Fertilizer impacts on the understorey of a regenerating Mountain Ash (Eucalyptus regnans F. Muell.) forest,Victoria

Abstract We examined the effects of adding fertilizers on nutrient concentrations in foliage, and on species composition and density of the understorey in a 10 year old Mountain Ash (Eucalyptus regnans F. Muell.) forest. Nutrient concentrations in foliage of three woody understorey species (Acacia dealbata, Pomaderris aspera and Olearia argophylla) showed no significant response to the addition of phosphorus and nitrogen either alone, in combination or combined with other nutrients. The phosphorus concentration in foliage and stems of two herbaceous species (Australina pusilla and Urtica incisa) was significantly increased by applying phosphorus. The addition of fertilizers had no significant effect on species composition and density of the understorey.     

Temporal fragmentation of a critically endangered forest ecosystem

Landscape change and habitat fragmentation is increasingly affecting forests worldwide. Assessments of patterns of spatial cover in forests over time can be critical as they reveal important information about landscape condition. In this study, we assessed landscape patterns across the Mountain Ash (Eucalyptus regnans) and Alpine Ash (Eucalyptus delegatensis) forests in the Central Highlands of Victoria between 1999 and 2019. These forests have experienced major disturbance over the past 20 years through a major fire (in 2009) and extensive industrial logging. We found that around 70% and 65% of the Mountain Ash and Alpine Ash forest areas, respectively, were either disturbed or within 200 m of a disturbed area. Inclusion of planned logging increased these disturbance categories to 72% and 70%, respectively. We also found that the isolation of Mountain Ash core areas (patches of undisturbed forest >1000 ha) increased significantly (P < 0.05) over our study period, with the proximity between disturbed areas conversely increasing significantly (P < 0.05). This means that continued and planned disturbance through industrial logging will have an amplified adverse effect on remaining undisturbed ash forest patches, which will become smaller and more dispersed across the landscape.     

Influence of fire severity on the regeneration,recruitment and distribution of eucalypts in the Cotter River Catchment,Australian Capital Territory

Abstract Plant responses to fire are variable between and within species and are influenced by numerous factors including fire severity. This study investigated the effects of fire severity on the regeneration and recruitment of forest eucalypts in the Cotter River Catchment, Australian Capital Territory (ACT). This study also examined the potential for the obligate seeder Eucalyptus delegatensis R.T. Baker (Myrtaceae) to expand into adjacent stands dominated by the facultative resprouter Eucalyptus fastigata H. Deane & Maiden (Myrtaceae) by seed shed and seedling establishment beyond the pre‐fire boundary. Sites were located in areas of either higher or lower fire severity, and transects were placed across the boundary of stands of E. delegatensis and E. fastigata. Species distributions, tree survival and seedling densities and heights were recorded, and the location of each boundary was determined as the region of maximum change in species composition along the transects. Eucalyptus delegatensis was the only eucalypt killed by higher severity fire. However, E. delegatensis seedling density was greater at higher severity sites than lower severity sites. Eucalyptus fastigata seedling density was low across all sites, with other eucalypts producing few, if any, seedlings. There was no evidence that E. delegatensis had increased its range into downslope stands dominated by E. fastigata. Patterns of vegetative recovery and seedling recruitment may be related to a number of factors, including differences in allocation patterns between seeders and sprouters, and the effects of overstory and understory competition. It is unclear what processes impede E. delegatensis seedling establishment beyond the stand boundary, but may involve an inability of E. delegatensis to shed seed sufficiently far downslope; unsuitable conditions for germination beyond the boundary; or, competition from a retained or resprouting overstory, despite the potential for increased dispersal distance soon after fire.     

Reproductive biology and success of invasive Australian acacias in Portugal

Reproductive traits are crucial for the establishment and maintenance of populations in new areas, and therefore for the invasion process. This work aimed to study the reproductive biology of four aggressive invasive Australian Acacia spp. in Portugal. Fruit and seed set, seed weight and germinability, and seedling growth were assessed for self‐ and outcross treatments in invasive populations of A. dealbata, A. longifolia, A. melanoxylon and A. saligna. Acacia spp. showed different investments in the production of reproductive units and in natural reproductive success, with A. dealbata, the most aggressive species, having the highest investment and reproductive success. Acacia melanoxylon showed a different reproductive strategy, andromonoecy, contrasting with the other hermaphroditic species. Acacia spp. were shown to be predominantly self‐incompatible, but a low level of spontaneous selfing enabled the production of viable offspring. Acacia dealbata and A. longifolia suffered pollen limitation. Self‐progeny had lower viability than progeny from outcrossing for A. dealbata and A. melanoxylon. Acacia spp. did not show higher compatibility rates in comparison with the native area. They had low fruit set but, as a result of their massive flower production, their realized reproductive success was high and could have contributed to the invasion. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174 , 574–588.     

