Quambalaria species: increasing threat to eucalypt plantations in Australia

Spotted gum (Corymbia citriodora subsp. variegata and C. maculata) is a valuable source of commercial timber and suitable for a wide range of different soil types in eastern Australia. The main biological constraint to further expansion of spotted gum plantations is Quambalaria shoot blight caused by the fungus Quambalaria pitereka. Surveys conducted to evaluate the impact of Quambalaria shoot blight have shown that the disease is present in all spotted gum plantations and on a range of Corymbia species and hybrids in subtropical and tropical regions surveyed in eastern Australia. More recently, Q. eucalypti has also been identified from a range of Eucalyptus species in these regions. Both pathogens have also been found associated with foliage blight and die-back of amenity trees and Q. pitereka in native stands of Corymbia species, which is the probable initial infection source for plantations. Infection by Q. pitereka commonly results in the repeated destruction of the growing tips and the subsequent formation of a bushy crown or death of trees in severe cases. In comparison, Q. eucalypti causes small, limited lesions and has in some cases been associated with insect feeding. It has not been recorded as causing severe shoot and stem blight. A better understanding of factors influencing disease development and host-pathogen interactions is essential in the development of a disease management strategy for these poorly understood but important pathogens in the rapidly expanding eucalypt (Corymbia and Eucalyptus spp.) plantation industry in subtropical and tropical eastern Australia.

Remembering the Peel Island Lazaret through re-imagining the Teerk Roo Ra forest

This paper discusses my current research which aims to re-member the site of the Peel Island Lazaret through re-imagining the Teerk Roo Ra forest as a series of animated artworks. Teerk Roo Ra National Park (formally known as Peel Island) is a small island in Moreton Bay, Queensland and is visible on the ferry journey from Cleveland to Stradbroke Island. The island has an intriguing history, and is the site of a former Lazaret and quarantine station. The Lazaret treated patients diagnosed with Hansen’s disease (or Leprosy), and operated between 1907 and 1959. In this paper I will discuss conceptions of the non-indigenous historical context of the Peel Island Lazaret and the notion of the liminal state (Turner,1967). Through this discussion conceptions of place from Australian cultural theorist Ross Gibson are also examined. The concept of two overlapping realms is then explored through the clues and shared stories about the people who inhabited the site. There is then an explanation of my own approach to re-member this place through re-imagining the forest that witnessed the events of the Lazaret. I then draw on theories of the uncanny from German Psychiatrist Ernst Jentsch, Austrian Neurologist Sigmund Freud and South African animation theorist Meg Rickards to argue that my experience of the forest of Teerk Roo Ra was an uncanny experience where two worlds or states of mind existed simultaneously and overlapped, causing a viscerally unsettling uncanny experience. Through an analysis of Czech Surrealist Animator Jan Švankmajer’s cinematic narrative Down to the cellar (1982), my creative work Structure #24(2011), and Australian Artist Patricia Piccinini’s cinematic artwork The Gathering (2007), I discuss the situation of the inanimate and the animate co-existing simultaneously. Using this approach I propose an understanding of the uncanny as an intellectual uncertainty as outlined by Jentsch (1906). I also develop the notion of the familiar being concealed and becoming unfamiliar through mimicry (Freud, 1919). These discussions form an introduction to my creative work Nocturne #5(2014) which re-members the forests of Teerk Roo Ra as an uncanny place primarily expressed through animation.

Impact of the invasive rust Puccinia psidii (myrtle rust) on native Myrtaceae in natural ecosystems in Australia

The invasive rust Puccinia psidii (myrtle rust) was detected in Australia in 2010 and is now established along the east coast from southern New South Wales to far north Queensland. Prior to reaching Australia, severe damage from P. psidii was mainly restricted to exotic eucalypt plantations in South America, guava plantations in Brazil, allspice plantations in Jamaica, and exotic Myrtaceous tree species in the USA; the only previous record of widespread damage in native environments is of endangered Eugenia koolauensis in Hawai’i. Using two rainforest tree species as indicators of the impact of P. psidii, we report for the first time severe damage to endemic Myrtaceae in native forests in Australia, after only 4 years’ exposure to P. psidii. A 3-year disease exclusion trial in a natural stand of Rhodamnia rubescens unequivocally showed that repeated, severe infection leads to gradual crown loss and ultimately tree mortality; trees were killed in less than 4 years. Significant (p < 0.001) correlations were found between both incidence (r = 0.36) and severity (r = 0.38) of P. psidii and subsequent crown loss (crown transparency). This provided supporting evidence to conclude a causal association between P. psidii and crown loss and tree mortality in our field assessments of R. rubescens and Rhodomyrtus psidioides across their native range. Assessments revealed high levels of damage by P. psidii to immature leaves, shoots and tree crowns—averaging 76 % (R. rubescens) and 95 % (R. psidioides) crown transparency—as well as tree mortality. For R. psidioides, we saw exceptionally high levels of tree mortality, with over half the trees surveyed dead and 40 % of stands with greater than 50 % tree mortality, including two stands where all trees were dead. Tree mortality was less prevalent for R. rubescens, with only 12 % of trees surveyed dead and two sites with greater than 50 % mortality. Any alternative causal agents for this tree mortality have been discounted. The ecological implications of this are unclear, but our work clearly illustrates the potential for P. psidii to negatively affect Australia’s biodiversity.

