Changes In Shrub Cover Research Articles

The Effect of Land Cover Changes on Surface Runoff Using the Soil and Water Assessment Tool in the Bila Watershed

Changes in land cover have a negative impact on land and water resources that occur in the watershed area. This study aims to analyze changes in land cover in 2016 and 2021 and their effects on surface runoff in the Bila Watershed. Analysis of land cover change using the Geographic Information System approach, and then analyzing the effect of land cover change on surface runoff from the results of the Soil and Water Assessment Tool Model. The results showed that the land cover of Bila Watershed when experiencing the highest change was in shrubs of 680.29 ha, dryland agriculture covering an area of 520.99 ha and secondary dryland forest covering an area of 155.76 ha. The effect of land cover changes on surface runoff varies. The highest increase in surface runoff was in shrub cover change to agricultural land and open land while the lowest increase in surface runoff was with changes in primary dryland forest land cover to secondary dryland forest. The surface runoff coefficient of the Bila Watershed in 2016 was included in the good category with a value of 0.16 while in 2021 was included in the moderate category with a value of 0.26.

Habitat Suitability for Small Mammals in Mediterranean Landscapes: How and Why Shrubs Matter

Fires are usually seen as a threat for biodiversity conservation in the Mediterranean, but natural afforestation after abandonment of traditional land uses is leading to the disappearance of open spaces that benefit many species of conservation interest. Fires create open habitats in which small mammals can live under more favourable conditions, such as lower predation, interspecific competition, and higher food availability. We analysed the role of changes in shrub cover and shrub preference by small mammals along the Mediterranean post-fire succession. We used data (period 2008–2018) from 17 plots woodlands and post-fire shrublands present in the study area (Barcelona’s Natural Parks, Catalonia, NE Spain), and vegetation structure was assessed by LiDAR technology for modelling ground-dwelling small mammal preferences. The diversity, abundance, and stability of Mediterranean small mammal communities negatively responded to vegetation structural complexity, which resulted from the combined effects of land abandonment and recovery after wildfires. We suggest that biotic factors such as vegetation profiles (providing food and shelter) and their interaction with predators and competitors could be responsible for the observed patterns. Considering the keystone role of small mammals in the sustainability of Mediterranean forest, our results could be useful for management under the current global change conditions.

Wood for thought? Untold consequences of the Himalayan gold collection in the Central Himalaya

Every year, in the Central Himalaya, the caterpillar fungus collectors collect fuelwood from the alpine shrublands to meet their energy needs for cooking and heating. The fuelwood collection continues unabated, and its long-term impact on the alpine ecology is still less understood. We conducted a questionnaire survey and fuelwood measurements in the summer of 2019 at the 'open-access' and 'closed-access' collection sites of caterpillar fungus in the Kailash Sacred Landscape of Nepal in the Central Himalaya. The ‘open access collection site’ referred to the site being accessible to any Nepali citizen from anywhere upon the payment of the collection fee. The ‘closed collection site’ referred to the site being accessible only to members of a particular community. The study objectives were to estimate fuelwood consumption by fungus harvesters and ascertain if fungus collection time and the number of people in a tent have an influence over fuelwood consumption in two sites. We randomly selected thirty harvesters in each fungus collection site for the study. The study results were supplemented by the satellite images to understand decadal changes in shrub cover at closed and open access collection sites. The open-access site had a more significant number of people in a tent, a longer length of stay, and a greater fuelwood consumption. The duration of stay at the open-access site far exceeded the recommended period of one month for harvesting the caterpillar fungus. On the contrary, the length of stay at the closed collection site was one month. The open-access site had a daily consumption of six kilogram fuelwood, and the closed site consumed four and a half kilograms of fuelwood daily. The decadal decline in shrub cover was higher in the open-access site. The study suggests that the current practices of fuelwood removal may be unsustainable and likely to deplete the alpine shrublands, and ultimately harm the caterpillar fungus, especially at the open-access collection sites. There is an urgency to replace the current fuelwood resource use practiced by collectors with more sustainable energy systems. Moreover, it is imperative to address this issue holistically through stringent policies that regulate the number of people and days spent at collection sites.

The Impact of Roads on the Redistribution of Plants and Associated Arthropods in a Hyper-Arid Ecosystem.