Causes of arrested succession in coastal dune forest

Dispersal or recruitment limitation may arrest succession after disturbance. In north-eastern South Africa the Acacia karroo successional pathway is used to facilitate coastal forest recovery after strip-mining. However, although A. karroo establishes naturally, it forms monospecific stands, arresting forest succession for decades. This casts doubt on the efficacy of this restoration pathway. We investigated the causes of arrested succession. The seed and seedling banks of A. karroo stands and of forest at Cape Vidal, and three A. karroo stands (7–27 years old) on rehabilitated strip-mined dunes at nearby Richards Bay were examined. The establishment and growth of seedlings at Cape Vidal were also considered. The seed bank was larger and more diverse in forest, but the seedling bank was larger in Acacia stands. At Richards Bay, the size of the seed bank increased and the seedling bank decreased with Acacia stand age. Excluding mammalian herbivores in Acacia stands at Cape Vidal resulted in greater species richness and survival of naturally established seedlings, as well as two experimentally planted species. Neither seed dispersal nor seedling establishment limited recruitment of tree species in Acacia stands. Herbivory arrested forest succession by causing the differential mortality of seedlings. In contrast, at Richards Bay where there were few mammalian herbivores, the advanced regeneration in A. karroo stands converged on the diversity of nearby forests 29 years after restoration. Controlling herbivore access and seeding Acacia stands with forest species are site-specific options for preventing arrested succession when using the A. karroo successional pathway.     

The population of Acacia tree species producing gum arabic in the Karamoja region, Uganda

The study aimed at determining the population status of the different Acacia tree species producing gum arabic in the undisturbed, grazed and cultivated habitats in the Karamoja region, Uganda. A total of 135 sample plots each measuring 20 × 20 m² (0.04 ha) with each habitat having 45 plots were selected and established in the seven counties using a simple random sampling technique. The tree species present, their abundances and sizes were recorded. Twelve Acacia species were identified and a total of 5535 recorded in the sampled area. Out of these, five were gum‐producing acacias. Acacia senegal dominated the acacias in all the seven counties and in all habitats of Karamoja with Acacia nilotica (72.3%), Acacia seyal (13.4%), Acacia sieberiana (4%) and Acacia gerrardii (2.6%). Non‐gum‐producing acacias constituted 7.19% of the total abundance. The tree densities increased with increase in tree size in the undisturbed and grazed habitats but decreased in the cultivated habitat. Most Acacia trees were of large size, an indication of old age and poor regeneration that could affect their future population status. It is recommended that further investigations be carried out into the causes of poor regeneration of Acacia species.     

Allelopathic Effects of Tree Species on Some Soil Microbial Populations and Herbaceous Plants

The allelopathic potential of four tree species on soil microbial populations and some herbaceous plants (two understory species and one general biotest species) was investigated. Effects of three nonindigenous tree species, Eucalyptus globulus Labill, Pinus radiata D.Don and Acacia melanoxylon R.Br., on microorganisms participating in the cycle of nitrogen were evaluated, comparing them with those produced by the autochthonous Quercus robur L. Influence of the trees on Lactuca sativa L., Dactylis glomerata L. and Trifolium repens L. was also checked in bioassays. Cell numbers of Nitrosomonas sp. were negatively affected by Acacia and Eucalyptus stands, mainly during spring, when flowers are especially abundant on the ground. Proteolytic microorganisms were also negatively affected by Eucalyptus and Pinus stands, whilst Quercus stand did not show any toxicity. Soil bioassays showed clear inhibitory effects on germination and growth of understory plants, particularly soils from Eucalyptus and Acacia stands. The greatest effects had the soil from Acacia stand, which was phytotoxic during the whole period of germination and growth of understory plants. Allelopathic phenomena could be, at least partially, responsible of the low species diversity in the understory of the nonindigenous tree stands.     

