Decomposition in tropical forests: a pan-tropical study of the effects of litter type, litter placement and mesofaunal exclusion across a precipitation gradient

1. Litter decomposition recycles nutrients and causes large fluxes of carbon dioxide into the atmosphere. It is typically assumed that climate, litter quality and decomposer communities determine litter decay rates, yet few comparative studies have examined their relative contributions in tropical forests. 2. We used a short-term litterbag experiment to quantify the effects of litter quality, placement and mesofaunal exclusion on decomposition in 23 tropical forests in 14 countries. Annual precipitation varied among sites (760-5797 mm). At each site, two standard substrates (Raphia farinifera and Laurus nobilis) were decomposed in fine- and coarse-mesh litterbags both above and below ground for approximately 1 year. 3. Decomposition was rapid, with >95% mass loss within a year at most sites. Litter quality, placement and mesofaunal exclusion all independently affected decomposition, but the magnitude depended upon site. Both the average decomposition rate at each site and the ratio of above- to below-ground decay increased linearly with annual precipitation, explaining 60-65% of among-site variation. Excluding mesofauna had the largest impact on decomposition, reducing decomposition rates by half on average, but the magnitude of decrease was largely independent of climate. This suggests that the decomposer community might play an important role in explaining patterns of decomposition among sites. Which litter type decomposed fastest varied by site, but was not related to climate. 4. Synthesis. A key goal of ecology is to identify general patterns across ecological communities, as well as relevant site-specific details to understand local dynamics. Our pan-tropical study shows that certain aspects of decomposition, including average decomposition rates and the ratio of above- to below-ground decomposition are highly correlated with a simple climatic index: mean annual precipitation. However, we found no relationship between precipitation and effects of mesofaunal exclusion or litter type, suggesting that site-specific details may also be required to understand how these factors affect decomposition at local scales.

Oviposition site selection by the bromeliad-dweller harvestman Bourguyia hamata (Arachnida : Opiliones)

Bourguyia hamata females oviposit almost exclusively inside the rosette formed by the curled leaves of the epiphytic bromeliad Aechmea nudicaulis. We investigated whether the architecture of the individual bromeliads influences oviposition site selection by this harvestman species. We collected data on the presence of clutches inside bromeliads, rosette length, rosette slope in relation to tree trunks, and the amount of debris inside the rosette. Additionally, we measured the water volume inside the rosettes as well as the variation in the humidity inside and outside bromeliads with long and short rosettes. Longer rosettes were preferred as oviposition site possibly because they accumulate more water and maintain lower internal humidity variation than the external environment. Although the slope of the rosettes did not influence the occurrence of oviposition, the probability of debris accumulation inside the rosettes increased with their slope, and the frequency of clutches was greater in bromeliads with small amounts of debris. A field experiment showed that bromeliads with water inside the rosette were more frequently used as oviposition sites than bromeliads without water. In conclusion, females oviposit predominantly in bromeliads that accumulate more water and have small amounts of debris inside the rosettes, probably because these characteristics promote a more adequate microhabitat for egg development.

Apocynaceae sensun strictum from the Mucuge Municipal Park, Bahia, Brazil, including the valid publication of two names in Mandevilla Lindl.

Apocynaceae sensun strictum from the Mucuge Municipal Park, Bahia, Brazil, including the valid publication of two names in Mandevilla Lindl. The flora of Rauvolfioideae and Apocynoideae, which together form Apocynaceae s.s., from the Mucuge Municipal Park, Chapada Diamantina, State of Bahia, Brazil, is presented. Eight species and five genera were recognized. Mandevilla is the most diverse genus, With four species: M. scabra (Hoffmans. ex Roem. & Schult.) K. Schum., M. tenuifolia (J.C. Mikan) Woodson, M. bahiensis (Woodson) M.F. Sales & Kinoshita-Gouvea, and M.microphylla (Stadelm.) M.F. Sales & Kinoshita-Gouvea, the last two are a new status and a new combination, respectively, whose names are being validly published here. The four remaining genera are each represented by one species: Couma rigida Mull. Arg., Stipecoma peltigera (Stadelm.) Mull Arg,, Temnadenia violacea (Veil.) Miers, and Himatanthus bracteatus (A. DC.) Woodson. Identification key, descriptions, comments and illustrations are presented for every species.

