solubilization of
soil phosphates. It is suggested that proteoid roots of B. integrifolia
chemically modify the soil environment, thereby enhancing nutrient uptake.
Horne, R. and J. Hickey (1991). "Review. Ecological sensitivity of
Australian rainforests to selective logging." Australian Journal of Ecology
16(1): 119-129.
A review of past studies of the ecological consequences of selective
logging in the major rain forest areas of Australia. The main aspects
covered are recovery of stand structure, regeneration capacity, individual
tree growth and species composition of stands, hydrological effects,
floristics, wildlife, soil nutrient levels, fire susceptibility, and
incursion of weeds and diseases. Following a single selective logging, the
changes indicated by individual studies often appeared to be relatively
minor. It is suggested that many of these effects are not extensive or
irreversible and might not persist beyond structural recovery of the rain
forest. However, two changes were identified as likely to persist beyond
structural recovery. These are (i) a post-logging difference in the
proportional representation of major overstorey tree species and (ii) a
reduction in the numbers of large-diameter trees. More extensive and
longer-lasting changes may result from multiple selective loggings,
especially if the interval between loggings is short. Even for light
logging intensities, a conservative interval of at least 60 years between
loggings is indicated, to allow canopy and below-canopy conditions to be
restored. The slower growth of the rain forests in Tasmania, compounded by
a geographical susceptibility to drought, increases the possibility of fire
damage following selective logging relative to the more northerly mainland
rain forests.
Judd, T. S., L. T. Bennett, et al. (1996). "The response of growth and
foliar nutrients to fertilizers in young Eucalyptus globulus (Labill.)
plantations in Gippsland, southeastern Australia." For. Ecol. Manage. 82:
1-3.
Fertilizer trials, which included rates of application of up to 400 kg/ha
N, 200 kg/ha P and 200 kg/ha K, were established in experimental
plantations of E. globulus at three sites in Gippsland, southeastern
Australia. These sites cover a range of annual rainfall and soil fertility,
from 620 mm on a deep infertile sand, to 1000 mm on a rich gradational clay
loam. Early growth at all sites was significantly increased by the addition
of fertilizers and by age 4 years was consistently best at the highest
combined rates of N and P. Foliar N and P concentrations were significantly
increased at all sites by combined additions of N and P at Age 1, but were
insensitive to treatment at Ages 2 and 4. Relationships between foliar
nutrient concentrations and growth were site dependent. Correlations
between foliar nutrients and growth in the same year were strongest at Age
1. Foliar nutrients at Age 1 were also strongly associated with growth at
later ages at all sites. The best growth was associated with foliar
concentrations at Age 1 of about 2.5% N and 0.23% P. Additions of P, alone
or with N, consistently decreased foliar N/P ratios at Age 1 to between 11
and 12 whereas N and P additions resulted in foliar N/P ratios of 15 to 16
at Age 4. These ratios indicate a greater requirement for P than N in the
first year suggesting that the N/P ratio of fertilizers should be 1:1
within the first year, increasing to 2:1 in later applications. General
recommendations for fertilizer addition in the routine establishment of E.
globulus are presented. Mean tree volumes at Age 4 ranged from 0.014 to
0.019 m3 in control treatments and from 0.031 to 0.055 m3 at the highest
rate of fertilizer addition. Growth responses to fertilizers were greatest,
in both absolute and relative terms, at the most fertile site and appeared
to be constrained by unfavourable soil texture and limited water
availability at the other sites. Because the responses of E. globulus are
site specific, detailed assessments of fertilizer requirements on soil
types other than those described here require the establishment of further
trials. A schedule for the establishment and monitoring of such trials is
proposed.
Kirkpatrick, J. B. (1983). "Treeless plant communities of the Tasmanian
High Country." MOUNTAIN ECOLOGY IN THE AUSTRALIAN REGION. Purdie, R.W. 12:
61-77.