Litter decomposition and nitrogen mineralization of soils in subtropical plantation forests of southern China,with special attention to comparisons between legumes and non-legumes

Litter decomposition and nitrogen mineralization were investigated in subtropical plantation forests in southern China. The CO₂ –C release from incubated litter and the forest floor of Acacia mangium, Acacia auriculaeformis, Eucalyptus citriodora, Pinus elliotii and Schima superba stands were used to estimate relative rates of litter decomposition. Decomposition was not positively correlated with litter nitrogen. E. citridora litter decomposed most rapidly and A. mangium litter most slowly, both with and without the addition of exotic nitrogen. Aerobic incubation and intact soil core incubation at 30 °C over a period of 30 days were used to assess nitrogen mineralization of six forest soils. Although there were differences in results obtained using the two methods, patterns between legume and non-legume species were the same regardless of method. All soils had pH values below 4.5, but this did not prevent nitrification. The dominant form of mineral nitrogen was nitrate for legume species and ammonium for non-legume species. The nitrogen mineralization potential was highest for soils in which legumes were growing.     

The response of fast- and slow-growing Acacia species to elevated atmospheric CO2: an analysis of the underlying components of relative growth rate

In this study we assessed the impact of elevated CO₂ with unlimited water and complete nutrient on the growth and nitrogen economy of ten woody Acacia species that differ in relative growth rate (RGR). Specifically, we asked whether fast- and slow-growing species systematically differ in their response to elevated CO₂. Four slow-growing species from semi-arid environments (Acacia aneura, A. colei, A. coriacea and A. tetragonophylla) and six fast-growing species from mesic environments (Acacia dealbata, A. implexa, A. mearnsii, A. melanoxylon, A. irrorata and A. saligna) were grown in glasshouses with either ambient (˜350 ppm) or elevated (˜700 ppm) atmospheric CO₂. All species reached greater final plant mass with the exception of A. aneura, and RGR, averaged across all species, increased by 10% over a 12-week period when plants were exposed to elevated CO₂. The stimulation of RGR was evident throughout the 12-week growth period. Elevated CO₂ resulted in less foliage area per unit foliage dry mass, which was mainly the result of an increase in foliage thickness with a smaller contribution from greater dry matter content per unit fresh mass. The net assimilation rate (NAR, increase in plant mass per unit foliage area and time) of the plants grown at elevated CO₂ was higher in all species (on average 30% higher than plants in ambient CO₂) and was responsible for the increase in RGR. The higher NAR was associated with a substantial increase in foliar nitrogen productivity in all ten Acacia species. Plant nitrogen concentration was unaltered by growth at elevated CO₂ for the slow-growing Acacia species, but declined by 10% for faster-growing species. The rate of nitrogen uptake per unit root mass was higher in seven of the species when grown under elevated CO₂, and leaf area per unit root mass was reduced by elevated CO₂ in seven of the species. The absolute increase in RGR due to growth under elevated CO₂ was greater for fast- than for slow-growing Acacia species. Received: 21 December 1998 / Accepted: 31 May 1999     

Convergence Between Dung Beetle Assemblages of a Post-Mining Vegetational Chronosequence and Unmined Dune Forest

Abstract In Maputaland, South Africa vegetative and microclimatic changes on mined dunes drive the composition of the dung beetle fauna toward convergence with that in natural dune forest on unmined dunes. We assessed the pattern of these changes using a 23‐year vegetational chronosequence on mined dunes, which passes from grassland (approximately 1 year) to open Acacia shrubland thicket to Acacia karroo‐dominated woodland (approximately 9 years). Across this sequence, which represents successional stages in the restoration of dune forest, there was a sequential trend toward convergence in dung beetle species composition in both the entire species complement and, particularly, in shade specialist species. However, species abundance patterns showed a trend toward convergence only in early chronosequence Acacia woodland, followed by a decline in similarity between dung beetle assemblages of older Acacia woodland and unmined natural forest. This trend toward divergence was common both to the entire species complement, which includes widespread taxa, and to species endemic to Maputaland or the east coast. These trends in similarity and dissimilarity between dung beetle assemblages closely parallel the greater physiognomic and microclimatic similarity between early Acacia woodland and natural forest and the relative dissimilarity of older Acacia woodland. In conclusion, although percentage similarities between dung beetle assemblages of approximately 12‐year woodland and natural forests were comparable with those between each natural forest stand, decline in similarity in older woodland stands suggests that lasting convergence in dung beetle species abundance will only be attained once the Acacia woodland is replaced by secondary natural forest.     