BIRD FORAGING IN ANACARDIUM PATCHES IN CENTRAL BRAZILIAN FIRE BREAKS: RELATIONSHIP BETWEEN FLOCK SIZE AND PATCH SIZE

Fire management ran increase the biomass of some plant species at fire breaks in reserves of the Cerrado. For example, numerous and large patches of monkey-nuts (Anacardium humile, Anacardiaceae) provide abundant food resources for wildlife in the lower strata of savanna woodlands managed by fire. The objective of this study was to examine the exploitation of A. humile patches by birds in managed savanna woodlands (fire breaks) at Emas National Park, southwest Brazil. The relationship between flock size and the size of Anacardium patches were also investigated. Fire breaks were sampled in September and October 2006, when fruits and flowers were abundant. Ara ararauna was often recorded exploiting resources of Anacardium patches. This species and other psittacids (Amazona aestiva, Alipiopsittaca xanthops, and Diopsittaca nobilis) consumed seeds usually on the ground around fruiting patches. Members of Aratinga aurea flocks and Ramphastos toco consumed pseudo-fruits. Larger flocks detected were those of A. aurea and A. ararauna. Groups of A. ararauna that exploited larger patches tended to be larger than flocks that exploited smaller patches. This study suggests that intra- and interspecific interactions and characteristics of Anacardium patches and of the surrounding vegetation are involved in the feeding ecology of birds in the lower stratum of managed woodlands. Fruiting Anacardium patches attract numerous frugivorous birds to fire breaks at Emas National Park. Further research is needed to a better understanding of the influence of fire management on birds in the Cerrado. Accepted 31 July 2009.

A Plant Needs Ants like a Dog Needs Fleas: Myrmelachista schumanni Ants Gall Many Tree Species to Create Housing

Hundreds of tropical plant species house ant colonies in specialized chambers called domatia. When, in 1873, Richard Spruce likened plant-ants to fleas and asserted that domatia are ant-created galls, he incited a debate that lasted almost a century. Although we now know that domatia are not galls and that most ant-plant interactions are mutualisms and not parasitisms, we revisit Spruce`s suggestion that ants can gall in light of our observations of the plant-ant Myrmelachista schumanni, which creates clearings in the Amazonian rain forest called ""supay-chakras,"" or ""devil`s gardens."" We observed swollen scars on the trunks of nonmyrmecophytic canopy trees surrounding supay-chakras, and within these swellings, we found networks of cavities inhabited by M. schumanni. Here, we summarize the evidence supporting the hypothesis that M. schumanni ants make these galls, and we hypothesize that the adaptive benefit of galling is to increase the amount of nesting space available to M. schumanni colonies.

