Ecophysiological responses of Terminalia sericea to fire history in a semi-arid woodland savanna, central Namibia

Microcharcoal is a proxy of biomass burning and widely used in paleoenvironment research to reconstruct the fire history, which is influenced by the climate and land cover changes of the past. At present, microcharcoal characteristics (amount, size, shape) are commonly quantified by visual inspection, which is a precise but time-consuming approach. A few computer-assisted methods have been developed, but with an insufficient degree of automation. This paper proposes a new methodology for microcharcoal statistical analysis based on digital image processing by ImageJ software, which improves statistical efficiency by 80–90%, and validation by manual statistical comparison. The method is then applied to reconstruct the fire-related environmental change in the Weiyuan loess section since about 40 thousand years before present (ka BP), northwest China with a semi-arid climate, found that the microcharcoal concentration is low in cold and dry climate and high in warm and humid climate. The two main contributions of this study are: 1) proposal of a new, reliable and high efficient automatic statistical method for microcharcoal analysis; and 2) using the new method in a semi-arid section, revealing the paleofire evolution patterns in the semi-arid region was mainly driven by the biomass rather than the aridity degree found in humid regions.

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The effect of fire history on soil nutrients and soil organic carbon in a semi-arid savanna woodland, central Namibia

African Journal of Range and Forage Science ◽

10.2989/10220119.2018.1526825 ◽

2018 ◽

Vol 36 (1) ◽

pp. 9-16

Author(s):

Elise Nghalipo ◽

Dave Joubert ◽

Heather Throop ◽

Alexander Groengroeft

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Nutrients ◽

Fire History ◽

Savanna Woodland ◽

Semi Arid

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Relationships between fire history, edaphic factors and woody vegetation structure and composition in a semi-arid savanna landscape (Niger, West Africa)

Applied Vegetation Science ◽

10.1111/j.1654-109x.2012.01187.x ◽

2012 ◽

Vol 15 (4) ◽

pp. 488-500 ◽

Cited By ~ 16

Author(s):

Abdoulaye Diouf ◽

Nicolas Barbier ◽

Anne Mette Lykke ◽

Pierre Couteron ◽

Vincent Deblauwe ◽

...

Keyword(s):

West Africa ◽

Vegetation Structure ◽

Fire History ◽

Woody Vegetation ◽

Edaphic Factors ◽

Semi Arid

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Testing the assumptions of the pyrodiversity begets biodiversity hypothesis for termites in semi-arid Australia

Royal Society Open Science ◽

10.1098/rsos.172055 ◽

2018 ◽

Vol 5 (4) ◽

pp. 172055 ◽

Cited By ~ 2

Author(s):

Hayley Davis ◽

Euan G. Ritchie ◽

Sarah Avitabile ◽

Tim Doherty ◽

Dale G. Nimmo

Keyword(s):

Species Richness ◽

Species Diversity ◽

Fire History ◽

Woody Debris ◽

Termite Species ◽

Study Region ◽

Probability Of Occurrence ◽

Mixed Support ◽

Semi Arid Region ◽

Semi Arid

Fire shapes the composition and functioning of ecosystems globally. In many regions, fire is actively managed to create diverse patch mosaics of fire-ages under the assumption that a diversity of post-fire-age classes will provide a greater variety of habitats, thereby enabling species with differing habitat requirements to coexist, and enhancing species diversity (the pyrodiversity begets biodiversity hypothesis). However, studies provide mixed support for this hypothesis. Here, using termite communities in a semi-arid region of southeast Australia, we test four key assumptions of the pyrodiversity begets biodiversity hypothesis (i) that fire shapes vegetation structure over sufficient time frames to influence species' occurrence, (ii) that animal species are linked to resources that are themselves shaped by fire and that peak at different times since fire, (iii) that species’ probability of occurrence or abundance peaks at varying times since fire and (iv) that providing a diversity of fire-ages increases species diversity at the landscape scale. Termite species and habitat elements were sampled in 100 sites across a range of fire-ages, nested within 20 landscapes chosen to represent a gradient of low to high pyrodiversity. We used regression modelling to explore relationships between termites, habitat and fire. Fire affected two habitat elements (coarse woody debris and the cover of woody vegetation) that were associated with the probability of occurrence of three termite species and overall species richness, thus supporting the first two assumptions of the pyrodiversity hypothesis. However, this did not result in those species or species richness being affected by fire history per se. Consequently, landscapes with a low diversity of fire histories had similar numbers of termite species as landscapes with high pyrodiversity. Our work suggests that encouraging a diversity of fire-ages for enhancing termite species richness in this study region is not necessary.

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Ageing mallee eucalypt vegetation after fire: insights for successional trajectories in semi-arid mallee ecosystems

Australian Journal of Botany ◽

10.1071/bt10051 ◽

2010 ◽

Vol 58 (5) ◽

pp. 363 ◽

Cited By ~ 59

Author(s):

Michael F. Clarke ◽

Sarah C. Avitabile ◽

Lauren Brown ◽

Kate E. Callister ◽

Angie Haslem ◽

...