The construction of vehicular roads likely affects the distribution of natural resources. Although the effects of roads on different ecosystem aspects have been extensively studied, studies in arid and, particularly, in hyper-arid ecosystems are scarce. In drylands, where water is the main limiting factor, the effect of roads on the redistribution of water may have strong subsequent effects on the ecosystem, especially when roads cross natural water flow paths. To fill this knowledge gap, we studied the effects of a road that runs across a slope on the distribution of plants and animals in a hyper-arid environment. Changes in shrub cover, below and above the road, were quantified by remote sensing and image classification, while plant-associated arthropods were vacuum-sampled from shrub canopies and from open (inter-shrub) areas. We found that the spatial distribution of shrubs, a vital resource facilitating many other organisms, was affected by the road, with an increase in the shrub cover immediately above the road and a decrease below it. Arthropod abundance generally followed shrub cover, but the exact pattern depended on the specific group sampled. While some arthropod groups (e.g., aphids, parasitic wasps and barklice) thrived under the disturbed conditions above the road, other arthropod groups (e.g., mites and true bugs) were less abundant in the disturbed patches. Our results highlight the strong effects of human-made structures on the distribution of flora and fauna in arid ecosystems.

Shrub Fractional Cover Estimation and Mapping of San Clemente Island Shrubland Based on Airborne Multispectral Imagery and Lidar Data

The purpose of this study is to map shrub distributions and estimate shrub cover fractions based on the classification of high-spatial-resolution aerial orthoimagery and light detection and ranging (LiDAR) data for portions of the highly disturbed coastal sage scrub landscapes of San Clemente Island, California. We utilized nine multi-temporal aerial orthoimage sets for the 2010 to 2018 period to map shrub cover. Pixel-based and object-based image analysis (OBIA) approaches to image classification of growth forms were tested. Shrub fractional cover was estimated for 10, 20 and 40 m grid sizes and assessed for accuracy. The most accurate estimates of shrub cover were generated with the OBIA method with both multispectral brightness values and canopy height estimates from a normalized digital surface model (nDSM). Fractional cover products derived from 2015 and 2017 orthoimagery with nDSM data incorporated yielded the highest accuracies. Major factors that influenced the accuracy of shrub maps and fractional cover estimates include the time of year and spatial resolution of the imagery, the type of classifier, feature inputs to the classifier, and the grid size used for fractional cover estimation. While tracking actual changes in shrub cover over time was not the purpose, this study illustrates the importance of consistent mapping approaches and high-quality inputs, including very-high-spatial-resolution imagery and an nDSM.

Can reindeer husbandry management slow down the shrubification of the Arctic?

Rapid climate change is threatening the stability and functioning of Arctic ecosystems. As the Arctic warms, shrubs have been widely observed to expand, which has potentially serious consequences for global climate regulation and for the ecological processes characterising these ecosystems. However, it is currently unclear why this shrubification has been spatially uneven across the Arctic, with herbivory being suggested as a key regulating factor. By taking advantage of freely available satellite imagery spanning three decades, we mapped changes in shrub cover in the Yamal Peninsula and related these to changes in summer temperature and reindeer population size. We found no evidence that shrubs had expanded in the study site, despite increasing summer temperatures. At the same time, herbivore pressure increased significantly, with the local reindeer population size growing by about 75%. Altogether, our results thus point towards increases in large herbivore pressure having compensated for the warming of the Peninsula, halting the shrubification of the area. This suggests that strategic semi-domesticated reindeer husbandry, which is a common practice across the Eurasian Arctic, could represent an efficient environmental management strategy for maintaining open tundra landscapes in the face of rapid climate change.

Temporal dimension of forest vulnerability to fire along successional trajectories

Understanding ecosystem vulnerability is essential in risk management to anticipate disasters. While valuable efforts have been made to characterize vulnerability components (exposure, sensitivity, and response capacity) at particular ecosystem stages, there is still a lack of context-specific studies accounting for the temporal dimension of vulnerability. In this study, we developed a procedure to identify the main natural dynamics of monospecific and mixed forests and to assess the variations of sensitivity and response capacity to fire along successional dynamics. In the procedure, we generated forest chronosequences by summarizing the dynamics between consecutive surveys of permanent plots into a set of longer successional trajectories represented in a multidimensional space. Then, we calculated several variables of sensitivity and response capacity to fire of forest stages associated with each trajectory and we assessed their variation along succession. The procedure was applied to Mediterranean forests in Spain dominated by a pine species poorly adapted to severe crown fires. We found that forest vulnerability components varied differently among successional trajectories, which depended on the composition and structure of their initial stages and the environmental context in which they occurred. Autosuccessional dynamics of pine forests showed relatively low sensitivity to fire along trajectories. However, their response capacity was related to the changes in shrub cover. In contrast, diversifying dynamics showed an increasing sensitivity to fire, but also a higher response capacity the greater the functional diversity along succession. These results highlight the need for considering the temporal dimension of vulnerability in risk management and the importance of assessing sensitivity and response capacity as independent components of vulnerability that can be modified through management at critical forest stages.