Analyses of the associations of 65 dominant species from 430 quadrats
located in Tasmanian treeless high altitude vegetation are used to provide
a framework and guidelines for the construction of a typology of plant
communities. These communities are listed and discussed within the context
of the following vegetation types: bolster heath, deciduous heath,
coniferous heath, heath, fjaeldmark, bog, fen, short alpine herbfield, tall
alpine herfield and tussock grassland. The distribution of communities is
best related to a climatically and geologically-controlled edaphic
gradient, a soil drainage gradient and to the vagaries of fire history. The
successional status of most of the plant communities is deduced from their
patterns of distribution. Several of the alpine dominants usually fail to
regenerate after fire. There is insufficient evidence to support a widely
suggested cyclic succession process involving bolster plants.
Kirkpatrick, J. B. and K. J. M. Dickinson (1984). "The impact of fire on
Tasmanian alpine vegetation and soils." Aust. J. Bot no. 6: pp.
Observations were made across 11-40-year-old fire boundaries in Tasmanian
alpine areas of varying macroenvironment and flora. Surface soil organic
matter and total nitrogen were significantly less where the vegetation had
been recently burned. There were no significant differences between
recently burned and recently unburned plots for phosphorus, potassium,
calcium, sodium and pH. The burned plots contained few or no gymnosperms or
deciduous shrubs, the most frequent dominants of the unburned vegetation.
Most other shrubs were markedly less important in the burned than in the
unburned plots, although most species of bolster form were little affected
by fire, and some composite shrubs were most abundant on the burned plots.
Most herbaceous species had equal or higher cover on the burned plots than
on the unburned plots. The burned vegetation of the eastern mountains
appeared to regenerate more quickly than that of the more oligotrophic
western mountains.
Kirkpatrick, J. B. (1986). "Conservation of plant species, alliances and
associations of the treeless high country of Tasmania, Australia." Biol.
Conserv. 37(1): 43-58.
The treeless high country of Tasmania has considerable conservation and
catchment value. Much of its area lies within National Parks and other
reserves of similar tenure, but many species and communities are confined
to land of less secure status. Much high mountain land is subject to
stockgrazing and burning, both of which activities have led to
deterioration in vegetation and soils. The reservation status of species
and communities can be made near perfect with relatively small additions to
the State Reserve system. However, the impacts of trampling and deliberate
fires do not respect reserve boundaries, and their mitigation or
elimination requires some intensive management.
Kirkpatrick, J. B. and F. Duncan (1987). "Tasmanian high altitude grassy
vegetation: Its distribution, community composition and conservation
status." Aust. J. Ecol. 12(1): 73-86.
Grassy woodland, grassy shrubland, grassy sedgeland, tussock grassland and
grassland are extensive on basalt, limestone and fine-textured Quaternary
deposits, are occasional on dolerite, granite and fine-grained sedimentary
rocks, but are absent from the siliceous mountains of Tasmania. With the
exception of limestone lithosols, the grassy communities are confined to
relatively deep soils with a low surface rock cover. Much of the area of
the grassy communities below the climatic treeline has clearly been forest
in the recent past, although some of the higher subalpine plains seem
likely to have been grassy at least since the peak of the Last Glacial.
Ladd, P., D. Orchiston, et al. (1992). "Holocene vegetation history of
Flinders Island." New Phytologist 122(4): 757-767.
Two swamp sites on Flinders Island in Bass Strait, Tasmania, provide
evidence of vegetation cover for the period 10 000 BP to present. Steppe
vegetation in which Compositae Liguliflorae taxa and chenopods were
important was present on the Flinders Island part of the Bassian Isthmus
during the earliest part of the record. However, it was replaced by
eucalypt forest or woodland with a grassy understorey and some shrubs as
sea level rose to form the present island by 6000 BP. Eucalypt dominated
vegetation became less important about 940 BP when Callitris became
prominent until very recently. This change may be related to a drier
climate. From pollen evidence in this study and that from other SE mainland
and Tasmanian sites it is suggested that apparent prominence of Casuarina
in SW Victoria and SE South Australia during the early Holocene was due to
local soil factors and drier climate. Later changes in soil and climate led
to a decrease in Casuarina and increase in Eucalyptus.
