How do Araucaria angustifolia trees grow in overstocked stands?

The objective of this study was to evaluate growth along the stem of Araucaria angustifolia (Bertol.) Kuntze trees competing in overstocked stands, in order to identify periods when growth and trunk shape are differentiated during the trees' lifespan. The research was carried out in a planted forest of Araucaria angustifolia established in 1946 in the Açungui National Forest in Campo Largo, Paraná, Brazil, when these trees were 65 years old. One thinning was recorded, at some time between 1970 and 1980. Forty-six trees were selected and divided into three development classes (DC) at 65 years of age; these classes considered diameter at 1.30 m (breast height, dbh) with a range of 20 cm (from 10 cm to 70 cm). In addition to dbh, total tree height, and crown height and diameter were measured in the field. From each tree, 14 disks were removed to analyze growth rings and confirm the age of the stand. Some trees in the smallest DC (10 ≤ dbh < 30 cm) were the product of natural regeneration (younger trees that grew after the initial planting). In 63% of the trees, at least one growth ring was missing at breast height. Missing rings at breast height were more common in trees with smaller dbh and crown diameters. The need for more growing space was observed at different periods during the studied lifespan of the trees from three DCs. It resulted in changes in stems shape from conical to cylindrical. Different growth patterns could be observed during the lives of some trees as they outgrew their competition.     

Effects of fertilizer and low rates of imidacloprid on Adelges tsugae (Hemiptera: Adelgidae)

Healthy hemlock trees, Tsuga canadensis (L.) Carrière, and hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), populations should favor retention and population growth of adelgid predators such as Laricobius nigrinus Fender (Coleoptera: Derodontidae) and Sasajiscymnus tsugae (Sasaji & McClure) (Coleoptera: Coccinellidae). Eastern hemlock trees between 15 and 38 cm diameter at breast height (dbh) were treated with 0, 10, or 25% of 1.5 g imidacloprid (Merit 75 WP) per 2.5 cm dbh and were either fertilized or not, in a 3 by 2 factorial design. After 2 yr, imidacloprid reduced the numbers of ovisacs and eggs found on trees in a dosage-dependent manner, while enhancing tree growth parameters such as new shoots or needles and the length of new shoots. Fertilized trees had greater adelgid fecundity, which was positively correlated with total foliar N in both winter generations. In February 2009 (27 mo after imidacloprid treatment), higher imidacloprid dosages to unfertilized trees resulted in reduced adelgid fecundity. Concentrations of N, P, and K were higher in the foliage of trees treated with insecticide, whereas foliar aluminum concentrations were consistently lower in trees with higher insecticide dosages. Trees treated with low rates of imidacloprid were healthier than untreated trees, but only trees treated with the 0.1 x dosage had sufficient adelgids to possibly sustain predators over extended periods.     

Megafaunal influences on tree recruitment in African equatorial forests

The forests of central Africa are distinct from counterpart forests in Amazonia by having fewer trees ≥ 10 cm dbh ha^?1, especially small trees < 20 cm dbh, and in having sapling cohorts with less diversity than canopy trees. We tested four hypotheses to investigate whether herbivory, in particular, browsing by forest elephants, could be a factor in these differences. We found that the density of small saplings and diversity of large saplings were inversely associated with local density of elephants. We then tested the hypothesis that steep slopes might serve as refugia from elephant foraging, but found that elephants routinely forage on slopes with an inclination of less than ca 30 deg. Nevertheless, the diversity of small trees (≥ 10 cm, < 20 cm dbh) was higher on slopes than on paired level‐ground sites. The incidence of break scars on saplings ≥ 2 cm dbh and < 6 cm dbh was greater (107/100 stems) on level ground than on slopes (77/100 stems), although high variability precluded statistical significance. After correcting for background breakage not caused by elephants, an estimated 71% of breaks on level ground and 43% of breaks on slopes were attributable to elephants. Liana loads borne by trees at different sites were highly variable and unrelated to slope. Apparently, disturbances are more critical to liana development than herbivory. Elephants, along with other large mammals such as gorillas, duikers, red river hogs and rodents, appear to act as powerful filters on the tree recruitment process in African forests that still retain intact megafaunal communities.     