The tax treatment of employee stock options : generous to a fault

In the 2000 budgets, both the federal and Ontario governments introduced changes to the tax treatment of employee stock options for the explicit purpose of making their tax treatment in Canada similar to or more favourable than that in the United States. The federal budget added a deferral, similar to that currently applicable to options granted by Canadian-controlled private corporations, for up to $100,000 per year of public company stock options. The Ontario budget introduced an exemption from tax for employees involved in research and development on the first $100,000 per year of employee benefits arising on the exercise of qualified stock options or on eligible capital gains arising from the sale of shares acquired by the exercise of eligible stock options. These proposals reflect the apparent acceptance by the two governments that there is a “brain drain” from Canada to the United States of knowledge workers in the “new” economy and that reductions in Canadian taxes should stem this drain. In the author’s view, the tax treatment of employee stock options, even without these changes, is overly generous. Both the federal and provincial proposals ignore the fact that most employee stock options are taxed more favourably in Canada than in the United States in any event. In particular, most employee stock option benefits in Canada are taxed at capital gains tax rates, whereas in the United States most are taxed at full rates. While the US Internal Revenue Code does provide capital gains tax treatment for certain employee stock option benefits, a number of preconditions must be met. Most important, the shares acquired pursuant to the options must be held for a minimum of one year after the option is exercised. In addition, there are monetary limits on the amount of options that qualify for capital gains treatment. In Canada, there are generally no holding period requirements or monetary limits that apply in order for the option holder to benefit from capital gains tax rates. Empirical evidence indicates that the vast majority of employees in the United States exercise their options and immediately sell the shares acquired. These “cashless exercises” do not benefit from capital gains treatment in the United States, whereas similar cashless exercises in Canada generally do. This empirical evidence suggests not only that the 2000 budget proposals are unwarranted, but also that the existing treatment of employee stock options in Canada is already more generous than that in the United States. This article begins with a theoretical “benchmark” for the taxation of employee stock options. The author suggests that employee stock options should be treated in the same manner as other income from employment. In theory, the value of the benefit should be included in income when the option is granted or vests. However, owing to the practical difficulty of valuing employee stock options, the theoretical benchmark proposed is that the value of the benefit (the difference between the fair market value of the shares acquired and the strike price under the option) be taxed when the shares are acquired, and the employer be entitled to a corresponding deduction. The employee stock option rules in Canada and the United States are then compared and contrasted with each other and the benchmark treatment. The article then examines the arguments that have been made for favourable treatment of employee stock options. Included in this critique is a review of the recent empirical work on the Canadian brain drain. Empirical studies suggest that the brain drain—if it exists at all—is small and that, despite what many newspapers and right-wing think-tanks would have us believe, lower taxes in the United States are not the cause. One study, concluding that taxes do have an effect on migration, suggests that even if Canada adopted a tax system identical to that in the United States, the brain drain would be reduced by a mere 10 percent. Indeed, even if Canada eliminated income tax altogether, it would not stop the brain drain. If governments here want to spend money in order to stem the brain drain, they should focus on other areas. For example, Canada produces fewer university graduates in the fields of mathematics, sciences, and engineering than any other G7 country except Italy. The short supply of university graduates in these fields, the apparent loss of top-calibre academics to US
universities, and the consequent lower levels of university research in these areas (an important spawning ground for new ideas in the “new” knowledge-based economy) suggest that Canada may be better served by devoting more resources to its university institutions, particularly in post-graduate programs, rather than continuing the current trend of budget cuts that universities have endured and may further endure if taxes are reduced.
As far as employee stock options are concerned, if Canada does want to look to the United States for guidance on tax reform (which it seems to do with increasing frequency of late), it should adopt the US rules applicable to nonstatutory options, which are close to the proposed benchmark treatment. In the absence of preferential tax treatment, employee stock options would still be included in compensation packages provided that there were sound business reasons for their use. No persuasive evidence has been put forward that the use of stock options, in the absence of tax incentives, is suboptimal. Indeed, the US experience suggests quite the opposite.

Distribution of disease caused by Phytophthora cinnamomi in Wilsons Promontory National Park and potential for further impact

The extent of disease caused by Phytophthora cinnamomi was determined within vegetation communities of Wilsons Promontory National Park. Aerial survey of visible symptoms by helicopter and systematic survey along all roads and tracks followed by isolation of the pathogen from soil found that in total 551 ha of moist foothill forest, heath and heathy woodland broad vegetation types were affected by the disease. P. cinnamomi was isolated from 93% of sites that, based on the presence of visible symptoms, were expected to yield the pathogen. The species-rich heathy woodland was most affected with 6.5% of the total area of this type showing symptoms of disease. The size of infestation ranged from 229 ha on the slopes of the Vereker Range in the north to less than 1 ha along the Sealers Cove Walking Track in the south. The potential for disease to spread into uninfested vegetation was estimated for all sites from which P. cinnamomi was isolated. Eight of 18 sites where evidence of disease was found were estimated to have a high potential for further disease spread. This study indicates that even though the disease may be waning in some areas of the Park, the pathogen is active and easily isolated from others and provides a continuing threat to susceptible vegetation communities.

A preliminary study of bryophytes and invertebrates of soil crusts in the Little Desert National Park and surrounds

This study is preliminary to ongoing investigations of soil crusts and associated invertebrates in north-west Victoria, focusing on the Little Desert National Park. Ninety quadrats from nine sites were sampled. Eighteen bryophyte species (nine mosses, nine liverworts) were identified within the quadrats. All invertebrates were from the Phylum Arthropoda. Overall abundance and diversity of invertebrates was low. While sampling in the drier months is valuable for observing the dynamics of soil crusts in this region, a more comprehensive assessment of species diversity is gained by sampling
during wetter periods.