Podger, F. and M. Brown (1989). "Vegetation damage caused by Phytophthora
cinnamomi on disturbed sites in temperate rainforest in western Tasmania."
Australian Journal of Botany 37(6): 443-480.
P. cinnamomi was isolated directly from 558 diseased plants of 39 species,
including 1 fern, 4 graminoids and 34 woody dicotyledons, all indigenous to
the cool temperate rain forest of Tasmania. Pathogenicity was proved by
greenhouse tests (20 spp.) and by field inoculation at two sites (19 spp.).
Of the 142 species in the rain forest flora, 69 were rated for the
susceptibility of field populations: 30% were highly susceptible and less
than 5% highly resistant. High proportions of susceptible species occurred
in Epacridaceae, Eucryphiaceae and Proteaceae. All 93 isolates tested were
the common A2 mating type. The fungus was consistently associated with
disease at 47 survey sites. Diseased plants were widely but patchily
distributed along exposed road and track edges within unburned rain forest
and in recently burned rain forest. The fungus was not recovered from soil
samples taken beneath healthy roadside regeneration, beneath undisturbed
rain forest or above 900 m alt. The disease has the characteristics of
attack by a recent invader and appears to be dependent upon disturbance
which increases soil temp. above 15ƒC, the lower threshold for infection by
P. cinnamomi. Post-fire recovery of forest canopy is expected to allow
re-establishment from external sources of seed of those susceptible species
which are both efficiently dispersed and tolerant of shade. Species lacking
such characteristics are at risk of local elimination but no single rain
forest species appears to be under threat of extinction from this pathogen.
Polglase, P. J., P. M. Attiwill, et al. (1986). "Immobilization of soil
nitrogen following wildfire in two eucalypt forests of south-eastern
Australia." Acta Oecol. Oecol. Plant. 7(3): 261-271.
Forests of Eucalyptus obliqua (Messmate) and E. regnans (Mountain Ash)
were burnt by crownfire in November of 1982. Litterfall increased 2-fold in
the 3 months following the fire, about 63% of which was scorched dead
leaves. Concentrations of N and P in these scorched leaves were about twice
those in leaf litter of unburnt forests. Thus in the first year after the
fire, total N and P in litterfall was 2.5 times greater than normal in
Mountain Ash and 1.5 times greater than normal in Messmate. Concentrations
of N and P in leaf litter of Messmate (which regrew from epicormic buds)
returned to normal after 12 months. Available P and total inorganic N in
the soil increased significantly after the fire. Inorganic N in the soil
beneath Messmate is normally NH sub(4)@)u+-N; even after intense fire, no
NO sub(3)@)u--N was produced. The increase in inorganic N was rapidly
immmobilized and returned to normal levels within 5 months.
Polglase, P. and P. Attiwill (1992). "Nitrogen and phosphorus cycling in
relation to stand age of Eucalyptus regnans F. Muell. I. Return from plant
to soil in litterfall." Plant and Soil 142(2): 157-166.
The N and P contents of the litter layer and the return of these nutrients
in litterfall were measured in seven stands of mountain ash (Eucalyptus
regnans) in Victoria, Australia, ranging in age from 5 years to _ 250
years. Both annual litterfall and nutrient return were correlated with
stand basal area and were high compared with other productive eucalypt
forests. In contrast, the fall of dead eucalypt leaves was constant with
stand age, demonstrating that sites are fully occupied at an early age.
Similarly, amounts of N and P in total leaf fall (overstorey plus
understorey) were constant with stand age, except for low amounts in the
stand aged 40 years where Acacia spp., important fixers of atmospheric N,
were not prevalent. The decomposition constant (k) of organic matter in the
litter layer decreased with stand age, from 0.3/year at age 5 years to
0.23/year at age 250 years. These constants also applied to N and P,
indicating a tight coupling between organic matter decomposition and
release of these nutrients from litter. The litter layer released _ 30
kg/ha of N at age 5 years, and _ 70 kg/ha at age 80 years. These results
are discussed in relation to growth of mountain ash following fire, and the
subsequent retention and accumulation of N during stand development.
