How widespread is woody plant encroachment in temperate Australia? Changes in woody vegetation cover in lowland woodland and coastal ecosystems in Victoria from 1989 to 2005

2010 ◽  
Vol 37 (4) ◽  
pp. 722-732 ◽  
Author(s):  
Ian D. Lunt ◽  
Lisa M. Winsemius ◽  
Simon P. McDonald ◽  
John W. Morgan ◽  
Remy L. Dehaan
Keyword(s):  
Vegetation Cover ◽  
Woody Plant ◽  
Coastal Ecosystems ◽  
Woody Vegetation ◽  
Woody Plant Encroachment

Continental-scale modelling of the effects of climatic and non-climatic disturbances on woody plant encroachment in the grasslands of Africa

2021 ◽  
Author(s):  
Francesco D'Adamo ◽  
Rebecca Spake ◽  
James Bullock ◽  
Booker Ogutu ◽  
Jadunandan Dash ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Woody Plant ◽  
Population Change ◽  
Sub Saharan Africa ◽  
Woody Vegetation ◽  
Woody Plant Encroachment ◽  
Continental Scale ◽  
Wide Range ◽  
Sub Saharan ◽  
Climatic Disturbances

<p>Grasslands cover ca. 7% (2,100,000 km2) of the African continent. They provide a wide range of ecosystem services (e.g., forage, water, recreational spaces, carbon sequestration), and host large wildlife communities. Despite their importance, African grasslands are reported to be suffering from degradation and, perhaps more worryingly, have received little consideration within international policies (e.g., United Nations Sustainable Development Goals). A key issue at present is widespread woody plant encroachment (WPE), which it is shifting African grassland from a grassy- to a (less palatable) woody-dominated biome. However, the way climatic (e.g., precipitation, soil moisture) and non-climatic disturbances (e.g., fire, population density) affect WPE is still poorly understood, particularly at large spatiotemporal scales. Here we identified grasslands in sub-Saharan Africa according to the ESA Climate Change Initiative (CCI) land cover product and use vegetation optical depth (VOD) from passive microwave observations as a proxy for woody vegetation change between 1992 and 2011. We then use independent climatic (precipitation and soil moisture) and non-climatic (burn intensity, population change) data to assess how both spatiotemporal variations and interactions between climatic and non-climatic drivers controlled rates of VOD increase during 1992-2011. We consider not only annual precipitation, soil moisture, fire, and population data, but also integrated and lagged precipitation data (both up to five years ahead of VOD) in these models. Preliminary results reveal a large overall increase in woody vegetation in sub-Saharan Africa grasslands as well as considerable spatiotemporal variation in VOD change that is not due to climatic factors alone.</p>

scholarly journals Microclimate feedbacks sustain power law clustering of encroaching coastal woody vegetation

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Heng Huang ◽  
Philip A. Tuley ◽  
Chengyi Tu ◽  
Julie C. Zinnert ◽  
Ignacio Rodriguez-Iturbe ◽  
...  
Keyword(s):  
Power Law ◽  
Woody Plant ◽  
Woody Vegetation ◽  
Power Law Distribution ◽  
Woody Plant Encroachment ◽  
Positive Feedbacks ◽  
Critical Transitions ◽  
High Resolution Imagery ◽  
Ecosystem Level ◽  
Vegetation Patchiness

AbstractThe spatial pattern of vegetation patchiness may follow universal characteristic rules when the system is close to critical transitions between alternative states, which improves the anticipation of ecosystem-level state changes which are currently difficult to detect in real systems. However, the spatial patterning of vegetation patches in temperature-driven ecosystems have not been investigated yet. Here, using high-resolution imagery from 1972 to 2013 and a stochastic cellular automata model, we show that in a North American coastal ecosystem where woody plant encroachment has been happening, the size distribution of woody patches follows a power law when the system approaches a critical transition, which is sustained by the local positive feedbacks between vegetation and the surrounding microclimate. Therefore, the observed power law distribution of woody vegetation patchiness may be suggestive of critical transitions associated with temperature-driven woody plant encroachment in coastal and potentially other ecosystems.