Shrub encroachment into grasslands: end of an era?

Shifts in the abundance of grasses and woody plants in drylands have occurred several times during the Holocene. However, our understanding of the rates and dynamics of this state-change in recent decades is limited to scattered studies conducted at disparate spatial and temporal scales; the potential misperceptions of shrub cover change could be remedied using cross spatiotemporal scale analyses that link field observations, repeat ground-level photography and remote sensing perspectives. The study was conducted across a semi-arid landscape in southern Arizona. Local data from long-term transects revealed three distinct chronological phases of shrub cover change: expansion (1961–1991, 0.7% y−1), decline (1992–1997, −2.3% y−1) and stabilization (1998–2012, 22–25% with no net cover change). Twenty-eight years (1984–2011) of broad-scale Landsat Thematic Mapper assessments confirm that shrub cover has been relatively stable in recent decades regardless of grazing regimes and landforms with the exception of the proliferation of succulents at lower elevations (verified by repeat photography acquired in 1987 and 2015) where the physical environment is the harshest, reflecting elevated temperature and winter precipitation deficit. Warmer, drier future climates are predicted to reduce woody plant carrying capacity and promote a shift to xerophytic succulents.

Coupling structural and functional thresholds for vegetation changes on a Mongolian shrubland

The concept of an ecological threshold has spurred important advances in understanding the nonlinear responses of ecosystems to various disturbances. Yet integrated evaluations of an ecosystem’s structural threshold and functional threshold are rare, and we know little about linkages between observed nonlinear changes in ecosystem structure along disturbance gradients and the associated changes in system feedbacks. We applied a two-step approach to perform integrated evaluations of structural and functional thresholds in a Mongolian shrubland. First, by using 6 years of data from plant communities along a gradient of grazing intensity, we identified the structural threshold in the changes in shrub cover along the gradient. We then identified the functional threshold at which wind erosion rates were accelerated due to sufficient decline in shrub cover. We found that shrub cover changed abruptly along the grazing gradient, indicating the presence of a structural threshold. Shrub cover decreased gradually along the grazing gradient to the threshold of 6.9%; thereafter it decreased rapidly. This level of shrub cover was close to that of the functional threshold (5.3%), namely the point at which the rate of wind erosion was accelerated. Our key finding is the coupling of structural and functional thresholds, suggesting that the modification of feedbacks between wind erosion and shrub cover might be associated with the nonlinear response of ecosystem structure to grazing. To bridge the gap between management applications and ecological threshold theory, it is essential to understand the potential feedback mechanisms that would contribute to nonlinear changes in ecosystem structure.

Ants respond more strongly to grazing than changes in shrub cover

AbstractIncreases in the cover or density of woody plants (encroachment) and overgrazing by European livestock are 2 major drivers of ecosystem structure and function in drylands and are often associated with land degradation. Although the effects of encroachment and overgrazing on vascular plants are relatively well known, little is known about their effects on arthropods such as ants. We examined ant community composition at sites ranging in shrub cover in a wooded dryland in eastern Australia, testing the notion that increasing shrub cover and grazing intensity would alter ant assemblages and functional group composition. We used ants because they are abundant, diverse, and respond to small‐scale environmental changes. Increasing shrub cover had no effect on ant richness, diversity, or evenness but increased the abundance of Subordinate Camponotini. Larger shrubs tended to have greater ant richness, and abundance of Cold Climate Specialists, but fewer Generalized Myrmicinae and Hot Climate Specialists. More intense grazing was associated with greater ant richness, diversity, and evenness; a greater abundance of Hot Climate Specialists and Dominant Dolichoridae; and lower abundance of Subordinate Camponotini. Our study indicates that changes in grazing intensity had stronger effects on ant richness than any increase in shrub cover. The effects of grazing likely resulted from changes in soil surface complexity such as barer ground associated with grazing‐induced degradation.