Polglase, P., P. Attiwill, et al. (1992). "Nitrogen and phosphorus cycling
in relation to stand age of Eucalyptus regnans F. Muell. II. N
mineralization and nitrification." Plant and Soil 142(2): 167-176.
Laboratory and in situ rates of N mineralization in soils from mountain
ash (Eucalyptus regnans) forests in Victoria, Australia, were measured
fortnightly for two years in stands aged 9, 40, 80 and _ 250 years
(overmature), and for one year in stands aged 5 and 46 years. Rates of
anaerobic mineralization (the laboratory test) showed little seasonal or
annual variation. In contrast, rates of in situ mineralization varied
markedly with season, being highest in spring and summer. Anaerobic
mineralization was highly correlated with stand age to 80 years, but
decreased between ages 80 and 250 years. In situ mineralization also
decreased between these two ages, but otherwise was not related to stand
age. Hence, the correlation between anaerobic and in situ mineralization
along the age sequence was weak, suggesting that the anaerobic test is of
maximum utility when this pool is in balance with inputs from decomposing
litter ('steady-state' ecosystems). Nitrification was strong in stands aged
9, 46, 80 and 250 years and weak in stands aged 5 and 40 years. Within
stands, the rate of nitrification during each period of in situ containment
was highly dependent on the supply of NH4 ions. Between stands, annual
rates of nitrification appear to be related to the balance between the N
capital of the site, its rate of turnover, and the demand for N by
heterotrophs and vegetation so that if NH4 supply is depleted, little is
left for autotrophic nitrifiers.
Polglase, P., P. Attiwill, et al. (1992). "Nitrogen and phosphorus cycling
in relation to stand age of Eucalyptus regnans F. Muell. III. Labile
inorganic and organic P, phosphatase activity and P availability." Plant
and Soil 142(2): 177-185.
Concentrations of labile inorganic P (Pi, dilute double acid-extractable),
labile organic P (Po, bicarbonate-extractable), microbial P, and
phosphatase activities were measured in mountain ash (Eucalyptus regnans)
stands aged 0, 5, 9, 16, 40, 46, 80 and 250 years in Victoria, Australia.
Labile Pi, initially 34 µg/g at age 0 years, decreased to 2.3 µg/g at age
16 years, and was constant thereafter. All other indices of available P
increased with stand age. Microbial P varied the most along the age
sequence, from 1.8 µg/g at 0 years to 99 µg/g at age 80 years. Oxidation of
organic P during the regeneration burn creates a large and readily
available source of Pi for the young, developing stand. After canopy
closure, the stand becomes increasingly dependent on P released by
mineralization. Phosphatase activities were as high as have been recorded,
and the organic pools are therefore significant stores of potentially
available P. At age 80 years (for example) the amount of labile Po and
microbial P in the surface 5 cm of soil was 26 kg/ha. However, the
adsorption maxima for Pi fixation were also as high as has been recorded,
and so it is apparent that roots must possess specialized mechanisms of
uptake to compete for mineralized P.
Potts, B. M. and J. B. Reid (1990). "The evolutionary significance of
hybridization in Eucalyptus." Evolution 44: 2151-2152.
New estimates of dispersal and levels of hybridization were obtained from
open-pollinated progenies from extra sites and from post-dispersal,
pre-selection seed samples collected from ants' nests and soil from the
forest floor immediately after fire to support the authors' earlier
conclusions that for E. risdonii pollen-mediated dispersal into the range
of E. amygdalina occurs over a greater distance than seed-mediated
dispersal. Recent criticisms of the subject [Schemske, D.W.; Morgan, M.T.
(1990) Evolution 44, 2150-2151] are answered.
Read, J. and R. S. Hill (1983). "Rainforest invasion onto Tasmanian
old-fields." Aust. J. Ecol no. 2: pp.
The regeneration of rainforest onto land cleared for grazing early this
century was studied on several sites in northern Tasmania. Drimys
lanceolata , a bird-dispersed species, was the main invader. The climax
forest species, Nothofagus cunninghamii and Atherosperma moschatum were
invading slowly from the forest edge with occasional trees established in
the field. Woody plants in the old-field were clumped around logs. This was
related to the role of logs in attracting seed and to possible roles as
competition-free sites and sites safe from browsing and climatic stresses.