Shared phylogeographic patterns and widespread chloroplast haplotype sharing in Eucalyptus species with different ecological tolerances

We examined the phylogeography of three south-east Australian trees (Eucalyptus delegatensis, Eucalyptus obliqua, and Eucalyptus regnans) with different tolerances, in terms of cold, drought, fire and soil to explore whether species with different ecologies share major phylogeographic patterns. A second aim of this study was to examine geographic patterns of chloroplast DNA (cpDNA) haplotype sharing among the three study species. Trees of E. delegatensis (n?=?120), E. obliqua (n?=?265) and E. regnans (n?=?270) were genotyped with five cpDNA microsatellite markers. The species shared major phylogeographic disjunctions, and common patterns at proposed glacial refugia (generally high haplotype diversity) and areas thought to have been treeless during the Last Glacial Maximum (LGM) (low diversity). Inter-specific sharing of haplotypes was extensive, and fixation of shared, regional haplotypes was more frequent in areas postulated as having been treeless at the LGM. Despite ecological differences, chloroplast microsatellite data suggest the three species have responded to past climatic changes in a similar way, by persisting in multiple, generally common refugia. We suggest that the natural ability of eucalypt species to hybridise with others with quite different or broader ecological tolerances may provide an “insurance policy” for response to rapidly changing abiotic conditions.     

N2 fixation by Acacia species increases under elevated atmospheric CO2

In the present study the effect of elevated CO₂ on growth and nitrogen fixation of seven Australian Acacia species was investigated. Two species from semi‐arid environments in central Australia (Acacia aneura and A. tetragonophylla) and five species from temperate south‐eastern Australia (Acacia irrorata, A. mearnsii, A. dealbata, A. implexa and A. melanoxylon) were grown for up to 148 d in controlled greenhouse conditions at either ambient (350 µmol mol^?1) or elevated (700 µmol mol^?1) CO₂ concentrations. After establishment of nodules, the plants were completely dependent on symbiotic nitrogen fixation. Six out of seven species had greater relative growth rates and lower whole plant nitrogen concentrations under elevated versus normal CO₂. Enhanced growth resulted in an increase in the amount of nitrogen fixed symbiotically for five of the species. In general, this was the consequence of lower whole‐plant nitrogen concentrations, which equate to a larger plant and greater nodule mass for a given amount of nitrogen. Since the average amount of nitrogen fixed per unit nodule mass was unaltered by atmospheric CO₂, more nitrogen could be fixed for a given amount of plant nitrogen. For three of the species, elevated CO₂ increased the rate of nitrogen fixation per unit nodule mass and time, but this was completely offset by a reduction in nodule mass per unit plant mass.     

Allelopathic interference of invasive <Emphasis Type="Italic">Acacia dealbata</Emphasis> Link on the physiological parameters of native understory species

The tree Acacia dealbata Link is an Australian woody legume that has become a serious environmental problem in Northwest Spain, where its expansion is assumed to reduce populations of native species and threaten local plant biodiversity. In order to investigate the potential involvement of allelopathic mechanisms in this process, net photosynthetic and respiration rates of four test native understory species (Hedera hibernica (G. Kirchn.) Bean, Dicranum sp., Dactylis glomerata L. and Leucobryum sp.) were evaluated using a Clark-type electrode in the presence of canopy leachate collected under A. dealbata stands at four times of the year for 2 years and macerate from their apical branches at the same sites and times. The first two test species were present both inside and outside of A. dealbata stands, while the last two were only located outside the stands. We found that there were significant differences in respiration and net photosynthetic rates between the control and A. dealbata extracts in all test species. The respiration rate was increased by both canopy leachate and macerate extracts on certain collection dates, but net photosynthetic rate was stimulated by macerate and inhibited by canopy leachate on other dates. The main phenological stages of A. dealbata in which respiration and net photosynthetic rates were more affected were blossoming, inflorescence formation and in periods after severe drought, in this decreasing order. Our results also showed that Dicranum sp., Leucobryum sp. and D. glomerata were more affected by aqueous extracts than other species during a 2-year period. We suggest that the observed inhibitory or stimulatory effects on the physiological parameters studied could have an adverse effect on the understory species, and that allelopathic interference seems to participate in this process.     