Spatial distribution patterns of two predominant emergent trees in a tropical rainforest in Sarawak,Malaysia

Spatial distribution patterns of two emergent tropical rainforest tree species (Dryobalanops aromatica & D. lanceolata) were examined in where they were dominant (17–20% of total basal area of canopy trees) in Sarawak, East Malaysia. Newly established seedlings (< 2 years old) were restricted to areas < 40 m from mother trees for both species, suggesting a limited seed dispersal. Seedling (< 1 cm in dbh) density was highest around conspecific adults ( 30 cm in dbh). Negative spatial patterns were observed between larger juveniles (1–5 cm in dbh) and conspecific adults for both species; the most dense populations of sapling (1–5 cm in dbh) and poles (5–30 cm in dbh) were found at a distance of 15–20 m from the nearest conspecific adult. Seedlings of both species were distributed randomly with respect to light conditions evaluated by a forest floor diffuse site factor and a canopy closure index. Saplings of both species, and poles of D. lanceolata, were distributed under more open conditions than expected from spatially random distributions, and from average light conditions of all species of the same size classes. Possible mechanisms for the observed distribution patterns and intermediate canopy dominance of Dryobalanops were discussed from the viewpoints of gap-dynamics and distance-dependent mortality.     

Intraspecific Variation in the Fruiting of an Amazonian Timber Tree: Implications for Management

Information concerning the fruit production of timber species is important for the assessment of the effects of logging practices and for the improvement of harvesting techniques. We assessed the effects of stem diameter, crown illumination, and liana load on Chrysophyllum lucentifolium subsp. pachycarpum fruiting over a 3-yr period in areas subjected to conventional and reduced impact logging 10–13 yr prior to the study and within a control area, in the eastern Brazilian Amazon. We further used this data set to estimate the proportion of fertile trees harvested following the adoption of 90 percent harvesting intensity and two different minimum diameter cutting limits (MDCL). Liana presence on > 50 percent of the crown was associated with a decrease in the odds of fruiting. Therefore, liana cutting aiming to increase fruiting output should target only trees in such a condition. We found no significant effects of logging treatments and crown illumination on the odds of fruiting. The percentage of reproductive trees, frequency, and intensity of fruiting increased markedly for trees > 40 cm dbh. The proportion of fertile trees harvested following the adoption of 50 cm dbh MDCL is relatively low (13–15%) and therefore, this practice is likely to have a low direct impact on C. lucentifolium fruiting at the population level. However, even for a population with relatively small fertile individuals and low proportion of trees ≥ 50 cm dbh, the MDCL should not be < 50 cm dbh, unless a lower harvest intensity is adopted.     

Influence of temperature and nutritional requirements for mycelial growth of Eutypa lata, a vineyard pathogenic fungus

Eutypa dieback (dying arm disease, eutypiosis) is a very devastating disease in many grape-producing areas around the world. This vascular disease is induced by the ascomycete Eutypa lata Pers. Fr. Tul & C. Tul. invading the trunk by pruning wounds. The environmental factors and the nutritional requirements regulating fungus development are yet poorly known. This work shows that the isolated strain of E. lata was able to grow in a large temperature range (2-30 degrees C). However, a higher temperature (35 degrees C) presented inhibitory effects on mycelial growth. E. lata was able to use various osidic molecules (C5, C6, C12, C18, C24, and starch); showing thus a large adaptation to the carbon source supplied. As nitrogen source, it used salts and numerous natural amino acids. A significant result was obtained with cysteine presenting obvious antifungal properties. This effect can further be used with the aim of setting up a curative treatment of the disease.     

Size-related flowering and fecundity in the tropical canopy tree species, Shorea acuminata (Dipterocarpaceae) during two consecutive general flowerings

We monitored the reproductive status of all trees with diameters at breast height (dbh) >30 cm in a 40-ha plot at Pasoh, west Malaysia, and investigated the individual fecundity of 15 Shorea acuminata Dyer (Dipterocarpaceae) trees using seed-trapping methods during two consecutive general flowering periods in 2001 (GF2001) and 2002 (GF2002). The proportion of flowering trees was higher, and not dependent on size, in GF2002 (84.2%), than in GF2001 (54.5%), when flowering mainly occurred in trees with a dbh ≤70 cm. Fecundity parameters of individual trees per event varied widely (221,000–35,200,000 flowers, 0–139,000 mature seeds, and 1.04–177 kg total dry matter mass of fruit (TDM) per tree). Monotonic increases with increasing tree size were observed for flower production and TDM amongst trees up to 90 cm in dbh, but not for mature seed production or for any of these parameters amongst larger trees. The pattern of reproductive investment during the two consecutive reproductive events clearly differed between medium-sized and large trees; the former concentrated their reproductive investment in one of the reproductive events whereas the latter allocated their investment more evenly to both reproductive events. Our results suggest size-related differences in the resource allocation pattern for reproduction. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Liana cover in the canopies of rainforest trees is not predicted by local ground‐based measures

