Callitris Glaucophylla Research Articles

Leichhardt’s maps: 100 years of change in vegetation structure in inland Queensland

AbstractAim To address the hypothesis that there has been a substantial increase in woody vegetation cover (‘vegetation thickening’) during the 100 years after the burning practices of aboriginal hunter‐gatherers were abruptly replaced by the management activities associated with pastoralism in north‐east Australia.Location Three hundred and eighty‐three sites on 3000 km transect, inland Queensland, Australia.Methods Vegetation structure descriptions from the route notes of the first European exploration of the location by Ludwig Leichhardt in 1844–45 were georeferenced and compiled. Leichhardt’s application of structural descriptors (e.g. ‘scrub’, ‘open forest’, ‘plain’) was interpreted as domains within a matrix of tall stratum and low stratum woody cover. Woody cover was also interpreted for the same locations using aerial photography that largely pre‐dates extensive land clearing (1940s–1970s) and compared with their structural domain in 1844–45. The fire‐sensitive tree, cypress‐pine (Callitris glaucophylla) was singled out for case study because it has been widely proposed that the density of this tree has substantially increased under European pastoral management.Results The coarse resolution of this analysis indicates that the structure of the vegetation has been stable over the first 100 years of pastoralism. For example treeless or sparsely treed plains described by Leichhardt (1844–45) had the same character on the aerial photography (1945–78). Leichhardt typically described vegetation that includes cypress‐pine as having a ‘thicket’ structure suggesting dense regenerating stands of small trees, consistent with the signature typical on the aerial photography.Main conclusions A large data set of geographically located descriptions of vegetation structure from the first European traverse of inland Australia compared with vegetation structure determined from aerial photography does not support the hypothesis that vegetation thickening has been extensive and substantial. On the contrary the study suggests that the structure of the vegetation has been relatively stable for the first 100 years of European settlement and pastoralism except for those areas that have been affected by broad‐scale clearing.

The response of sap flow to pulses of rain in a temperate Australian woodland

In water-limited systems, pulses of rainfall can trigger a cascade of plant physiological responses. However, the timing and size of the physiological response can vary depending on plant and environmental characteristics, such as rooting depth, plant size, rainfall amount, or antecedent soil moisture. We investigated the influence of pulses of rainfall on the response of sap flow of two dominant evergreen tree species, Eucalyptus crebra (a broadleaf) and Callitris glaucophylla (a needle leaved tree), in a remnant open woodland in eastern Australia. Sap flow data were collected using heat-pulse sensors installed in six trees of each species over a 2 year period which encompassed the tail-end of a widespread drought. Our objectives were to estimate the magnitude that a rainfall pulse had to exceed to increase tree water use (i.e., define the threshold response), and to determine how tree and environmental factors influenced the increase in tree water use following a rainfall pulse. We used data filtering techniques to isolate rainfall pulses, and analysed the resulting data with multivariate statistical analysis. We found that rainfall pulses less than 20 mm did not significantly increase tree water use (P > 0.05). Using partial regression analysis to hold all other variables constant, we determined that the size of the rain event (P < 0.05, R2 = 0.59), antecedent soil moisture (P < 0.05, R2 = 0.29), and tree size (DBH, cm, P < 0.05, R2 = 0.15), all significantly affected the response to rainfall. Our results suggest that the conceptual Threshold-Delay model describing physiological responses to rainfall pulses could be modified to include these factors. We further conclude that modelling of stand water use over an annual cycle could be improved by incorporating the T-D behaviour of tree transpiration.

A preliminary examination of White Cypress Pine management and soil and vegetation condition.

A preliminary examination of White Cypress Pine management and soil and vegetation condition.