Predicting tree diameter and height from above-ground biomass for four eucalypt species

Summary Previous work has suggested that tree stems are structured dimensionally to resist the forces to which they are subjected by the weight of the crown and the action of wind, snow and other loads on the crown. This proposition has been used to develop allometric relationships relating diameter at breast height or height of individual trees growing in even-aged monoculture to their above-ground fresh biomass. These models have practical application as estimators of tree diameters or heights from tree biomass as extensions of mechanistically based models of forest tree growth which predict tree biomasses. The present work applied these models to Eucalyptus regnans F. Muell, E. delegatensis R. Baker, E. nitens (Deane: Maiden) Maiden and E. grandis Hill ex Maiden trees, growing in plantation or regrowth stands, aged between 1.5 and 20 years, at eight geographically diverse sites extending from temperate to sub-tropical regions of Australia. While the models held for the various species at the various sites, their parameter values differed significantly between sites and/or species. This suggested there may be some inadequacy in the models. However, the differences were small and it was found reasonable to fit single models across all species and sites for practical use in estimating diameter or height. The errors about predicted values of height and diameter from these models were quantified. The models were also found to estimate diameter or height with little loss of precision when dry biomass was used in place of fresh biomass.     

Soil nutrients are not responsible for arrested succession in disturbed coastal dune forest

Coastal dune forest succession frequently proceeds via the Acacia karroo pathway, but may become arrested. We examine whether soil fertility arrests forest succession in A. karroo stands in coastal dune forest in KwaZulu-Natal province, South Africa. We examined soil fertility of A. karroo stands, the adjacent forest, and forested dune slacks at Cape Vidal, and four rehabilitating A. karroo stands (13- to 28-yr-old) at Richards Bay. The effect of nitrogen supplementation on growth of three tree species (a forest pioneer, a late successional forest species, and A. karroo) was compared between A. karroo stands and adjacent dune forest at Cape Vidal. Soil fertility in A. karroo stands and the adjacent forest at Cape Vidal was similar and neither total nor readily mineralisable nitrogen were limiting in either habitat. At Richards Bay, where the dunes were previously strip-mined, total nitrogen accumulated rapidly (2.1–8.0 g N m⁻² yr⁻¹) and the oldest rehabilitating A. karroo stands (26–28 yr) had similar total nitrogen and other soil nutrient levels as stands twice their age at Cape Vidal. Seedling growth was unaffected by nitrogen supplementation. All species grew fastest in A. karroo stands demonstrating that soil nutrient levels in disturbed forest colonised by A. karroo are suitable for the growth of forest tree species. Soil fertility, including available nitrogen, is not limiting secondary succession at Cape Vidal, yet forest species are not replacing A. karroo stands at this site. Post-emergence factors, such as herbivory, are likely responsible for the arrested succession of forest in A. karroo stands.     

Responses of litter arthropods to major natural or artificial ecological disturbances in mountain ash forest

Pitfall trapping was used in commercial Mountain Ash (Eucalyptus regnans) regrowth forest to study the effects on epigeal arthropods of high-intensity wildfire plus salvage logging, and of harvesting by clearfelling plus slash burning, followed by fire-induced natural or artificially established regeneration respectively. The study, the first of its kind in the Victorian Central Highlands, 60 km east of Melbourne, was based on 146 922 specimens of 30 ordinal or lower level taxa collected over a 3-year period. The abrupt replacement of the ecologically complex regrowth forest by ecologically much simpler even-aged regeneration caused appreciable instability among the litter-frequenting arthropods. An immediate decline in diversity occurred due to short-term boosts in activity of some common ‘major’ taxa (notably a species of seed-harvesting ant) and the suppression of other taxa. A broad mix of functionally diverse taxa reappeared within two years of regeneration, and all but three rarely trapped ‘minor’ taxa present in undisturbed 43–46 year old regrowth (‘control’) forest had returned within 5 years. Epigeal arthropods therefore appeared to be affected only over a short period relative to the nominal 80–150 year rotation of the E. regnans ecosystem. Research is needed at the species level to achieve a more precise assessment of arthropod responses to major ecological disturbances.     