Changes in dominance by particular life forms appeared to be related to
dispersal events, environmental modification by the developing vegetation
and life history characteristics. The extremely slow invasion by climax
species is due to the absence of bare mineral soil as well as to dispersla
characteristics, browsing and possibly exposure to climatic stresses.
Read, J. (1995). "The importance of comparative growth rates in determining
the canopy composition of Tasmanian rainforest." Australian Journal of
Botany 43(3): 243-271.
Growth rates of the rain forest canopy species Atherosperma moschatum,
Eucryphia, Nothofagus cunninghamii, Athrotaxis selaginoides and
Phyllocladus aspleniifolius were measured in naturally-occurring seedlings
and in seedlings grown in greenhouse pot trials. The highest field growth
rates were recorded in N. cunninghamii on lowland sites in fertile,
well-drained soils. On poorer soils, growth rates of N. cunninghamii were
lower and there was little difference in growth rates between species. On
the most acidic and probably infertile soil, the growth rates of P.
aspleniifolius was 1.4 times greater than that of N. cunninghamii, although
not significantly different at the 95% level. Similar trends in growth
rates were recorded in pot trials. High growth rates were recorded in N.
cunninghamii and E. lucida on fertile, well-drained soils, with generally
lower growth rates in Atherosperma moschatum, P. aspleniifolius and
Athrotaxis selaginoides. No significant differences in growth rates was
recorded among N. cunninghamii, E. lucida, Atherosperma moschatum and P.
aspleniifolius when grown in poor soils or in low nutrient treatments. The
trends in comparative growth rates correlate with the measured canopy
composition of the study sites. Nothofagus cunninghamii dominates forest
stands on sites where it has a clearly superior growth rate compared with
co-occurring light-demanding species. Mixed canopies occur on sites where
there is little or no difference between species' growth rates. However,
not all patterns of canopy dominance can be explained by comparative growth
rates alone. For example, P. aspleniifolius commonly dominates forest
stands at low- to mid-altitude where growth rates of all species are very
low, but without necessarily a higher growth rate in P. aspleniifolius than
in co-occurring species. The results of the growth rate studies are
integrated with some other aspects of the biology of these species in a
discussion of the mechanisms determining canopy composition of Tasmanian
rain forests.
Skinner, M. F. and P. M. Attiwill (1981). "The Productivity of Pine
Plantations in Relation to Previous Land Use II. Phosphorus Adsorption
Isotherms and the Growth of Pine Seedlings." Plant And Soil 61(3): 329-339.
The improved growth of pine (Pinus radiata ) plantations on pasture soils
compared with that on soils which previously supported native eucalypt
forest is primarily explained in terms of soil phosphorus. Pasture
development has resulted in a decrease in the P adsorption maximum of about
300 mu g g super(-1) soil, a figure which agress with the increase in total
P due to the application of superphosphate. P adsorption isotherms were
used to calculate additions of P to give comparable levels of soil solution
P in eucalypt and pasture soils. The growth of pine seedlings in soils thus
amended showed a strong N x P interaction. When P was non-limiting,
addition of N raised productivity of the eucalypt soil above that of the
pasture soil. It is postulated that the different nature of the N x P
interaction in eucalypt and pasture soils results from differences in the
nitrogen cycle in the two soils.
Thomas, I. and J. B. Kirkpatrick (1996). "The roles of coastlines, people
and fire in the development of heathlands in northeast Tasmania." J.
Biogeogr. 23(5): 717-728.