A stable oxygen, but not carbon, isotope chronology of Callitris columellaris reflects recent climate change in north-western Australia

We investigated the dendroclimatic potential of stable carbon (δ13C) and oxygen (δ18O) abundances in tree rings of Callitris columellaris F. Muell. Tree-ring chronologies were constructed from the central Pilbara, north-western Australia and span 1919–1999. Variation in δ18O was more strongly related to climate than δ13C; ecological and physiological factors may have dampened the climate signal in the δ13C chronology. Tree-ring δ18O was most strongly correlated with relative humidity (RH) and rainfall (r = −0.36 and −0.39) of the wettest months of the summer period, January and February. The correlation with RH reflects its effect on evaporative enrichment of leaf water. However, tree-ring δ18O may also partly reflect the variability in 18O signatures of rainfall, which are influenced by the amount of rainfall and atmospheric humidity. From the δ18O chronology, we inferred that from 1919 to 1955 summers were relatively dry and warm, but since 1955, summers in the Pilbara region have become increasingly cooler and more humid. Since 1980, conditions have been the wettest and coolest of the last 80 years. These inferred changes in climate correspond to a measured increase in rainfall since 1980 in north-western Australia associated with a greater intensity of tropical cyclones. We conclude that δ18O abundances in tree rings of C. columellaris have significant potential for reconstructing the climate of semi-arid Australia, a region for which observational climate records are sparse.

Roads, fire and aggressive competitors: Determinants of bird distribution in subtropical production forests

Forestry practices such as fuel-reduction burning and maintenance of road networks can negatively impact avian assemblages, both directly by changing habitat structure and indirectly by creating conditions favorable for predators or competitors. The Brigalow Belt forests include some of the largest contiguous areas of native forest in the temperate and sub-humid zones of eastern Australia. Over 1 million ha of these forests are proposed to be converted from forestry to conservation tenure, yet the impacts on the avifauna of current and potential future forest management practices are not known. We investigated the influence of road edges and habitat type and structure on the avifauna of a 356 000 ha forest. Survey sites were either <50 m or >300 m from a road, and in either cypress pine Callitris glaucophylla forest, spotted gum Corymbia citriodora forest with a regenerating cypress pine/buloke Allocasuarina luehmannii understorey or spotted gum forest with an open understorey due to fuel-reduction burning. The avifauna differed significantly among vegetation types but not with proximity to a road, with the greatest differences between cypress pine and both types of spotted gum forest. The noisy miner Manorina melanocephala, an aggressive avian competitor, appears to be the factor mediating these assemblage-level differences. Noisy miners were rare in cypress pine forest but were three times more numerous than any other species in spotted gum forest. Spotted gum forest with a regenerating understorey had fewer noisy miners. Although total bird abundance was highest in open spotted gum forest, the species richness and abundance of passerines smaller than noisy miners was significantly lower in this forest type. Abundance of small passerines was eight times higher in sites where <3 noisy miners were recorded. Only one species, the eastern yellow robin, was influenced by proximity to a road edge. Cypress pine forest is potentially an important refuge for smaller birds. The results suggest that burning regimes that reduce regeneration of the cypress pine and buloke subcanopy in spotted gum forest potentially are exacerbating the problem of noisy miner domination of the avifauna.

Koalas continue to occupy their previous home-ranges after selective logging in Callitris - Eucalyptus forest

The koala (Phascolarctos cinereus) is a charismatic, high-profile species whose conservation needs are commonly perceived to be incompatible with logging. However, koala biology and the results of chronosequence studies elsewhere suggest that this species may tolerate a degree of habitat alteration caused by logging. In this study, 30 koalas, five in each of six areas available for logging within a mixed white cypress pine (Callitris glaucophylla)–Eucalyptus forest in north-western New South Wales, were radio-tracked for one year during 1997–1998 to determine their movements, home-range sizes and tree preferences. Five months after the study began, three of these areas were logged selectively for sawlogs and thinnings of the white cypress pine, a tree that is important to koalas for daytime shelter. This removed about one-quarter of the stand basal area, but the eucalypt component was unaffected. The remaining three areas were left undisturbed as controls. Radio-tracking continued in all six areas for another seven months. Koalas continued to occupy all or part of their previous home-ranges after selective logging, and home-range sizes remained similar between logged and unlogged areas. Home-ranges for both sexes overlapped and were ~12 ha for males and 9 ha for females. Koala survival and the proportions of breeding females were similar in logged and unlogged areas. The principal food trees of the koala were red gums, mainly Eucalyptus blakelyi and E. chloroclada, and the pilliga box (E. pilligaensis), none of which were logged in this study. These results suggest that selective logging for white cypress pine does not appear to adversely affect koala populations and that koalas may not be as sensitive to logging as previously thought. Further work is required to determine thresholds in the level of retention of koala food trees in logging operations.