scholarly journals Social and Ecological Dimensions of Urban Conservation Grasslands and Their Management through Prescribed Burning and Woody Vegetation Removal

2020 ◽  
Vol 12 (8) ◽  
pp. 3461 ◽  
Author(s):  
Alison Farrar ◽  
Dave Kendal ◽  
Kathryn J. H. Williams ◽  
Ben J. Zeeman
Keyword(s):  
Native Species ◽  
Prescribed Burning ◽  
Woody Plant ◽  
Community Education ◽  
Woody Vegetation ◽  
Woody Plant Encroachment ◽  
Management Actions ◽  
Grassland Conservation ◽  
Natural Grasslands ◽  
Eastern Australia

Natural grasslands are threatened globally. In south-eastern Australia, remnants of critically endangered natural grasslands are increasingly being isolated in urban areas. Urbanisation has led to reduced fire frequency and woody plant encroachment in some patches. Grasslands are currently being managed under the assumption that desirable management actions to address these threats (prescribed burning and removing woody vegetation) (1) lead to improved conservation outcomes and (2) are restricted by negative public attitudes. In this study, we tested these two assumptions in the context of native grassland conservation reserves in Melbourne, Australia. Firstly, we investigated differences in species and functional trait composition between patches that had been recently burnt, patches that were unburnt and patches subject to woody vegetation encroachment. We found that the functional traits of species converged in areas subject to woody plant encroachment and areas frequently disturbed by fire. Burning promoted native species, and patches of woody plants supressed the dominant grass, providing a wider range of habitat conditions. Secondly, we surveyed 477 residents living adjacent to these grassland conservation reserves to measure values, beliefs and attitudes and the acceptance of prescribed burning and removing woody vegetation. We found conflict in people’s attitudes to grasslands, with both strongly positive and strongly negative attitudes expressed. The majority of residents found prescribed burning an acceptable management practice (contrary to expectations) and removing trees and shrubs from grasslands to be unacceptable. Both cognitive factors (values and beliefs) and landscape features were important in influencing these opinions. This research provides some guidance for managing urban grassland reserves as a social–ecological system, showing that ecological management, community education and engagement and landscape design features can be integrated to influence social and ecological outcomes.

Conservation and Restoration of Grasslands

2018 ◽  
Author(s):  
Brian J. Wilsey
Keyword(s):  
Community Assembly ◽  
Woody Plants ◽  
Woody Plant ◽  
Priority Effects ◽  
Woody Plant Encroachment ◽  
Humpty Dumpty ◽  
Alternate States ◽  
Density And Biomass ◽  
Acid Test ◽  
Stocking Rates

Conservation programs alter herbivore stocking rates and find and protect the remaining areas that have not been plowed or converted to crops. Restoration is an ‘Acid Test’ for ecology. If we fully understand how grassland systems function and assemble after disturbance, then it should be easy to restore them after they have been degraded or destroyed. Alternatively, the idea that restorations will not be equivalent to remnants has been termed the ‘Humpty Dumpty’ hypothesis—once lost, it cannot be put back together again. Community assembly may follow rules, and if these rules are uncovered, then we may be able to accurately predict final species composition after assembly. Priority effects are sometimes found depending on species arrival orders, and they can result in alternate states. Woody plant encroachment is the increase in density and biomass of woody plants, and it is strongly affecting grassland C and water cycles.

scholarly journals Woody Vegetation Cover, Attrition, and Patch Metrics over Eight Decades in Central Texas, United States

2021 ◽  
Vol 78 ◽  
pp. 54-66
Author(s):  
Edward C. Rhodes ◽  
Jay P. Angerer ◽  
William E. Fox ◽  
Jason R. McAlister
Keyword(s):  
United States ◽  
Vegetation Cover ◽  
Woody Vegetation ◽  
Central Texas

scholarly journals Assessing the impact of climate variability on catchment water balance and vegetation cover

