The Construction of Mediterranean Scrub in Biogeography and Ecology, C.M. Ť Rodrigue, AAG 2005

The Construction of Mediterranean Scrub in Biogeography and Ecology

Extended Quotations

Association of American Geographers, Denver, 5-9 April 2005

Christine M. Rodrigue
Department of Geography
California State University
Long Beach, CA 90840-1101
https://home.csulb.edu/~rodrigue/
rodrigue@csulb.edu

The Literature of the Mediterranean Scrub

Succession in Mediterranean Landscapes in the European Tradition

Smithson, Peter; Addison, Ken; and Atkinson, Ken. 2002. Fundamentals of the Physical Environment, 3rd ed. London and New York: Routledge (a popular British textbook in physical geography):

Although plant species differ between (sic) each of the five main regions, evolutionary convergence has led in each to a vegetation which is dominated by evergreen woodland with sclerophyllous trees and evergreen shrubs. In all Mediterranean regions much of this woodland has been replaced by agricultural land, originally for the traditional dry-farmed crops of cereals and tree corops (e.g., the vine, olive, carob, almond), but increasingly for high-value irrigated land use (e.g., vegetables, citrus fruits, rice). Outside the limits of farmland, human impacts on the natural vegetation have been severe, mainly through grazing, ranching, wood collection and deliberate firing. The native woodland has therefore been replaced by dense scrub (maquis in France; matorral in Spain) or aromatic heath (garrigue in France; monte bajo in Spain). In California scrub known as chaparral is common, whilst the term matorral is used in central Chile. In South Africa the scrubby veld contrasts with the heathy fynbos. In southwestern and southern Australia the term mallee is used for similar vegetation formations (p. 524).

Walter, Heinrich. 1977. Vegetation of the Earth in Relation to Climate and the Eco-Physiological Conditions. Tr. Joy Wieser. New York, Heidelberg, Berlin: Springer-Verlag.

Nowadays there are only a few remaining places, in the mountainous regions of North Africa, where typical Quercus ilex forest still exists. Elsewhere the trees are cut down every 20 years, while still young, and they regenerate by means and (sic) shoots from the old stump. This leads to the formation of a maqui, consisting of bushes the height of a man. Maqui is also encountered on slopes where the soil is too shallow to support tall forest. Sclerophyllous species, usually shrub-like in form, may develop into big trees in a suitable habitat and can achieve a considerable age. Imposing old specimens of Quercus ilex can be seen in gardens and parks. In places where the young woody plants are cut every six to eight years and the areas regularly burned and grazed, the trees disappear entirely and open societies called garigue are formed (phrygana in Greece, tomillares in Spain, batha in Palestine) (p. 117).
... If cultivation or grazing is stopped then successions tending towards the true zonal vegetation take over... (p. 118).

Woodward, Susan L. 1996. Mediterranean shrublands. Part of Introduction to "Biomes," course supplement to GEOG 335, Biogeography, a course taught at Radford University, Radford, VA. Available at http://www.runet.edu/~swoodwar/CLASSES/GEOG235/biomes/medit/medit.html or http://www.runet.edu/%7Eswoodwar/CLASSES/GEOG235/biomes/medit/medit.html. Woodward is an American author (trained at UCLA by a European biogeographer), but she takes a European stance toward this vegetation.

Mediterranean regions have long been impacted by humans especially through the use of fire and the grazing of livestock. The Mediterranean proper, we know from classical Greek literature, was formerly forested with live oaks, pines, cedars, wild carob and wild olive. The shrublands of California, likewise, are believed much more extensive today than before aboriginal burning and Spanish livestock grazing. ... The Mediterranean proper--Europe, North Africa, and Asia Minor: around the Mediterranean Sea, which penetrates deeply into the Old World land masses, the biome reaches its maximum extent. Much of the formation is considered a subclimax developed on degraded and eroded soils and maintained in part by fire and goats. It is from this region that many culinary herbs associated with Italian cuisine originate. The shrublands are known locally as maquis. ... California: The chaparral (from the Spanish chapa or scrub oak) of southern California consists of two plant associations, the coastal sage and the foothills chaparral. The former is indicated by the presence of "soft" shrubs such as true sage (Salvia spp.). Inland, the latter is represented by a rich variety of "hard" woody shrubs that occurs in a mosaic reflecting fire history. A twenty-year cycle of fire maintains a subclimax of chamise (Adenostoma fasciculatum). In communities with less frequent or reguar burns, chamise gives way to ceonothus, mountain mahogany, sumac, toyon, and manzanita. Dwarfed oaks and drought-resistant, closed-cone pines also occur. ... Where fires have been prevented (and grazing also) for 50 years or more on Catalina and Santa Cruz islands (Channel Island group), an "elfin forest" of live oaks has developed. Some believe with even more prolonged suppression of fire, an oak savanna--perhaps the real climatic climax--would occur. ... Chile: In Chile the formation is known as matorral (from the Spanish mata for shrub), and as in California, is confined to the coast by high mountains. The flora consists of many more deciduous species than are found in California's chaparral and many species also have thorns. Overgrazing during the Spanish colonial period has been implicated in prevalence of these thorny, deciduous shrubs.