Daily, seasonal and annual patterns of transpiration from a stand of remnant vegetation dominated by a coniferous Callitris species and a broad‐leaved Eucalyptus species

Quantifying water use of native vegetation is an important contribution to understanding landscape ecohydrology. Few studies provide long‐term (more than one growing season) estimates of water use and even fewer quantify interseasonal and interannual variation in transpiration. Globally, changes in land use are significantly altering landscape ecohydrology, resulting in problems such as dryland salinity and excessive groundwater recharge. Estimating stand water use is complex in multispecies forests, due to the differences in relationships among sapwood area, basal area and tree size for co‐occurring species. In this article, we examine seasonal and interannual variation in transpiration rate of the tree canopy of two co‐occurring species (a conifer Callitris glaucophylla J. Thompson &amp; L.A.S. Johnson and a broad‐leaved Eucalyptus crebra F. Muell.) in an open woodland in eastern Australia. Evapotranspiration of understorey species was measured using an open‐top chamber, and tree water use was measured using heat‐pulse sap flow sensors. Annual stand transpiration was 309 mm in 2003, a year of below average rainfall, and 629 mm in 2004, a year with higher‐than‐average rainfall. Despite an almost doubling (522 vs. 1062 mm) of annual rainfall between 2003 and 2004, annual tree water use remained a constant fraction (59%) of rainfall, indicative of compensatory mechanisms linking annual rainfall, leaf area index and tree water use. Deep drainage was estimated to be 4% of rainfall (20.8 mm) in 2003 and 2% (21.2 mm) in 2004, indicating that this native woodland was able to minimize deep drainage despite large interannual variability in rainfall.

Growth and survival of two north Australian relictual tree species, Allosyncarpia ternata (Myrtaceae) and Callitris intratropica (Cupressaceae)

AbstractAllosyncarpia ternata (an angiosperm) and Callitris intratropica (a gymnosperm) are two fire‐sensitive tree species of the Australian monsoonal tropics. Studies using historical aerial photography have revealed recent expansion of A. ternata rainforests. There has simultaneously been a widespread collapse of C. intratropica populations in northern Australian savannas, presumably because of cessation of traditional Aboriginal landscape burning. To explain the demography behind these contrasting trends, stand structure, survival, and growth of the two species were recorded over a 16‐year period at the boundary of a rainforest patch and also in adjacent savanna, in Kakadu National Park. Ages of the largest trees of each species, estimated by using a Bayesian analysis of tree‐diameter increments, were approximately 433 years for A. ternata and 235 years for C. intratropica on the rainforest boundary, and 417 years for C. intratropica in the adjacent savanna. Densities of juveniles (seedlings and re‐sprouts &lt;0.5 m high) were 325–6,000 times higher for A. ternata than for C. intratropica. Life‐table calculations indicated there was sufficient recruitment of A. ternata, but not C. intratropica, to overcome observed mortality rates and maintain a stable population. This is almost certainly because A. ternata re‐sprouts prolifically after fire whereas C. intratropica is an obligate seeder. These results highlight the critical need for careful fire management to maintain populations of a characteristic Australian gymnosperm over much of its range.

Soil and vegetation response to thinning White Cypress Pine (Callitris glaucophylla) on the North Western Slopes of New South Wales, Australia

Dense White Cypress Pine (Callitris glaucophylla J. Thompson and L.A.S. Johnson) regrowth occurs frequently across previously cleared landscapes in New South Wales (NSW), and is thought to adversely affect agricultural production and to cause land degradation. The NSW Native Vegetation Act (2003) requires that management of native vegetation including pre- 1990 regrowth must 'improve or maintain' site condition, yet there is currently limited informa- tion regarding techniques for the optimum man- agement of C. glaucophylla in this regard. We conducted a preliminary study to examine floristic composition, soil condition (to 50 cm) and carbon storage under 'Dense' (dense regrowth), 'Thin- ned' (dense regrowth thinned 2000/2001) and 'Un-colonised' (pasture not yet recolonised by C. glaucophylla) plots on private lands in NSW. Reduced tree density from thinning resulted in increased biomass of the remaining individual trees. Un-colonised plots had significantly more groundcover than thinned plots, which had sig- nificantly more groundcover than dense plots. Differences in plant diversity however, were ex- plained by site factors rather than land use. Soils in the dense plots were the most acid but soil pH was significantly higher in thinned plots and pH was highest in soil of the un-colonised plots. Mean values for carbon, nitrogen, sulphur and extract- able phosphorus varied among sites, although each were significantly more abundant in the mineral soil of dense and thinned plots compared with un-colonised plots, suggesting that thinning had had a minimal effect on the soil parameters assessed. Accounting for all site components, site carbon storage was significantly higher in dense and thinned plots compared with un-colonised plots due to elevated levels of soil and litter car- bon as well as the presence of trees. The results indicate that thinning dense C. glaucophylla can maintain and (by some measures) improve site condition. However, given the variability in some of the parameters assessed, further study across a wider range of soil types and rainfall gradients is proposed.