Two alien invasive acacias in Italy: Differences and similarities in their flowering and insect visitors

In Italy, alien acacias have been introduced for ornamental and reforestation purposes, and some species became invasive occupying patches of the Mediterranean landscape. On the Island of Elba (Central Italy), Acacia dealbata and A. pycnantha form dense stands at short distance, showing an impressive massive flowering at the end of the winter/early spring. Our aim was to investigate the behaviour of the two species in relation to the flowering features, from phenology to floral characteristics, and their replay to the observed flower visitors. Differences between the two species emerged on all the parameters considered. A. pycnantha peak of flowering occurred later than A. dealbata and showed larger flower heads (FHs), more flowers/head, stamens/flower and polyads. On A. dealbata, we recorded longer racemes and more FHs/raceme, determining a more flower-dense crown. Even if contacts with flower visitors were generally low on both species, A. dealbata showed a more heterogeneous visitor assemblage. Both acacias species interacted with local generalist pollinators, as bumblebees and honey bees. Flower handling and resource collection strategy by the honey bee indicate a long-term relationship between the bee and the acacias, with bees investing longer time on the larger A. pycnantha flower heads.     

Recovery of species diversity and composition of braconid parasitic wasps after reforestation of degraded grasslands in lowland East Kalimantan

Human-induced disturbances and wildfires can transform areas of tropical rainforest into Imperata-dominated grassland, but it may be possible that recovery of biodiversity is facilitated by reforestation with fast-growing trees. We compared the assemblages of braconid wasps as parasitoids of taxonomically diverse groups of insects among Imperata grasslands, young and mature plantations of Acacia mangium, young secondary forests after wildfires, and old secondary forests in the lowland of East Kalimantan. The abundance and species richness of braconids, which had declined in Imperata grasslands, somewhat increased in Acacia plantations, and also the species composition of braconids in Acacia plantations was transitional between Imperata grasslands and old secondary forests. Parasitoids of detritivores and wood borers increased markedly after plantation, while those of herbivores showed a distinct turnover of species all over the range from grasslands to old secondary forests. The plantation of A. mangium had most likely facilitated the recovery of the diversity of host forest and their parasitoids, but the recovery was just at the rudimentary stage even in mature plantations. Monitoring of parasitic wasps would be useful to test the continuous recovery of forest biodiversity in plantation stands.     

The effect of soil legacy on competition and invasion by Acacia dealbata Link

Plant–soil feedbacks can exacerbate competition between invasive and native species, although the net effect of the interaction between soil biota and competition is likely to be species-specific. Very few studies have addressed the combined effect of soil and competition on plant performance and invasion by exotic woody species. This study explores plant growth and competition between Acacia dealbata and Pinus pinaster in three different soils—native, disturbed and invaded—in Portugal. The invasion of native P. pinaster forests by A. dealbata can be explained by the stronger competition ability of the exotic tree species. Competition is stronger in the native soil, allowing the establishment of A. dealbata in this soil and the displacement of P. pinaster. During invasion, A. dealbata changes soil conditions and establishes positive plant–soil feedbacks that promote its own germination and growth and increase P. pinaster mortality. Soil disturbance by the introduction of a different exotic species, Eucalyptus globulus, did not promote invasion by A. dealbata. We found a significant effect of soil legacy on both growth and competitive ability of the invasive A. dealbata. The ability of A. dealbata to outcompete the native P. pinaster in its own soil and the positive plant–soil feedbacks established after invasion are important mechanisms for A. dealbata invasion.     

Diet of Buffy Tufted-Eared Marmosets (Callithrix aurita) in a Forest Fragment in Southeastern Brazil

The feeding ecology of the Atlantic forest marmosets (Callithrix spp.) in southeastern Brazil is poorly known, and few studies have focused on buffy tufted-eared marmosets, Callithrix aurita. We determined the food items and investigated the seasonal variation in the diet of a group of four Callithrix aurita in a 17-ha semideciduous forest fragment in southern Minas Gerais State, Brazil. We recorded daily feeding activities between October 1994 and September 1995 using scan sampling at 5-min intervals. The marmosets devoted feeding time to gums (50.5%), fruits (11%), and animal prey (38.5%) in a total of 499 records. Plant resources comprised 27 species from 16 families. They used Acacia paniculata (Mimosoideae, Leguminosae), the main gum source (82%), year-round. Maclura tinctoria (Moraceae) was the fruit species that they consumed most (22%). The marmosets preyed on caterpillars (33%), katydids (5%), and homopterans (4%). Feeding on fruits varied seasonally and was inversely related to gum feeding. Consumption of animal prey remained constant over the year. The wide and year-round dependence on gum suggests that Acacia may play a critical role in marmoset persistence in forest fragments.