Pollen analysis of a core taken from a reed marsh in northeastern Tasmania
near Bass Strait highlights the interplay between climatic changes, sea
level rises and the effects of Aborigines during the Holocene. Prior to
10,000 BP the region formed part of the Bassian landbridge which connected
Tasmania to the Australian mainland. Vegetation at that time was
characterized by shrubby grasslands with a very sparse tree cover. After
9000 BP, Eucalyptus forests prospered until about 6000 BP. A combination of
salt spray from a stabilizing mid-Holocene coast, the progressive effects
of soil podsolization and burning by Aborigines, eventually favoured the
replacement of grassy Eucalyptus forests by Allocasuarina with an
increasingly heathy understorey. The treeless heaths dominated by dwarfed
Allocasuarina which presently dominate the area are regarded as part of a
degradation sequence in which the above factors are implicated.
Tyler, P. A. (1992). "A lakeland from the Dreamtime. The Second Founders'
Lecture." Br. Phycol. J no. 4: pp.
The mountainous wilderness of Tasmania's World Heritage Area and
contiguous land is a district of lakes and rivers of immense beauty and
interest. A congruence of change in climate, relief, geology, soils and
vegetation divides the island into western and eastern provinces. A jagged,
western land of ancient rocks is mantled by peat-forming rainforest and
sedgeland, where creeks run, unenriched with minerals, to topaz, red-window
lakes. Eastwards lies a younger, flatter land, covered by sclerophyll
forests of Eucalyptus . Minerals from the soluble rocks give the lakes
distinctive chemistry compared with the brown dilute sea-water which drains
the western quartz. No peat extracts stain these eastern lakes and they lie
crystal clear with deep green windows. In this wilderness is a rich
diversity of rare microscopic organisms. Some, long forgotten, have been
rediscovered there. Others, new and novel, turn up with every cast of the
net. Among the richest sites are the coastal, fresh-water lagoons which the
Aboriginal inhabitants would have known intimately. Beside the Gordon River
are small lakes of very special interest. Periodically, they are topped up
with salt water from the estuary, keeping them meromictic, with brackish
water below and fresh water above. Such lakes and their unusual features
are uncommon in the world. They have social relevance. Because of their
meromictic condition, their sediments hold an especially fine-resolution
chronology of prehistoric climates and vegetational changes which shaped
Aboriginal fortunes to the times of European contact. Tasmania must stand
as one of the finest lake districts of the world. Perhaps nowhere else is
there such limnological richness and diversity in so small an encompass as
this island. Add to this its predominantly pristine nature, its uniqueness
and its beauty, and we have in all respects a World Heritage wetland
unsurpassed in this degraded world.
West, P. and G. Osler (1995). "Growth response to thinning and its relation
to site resources in Eucalyptus regnans." Canadian Journal of Forest
Research 25(1): 69-80.
The factors determining individual tree growth response are examined
during the 4 years following thinning in experiments in even-aged, 8- or
12-year-old regrowth Eucalyptus regnans forest at one site in Tasmania and
one site in Victoria. At the Tasmanian site, a vigorous understorey
dominated by a sedge developed after the thinning. At that site, light-use
efficiency by the trees was unaffected by thinning and the aboveground
biomass production by the trees in the thinned stand was substantially less
than that in the unthinned stand. At the site in Victoria, little
understorey developed, light-use efficiency by trees in the thinned stand
was greater than that in the unthinned stand, and aboveground biomass
production was unaffected by thinning even though the leaf weight of the
thinned stand was far less than that of the unthinned stand. Where the
understorey developed, it was concluded that it competed successfully with
the trees for water, thereby reducing production in the thinned stand when
compared with the unthinned stand. The individual tree growth response that
occurred in the thinned stand at that site appeared to be due solely to the
extra light available to individual trees following the canopy opening.
Where the understorey did not develop, it was concluded that individual
tree growth response was due not only to the extra light available to
individual trees but also to the increased availability of belowground
resources, most probably soil water. Application of a pre-existing stand
growth model suggested that at that site the tendency for increased growth
resulting from extra water availability in the thinned stand was just
balanced by decreased growth due to lower radiation absorption by the
reduced canopy, so that net production was unaffected by thinning.
Weston, C. J. and P. M. Attiwill (1990). "Effects of fire and harvesting on
nitrogen transformations and ionic mobility in soils of Eucalyptus regnans
forests of south-eastern Australia." Oecologia 83(1): 20-26.
