Ecological connectivity or Barrier Fence? Critical choices on the agricultural margins of Western Australia

Western Australia's State Barrier Fence represents a continuation of colonial era attitudes that considered kangaroos, emus and dingoes as ‘vermin’. Recent plans to upgrade and extend the Barrier Fence have shown little regard for ecological impacts or statutory environmental assessment processes.     

The human dimension of fire regimes on Earth

Humans and their ancestors are unique in being a fire-making species, but 'natural' (i.e. independent of humans) fires have an ancient, geological history on Earth. Natural fires have influenced biological evolution and global biogeochemical cycles, making fire integral to the functioning of some biomes. Globally, debate rages about the impact on ecosystems of prehistoric human-set fires, with views ranging from catastrophic to negligible. Understanding of the diversity of human fire regimes on Earth in the past, present and future remains rudimentary. It remains uncertain how humans have caused a departure from 'natural' background levels that vary with climate change. Available evidence shows that modern humans can increase or decrease background levels of natural fire activity by clearing forests, promoting grazing, dispersing plants, altering ignition patterns and actively suppressing fires, thereby causing substantial ecosystem changes and loss of biodiversity. Some of these contemporary fire regimes cause substantial economic disruptions owing to the destruction of infrastructure, degradation of ecosystem services, loss of life, and smoke-related health effects. These episodic disasters help frame negative public attitudes towards landscape fires, despite the need for burning to sustain some ecosystems. Greenhouse gas-induced warming and changes in the hydrological cycle may increase the occurrence of large, severe fires, with potentially significant feedbacks to the Earth system. Improved understanding of human fire regimes demands: (1) better data on past and current human influences on fire regimes to enable global comparative analyses, (2) a greater understanding of different cultural traditions of landscape burning and their positive and negative social, economic and ecological effects, and (3) more realistic representations of anthropogenic fire in global vegetation and climate change models. We provide an historical framework to promote understanding of the development and diversification of fire regimes, covering the pre-human period, human domestication of fire, and the subsequent transition from subsistence agriculture to industrial economies. All of these phases still occur on Earth, providing opportunities for comparative research.     

Pyrogeographic models,feedbacks and the future of global fire regimes

Conceptual and phenomenological macroecological models of current global fire activity have demonstrated the overwhelming control exerted by primary productivity. Fire activity is very high in savanna regions with intermediate primary productivity, and very low in both densely forested regions with high productivity and arid/cold regions with low productivity. However, predicting future global fire activity using such macroecological models of fire's global ‘niche’ may not be possible because of the feedbacks between fire, climate and vegetation that underpin the fire?productivity relationship. Improving forecasts of global fire activity demands the use of dynamic models to determine how climate, CO₂, vegetation (i.e. canopy closure and plant functional types) and primary productivity constrain fire and evaluation of the strength of feedbacks amongst these variables.     

A fine-resolution Pliocene pollen and charcoal record from Yallalie, south-western Australia

Aim This paper aims to reconstruct a high‐resolution fire and vegetation history from a period when humans were absent in Australia. This is then used to comment on the frequency of natural fire in high biodiversity heathland, and to compare this with historical fire regime in the same region. Methods A section of varved sediment covering a period of c. 84 years was taken from Palaeolake Yallalie in south‐western Australia. The sediments were separated into approximately single to small multiples of years and then analysed for charcoal, pollen and sediment analysis to reconstruct the environmental conditions at the time. Results The charcoal record indicates fire recurrence to have been roughly between 5 and 13 years, a little longer than those of the historical period. The pollen record was dominated by Casuarinaceae, Myrtaceae and a large number of Proteaceae species; these are intermixed with Araucariaceae, Nothofagus and Podocarpus. This suggests there was a mix of sclerophyll woodland and a mosaic of rain forest elements, thus conditions must have been wetter, particularly in the summers, compared with today. Conclusions We assume that fire was most likely confined to the sclerophyll vegetation, and that fire has been a significant feature of the environment long before humans entered Australia. The slightly longer fire recurrence times compared with the present result from the intermittent nature of lightning and wetter summers at the time.     

Fire‐mediated niche‐separation between two sympatric small mammal species

Fire is a key ecological process influencing the population dynamics of small mammals. Whilst shifting competitive advantage amongst small mammal species following a single fire event is well‐documented, there has been little investigation of the potential influence of fire frequency on small mammal interspecific interactions. In this study, we investigated the effect of fire frequency on the abundance of two small dasyurid mammals, Antechinus stuartii and A. flavipes, which occur sympatrically in some parts of their range. The two antechinus species are known to have different habitat preferences, so it is possible that fire regimes may promote their coexistence in areas of sympatry by altering vegetation structure. To investigate this possibility, we estimated the abundance of both species using replicate sites which differed in the number of times burnt (1–4) during the last four decades, but with identical time‐since‐fire. Proportionally, we captured greater numbers of A. stuartii in less frequently burnt sites and greater numbers of A. flavipes in more‐frequently burnt sites. Hence, fire may mediate niche‐separation between these two species. To clarify further this pattern of response to fire frequency, we investigated which structural habitat variables differed between fire frequencies, and compared antechinus abundances with structural vegetation characteristics. We found a trend for lower ground cover density under higher fire frequencies. This offers one potential explanation of the patterns of abundance that we observed. Our study provided insights into the complexities of small mammal responses to fire, and strongly suggests that fire could mediate competitive interactions between species.     