Lianas (woody climbers) are structural parasites of trees that compete with them for light and below‐ground resources. Most studies of liana–tree interactions are based on ground‐level observations of liana stem density and size, with these assessments generally assumed to reflect the amount of liana canopy cover and overall burden to the tree. We tested this assumption in a 1‐ha plot of lowland rainforest in tropical Australia. We recorded 1072 liana stems (≥1 cm diameter at breast height {dbh}) ha^?1 across all trees (≥10 cm dbh) on the plot and selected 58 trees for detailed study. We estimated liana canopy cover on selected trees that hosted 0–15 liana individuals, using a 47‐m‐tall canopy crane. Notably, we found no significant correlations between liana canopy cover and three commonly used ground‐based measurements of liana abundance as follows: liana stem counts per tree, liana above‐ground biomass per tree and liana basal area per tree. We also explored the role of tree size and liana infestation and found that larger trees (≥20 cm dbh) were more likely to support lianas and to host more liana stems than smaller trees (≤20 cm dbh). This pattern of liana stem density, however, did not correlate with greater liana coverage in the canopy. Tree family was also found to have a significant effect on likelihood of hosting lianas, with trees in some families 3–4 times more likely to host a liana than other families. We suggest that local ground‐based measures of liana–tree infestation may not accurately reflect liana canopy cover for individual trees because they were frequently observed spreading through neighbouring trees at our site. We believe that future liana research will benefit from new technologies such as high‐quality aerial photography taken from drones when the aim is to detect the relative burden of lianas on individual trees.     

Small-scale variation in chemical property within logs of Japanese beech in relation to spatial distribution and decay ability of fungi

Fungal communities within a naturally fallen bough of Japanese beech (Fagus crenata) were investigated with reference to chemical properties of decay columns. Five logs were cut out from the fallen bough, which ranged from 10.7 to 20.5 cm in diameter. Nine fungal species and one sterile fungus were isolated from decay columns that elongated along a longitudinal axis and were delimited by black zone lines and wood discoloration. Lampteromyces japonicus and Trichoderma spp. were isolated from all five logs. Lampteromyces japonicus and Antrodiella albocinnamomea occupied the largest volume in the logs. Lignin and carbohydrate contents, lignocellulose index (LCI), nitrogen content, and water content were different among decay columns colonized by different fungal species in each log. In L. japonicus, LCI of decay column was correlated to that of wood blocks decayed under pure culture condition by the fungi isolated from the decay columns. These results suggest that the small-scale variation in chemical properties within fallen logs of Japanese beech reflects the distribution and the decay ability of colonized fungi.     

Population structure and dynamics oi Juniperus excelsa in Balouchistan,Pakistan

Abstract. 60 monospecific stands of Juniperus excelsa were sampled at four locations in Balouchistan. Density, basal area and height of individuals were recorded. Soils were analysed for selected physical and chemical characteristics and the degree of disturbance due to logging and burning was noted. The density of juniper trees (> 6 cm dbh) ranged from 56 to 332 stems / ha (average 174 stems / ha). Higher densities were recorded for relatively undisturbed stands and on west facing slopes. Density of seedlings and saplings (< 6 cm dbh) was strongly correlated with tree density and tree basal area. Among the edaphic variables CaC0₃ was correlated with juniper density and basal area. Diameter distributions within stands were mostly skewed and unimodal with gaps appearing in large size classes. The male to female ratio was close to 1. Cross-sections of 16 trees were used to determine age and growth rate. Number of rings in trees with 20 to 30 cm dbh ranged from 95 to 221 (x = 160 ± 38). Diameter and age were not related. Mean annual diameter increment ranged from 6 to 16 yr / cm x = 10 ± 3 yr / cm). It is concluded that size class gaps and low seedling / sapling densities are the consequence of anthropogenic disturbance.     