Effects of fire and forest harvesting on inorganic-N in the soil, on net
N-mineralization, and on the leaching of NO super(-)@)d3-N and metallic
cations were measured in forests of Eucalyptus regnans) following a severe
wildfire in 1983. The concentrations of NO super(-)@)d3-N and metallic
cations in soil solution increased with increasing fire intensity.
Processes which limit the production and persistence of NO super(-)@)d3-N
in soil solution following disturbance will significantly reduce nutrient
losses or redistribution.
Weston, C. J. and P. M. Attiwill (1996). "Clearfelling and burning effects
on nitrogen mineralization and leaching in soils of old-age Eucalyptus
regnans forests." For. Ecol. Manage. 89: 1-3.
An argument against clearfelling and burning operations in forests is that
nutrient reserves may be diminished, leading to productivity decline over
successive rotations. Nitrogen is of primary concern as it is readily
volatilised and may be leached and thus the retention of nitrogen is a key
recovery process following perturbation. In this study we measured N
mineralization in situ and nitrogen concentrations in soil water from an
old-age Eucalyptus regnans forest (about 250 years old) and from
clearfelled forest in which treatment areas of unburnt ground, burnt ground
and burnt ground maintained free from regrowth were established. Total
inorganic N in the soil (0-5 cm) increased to a maximum of 168 mu g/g of
dry soil in clearfelled forest following burning, compared with 33 mu g/g
of dry soil in undisturbed forest. Increased total inorganic N in the soil
returned to a concentration equal to that in undisturbed forest most
rapidly in the clearfelled unburnt forest (6-9 months) and persisted for
the longest amount of time in the most severely disturbed site (clearfelled
burnt+herbicide-treated forest; 15-18 months). Net annual N mineralization
in undisturbed forest soils (0-5 cm) averaged 74.9 mu g/g of dry soil over
the two years of the study. In contrast, annual average N mineralization
was negative in two of the three clearfelled sites with 148.3 mu g/g of dry
soil of N immobilized in clearfelled and burnt forest. The concentration of
NO sub(3-) in soil water increased with increasing forest disturbance. Over
the first 260 days following clearfelling NO sub(3-)-N concentrations in
soil water at 10 cm depth averaged 2.6 mg/l in undisturbed forest, 8.5 mg/l
in clearfelled unburnt forest, 24.2 mg/l in clearfelled burnt forest, and
60.3 mg/l in clearfelled burnt+herbicide treated forest. Studies of net N
mineralization in situ, and of NO sub(3-) in soil water, support the
hypothesis that inorganic N was immobilized in all disturbed forests.
Immobilization of N by soil micro-organisms is alone not sufficient to
limit nitrification and NO sub(3-) leaching in disturbed E. regnans
forests. Rapid uptake of N by regrowing vegetation is essential in reducing
the availability of substrate for nitrification (NH sub(4+)) as well as in
reducing NO sub(3-) concentrations in soil water. Clearfelling of the E.
regnans catchment in this study did not significantly increase streamwater
NO sub(3-) concentrations and demonstrates the resilience of E. regnans
forests to leaching losses of N following destructive disturbance.
Wilkinson, G., M. Battaglia, et al. (1993). "Silvicultural use and effects
of fire." Technical Bulletin Native Forest Silviculture, Forestry
Commission, Tasmania No. 11, 60 pp.; 11 pp. of ref. PUBLISHER
INFORMATION(Forestry Commission): Tasmamia.
A discussion is presented in 3 parts on the effects of fire on the
silvicultural management of Tasmania's native forests which are mostly
eucalypt (Eucalyptus spp.) forests. Part A provides guidelines for the
silvicultural use of fire for site preparation and fuel reduction and for
the management of forests damaged by fire. Part B contains a summary of the
ecological effects of fire in Tasmania's forests. Part C is a comprehensive
literature review (on which parts A and B are based) and includes sections
on (i) prehistory of fire in Tasmania, (ii) eucalypt fire ecology, (iii)
ecological models of vegetation, fire and time, and (iv) effects of fire on
soils, water, air, vegetation and fauna.