Inclusion of phytosociological data in an index of vegetation fire danger: application and mapping on the Karst area around Trieste (Italy)

In this paper we propose a method to produce maps of fire danger index (FDI). The index includes in the formula a vegetation pyrogenic potential index (VPPI) based on floristic phytosociological data. The map of FDI is produced by integrating available phytosociological maps of vegetation, geomorphology and climate, using the Geographic Information System technology. The method is applied to an area of the coastal Classical Karst (NE-Italy). While fire risk maps based on the incidence of previous fires are useful for facilitating emergency operations, e.g. the allocation of fire fighting resources, we conclude that the proposed index offers an effective tool to plan actions for fire prevention.     

Exploring methods for rapid assessment of woody vegetation in the Batemi Valley, North-central Tanzania

Conservation of local biological resources in remote areas requires efficient data and collection methods. This paper describes part of a local conservation initiative in Northern Tanzania in which an indigenous conservation group enlisted the support of outside scientists to explore means of preparing baseline ecological reports. Two factors are seen as important: one is local use of ecological resources and the other is local availability. This paper focuses on the second of these and considers woody species. A variety of ecological field methods, statistical analysis and remote sensing and mapping techniques are used to generate baseline ecological inventories. The fieldwork identified 101 woody species, representing 54 genera and 37 families in the Batemi area. There are three main vegetation types: Vangueria apiculata-Ficus sycomorus-Trichilia emetica type; Croton dictygamous-Euphorbia tirucalli-Grewia bicolor type; and Acacia tortilis-Balanites aegyptica-Euphorbia candelabrum type. The Landsat TM map identified four main land-cover classes: (1) bushland and woodland thicket, (2) woodland (3) wooded grassland, and (4) grassland with scattered trees, which includes agricultural areas and villages. The combination of these data and methods can be useful for conservation planning and long-term monitoring, but it is clear that ground-level local assessment is necessary to detect subtleties of human-environment interaction that are required for conservation planning.     

森林植被的自然火干扰

森林植被的自然火干扰邱扬（山西大学黄土高原研究所,太原０３０００６）ＮａｔｕｒａｌＦｉｒｅＤｉｓｔｕｒｂａｎｃｅｏｆＦｏｒｅｓｔＶｅｇｅｔａｔｉｏｎ．ＱｉｕＹａｎｇ（ＩｎｓｔｉｔｕｔｅｏｆＬｏｅｓＰｌａｔｅａｕ,ＳｈａｎｘｉＵｎｉｖｅｒｓｉｔｙ,...     

Two fine‐resolution Pliocene charcoal records and their bearing on pre‐human fire frequency in south‐western Australia

Abstract Yallalie is a probable meteor impact crater and in the Upper Pliocene contained a substantial lake. Two Mid‐Pliocene finely laminated sediment records from Palaeolake Yallalie, from about 3 million years ago, provide evidence of fire and fire frequency in the sclerophyll woodland and heaths of south‐western Australia in the absence of humans. Fine charcoal was observed in all samples examined, and was deposited at a rate of about 0.3–0.8 cm² cm^?2 year^?1 in Palaeolake Yallalie. This evidence suggests the occurrence of annual fires occurring every year in the slightly warmer and wetter climate compared with today. The near coastal western location and the prevailing westerly winds probably carry charcoal from the near region or lake catchment scale. The data indicate that local fires occurred at a variety of time intervals between 3 and 13 years, with a typical average of 6–10 years. The results are comparable with those of Atahan et al. (2004) for the same site but from a period of about 200 000 years later in the Mid‐Pliocene. Thus, the records which differ in age by some hundreds of thousands of years have all recorded fire frequencies that are longer than for the historical period and this may have important implications for the long‐term survival of the integrity of the high biodiversity plant communities of the region.     

Exploring the generality of associations between plant functional traits: evidence within ecological groups along an altitudinal gradient in Hyrcanian forest

We hypothesized that associations among plant functional traits may differ within different ecological assemblages and plant communities. Association among plant traits including plant maximum height, seed weight, fruit type, pollination mode, mean leaf area, and leaf type were explored within life forms, plant strategy groups along with lowland and montane forest vegetation. In total, 83 sampling plots of 400 m² were placed along a 2400 m altitudinal gradient in Hyrcanian forest. Importance‐values of species within vegetation types were used for weighting data and trait associations were explored using categorical principal component analysis. A G‐test and Fisher's exact test of independence were used to retest significance of the correlations. Different paired trait associations (association lines) including height–leaf, height–seed, height–pollination, leaf–seed, seed–fruit and fruit–pollination were observed and their ecological or physiological basis was discussed. Life forms, strategy types and vegetation types differed based on association lines. Some of the well‐known trade‐offs appear by increasing scale from ecological groups to vegetation types in Hyrcanian forest. The observed patterns of trait associations in Hyrcanian forest and several other ecosystems of the world call the generality of previously accepted trait correlations into question.