Structure of biological soil crust communities inCallitris glaucophyllawoodlands of New South Wales, Australia

Abstract:Question:What is the nature of the relationships between cover, diversity and abundance of biological soil crusts, cover and diversity of vascular plants, and annual rainfall, soil texture and forestry practices inCallitris glaucophyllawoodlands? Location: Arid and semi‐aridCallitris glaucophylla‐domi‐nated woodlands of eastern Australia.Methods:We documented soil crust‐forming mosses, lichens and liverworts at 83 woodland sites along a gradient of declining rainfall. Linear and non‐linear regression were used to examine relationships between soil crust species and attributes of vascular plant communities, and a similarity matrix (species abundance X sites) was subjected to Non‐metric Multi‐Dimensional Scaling (MDS), and Analysis of Similarities (ANOSIM) to show the degree of association between groups of taxa, and soil texture, rainfall classes and forestry practices.Results: We collected 86 taxa. Mosses were dominated by the familyPottiaceae, and lichens were dominated by squamulose forms. Average annual rainfall was highly correlated with soil crust community composition, and loamy soils supported a greater cover and diversity of taxa compared with sandy soils. Increases in tree cover were associated with significant, though weak, increases in abundance, but not diversity, of crusts. Crusts tended to be more diverse in areas that (1) had a sparse cover of ground‐storey plants; (2) were relatively stable ‐ as indicated by the proportion of perennial and/or native plants; (3) had more stable soil surfaces; and (4) were unlogged. Litter cover, overstorey thinning, and livestock grazing had no appreciable effect on crust diversity or cover.Conclusions:Callitris glaucophyllawoodlands provide substantial habitat for soil crust organisms, and the dense tree cover and closed canopies ofCallitrisdo not appear to have a major influence on the structure of biological crust communities. Unlike other woodland systems, relatively few patches would be required to reserve a high diversity of crust species.

Comparative in-ground natural durability of white and black cypress pines (Callitris glaucophylla and C. endlicheri)

SummaryStakes composed of outer heartwood of Callitris glaucophylla (white cypress pine), Callitris endlichen (black cypress pine), Corymbia maculata (spotted gum) and Eucalyptus regnans (mountain ash) were exposed to in-ground accelerated testing for 280 weeks (5.4 y). The time for each stake to reach unservice-ability (loss of 60–75% of cross-section) due to microbial attack was recorded. The time for Ca. glaucophylla was not significantly different (P > 0.05) from that of Co. maculata. Both these Class 2 timbers were significantly different in durability from Ca. endlichen which, in turn, was significantly different (P < 0.05) from E. regnans, a less durable Class 4 timber. Calibration with long-term field test results for Ca. glaucophylla and Co. maculata suggested that Ca. endlichen should remain Class 2. The sapwood of both Callitris species showed evidence of higher natural durability than that of Pinus radiata. Other comparisons demonstrated that no significant difference was found in time to unserviceability of Ca. glaucophylla from two sites (Forbes and Gilgandra, both NSW), and similarly for Ca. endlicheri. Also, no significant correlation between time to unserviceability and density was found.

Is cellulose extraction necessary for developing stable carbon and oxygen isotopes chronologies from Callitris glaucophylla?