2011 ◽  
Vol 8 (3) ◽  
pp. 6291-6329 ◽  
Author(s):  
X. Xu ◽  
D. Yang ◽  
M. Sivapalan
Keyword(s):  
Statistical Analysis ◽  
Water Balance ◽  
Climate Variability ◽  
Vegetation Cover ◽  
Growing Season ◽  
Woody Vegetation ◽  
Elasticity Analysis ◽  
Total Runoff ◽  
Subsurface Runoff ◽  
Growing Season Precipitation

Abstract. Understanding the interactions among climate, vegetation cover and the water cycle lies at the heart of the study of watershed ecohydrology. Recently, considerable attention is being paid to the effect of climate variability (e.g., precipitation and temperature) on catchment water balance and also associated vegetation cover. In this paper, we investigate the general pattern of long-term water balance and vegetation cover (as reflected in fPAR) among 193 study catchments in Australia through statistical analysis. We then employ the elasticity analysis approach for quantifying the effects of climate variability on hydrologic partitioning (including total runoff, surface and subsurface runoff) and on vegetation cover (including total, woody and non-woody vegetation cover). Based on the results of statistical analysis, we conclude that annual runoff (R), evapotranspiration (E) and runoff coefficient (R/P) all increase with vegetation cover for catchments in which woody vegetation is dominant and annual precipitation is relatively high. Annual evapotranspiration (E) is mainly controlled by water availability rather than energy availability for catchments in relatively dry climates in which non-woody vegetation is dominant. The ratio of subsurface runoff to total runoff (Rg/R) also increases with woody vegetation cover. Through the elasticity analysis of catchment runoff, it is shown that precipitation (P) in the current year is the most important factor affecting the change in annual total runoff (R), surface runoff (Rs) and subsurface runoff (Rg). The significance of other controlling factors is in the order of the annual precipitation in the previous year (P−1 and P−2), which represent the net effect of soil moisture, and the annual mean temperature (T) in the current year. Change of P by +1 % causes a +3.35 % change of R, a +3.47 % change of Rs and a +2.89 % change of Rg, on average. Likewise a change of temperature of +1° causes a −0.05 % change of R, a −0.07 % change of Rs and a −0.10 % change of Rg, on average. Results of elasticity analysis on the maximum monthly vegetation cover indicate that incoming shortwave radiation during the growing season (Rsd,grow) is the most important factor affecting the change in vegetation cover. Change of Rsd,grow by +1 % produces a −1.08 % change of total vegetation cover (Ft) on average. The significance of other causative factors is in the order of the precipitation during growing season, mean temperature during growing season and precipitation during non-growing season. The growing season precipitation is more significant than the non-growing season precipitation to non-woody vegetation cover, but the both have equivalent effects to woody vegetation cover.

scholarly journals Monitoring scrub weed change in the Canterbury region using satellite imagery

2007 ◽  
Vol 60 ◽  
pp. 137-140 ◽  
Author(s):  
J.D. Shepherd ◽  
J.R. Dymond ◽  
J.R.I. Cuff
Keyword(s):  
Satellite Imagery ◽  
Vegetation Cover ◽  
Satellite Image ◽  
Visual Assessment ◽  
Woody Vegetation ◽  
Spatial Change ◽  
Valid Data ◽  
Woody Cover ◽  
Landsat Satellite ◽  
Thematic Data

The spatial change of woody vegetation in the Canterbury region was automatically mapped between 1990 and 2001 using Landsat satellite image mosaics The intersection of valid data from these mosaics gave coverage of 84 of the Canterbury region Changes in woody cover greater than 5 ha were identified Of the 5 ha areas of woody change only those that were likely to have been a scrub change were selected using ancillary thematic data for current vegetation cover (eg afforestation and deforestation were excluded) This resulted in 2466 polygons of potential scrub change These polygons were rapidly checked by visual assessment of the satellite imagery and assigned to exotic or indigenous scrub change categories Between 1990 and 2001 the total scrub weed area in the Canterbury region increased by 3600 400 ha and indigenous scrub increased by 2300 400 ha

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