Community development and ecology : exploring the links

This paper will explore connections between the concepts of community development and ecology. Initially the tendency was to think there should be a total melding of the principles and practices of community development with those of an ecological understanding but on reflection this has not and indeed is not necessarily the case. The relative epistemological positioning of two different groups, one strongly associating with social justice and the need for people to be at the centre of our economic, environmental and social understanding; and the other clearly seeing the plant and ecology/environment being paramount. While there are a myriad of connections the focus of much community development has been around human welfare based on principles of social, political and economic justice. This has at times been to the detriment of ecological sustainability. Conversely ecology and particularly aspects of deep ecology have focussed on the 'other than human' aspects of the planet and at times seemed almost 'anti 'human and overlooking the need to work with the social almost entirely. This paper briefly outlines the historical separation of the social from the ecological then goes on to explore alternative understandings that bring together principles of community development and ecology. Three examples are used to highlight the principles and practices that are being used across diverse contexts but all informed by common norms and values that are consistent with both community development and ecology. Concepts such as subsidiarity, participation and empowerment that form the basis of community development praxis are critical to the development of local sustainability. The combination of these aspects is evidenced in the three examples. Each is very clearly located in the local context and is built on sound ecological and community development understandings but each is also well aware that the need for a broader perspective is imperative to achieving global goals.

Evaluating quality of life in hip and knee replacement: psychometric properties of the World Health Organization Quality of Life short version instrument

Objective: To evaluate the psychometric properties of the World Health Organization Quality of Life short version instrument (WHOQOL-BREF), and to determine its responsiveness in assessing early outcome after total hip or knee replacement surgery.

Methods: At baseline (entry to an orthopedic waiting list), 279 participants completed the WHOQOL-BREF instrument, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Assessment of Quality of Life (AQOL) instrument, Kessler Psychological Distress (K10) scale, and the modified Health Assessment Questionnaire (MHAQ). A total of 74 patients completed reassessments 3 months after surgery.

Results: The WHOQOL-BREF demonstrated acceptable internal consistency for all domains (Cronbach's = 0.76-0.84) and moderate concurrent validity for the physical and psychological domains (r = 0.67 for physical versus AQOL; r = -0.71 for psychological versus K10). Minimal ceiling or floor effects were identified at baseline or 3 months, except for the social relationships domain. The disease-specific WOMAC subscales were most responsive to change (relative efficiency [RE] 0.66-1.00). Apart from social relationships, all WHOQOL-BREF scores improved significantly after surgery. The physical domain was more responsive than the AQOL (RE 0.50 versus 0.42) and was similar to the MHAQ (RE 0.55 for MHAQ). The responsiveness of the psychological domain was similar to that of the K10 scale (RE 0.11 versus 0.08).

Conclusion: The WHOQOL-BREF has good psychometric properties for use in persons with severe joint disease, and by providing complementary information, it offers clinicians and researchers an additional tool for comprehensively assessing quality of life in this patient group.

Flowering ecology of honey-producing flora in South-East Australia

This report examines the flowering ecology (flowering patterns and the production of floral resources, i.e. nectar and pollen) of important Australian melliferous (honey-producing) flora. Aspects of flowering ecology that can have a negative impact on invertebrates, including honeybees, were also investigated. The research was based on information sourced by highly experienced, commercial beekeepers and, so, provides a valuable written record of long-term observations relating to flowering ecology which otherwise may be lost following the death of beekeepers. Results of this study are of far-reaching importance, not only to the beekeeping industry, but to land managers, the general public and the future of Australian flora and fauna.

An understanding of flowering ecology is vital for many reasons, including implementing appropriate management practices which ensure the sustainability and growth of natural resources and industries like the beekeeping industry. Despite the importance of such studies, very little research has considered flowering ecology in Australian flora. Furthermore, research often was based on short-term data; long-term data are widely acknowledged as being necessary in such research in order to determine ‘real’ flowering patterns. Thus, studies of flowering ecology which use long-term data are vital.