Carbon balance and component CO2 fluxes in boreal Scots pine stands

The forest vegetation takes up atmospheric carbon dioxide (CO2) in photosynthesis. Part of the fixed carbon is released back into the atmosphere during plant respiration but a substantial part is stored as plant biomass, especially in the stems of trees. Carbon also accumulates in the soil as litter and via the roots. CO2 is released into the atmosphere from these carbon stocks in the decomposition of dead biomass. Carbon balance of a forest stand is the difference between the CO2 uptake and CO2 efflux. This study quantifies and analyses the dynamics of carbon balance and component CO2 fluxes in four Southern Finnish Scots pine stands that covered the typical economic rotation time of 80 years. The study was based on direct flux measurements with chambers and eddy covariance (EC), and modelling of component CO2 fluxes. The net CO2 exchange of the stand was partitioned into component fluxes: photosynthesis of trees and ground vegetation, respiration of tree foliage and stems, and CO2 efflux from the soil. The relationships between the component fluxes and the environmental factors (light, temperature, atmospheric CO2, air humidity and soil moisture) were studied with mathematical modelling. The annual CO2 balance varied from a source of about 400 g C/m2 at a recently clearcut site to net CO2 uptake of 200 300 g C/m2 in a middle-aged (40-year-old) and a mature (75-year-old) stand. A 12-year-old sapling site was at the turning point from source to a sink of CO2. In the middle-aged stand, photosynthetic production was dominated by trees. Under closed pine canopies, ground vegetation accounted for 10 20% of stand photosynthesis whereas at the open sites the proportion and also the absolute photosynthesis of ground vegetation was much higher. The aboveground respiration was dominated by tree foliage which accounted for one third of the ecosystem respiration. Rate of wood respiration was in the order of 10% of total ecosystem respiration. CO2 efflux from the soil dominated the ecosystem respiratory fluxes in all phases of stand development. Instantaneous and delayed responses to the environmental driving factors could predict well within-year variability in photosynthetic production: In the short term and during the growing season photosynthesis follows primarily light while the seasonal variation is more strongly connected to temperature. The temperature relationship of the annual cycle of photosynthesis was found to be almost equal in the southern boreal zone and at the timberline in the northern boreal zone. The respiratory fluxes showed instantaneous and seasonal temperature relationships but they could also be connected to photosynthesis at an annual timescale.

Environmental and climatic dependences of stable isotope ratios in tree rings on different temporal scales

This work examines stable isotope ratios of carbon, oxygen and hydrogen in annual growth rings of trees. Isotopic composition in wood cellulose is used as a tool to study past climate. The method benefits from the accurate and precise dating provided by dendrochronology. In this study the origin, nature and the strength of climatic correlations are studied on different temporal scales and at different sites in Finland. The origin of carbon isotopic signal is in photosynthetic fractionation. The basic physical and chemical fractionations involved are reasonably well understood. This was confirmed by measuring instantaneous photosynthetic discrimination on Scots pine (Pinus sylvestris L.). The internal conductance of CO2 was recognized to have a significant impact on the observed fractionation, and further investigations are suggested to quantify its role in controlling the isotopic signal of photosynthates. Isotopic composition of the produced biomass can potentially be affected by variety of external factors that induce physiological changes in trees. Response of carbon isotopic signal in tree ring cellulose to changes in resource availability was assessed in a manipulation experiment. It showed that the signal was relatively stable despite of changes in water and nitrogen availability to the tree. Palaeoclimatic reconstructions are typically based on functions describing empirical relationship between isotopic and climatic parameters. These empirical relationships may change depending on the site conditions, species and timeframe studied. Annual variation in Scots pine tree ring carbon and oxygen isotopic composition was studied in northern and in central eastern Finland and annual variation in tree ring latewood carbon, oxygen and hydrogen isotopic ratio in Oak (Quercus robur L.) was studied in southern Finland. In all of the studied sites at least one of the studied isotope ratios was shown to record climate strongly enough to be used in climatic reconstructions. Using the observed relationships, four-century-long climate reconstructions from living Scots pine were created for northern and central eastern Finland. Also temporal stability of the relationships between three proxy indicators, tree ring growth and carbon and oxygen isotopic composition was studied during the four-hundred-year period. Isotope ratios measured from tree rings in Finland were shown to be sensitive indicators of climate. Increasing understanding of environmental controls and physiological mechanisms affecting tree ring isotopic composition will make possible more accurate interpretation of isotope data. This study also demonstrated that by measuring multiple isotopes and physical proxies from the same tree rings, additional information on tree physiology can be obtained. Thus isotopic ratios measured from tree ring cellulose provide means to improve the reliability of climate reconstructions.