We examined the necessity of extracting cellulose for the development of stable carbon and oxygen isotope chronologies from Callitris glaucophylla J. Thompson and L.A.S. Johnson (Cupressaceae). We compared relationships among isotopes of whole wood, cellulose and climate for the period 1979–1999 and using a moving interval technique with a 10-year window. Isotopes of whole wood and cellulose were significantly correlated and had similar relationships with climate when considered over the entire period. In general, variation in δ 13C and δ 18O was related to summer temperature relative humidity and rainfall. However, δ 13C and δ 18O of whole wood generally exhibited weaker and more variable correlations with climate through time than cellulose. In addition, isotopes of whole wood did not deviate from 1979 to 1999 mean values in the same way as isotopes of cellulose. The instability of whole wood–climate relationships may be due to the inclusion in whole wood of a climate signal from lignin that is more variable between tree rings than cellulose. Overall, it appears that C. glaucophylla at least whole wood does not record climate in the same way as cellulose and stable isotopes of cellulose provide a more temporally stable proxy of past climate. We suggest that when developing isotope chronologies for other species the suitability of whole wood vs. cellulose as a proxy for climate should be assessed with consideration of the temporal stability of their relationship with climate.

Termite repellent sesquiterpenoids from Callitris glaucophylla heartwood

Fractions of methanol and ethanol extracts from the heartwood of white cypress pine (Callitris glaucophylla Thompson et Johnson) were investigated for their repellent activity against subterranean termite Coptotermes formosanus Shiraki worker using a two-choice semicircular filter paper test at 0.5% (w/w) concentration. Fraction CY-E2 composed of (−)-citronellic acid, guaiol, α-, β-, and γ-eudesmol isomers as well as an unknown compound, showed the highest statistically significant repellency (97.8% ± 2.2 SEM) of all fractions tested. Bioactivity-guided fractionations using high-performance liquid chromatography led to the isolation of two, oxygenated eudesmane-type sesquiterpenes with α-methylene moieties, both termite-repellent compounds. These compounds were subsequently identified as ilicic acid methyl ester (IAME) and costic acid by means of spectroscopic analyses, electron impact mass spectrometry, and nuclear magnetic resonance spectroscopy. We report the isolation of both IAME and costic acid from C. glaucophylla heartwood for the first time.

Airborne laser scanning: Exploratory data analysis indicates potential variables for classification of individual trees or forest stands according to species

Understanding your data through exploratory data analysis is a necessary first stage of data analysis particularly for observational data. The checking of data integrity and understanding the distributions, correlations and relationships between potentially important variables is a fundamental part of the analysis process prior to model development and hypothesis testing. In this paper, exploratory data analysis is used to assess the potential of laser return type and return intensity as variables for classification of individual trees or forest stands according to species. For narrow footprint lidar instruments that record up to two return amplitudes for each output pulse, the usual pre-classification of return data into first and last intensity returns camouflages the fact that a number of the return signals have only “single amplitude” (singular) returns. The importance of singular returns for species discrimination has received little discussion in the remote sensing literature. A map view of the different types of returns overlaid on field species data indicated that it is possible to visually distinguish between vegetation types that produce a high proportion of singular returns, compared to vegetation types that produce a lower proportion of singular returns, at least when using a specific laser footprint size. Using lidar data and the corresponding field data derived from a subtropical woodland area of South East Queensland, Australia, map scatterplots of return types combined with field data enabled, in some cases, visual discrimination at the individual tree level between White Cypress Pine ( Callitris glaucophylla) and Poplar Box ( Eucalyptus populnea). While a clear distinction between these two species was not always visually obvious at the individual tree level, due to other extraneous sources of variation in the dataset, the observation was supported in general at the site level. Sites dominated by Poplar Box generally exhibited a lower proportion of singular returns compared to sites dominated by Cypress Pine. While return intensity statistics for this particular dataset were not found to be as useful for classification as the proportions of laser return types, an examination of the return intensity data leads to an explanation of how return intensity statistics are affected by forest structure. Exploratory data analysis indicated that a large component of variation in the intensity of the return signals from a forest canopy is associated with reflections of only part of the laser footprint. Consequently, intensity return statistics for the forest canopy, such as average and standard deviation, are related not only to the reflective properties of the vegetation, but also to the larger scale properties of the forest such as canopy openness and the spacing and type of foliage components within individual tree crowns.