Flowering ecology of a Box-Ironbark Eucalyptus community

Box-Ironbark forests occur on the inland hills of the Great Dividing Range in Australia, from western Victoria to southern Queensland. These dry, open forests are characteristically dominated by Eucalyptus species such as Red Ironbark E. tricarpa, Mugga Ironbark E. sideroxylon and Grey Box E. microcarpa. Within these forests, several Eucalyptus species are a major source of nectar for the blossom-feeding birds and marsupials that form a distinctive component of the fauna. In Victoria, approximately 83% of the original pre - European forests of the Box-Ironbark region have been cleared, and the remaining fragmented forests have been heavily exploited for gold and timber. This exploitation has lead to a change in the structure of these forests, from one dominated by large 80-100 cm diameter, widely -spaced trees to mostly small (≥40 cm DBH), more densely - spaced trees. This thesis examines the flowering ecology of seven Eucalyptus species within a Box-Ironbark community. These species are characteristic of Victorian Box-Ironbark forests; River Red Gum E. camaldulensis, Yellow Gum E. leucoxylon, Red Stringybark E. macrorhyncha, Yellow Box E. melliodora, Grey Box E. microcarpa, Red Box E. polyanthemos and Red Ironbark E. tricarpa. Specifically, the topics examined in this thesis are: (1) the floral character traits of species, and the extent to which these traits can be associated with syndromes of bird or insect pollination; (2) the timing, frequency, duration, intensity, and synchrony of flowering of populations and individual trees; (3) the factors that may explain variation in flowering patterns of individual trees through examination of the relationships between flowering and tree-specific factors of individually marked trees; (4) the influence of tree size on the flowering patterns of individually marked trees, and (5) the spatial and temporal distribution of the floral resources of a dominant species, E. tricarpa. The results are discussed in relation to the evolutionary processes that may have lead to the flowering patterns, and the likely effects of these flowering patterns on blossom-feeding fauna of the Box-Ironbark region. Flowering observations were made for approximately 100 individually marked trees for each species (a total of 754 trees). The flower cover of each tree was assessed at a mean interval of 22 (+ 0.6) days for three years; 1997, 1998 and 1999. The seven species of eucalypt each had characteristic flowering seasons, the timing of which was similar each year. In particular, the timing of peak flowering intensity was consistent between years. Other spatial and temporal aspects of flowering patterns for each species, including the percentage of trees that flowered, frequency of flowering, intensity of flowering and duration of flowering, displayed significant variation between years, between forest stands (sites) and between individual trees within sites. All seven species displayed similar trends in flowering phenology over the study, such that 1997 was a relatively 'poor' flowering year, 1998 a 'good' year and 1999 an 'average' year in this study area. The floral character traits and flowering seasons of the seven Eucalyptus species suggest that each species has traits that can be broadly associated with particular pollinator types. Differences between species in floral traits were most apparent between 'summer' and 'winter' flowering species. Winter - flowering species displayed pollination syndromes associated with bird pollination and summer -flowering species displayed syndromes more associated with insect pollination. Winter - flowering E. tricarpa and E. leucoxylon flowers, for example, were significantly larger, and contained significantly greater volumes of nectar, than those of the summer flowering species, such as E. camaldulensis and E. melliodom. An examination of environmental and tree-specific factors was undertaken to investigate relationships between flowering patterns of individually marked trees of E. microcarpa and E. tricarpa and a range of measures that may influence the observed patterns. A positive association with tree-size was the most consistent explanatory variable for variation between trees in the frequency and intensity of flowering. Competition from near-neighbours, tree health and the number of shrubs within the canopy area were also explanatory variables. The relationship between tree size and flowering phenology was further examined by using the marked trees of all seven species, selected to represent five size-classes. Larger trees (≥40 cm DBH) flowered more frequently, more intensely, and for a greater duration than smaller trees. Larger trees provide more abundant floral resources than smaller trees because they have more flowers per unit area of canopy, they have larger canopies in which more flowers can be supported, and they provide a greater abundance of floral resources over the duration of the flowering season. Heterogeneity in the distribution of floral resources was further highlighted by the study of flowering patterns of E. tricarpa at several spatial and temporal scales. A total of approximately 5,500 trees of different size classes were sampled for flower cover along transects in major forest blocks at each of five sample dates. The abundance of flowers varied between forest blocks, between transects and among tree size - classes. Nectar volumes in flowers of E. tricarpa were sampled. The volume of nectar varied significantly among flowers, between trees, and between forest stands. Mean nectar volume per flower was similar on each sample date. The study of large numbers of individual trees for each of seven species was useful in obtaining quantitative data on flowering patterns of species' populations and individual trees. The timing of flowering for a species is likely to be a result of evolutionary selective forces tempered by environmental conditions. The seven species' populations showed a similar pattern in the frequency and intensity of flowering between years (e.g. 1998 was a 'good' year for most species) suggesting that there is some underlying environmental influence acting on these aspects of flowering. For individual trees, the timing of flowering may be influenced by tree-specific factors that affect the ability of each tree to access soil moisture and nutrients. In turn, local weather patterns, edaphic and biotic associations are likely to influence the available soil moisture. The relationships between the timing of flowering and environmental conditions are likely to be complex. There was no evidence that competition for pollinators has a strong selective influence on the timing of flowering. However, as there is year-round flowering in this community, particular types of pollinators may be differentiated along a temporal gradient (e.g. insects in summer, birds in winter). This type of differentiation may have resulted in the co-evolution of floral traits and pollinator types, with flowers displaying adaptations that match the morphologies and energy requirements of the most abundant pollinators in any particular season. Spatial variation in flowering patterns was evident at several levels. This is likely to occur because of variation in climate, weather patterns, soil types, degrees of disturbance and biotic associations, which vary across the Box-Ironbark region. There was no consistency among sites between years in flowering patterns suggesting that factors affecting flowering at this level are complex. Blossom-feeding animals are confronted with a highly spatially and temporally patchy resource. This patchiness has been increased with human exploitation of these forests leading to a much greater abundance of small trees and fewer large trees. Blossom-feeding birds are likely to respond to this variation in different ways, depending upon diet-breadth, mobility and morphological and behavioural characteristics. Future conservation of the blossom-feeding fauna of Box-Ironbark forests would benefit from the retention of a greater number of large trees, the protection and enhancement of existing remnants, and revegetation with key species, such as E. leucoxylon, E. microcarpa and E. tricarpa. The selective clearing of summer flowering species, which occur on the more fertile areas, may have negatively affected the year-round abundance and distribution of floral resources. The unpredictability of the spatial distribution of flowering patches within the region means that all remnants are likely to be important foraging areas in some years.