Congruence between floristic patterns of trees and lianas in a southwest Amazonian rain forest

The congruence in floristic patterns between different life-forms of woody plants remains poorly understood in tropical rain forests. We explored whether the floristic patterns of woody plants, divided into small trees 2.5–10 cm dbh, large trees ≥10 cm dbh, and lianas ≥2.5 cm dbh were associated with each other or with patterns in soil properties, elevation, and geographical distances between sample plots. We also tested whether ecological amplitudes in relation to environmental variables differed among the plant groups. Trees and lianas were inventoried in 44 0.1-ha plots, distributed among three lowland and two submontane sites in the Madidi National Park, Bolivia. Soil samples were analysed for physico-chemical properties. Floristic differences between sites (as measured with each plant group separately) yielded significant Mantel correlations with each other, and with pH, Ca, Mg, elevation and geographical distance. Mantel correlations with edaphic distances were higher for large trees than small trees, but for Mantel correlations with geographical distance the situation was reversed. Environmental and geographical distances explained 31% of the variation in floristic differences for large trees, 22% for small trees, and 10% for lianas. The ecological amplitudes of lianas were wider than those of all trees for pH, Mg and elevation. The amplitudes of the two size classes of trees did not differ. In principal coordinates ordination, the three plant groups produced similar overall floristic patterns that were explainable by environmental factors.     

Variation in litter under individual tree crowns: Implications for scattered tree ecosystems

In forest ecosystems litter is usually assessed in terms of the average amount produced by the canopy. In scattered tree ecosystems this approach is problematic because the canopy is discontinuous and the spatial arrangement of litter highly variable. We addressed this problem by quantifying the spatial variation in litter load and litter composition associated with individual trees in a Eucalyptus melliodora – Eucalyptus blakelyi woodland. Litter was sampled under crowns and in grassland adjacent to 10 E. blakelyi and 10 E. melliodora trees ranging in diameter at breast height (dbh) from 14 to 129 cm. A total of 302 L samples were collected from these trees, at distances ranging from 0 to 42 m from main stem. The sampled litter loads ranged from 0.02 to 109.3 t ha^?1 and were significantly higher under tree crowns than in grassland for litter and each component of litter (leaves, bark, fine twigs, coarse twigs). In particular, the mean litter load under tree crowns (12.5 t ha^?1) was an order of magnitude higher than the mean litter load in grassland (1.27 t ha^?1). There was a significant (P = 0.0103) positive relationship between mean litter load under the tree crown and dbh, indicating larger trees produced more litter per unit area of ground than smaller trees. Generalized Linear Modelling produced highly significant (P < 0.0001) models predicting the spatial variation in litter load and litter composition in terms of distance from main stem and dbh. Our models demonstrate gradients in litter load and composition under tree crowns. These gradients were most pronounced for the large trees in our study. The disproportionate input of litter and variety of litter components associated with large trees in our study supports their keystone role in scattered tree ecosystems and highlights the need to maintain these structures in agricultural landscapes.     

Characteristics of snags and forest structure in southern mistbelt forests of the Amatole region,South Africa

Standing dead trees (or snags) are an important component of forest ecosystems, especially for tree cavity‐nesting vertebrate species, but their prevalence in South African forests remains under studied. Consequently, we investigated forest structure, and the presence and abundance of snags in six southern mistbelt forests in the Eastern Cape, South Africa. These forests have had varying levels of timber extraction over the past 150 years or more. We found snags were relatively rare in all six forests (<4.3% of trees sampled). Mean diameter at breast height (dbh) of snags ranged from 52 to 82 cm across the forests, with smaller snags in Kologha Forest and larger snags in Tyume Forest. A bimodal distribution of snag successional stages was found, with frequencies peaking at early and late stages, and few in the intermediate stages. Tree species diversity in the forests was relatively low (twelve–nineteen species across forests; only 28 species in total). There was no significant difference in dbh of trees between forests, with most occurring in the 20–29‐cm dbh size class. Future studies are required to identify trees that most likely support suitable cavities for tree cavity‐nesting bird species, and to determine cavity‐nester assemblage requirements in southern African forests.     