Correlations between substrate availability, dissolved CH4, and CH4 emissions in an arctic wetland subject to warming and plant removal

AbstractThe Arctic is warming which may potentially affect substrate availability, organic matter decomposition, plant growth, and plant species composition. This may lead to changes in the exchange of methane (CH4) and carbon dioxide (CO2) between the soil system and the atmosphere. Yet the correlations among substrate availability, CH4 production, and net emissions of CH4 have been scarcely studied in arctic wetlands. Presently, the impact of increasing temperatures on CH4 exchange is uncertain as the two existing reports on field warming in arctic wetlands present opposite results. We here report results on how summer warming and shrub removal affect soil water substrate (acetate, formate, oxalate, and dissolved organic carbon) concentrations as well as dissolved CH4 and CH4 emissions in a fen at Disko Island (West Greenland). The peak in dissolved CH4 followed the peak in acetate concentration, and appeared after the peak in CH4 emissions, which indicates a lack of correlation between CH4 production and emissions. The peak in CH4 emissions coincided with maximum gross ecosystem production suggesting that CH4 emissions are closely linked to photosynthesis. This was supported by an experiment with removal of the sedge Carex aquatilis ssp. stans which contributed with up to 77% of the CH4 emitted from the ecosystem. By contrast, shrub removal and summer warming did not significantly affect CH4 emissions, possibly due to the treatments impacting CH4 production more than emissions. This implies that such wetlands may be less sensitive to moderate warming and changes in shrub cover than previously assumed.

Nest-site selection and nest success of an Arctic-breeding passerine, Smith's Longspur, in a changing climate

ABSTRACT Despite changes in shrub cover and weather patterns associated with climate change in the Arctic, little is known about the breeding requirements of most passerines tied to northern regions. We investigated the nesting biology and nest habitat characteristics of Smith's Longspurs (Calcarius pictus) in 2 study areas in the Brooks Range of Alaska, USA. First, we examined variation in nesting phenology in relation to local temperatures. We then characterized nesting habitat and analyzed nest-site selection for a subset of nests (n = 86) in comparison with paired random points. Finally, we estimated the daily survival rate of 257 nests found in 2007–2013 with respect to both habitat characteristics and weather variables. Nest initiation was delayed in years with snow events, heavy rain, and freezing temperatures early in the breeding season. Nests were typically found in open, low-shrub tundra, and never among tall shrubs (mean shrub height at nests = 26.8 ± 6.7 cm). We observed weak nest-site select...

Range Expansion of Moose in Arctic Alaska Linked to Warming and Increased Shrub Habitat.

Twentieth century warming has increased vegetation productivity and shrub cover across northern tundra and treeline regions, but effects on terrestrial wildlife have not been demonstrated on a comparable scale. During this period, Alaskan moose (Alces alces gigas) extended their range from the boreal forest into tundra riparian shrub habitat; similar extensions have been observed in Canada (A. a. andersoni) and Eurasia (A. a. alces). Northern moose distribution is thought to be limited by forage availability above the snow in late winter, so the observed increase in shrub habitat could be causing the northward moose establishment, but a previous hypothesis suggested that hunting cessation triggered moose establishment. Here, we use recent changes in shrub cover and empirical relationships between shrub height and growing season temperature to estimate available moose habitat in Arctic Alaska c. 1860. We estimate that riparian shrubs were approximately 1.1 m tall c. 1860, greatly reducing the available forage above the snowpack, compared to 2 m tall in 2009. We believe that increases in riparian shrub habitat after 1860 allowed moose to colonize tundra regions of Alaska hundreds of kilometers north and west of previous distribution limits. The northern shift in the distribution of moose, like that of snowshoe hares, has been in response to the spread of their shrub habitat in the Arctic, but at the same time, herbivores have likely had pronounced impacts on the structure and function of these shrub communities. These northward range shifts are a bellwether for other boreal species and their associated predators.