Splittings of free groups, normal forms and partitions of ends

Splittings of a free group correspond to embedded spheres in the 3-manifold M = # (k) S (2) x S (1). These can be represented in a normal form due to Hatcher. In this paper, we determine the normal form in terms of crossings of partitions of ends corresponding to normal spheres, using a graph of trees representation for normal forms. In particular, we give a constructive proof of a criterion determining when a conjugacy class in pi (2)(M) can be represented by an embedded sphere.

Productive coexistence and gain in agroforestry systems.

Productive coexistence and coexistence gain of populations were studied using nine years' data from field experiments of Taxodium ascendens-intercrop systems in Lixiahe, Jiangsu Province, China. A theoretical framework for productive coexistence in agroforestry was developed. Interaction patterns between trees and intercrops were presented within this framework. A model framework was developed to describe the coexistence gain and interaction of populations in T. ascendens-intercrop systems. Facilitation and resource sharing were identified as main contribution to the advantage of species combination in agroforestry. The model of population interaction developed in the present study was accepted for describing the interaction of populations in T. ascendens-intercrop systems, because it explained a high proportion of the variance of experimental data and fitted well the observations in most intercropping types. The model developed in the present study provides flexibility for describing different patterns of intra- and inter-specific interactions. Model coefficients were applied to the determination of the ecological compatibility of species. Managed T. ascendens-intercrop systems were advantageous as compared to a monoculture of trees or arable crops. In T. ascendens stands up to the age of three, arable crops contributed about 50-80 % of the total biomass yield of agroforestry. The diameter or height growth of T. ascendens was not significantly influenced by intercrops, indicating that intercropping under trees produced extra yields but did not depress the tree growth. When the trees were young (during the first three years), T. ascendens did not depress the crop yields, and a land equivalent ratio greater than unity was obtained together with a high yield of both components. The diameter and height of the trees were similar in four spacing configurations with an equal number of trees per hectare up to the age of eight, but wider between-rows open range were beneficial for the intercrops. The relationship between open-ranges and species coexistence was also analysed and the distribution of soil nutrients studied.

Metsän erirakenteisuutta edistävien hakkuiden kannattavuustarkastelu metsäaluetasolla