Growth, yield, and nutrient status of pecans fertilized with biosolids and inoculated with rizosphere fungi

The application of anaerobically digested biosolids as a nutrient source for pecan, Carya illinoinensis (Wangeh.) K. Koch, cultivar Western, was evaluated. Conventional NPK fertilizers (CF) and biosolids included a treatment with the rhizospheric fungi Pisolithus tinctorius+Scleroderma sp. and Trichoderma sp. After an average of three years, the tree trunks with biosolid treatment grew 9.5% more than with CF; the length of the bearing shoots was 18.1 and 18.3cm and the production of nuts/tree was 9.26 and 8.75kg for pecans with CF and with biosolids, respectively. Western foliar nutrient concentration and nut quality were statistically equal in trees with CF and with biosolids. Soil inoculation with mycorrhizal fungi improved shoot growth by 19.4% when CF was applied, but did not when biosolids were used. Nutrient status and yield did not increase with mycorrhizal fungi. The addition of Trichoderma sp. did not favor any of the variables evaluated with both nutrient sources. Biosolids are efficient fertilizer at promoting the growth, production and nut quality of pecan trees.     

Modelling fallen branch volumes in a temperate eucalypt woodland: implications for large senescent trees and benchmark loads of coarse woody debris

Fallen branches are a substantial component of coarse woody debris and a key ecological resource. The depletion of stocks of coarse woody debris since European settlement has contributed to the degradation of Australian grassy box woodlands, including the loss of biodiversity. Restoration options for remnant woodlands include the augmentation of coarse woody debris stocks. However, the extensive modification of grassy box woodlands has left few reference sites for establishing benchmarks to guide such restoration. In this paper we demonstrate a method for predicting fallen branch debris loads in the absence of reference sites, using data from a yellow box–red gum woodland. Our methodology is in two stages: first, the total volume of branch debris under individual trees was modelled; and second, these models were applied to groups of trees to predict stand‐level loads of fallen branch debris. Although the models were developed for yellow box–red gum woodlands, the methodology would be applicable to other communities that lack reference sites. Predicted benchmark loads of fallen branch debris for yellow box–red gum woodland were between 7.0 m³ ha^?1 and 11.9 m³ ha^?1. Large senescing trees contributed the bulk of fallen branch debris. Model predictions indicated a 100‐cm diameter at breast height (dbh) tree was 10 times more likely to produce debris than a 50‐cm dbh tree, and if debris was present a 100‐cm dbh tree produced approximately 10 times the volume of branch debris produced by a 50‐cm dbh tree. These results highlight the importance of large senescing trees for the production of fallen branch debris and support the keystone role of large trees within remnant woodlands, and the need to conserve these structures. Our results also support the active management of regrowth woodland stands to facilitate the progression of individual trees to maturity and senescence. In particular, thinning of regrowth stands may promote the growth of retained trees, ensuring they contribute to fallen branch debris stocks with a minimum time lag.     

1989年大兴安岭图强林业局兴安落叶松结实状况

种源是森林天然更新和人工促进森林天然更新的重要条件。但是,种源并非年年都是丰富的,因为,树木不是每年都结实,而有丰年与歉年之分。兴安落叶松(Larix gmelinii),据研究从1957—1988年有7次种子年,结实与气候因子有关。此外,不少树种的结实规律也受到采伐和火灾的干扰,如红松林的结实     

Early detection of Biscogniauxia nummularia in symptomless European beech (Fagus sylvatica L.) by TaqMan quantitative real-time PCR

AIMS: To develop a quantitative real-time PCR (Rt PCR) assay for the early detection of Biscogniauxia nummularia, a xylariaceous fungus that causes strip-canker and wood decay on European beech (Fagus sylvatica L.). METHODS AND RESULTS: The molecular assay was based on TaqMan chemistry using species-specific primers and a fluorogenic probe designed on the ITS1 sequence of rRNA gene clusters. The specificity of the oligonucleotides and the probe were tested using the DNA of B. nummularia isolates from different geographic areas, of phylogenetically related species, and of some fungi commonly colonizing European beech bark and wood. A total of 31 symptomless and symptomatic shoots of European beech were collected from three forest sites in the Apennine Mountains of Italy. The percentage of positive detections of B. nummularia with the TaqMan assay was 78.6%, compared with only 14.3% of positive isolations on growth media for two sites. CONCLUSIONS: In shoots, the quantitative Rt PCR assay detected down to 8.0-fg fungal DNA per microgram of total DNA extracted. SIGNIFICANCE AND IMPACT OF THE STUDY: The assay developed in quantitative Rt PCR, by using TaqMan chemistry, revealed a rapid and sensitive method useful for the early detection of B. nummularia in symptomless European beech twigs.     