Postfire shrub cover dynamics: A 70-year fire chronosequence in mountain big sagebrush communities

Fire is natural in sagebrush (Artemisia L.) communities. In this study, we quantify effects of time since last burn (TSLB) on shrub cover over a 70-year (yr) fire chronosequence. We sampled mountain big sagebrush communities with very large-scale aerial (VLSA) imagery and measured sagebrush, antelope bitterbrush (Purshia tridentata [Pursh] DC.), and spineless horsebrush (Tetradymia canescens DC.) cover. We used segmented regression to describe two cover phases with respect to TSLB. Phase 1 was when cover responded to TSLB and Phase 2 was when cover had reached a steady state with respect to TSLB meaning that expected shrub cover did not change with increasing TSLB. In the first year after burning, total shrub cover was 5%. In Phase 1, total shrub, sagebrush, and bitterbrush cover increased with TSLB. Bitterbrush transitioned to Phase 2 in 6 yr, but 19 and 18 yr, respectively, were needed for sagebrush and total shrub to transition. Horsebrush cover decreased with TSLB from 2.1% to 0.2% over 27 yr. Steady-state cover for sagebrush, bitterbrush, and total shrub were 30.6, 2.8, and 39.8%, respectively. These data describe postfire shrub cover change in mountain big sagebrush communities that can be used in management plans that meet shrub cover objectives.

Shrub Expansion in SW Greenland Under Modest Regional Warming: Disentangling Effects of Human Disturbance and Grazing

Shrub expansion has been observed widely in tundra areas across the Arctic. This phenomenon has been partially attributed to increasing temperatures over the past century. However, relationships among shrub expansion, grazing, and human disturbance have been studied little. SW Greenland is a subarctic to low-arctic region with a long and complex land-use history and only modest temperature increases over the past 50 years (0.2 °C decade-1), but changes in shrub cover have not previously been studied in this region. We compiled historical photographs of vegetation in SW Greenland (1898–1974) and repeated the photos in 2010 and 2011. Sixty-four photo pairs were cropped into 133 smaller units and classified by aspect, substrate stability, muskoxen grazing, and human disturbance. The photo material was evaluated by 22 experts with respect to changes in shrub cover, revealing a general increase across the whole data set, and in a subset including only undisturbed sites. Shrub cover increased most on E and SE slopes, in sites with stable substrate, and in areas characterized by human disturbance and without muskoxen grazing. The general shrub cover increase could be caused mainly by changed land-use intensity, but effects of the moderately increased temperatures cannot be ruled out.

Grazing dampens the positive effects of shrub encroachment on ecosystem functions in a semi‐arid woodland

Summary The encroachment of woody plants into grasslands, open woodlands and savannah has been widely reported over the past few decades. Overgrazing is a probable cause of shrub encroachment and could be a stronger driver of declining ecosystem structure and functioning in shrublands than encroachment per se. We examined the relative effects of changes in shrub cover and grazing rate on ecosystem functions at sandy and loamy sites in eastern Australia varying in shrub cover and grazing. Our aim was to test the notion that the negative effects on ecosystem functioning commonly attributed to encroachment are more likely due to grazing than to increase in shrub cover per se. Structural equation modelling indicated a generally strong positive effect of increasing shrub cover, and a generally negative, or slight effect of grazing on multiple measures of ecosystem function related to plant productivity, water infiltration, nutrient cycling and surface stability. On loamy soils, grazing generally dampened the positive effects of increasing shrub cover on most response variables. On sandy soils, however, although there were generally stronger effects of grazing, most attributes did not change in response to increasing shrub cover. Synthesis and applications. Our results indicate that, contrary to the prevailing opinion, increasing shrub cover was generally associated with increases (or no change) in functional and structural measures indicative of healthy systems. The dampening of the positive effects of shrub cover caused by grazing was site (soil texture) specific, reinforcing the notion that the effects of increasing shrub cover and their interaction with grazing are context dependent. Our study provides the basis for improved understanding and management of shrublands for a number of competing goals and suggests that managing grazing rates is a better strategy than focusing on shrub removal. Using low levels of grazing is likely to maximize the benefits from shrublands, such as the maintenance of biodiversity, water infiltration and C sequestration, while maintaining a productive herbaceous community.

Effects of prolonged drought on the vegetation cover of sand dunes in the NW Negev Desert: Field survey, remote sensing and conceptual modeling

Luminescence dating of stable sand dunes in the large deserts of the world has shown several episodes of mobility during the last 30 k years. The logical explanation for the mobility of fixed dunes is severe drought. Though drought length can be estimated, the level of precipitation drop is unknown. The stabilized sand dunes of the northwestern Negev Desert, Israel have been under an unprecedented prolonged drought since 1995. This has resulted in a vast decrease of shrubs cover on the fixed sand dunes, which changes along the rainfall gradient. In the north, an average of 27% of the shrubs had wilted by 2009, and in the drier southern area, 68% of the shrubs had withered. This loss of shrubbery is not expected to induce dune remobilization because the existing bio-crust cover is not negatively affected by the drought. Eleven aerial photographs taken over the drier southern area from 1956 to 2005 show the change in shrub cover due to human impact and the recent severe drought.