Comparison of cellulose extraction methods for analysis of stable isotope ratios of carbon and oxygen in plant material

The Jayme-Wise and diglyme-HCl methods for extracting cellulose from plant material for stable-isotope analysis differ considerably in ease of use, with the latter requiring significantly less time and specialized equipment. However, the diglyme-HCl method leaves a small lignin residue in the crude cellulose that may affect stable-isotope values, whereas alpha-cellulose produced by the Jayme-Wise method is relatively pure. We examined whether adding a bleaching step to the diglyme-HCl method could produce cellulose of comparable purity to alpha-cellulose by comparing the yield, percent carbon, and carbon (delta13C) and oxygen (delta18O) stable isotope ratios of the two celluloses. We tested each method on the wood of five species that differ in ease of delignification, Eucalyptus maculata Hook., E. botryoides Sm., E. resinifera Sm., Pinus pinaster Ait. and Callitris glaucophylla J. Thompson & L.A.S. Johnson, as well as the foliage of C. glaucophylla. For hardwoods such as the eucalypts, the diglyme-HCl method without bleaching produced cellulose with delta13C and delta18O ratios similar to alpha-cellulose. For the softwood, C. glaucophylla, 3 h of bleaching with acidified chlorite following treatment with diglyme-HCl produced cellulose with delta13C and delta18O ratios similar to alpha-cellulose. Bleached and unbleached crude celluloses and alpha-cellulose of P. pinaster were similar in delta18O, but not delta13C. Both types of crude cellulose produced from the foliage of C. glaucophylla had significantly different isotope ratios from alpha-cellulose. Overall, the diglyme-HCl method, with or without bleaching, appears to be a simple, fast method for extracting alpha-cellulose from hardwoods for stable-isotope analyses, but its suitability for softwoods and foliage needs to be evaluated depending on the species.

Investigating Antitermitic Compounds from Australian White Cypress Heartwood (Callitris glaucophylla Thompson et Johnson) Against Coptotermes formosanus Shiraki

Antitermitic activities of extracts obtained from the heartwood of Australian white cypress (Callitris glaucophylla Thompson et Johnson) were investigated in an attempt to detect and identify the presence of biologically active compounds against Coptotermes formosanus Shiraki. Extraction of compounds was achieved by successive extraction using dichloromethane and methanol. Three sesquiterpene alcohols, guaiol, α-eudesmol and β-eudesmol and two monoterpene acids, (−)-citronellic acid and geranic acid, were found in the C. glaucophylla heartwood extracts based on high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS) analysis. Antitermitic activity of each fraction obtained from methanol extracts was demonstrated by repellent and no-choice feeding tests. One of the strong termiticidal active compounds identified was columellarin and another sesquiterpene lactone fraction showed repellent activity.

Ecosystem wicks: Woodland trees enhance water infiltration in a fragmented agricultural landscape in eastern Australia

Abstract Since European settlement, Eucalyptus box woodlands have been substantially modified by agricultural practices, and in many areas in southern Australia are now restricted to scattered or clumped trees. We report here on a study to examine the impact of trees on water flow (infiltration) in an agricultural landscape with substantial areas of extant native vegetation. We examined infiltration through coarse‐ and fine‐textured soils within four landscape strata, the zones below Eucalyptus melliodora and Callitris glaucophylla canopies, the intertree zone dominated by perennial grasses and a landscape homogenized by cultivation and dominated by annual crops. We measured sorptivity, the early phase of water flow, and steady‐state infiltration with disc permeameters at two supply potentials. These different potentials enabled us to separate infiltration into (i) flow through large (biopores) and small pores and (ii) flow through small pores only where biopores are prevented from conducting water. On the fine‐textured soils, both sorptivity and steady‐state infiltration were significantly greater (approximately fivefold) under the timbered strata compared with the grassy slopes or cultivation. Differences were attributable to the greater proportion of macropores below the tree canopies compared with the nontimbered strata. The lack of a significant difference on the coarse‐textured soils, despite their macropore status, was attributed to differences in surface litter and plant cover, which would maintain continuous macropores at the surface and thus conduct large amounts of water. The tendency of slopes covered by cryptogamic crusts and grasses to shed run‐off and for the trees to absorb substantial quantities of water reinforced the important ecological service provided by trees, which moderates large run‐off events and captures small amounts of water leaking from the grassy patches. In the absence of these ‘ecosystem wicks’, run‐off would find its way into regional groundwater and contribute to rising salinity.

How important are different types of temperate woodlands for ground-foraging birds?