Tutkimuksessa vertailtiin metsän erirakenteisuutta edistävien poimintahakkuiden ja pienaukkohakkuiden kannattavuutta metsänhoitosuositusten mukaiseen metsänkasvatukseen Keski-Suomessa. Poimintahakkuut ja pienaukkohakkuut ovat menetelmiä, joilla voidaan lisätä luonnonmetsän häiriödynamiikan mukaista pienipiirteistä elinympäristöjen vaihtelua ja siksi ne sopivat etenkin erityiskohteisiin monimuotoisuuden, maiseman tai metsien monikäytön vuoksi. Ne johtavat yleensä vähitellen eri-ikäisrakenteiseen metsään, jossa puuston läpimittaluokkajakauma muistuttaa käänteistä J-kirjainta. Eri-ikäisrakenteisen metsänkäsittelyn taloudellista kannattavuutta puoltavat uudistumiskustannusten poisjäänti ja tukkipuihin painottuvat säännöllisin väliajoin toteutuvat hakkuut. Menetelmän soveltumista Suomen olosuhteisiin pidetään kuitenkin epävarmana. Tässä tutkimuksessa tarkasteltiin tasaikäisrakenteisen metsän muuttamista eri-ikäisrakenteiseksi 40 vuoden siirtymäaikana Metsähallituksen hallinnoimassa Isojäven ympäristöarvometsässä Kuhmoisissa. Tutkimusaineisto koostui 405 kuusivaltaisesta tasaikäisestä kuviosta, joiden pinta-alasta metsämaata on 636 hehtaaria. Metsän kehitystä simuloitiin puutason kasvumalleja käyttäen ja käsittelytoimenpiteet simuloitiin viisivuotiskausittain SIMO-metsäsuunnitteluohjelmistolla. Simulointien avulla selvitettiin jokaisen käsittelyskenaarion hakkuumäärät puutavaralajeittain, diskontatut kassavirrat ja puustopääoman muutos tarkasteluajanjakson aikana. Puunkorjuun yksikkökustannusten laskennan apuna käytettiin automatisoitua seurantajärjestelmää, jossa metsäkoneisiin asennettuilla matkapuhelimilla kerättiin MobiDoc2-sovelluksella metsäkoneiden käytöstä kiihtyvyystiedot, GPS-paikkatiedot ja syötetiedot. Lopulta jokaiselle käsittelyskenaariolle laskettiin metsän puuntuotannollista arvoa kuvaavalla tuottoarvon yhtälöllä nettonykyarvot, josta vähennettiin diskontatut puunkorjuun kustannukset. Tutkimuksen tulosten mukaan poimintahakkuun NPV oli 3 prosentin korkokannalla noin 91 % (7420 €/ha) ja pienaukkohakkuiden noin 99 % (8076 €/ha) metsänhoitosuositusten mukaisesta käsittelystä (8176 €/ha). Komparatiivinen statiikka osoitti, että korkokannan kasvattaminen 5 prosenttiin ei olennaisesti lisännyt nettonykyarvojen eroja. Poimintahakkuiden puunkorjuun yksikkökustannukset olivat 0,8 €/m3 harvennushakkuita pienemmät ja 7,2 €/m3 uudistushakkuita suuremmat. Pienaukkohakkuiden yksikkökustannukset olivat 0,7 €/m3 uudistushakkuita suuremmat.Tulosten perusteella on väistämätöntä että siirtymävaihe tasaikäisrakenteisesta eri-ikäisrakenteiseksi metsäksi aiheuttaa taloudellisia tappioita siitäkin huolimatta, että hakkuut ovat voimakkaita ja tehdään varttuneeseen kasvatusmetsään. Tappion määrä on metsän peitteisyyden ylläpidosta aiheutuva vaihtoehtoiskustannus.

The status and use of tree biomass in a semi-arid village ecosystem

The status of the tree biomass resource was investigated in Ungra, a semi-arid village ecosystem in South India. There were 57 tree species with 12 trees capita−1 and 35 trees ha−1. Multiple benefit yielding local tree species dominated the village ecosystem, while fuel only or single end use trees accounted for a small proportion of trees. The standing tree biomass is adequate to meet the requirement of biomass fuels for cooking only for about two years. Village tree biomass is presently being depleted largely for export to urban areas. Tree regeneration is now characterized by transformation from multiple-use local tree species to a few single-use species. A large potential exists for tree biomass production along field boundaries (bunds), stream banks and roadsides. Biomass estimation equations were developed for 10 species.

Differentiation of embryoids and plantlets from shoot callus of sandalwood

Callus cultures of sandalwood (Santalum album L.) were established from shoot segments and shoot tips of trees over 20 years old. Shoots were induced directly from shoot tip callus, while in shoot segments embryoids developed from the callus within 4 weeks after subculturing on to a medium supplemented with gibberellic acid (GA). Embryoids of 4–5 mm were transferred to basal medium or basal medium supplemented with low concentrations of auxin showed plantlet development.

A landscape approach to conservation of birds

Landscape ecology as a discipline in science is rather young. However its principles appear promising in outlining conservation strategies including a wide range of organisms, particularly birds. Birds due to their mobility use a variety of environmental resources, especially habitats. However, currently these habitats are only available in patches over most of the tropical world. Further whatever is left is under constant human pressure. This paper, therefore, addresses this problem and suggests means of dealing with it using the landscape approach as outlined by landscape ecology. The landscape approach starts with the realization that patches of habitats are open and interact with one another. Corridors of trees along roads, hedgerows and canals in a landscape can aid in the movement of species. Hence the landscape approach considers patches of habitats as interacting elements in the large matrix of the landscape. The landscape approach also integrates concepts. It puts together often debated issues such as whether to preserve maximum species diversity, to maximize representativeness, or to preserve only the valuable species. Based on a case study of the Uttara Kannada district in Karnataka, these oft-opposing views and complications can be dealt with practically and synthesized into a conservation strategy far the diverse avifauna of the Western Chats.