Keyword(s):

Fire History ◽

Food Sources ◽

Validation Data ◽

Class Distribution ◽

Age Class ◽

Ecological Features ◽

Time Since Fire ◽

The Status ◽

Minimum Age ◽

Semi Arid

A critical requirement in the ecological management of fire is knowledge of the age-class distribution of the vegetation. Such knowledge is important because it underpins the distribution of ecological features important to plants and animals including retreat sites, food sources and foraging microhabitats. However, in many regions, knowledge of the age-class distribution of vegetation is severely constrained by the limited data available on fire history. Much fire-history mapping is restricted to post-1972 fires, following satellite imagery becoming widely available. To investigate fire history in the semi-arid Murray Mallee region in southern Australia, we developed regression models for six species of mallee eucalypt (Eucalyptus oleosa F.Muell. ex. Miq. subsp. oleosa, E. leptophylla F.Muell. ex. Miq., E. dumosa J. Oxley, E. costata subsp. murrayana L. A. S. Johnson & K. D. Hill, E. gracilis F.Muell. and E. socialis F.Muell. ex. Miq.) to quantify the relationship between mean stem diameter and stem age (indicated by fire-year) at sites of known time since fire. We then used these models to predict mean stem age, and thus infer fire-year, for sites where the time since fire was not known. Validation of the models with independent data revealed a highly significant correlation between the actual and predicted time since fire (r = 0.71, P < 0.001, n = 88), confirming the utility of this method for ageing stands of mallee eucalypt vegetation. Validation data suggest the models provide a conservative estimate of the age of a site (i.e. they may under-estimate the minimum age of sites >35 years since fire). Nevertheless, this approach enables examination of post-fire chronosequences in semi-arid mallee ecosystems to be extended from 35 years post-fire to over 100 years. The predicted ages identified for mallee stands imply a need for redefining what is meant by ‘old-growth’ mallee, and challenges current perceptions of an over-abundance of ‘long-unburnt’ mallee vegetation. Given the strong influence of fire on semi-arid mallee vegetation, this approach offers the potential for a better understanding of long-term successional dynamics and the status of biota in an ecosystem that encompasses more than 250 000 km2 of southern Australia.

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The Mallee fire and biodiversity project

Proceedings of the Royal Society of Victoria ◽

10.1071/rs12038 ◽

2012 ◽

Vol 124 (1) ◽

pp. 38 ◽

Cited By ~ 3

Author(s):

Simon J. Watson ◽

Rick S. Taylor ◽

Lisa Spence-Bailey ◽

Dale G. Nimmo ◽

Sally Kenny ◽

...

Keyword(s):

Vegetation Structure ◽

Vascular Plants ◽

Fire History ◽

Time Frame ◽

Vegetation Types ◽

Ecological Process ◽

Age Classes ◽

Mammal Species ◽

Semi Arid ◽

Conservation And Management

Fire is a widespread disturbance and an important ecological process in semi-arid mallee ecosystems of southern Australia. Understanding the effects of fire on plants and animals is a key challenge for the conservation and management of biodiversity in this ecosystem. Commencing in 2006, the Mallee Fire and Biodiversity Project is investigating the effects of fire on a range of taxa (vascular plants, invertebrates, reptiles, birds and mammals), with a focus on the influence of the properties of ‘fire mosaics’ on biota. A ‘whole of landscape’ design was employed, in which the flora and fauna were sampled in 28 study landscapes, each 4 km in diameter (12.5 km2) across a 104, 000 km2 area of the Murray Mallee region of Victoria, SA and NSW. Here, we summarise some key results and outputs from this project to date. These include: detailed maps of fire history and major vegetation types; a method for predicting the age of mallee vegetation; novel information about the distribution of fire age-classes in the region; and changes to vegetation structure and in the occurrence of reptile, bird and mammal species over a century-long post-fire time-frame. We also present an overview of the effects of fire mosaics (extent of particular age classes, diversity of fire age-classes) on the richness of some mallee fauna. A wealth of knowledge has been developed through the Mallee Fire and Biodiversity Project that will assist the management of mallee ecosystems in southern Australia for the future.

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Vegetation responses to fire history and soil properties in grazed semi-arid tropical savanna

The Rangeland Journal ◽

10.1071/rj17075 ◽

2018 ◽

Vol 40 (3) ◽

pp. 271 ◽

Cited By ~ 2

Author(s):

Gabrielle Lebbink ◽

Rod Fensham ◽

Robyn Cowley

Keyword(s):

Soil Properties ◽

Fire History ◽

Fire Regimes ◽

Fire Season ◽

Individual Plant ◽

Vegetation Composition ◽

Mixed Effect ◽

Total Species Richness ◽

Floristic Patterns ◽

Semi Arid

A long-term (1993–2016) fire experiment in the grazed semi-arid savanna of the Northern Territory was used to investigate the relative impacts of soil properties and fire history on vegetation composition and diversity in grassland and woodland habitats. Subtle variation in soil texture influenced vegetation composition and abundance independently of fire variables and was generally a more important control on floristic patterns. Total species richness, lifeform richness and the abundance and presence of many individual plant species declined with increasing clay content. Linear mixed effect models with combined habitat data, showed total richness and richness of annual and perennial forbs, annual grasses and legumes increased with more frequent fire. Perennial grass abundance and richness was not influenced by fire. Total and lifeform mean richness did not vary between two and four yearly or early and late burnt treatments. Richness and abundance was generally significantly higher on burnt blocks than unburnt blocks regardless of fire season or interval. These results suggest greater diversity after burning is a result of an increase in ephemeral species. However, the overall influence of fire on floristic patterns is relatively moderate and fire regimes may therefore be manipulated for other management imperatives, such as fauna conservation, carbon sequestration and pastoral productivity without substantial impacts on botanical values in semi-arid tropical savannas.

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