There is widespread concern about population decline in a number of woodland-dependent birds in southern Australia. Of all declining species, approximately half forage on the ground. This study examined the avifaunal assemblages of temperate woodlands of the Northern Plains, Victoria, to investigate the importance of woodland habitats for ground-foraging species. Four main types of woodland were surveyed (white cypress-pine, black box, grey box and river red gum) and, in total, 89 bird species were detected. All four woodland types differed in habitat structure and, in turn, supported significantly different avifaunal assemblages. Forty of the 89 species (45%) foraged, at least in part, on the ground. Species richness and abundance of ground-foragers differed significantly between woodland types, being highest in white cypress-pine and black box. There was a greater richness of ground-foragers during the breeding than non-breeding season, but abundance did not vary seasonally. Overall, ground-foraging birds comprised a greater proportion of species (&gt;55%) and individuals (&gt;60%) in white cypress-pine and black box woodland than in grey box and river red gum (42–48% of species, &lt;50% individuals). Those ground-foragers regarded as declining also occurred in greatest richness in white cypress-pine woodlands, one of the most depleted habitats in the region. The lowest richness of ‘declining’ ground-foraging species was in river red gum woodland, the most widespread woodland type. Throughout Australia, the proportion of ground-foraging species in bird assemblages tends to be greater in temperate, semi-arid or arid woodlands than in moist forests and rainforests. However, in many regions woodland habitats are severely depleted and their open ground layer is particularly vulnerable to degradation. The extent of suitable habitat for ground-foraging birds in temperate woodlands may be much less than is apparent from current measures of tree cover. Sustainable management of drier (non-riverine) temperate woodlands is required to conserve this important element of the Australian avifauna.

White cypress pine (Callitris glaucophylla): a review of its roles in landscape and ecological processes in eastern Australia

Callitris glaucophylla (J.Thompson &amp; L.Johnson, white cypress pine) woodlands are an important vegetation community over relatively large areas of continental eastern Australia. C. glaucophylla communities were originally reserved because of their value to the timber industry, but renewed attention is being placed on these woodlands because of their putative role in the conservation of native plants and animals. The pre-European distribution of C. glaucophylla was altered dramatically in the past century because of a combination of grazing by domestic livestock and feral animals, altered fire regimes and weed invasion. Today, the majority of C. glaucophylla woodlands are highly fragmented remnants, with many managed as formal forestry reserves. Selective logging during the past 30 years has led to a community that is dominated by single-aged stands, often at high densities, leading to the perception that C. glaucophylla communities are severely degraded and floristically depauperate. Increased interest in the structure and function of grassy woodlands in eastern Australia over the past decade has led to a re-evaluation of the importance of this vegetation community for habitat and for maintaining essential ecosystem processes. The timing of this review is appropriate because (1) much has been published on the ecological role of C. glaucophylla over the past decade in Australia, although mostly in unpublished reports, and (2) there is a need to resolve some of the conflicting issues relating to the value of C. glaucophylla woodlands for healthy soils and vegetation. Here, we review the ecological role of C. glaucophylla, with an emphasis on eastern Australia, drawing on a range of published and unpublished literature. We describe the characteristics and distribution of C. glaucophylla in eastern Australia, its role in soil and ecological processes, and the impacts of fire and grazing. Finally, we discuss the management of C. glaucophylla for a range of landuses.

Plant cover and composition in relation to density of Callitris glaucophylla (white cypress pine) along a rainfall gradient in eastern Australia

Despite the widespread distribution of Callitris glaucophylla J.Thompson &amp; L.Johnson (white cypress pine) over large areas of eastern Australia, little is known about its impact on the diversity and cover of understorey plants. We examined C. glaucophylla woodlands to see whether stand density and land management influenced the cover and composition of the understorey vegetation. The cover and diversity of understorey plant communities were measured at 83 sites along a gradient in average annual rainfall (215–532 mm) in eastern Australia. The diversity and cover of understorey plants and the cover of trees increased, and the composition of the understorey community changed with increases in average annual rainfall. There were no clear relationships, however, between tree cover or density, and the cover or diversity of understorey plants. Sites that had not been logged contained significantly greater proportions of native and perennial vascular plants, and sites with extant eucalypts had a significantly higher proportion of shrubs than those sites without eucalypts. We attributed these differences to past forestry disturbance regimes which are correlated with the presence of mature eucalypts. Our results do not support the proposition that dense stands of C. glaucophylla suppress the understorey vegetation.