Effects of Logging on the Diversity of Lianas in a Lowland Tropical Rain Forest in Hainan Island, South China

Lianas are an integral part of tropical forest ecosystems, which usually respond strongly to severe disturbances, such as logging. To compare the effect of different logging systems on the lianas diversity in tropical rain forest, we recorded all lianas and trees ≥1 cm dbh in two 40-year-old forest sites after clear cutting (CC) and selective cutting (SC) as well as in an old-growth (OG) lowland tropical rain forest on Hainan Island in south China. Results showed that OG contained fewer liana stems and lower species richness (stems: 261, richness: 42 in 1 ha) than CC (606, 52) and SC (727, 50). However, OG had the highest Fisher's α diversity index (17.3) and species richness per stem (0.184). Species composition and dbh class distribution of lianas varied significantly with different logging systems. The mean liana dbh in OG (22.1 cm) were higher than those in CC (7.0 cm) and SC (10.4 cm). Stem twining was the most frequent climbing mechanism represented in the forest, as shown by the greatest species richness, abundance, basal area, and host tree number with this mechanism. The percent of host tree stems ≥4 cm dbh hosting at least one liana individual in SC (39%) was higher than CC (23%) and OG (19.5%). Large host trees (dbh≥60 cm) were more likely to be infested by lianas in SC and OG. Our study demonstrated that logging disturbance could significantly change the composition and structure of liana communities in the lowland tropical rain forest of south China.
     

Genetic control of Eucalyptus urophylla and E. grandis resistance to canker caused by Chrysoporthe cubensis

Chrysophorte cubensis induced canker occurs in nearly all tropical and subtropical regions where eucalypts are planted, causing losses in both wood quality and volume productivity, especially so in the warmer and more humid regions of Brazil. The wide inter and intra-specific genetic variability of resistance to canker among Eucalyptus species facilitates the selection of resistant plants. In this study, we evaluated resistance to this pathogen in five Eucalyptus grandis (G) and 15 E. urophylla (U) trees, as well as in 495 individuals from 27 progenies derived from crosses between the trees. In the field, six-months-old test seedlings were inoculated with C. cubensis. Lesion length in the xylem and bark was measured eight months later. The results demonstrated that xylem lesions could preferentially be used for the selection of resistant clones. Eight trees (7 U and 1 G) were susceptible, and the remainder (8 U and 4 G) resistant. Individual narrow and broad sense heritability estimates were 17 and 81%, respectively, thereby suggesting that canker resistance is quantitative and highly dependent on dominance and epistasis.     

Variable rainfall has a greater effect than fire on the demography of the dominant tree in a semi‐arid Eucalyptus savanna

Rainfall, fire and competition are emphasized as determinants of the density and basal area of woody vegetation in savanna. The semi‐arid savannas of Australia have substantial multi‐year rainfall deficits and insufficient grass fuel to carry annual fire in contrast to the mesic savannas in more northern regions. This study investigates the influence of rainfall deficit and excess, fire and woody competition on the population dynamics of a dominant tree in a semi‐arid savanna. All individuals of Eucalyptus melanophloia were mapped and monitored in three, 1‐ha plots over an 8.5 year period encompassing wet and dry periods. The plots were unburnt, burnt once and burnt twice. A competition index incorporating the size and distance of neighbours to target individuals was determined. Supplementary studies examined seedling recruitment and the transition of juvenile trees into the sapling layer. Mortality of burnt seedlings was related to lignotuber area but the majority of seedlings are fire resistant within 12 months of germination. Most of the juveniles (≤1 cm dbh) of E. melanophloia either died in the dry period or persisted as juveniles throughout 8.5 years of monitoring. Mortality of juveniles was positively related to woody competition and was higher in the dry period than the wet period. The transition of juveniles to a larger size class occurred at extremely low rates, and a subsidiary study along a clearing boundary suggests release from woody competition allows transition into the sapling layer. From three fires the highest proportion of saplings (1–10 cm dbh) reduced to juveniles was only 5.6% suggesting rates of ‘top‐kill’ of E. melanophloia as a result of fire are relatively low. Girth growth was enhanced in wet years, particularly for larger trees (>10 cm dbh), but all trees regardless of size or woody competition levels are vulnerable to drought‐induced mortality. Overall the results suggest that variations in rainfall, especially drought‐induced mortality, have a much stronger influence on the tree demographics of E. melanophloia in a semi‐arid savanna of north‐eastern Australia than fire.