Effects of vegetation, fire and other disturbance factors on small mammal ecology and conservation

The relationship of vegetation and disturbance factors to the distribution, abundance and diversity of small mammals in the eastern Otway region, Victoria were investigated. Antechinus stuartii, Rattus fuscipes and Rattus lutreolus were widely distributed and occurred in the majority of the eleven floristic vegetation groups identified. Antechinus minimus, Antechinus swainsonnii and Pseudomys novaehollandiae had restricted distributions and were recorded in only two or three vegetation groups. New information on the distribution of the rare species P. novaehollandiae, was obtained and two floristically rich vegetation groups that it preferred were identified. Species-rich small mammal communities occurred in vegetation communities with high numbers of sclerophyll plant species and high structural diversity. Maximum food resources were considered to be provided in these communities. Local habitat diversity was also correlated with species-richness. Small mammal abundance was maximum in non-sclerophyllous canmunities, where high plant productivity was considered to be important. For the first time, the presence of the plant pathogen Phytophthora cinnamomi was shown to affect small mammals. It was associated with small mammal communities of low species richness and abundance, Recovery of small mammal populations after wildfire was slow until the fourth year. Mus musculus reached peak abundance from 2-3 years and then declined rapidly. P. novaehollandiae was the only native species that achieved maximum abundance early in the succession. A. stuartii, R. fuscipes and R. lutreolus approached maximum abundance in mid-succession, while Isoodon obesulus was a mid- to late-successional species. A. minimus survived the fire, but did not persist after one year. The pattern of succession was influenced by attributes of species, such as survival after fire, their ability to disperse and reproduce.