Nitrification activity and levels of inorganic nitrogen in soils of a semi-arid ecosystem following a drought-induced shrub death

In arid ecosystems, higher rates of biogeochemical cycles occur in soils under shrub canopies than in inter-shrubs spaces. Therefore, changes in shrub cover may have great impact on ecosystem functioning. Recently, a drought-induced massive shrub death was observed in the semi-arid northern Negev Desert in Israel. The aim of this study was to examine the consequences of the shrub death on the levels of soil inorganic nitrogen and the structure of ammonia-oxidizers communities. Compared to soil samples from the winter that preceded the shrubs death, soil samples that were collected at the end of the first winter following the shrub death contained significantly higher nitrate concentrations, exhibited lower ammonia oxidation potential and similar community structure of ammonia oxidizers. In addition, the numbers of ammonia-oxidizers were higher in the soil under dead Thymelaea hirsute shrubs than under live shrub canopies. The results suggested that the activities of the nitrogen transforming microbes were moderately affected by the drought and resulted in nitrate accumulation due to the absence of major nitrogen consumers (shrubs). During rainfall events, this nitrate can be washed away by run-off and contaminate downstream water bodies or alternatively denitrified to gaseous nitrogen (including nitrogen oxides).

Shrub Cover on the North Slope of Alaska: a circa 2000 Baseline Map

In situ observations show increases in shrub cover in different arctic regions in recent decades and have been cited to explain the increases in arctic vegetation productivity revealed by satellite remote sensing. A widespread increase in shrub cover, particularly tall shrub cover, is likely to profoundly alter the tundra biome because of its influence on biogeochemical cycling and feedbacks to climate. To monitor changes in shrub cover, aid field studies, and inform ecosystem models, we mapped shrub cover across the North Slope of Alaska. First, images from the IKONOS and SPOT satellite sensors were used to detect tall (>1 m) and short shrub presence at high resolution (<5 m grid cells) in different parts of the domain. The resulting maps were then used to train a Random Forest regression algorithm that mapped total and tall shrub cover, expressed as a percent of the total surface area, at 30 m resolution from a mosaic of Landsat scenes. The final shrub cover maps correspond well with field measurements (r2 = 0.7, root mean square error = 17%, N = 24) and compared well with the existing vegetation type maps of the study area and a gridded temperature data set not used in the map generation.

Monitoring shrubland habitat changes through object-based change identification with airborne multispectral imagery

An object-based approach to generating shrub cover change maps of potential use for monitoring shrubland habitat reserves was developed and tested. A high fidelity, bi-temporal airborne image data set was generated through frame-based image acquisition, precise image-to-image registration, radiometric normalization, and selection of near-anniversary image acquisition dates with similar precipitation conditions prior to both image acquisitions. Image segmentation and classification processes were applied to the bi-temporal layer stack of very high spatial resolution visible and near infrared (V/NIR) image data, such that shrub change objects were delineated and identified directly. Image segments derived from the bi-temporal V/NIR image data set having 1 m spatial resolution delineated most shrub change features in a qualitatively realistic manner. A Standard Nearest Neighbor classifier with segment mean and standard deviation measures of Red, NIR, and normalized difference vegetation index (NDVI) image features yielded the shrub change map that agreed more closely with reference data than the classifier based on fuzzy membership functions. The overall accuracy and kappa statistics for the optimal shrub change map were 0.83 and 0.64, respectively, with the predominant error being associated with “over-classification” of no-change objects as some type of shrub change. No statistical difference in accuracies of three- and five-class maps was found, suggesting that changes in true shrubs and sub-shrubs within coastal sage scrub vegetation communities can be differentiated reliably. A net 5% loss of shrub cover was determined for the 1998–2005 period from the shrub change map of the study area. The greatest decrease and net loss of shrub cover occurred within the urban edge zone and within flat-lying areas. Patterns of shrub loss appear to be more related to anthropogenic disturbance than effects of the severe seven-year drought that occurred between image acquisition dates.