Woody plant seedling distribution under invasive Lantana camara thickets in a dry-forest plot in Mudumalai, southern India

Lantana camara, a shrub of Central and South American origin, has become invasive across dry forests worldwide. The effect of the thicket-forming habit of L. camara as a dispersal and recruitment barrier in a community of native woody seedlings was examined in a 50-ha permanent plot located in the seasonally dry forest of Mudumalai, southern India. Sixty 100-m(2) plots were enumerated for native woody seedlings between 10-100 cm in height. Of these, 30 plots had no L. camara thickets, while the other 30 had dense thickets. The frequency of occurrence and abundance of seedlings were modelled as a function of dispersal mode (mammal, bird or mechanical) and affinities to forest habitats (dry forest, moist forest or ubiquitous) as well as presence or absence of dense L. camara thickets. Furthermore, frequency of occurrence and abundance of individual species were also compared between thickets and no L. camara. At the community level, L. camara density, dispersal mode and forest habitat affinities of species determined both frequency of occurrence and abundance of seedlings, with the abundance of dry-forest mammal-dispersed species and ubiquitous mechanically dispersed species being significantly lower under L. camara thickets. Phyllanthus emblica and Kydia calycina were found to be significantly less abundant under L. camara, whereas most other species were not affected by the presence of thickets. It was inferred that, by affecting the establishment of native tree seedlings, L. camara thickets could eventually alter the community composition of such forests.

Efficient statistical modeling for the compression of tree structured intermediate code

We propose a scheme for the compression of tree structured intermediate code consisting of a sequence of trees specified by a regular tree grammar. The scheme is based on arithmetic coding, and the model that works in conjunction with the coder is automatically generated from the syntactical specification of the tree language. Experiments on data sets consisting of intermediate code trees yield compression ratios ranging from 2.5 to 8, for file sizes ranging from 167 bytes to 1 megabyte.

Topological analysis of general linear networks

A new method of network analysis, a generalization in several different senses of existing methods and applicable to all networks for which a branch-admittance (or impedance) matrix can be formed, is presented. The treatment of network determinants is very general and essentially four terminal rather than three terminal, and leads to simple expressions based on trees of a simple graph associated with the network and matrix, and involving products of low-order, usually(2 times 2)determinants of tree-branch admittances, in addition to tree-branch products as in existing methods. By comparison with existing methods, the total number of trees and of tree pairs is usually considerably reduced, and this fact, together with an easy method of tree-pair sign determination which is also presented, makes the new method simpler in general. The method can be very easily adapted, by the use of infinite parameters, to accommodate ideal transformers, operational amplifiers, and other forms of network constraint; in fact, is thought to be applicable to all linear networks.

Long-term effects of Macroternies termites, herbivores and annual early fire on woody undergrowth community in Sudanian woodland, Burkina Faso

Termites, herbivores and fire are recognized as major guilds that structure woody plant communities in African savanna and woodland ecosystems. An understanding of their interaction is crucial to design appropriate management regimes. The aim of this study was to evaluate the long-term impacts of herbivore, fire and termite activities on regeneration of trees. Permanent experimental quadrats were established in 1992 in the Sudanian woodland of Burkina Faso subjected to grazing by livestock and annual early fire and the control. Within the treatment quadrats, an inventory of the woody undergrowth community was conducted on termitaria occupied by Macrotermes subhyalinus, extended termitosphere (within 5 m radius from the mound base) and adjacent area (beyond 5 m from the mound base). Hierarchical analysis was performed to determine significant differences in species richness, abundance and diversity indices among vegetation patches within fire and herbivory treatments. Grazed quadrats had significantly (P < 0.001) more species and stem density of woody undergrowth than non-grazed quadrats but maintained similar level of species richness and stem density of woody undergrowth on termitaria. There were not significant differences (P>0.05) in species richness and stem density between burnt and unburnt quadrats. Termitaria supported a highly diverse woody undergrowth with higher stem density than either the extended termitosphere or rest of quadrats. The density of woody undergrowth was significantly related with mature trees of selected species on termitaria (R-2 = 0.593; P<0.001) than that on the extended termitosphere (R-2 = 0.333; P<0.001) and adjacent area (R-2 = 0.197; P<0.001). It can be concluded that termites facilitate the regeneration of woody species while grazing and annual early fire play a minor role in the regeneration of woody species. The current policy that prohibits grazing should be revised to accommodate the interests of livestock herders. (C) 2014 Elsevier GmbH. All rights reserved.