LaBianca, Řystein S.; with Christopherson, Gary L.; Watson, Richard P.; Low, Russanne D.; and Schnurrenberger, Douglas W. 1997? A forest that refuses to disappear: cycles of environmental degeneration and regeneration in Jordan. Report to the National Geographic Society Research Grant Number 5758-96. Available at http://www.casa.arizona.edu/MPP/ngs_report/ngs_rep.html.

...the outlines of the story of how the prehistoric Mediterranean woodland forest was destroyed has begun to come to light. This story begins with mention of the burgeoning evidence for the beginnings of agriculture in the Near East having occurred in the Mediterranean forests of the Southern Levant. The discovery of forest-dwelling Epipalaeolithic cultures associated with this achievement in the Hisban Region is consistent with other findings that point to the existence of a Mediterranean Woodland Forest here during Early Holocene and Neolithic times.
The first major deforestation event in this region appears to have occurred during the Early Bronze Age. Additional forests were cut down during the Iron Age, and by Roman-Byzantine times what remained of the virgin forest was nearly completely removed. Contrary to what is often asserted, sustained regeneration of forests appears to have gotten underway during Early Islamic times. This process of recovery of the ancient forest continued until the middle of the nineteenth century when isolated stands of forests could still be seen. This regenerated forest was then cut down again as a consequence of resettlement of the region and the building of the Hejaz Railroad.

Succession in Mediterranean Landscapes in the European Tradition: Skepticism

Trabaud, Louis, and Galtié, Jean-François. 1996. Effects of fire frequency on plant communities and landscape pattern in the Massif des Aspres (southern France). Landscape Ecology 11, 4: 215-224. Available at http://landscape.forest.wisc.edu/landscapeecology/articles/v11i04p215.pdf.

Has the frequency of fire produced the presence of the shrublands or has the existence of the shrublands allowed the occurrence of repeated wildfires? Is this type of vegetation due to wildfires or does the vegetational type induce wildfires? Or is it a question of both processes acting synergetically (p. 223)?
...The decrease in cork oak extent raises the question of the climax notion for certain species at certain times. With or without fire action there is a considerable decrease in cork oak forests: 60.1% have disappeared, transformed into treed shrublands or holm oak forests. The reason for this phenomenon could be that many Q. suber forests had been planted during the 19th century on old fields outside its natural range (Barello 1983, 1989) (p. 223).
...Another question: why, throughout the area without fire disturbance, has a progressive dynamics not followed its “natural” process, with a reversion to primeval forest? With or without fire, communities and landscapes have not reached a stable equilibrium (p. 223).

Rackham, Oliver. 2003. Fire in the European Mediterranean. Arid Lands Newsletter 54 (November/December). Available at http://ag.arizona.edu/OALS/ALN/aln54/rackham.html.

Most Mediterranean countries regard themselves as ruined landscapes, "degraded" through thousands of years of misuse of the land, which might be "restored" to the forests supposed to have existed in an idealized past (#forest).

Chaparral in the American Tradition: Natural Formation

Gabler, Robert E.; Sager, Robert J.; Brazier, Sheila M.; and Wise, Daniel L. 1987. Essentials of Physical Geography, 3rd ed. Philadelphia and other places: Saunders College Publishing (a common American introductory physical geography textbook).

The general look of the vegetation is a thick scrub, called chaparral in the western United States and maquis in the Mediterranean region... Wherever moisture is concentrated in depressions or on the cooler north-facing hills slopes, deciduous and evergreen oaks occur in groves. Drought-resisting needle-leaf trees, especially pines, are also part of the overall vegetation association. Thus the vegetation is a mosaic related to site characteristics and microclimate.

MacDonald, Glen. 2003. Biogeography: Space, Time, and Life. New York: John Wiley and Sons (a popular biogeography textbook).

The typical vegetation structure of the Mediterranean biome includes a mosaic. ... The distribution of woodland, shrubland, and grassland can reflect a number of factors, including regional rainfall differences, slope aspect, substrate, and disturbance. In regions where annual precipitation is less than 40 cm there is often insufficient deep percolation of water to support deep-rooted shrubs. In these areas small shrubs, annual plants, and grasses predominate. Fire is common during the long dry summers and can restrict shrub and tree dominance. In addition, it is thought that some of the extensive shrublands around the Mediterranean Sea are the result of overgrazing by goats and other livestock, followed by erosion of the topsoil.

Radtke, Klaus W. 1983. Living More Safely in the Chaparral-Urban Interface. USDA, Forest Services, Pacific Southwest Forest and Range Experiment Station, General Technical Report PSW-67. Available from http://www.geosafetyinc.com/environment-publications.asp.

Mediterranean regions are found in the countries of Europe, Africa, and Asia that border the Mediterranean Sea; in southwest Australia and South Africa; and in Central Chile, Mexico, and the State of California. The climate is characterized by hot, dry summers and wet, moderate winters, Rainfall ranges from about 10 inches (250 mm) to above 32 inches (800 mm). The mixtures of plant species within these areas are determined by such factors as aspect and steepness of slope, soils, elevation, fire frequency, and local climate.

Minnich, Richard A. 1983. Fire mosaics in southern California and northern Baja Caliofrnia. Science 219: 1287-1294.

Major plant communities form broad zonal belts that increase in elevation southward into Baja California. Grasslands and coastal sage scrub in lower coastal valleys are replaced by chaparral on mesic coastal slopes of the mountains. Mixed evergreen forest and mixed conifer forest occupy the highest mountains and grade into pinyon and juniper forests and various scrub communities on the east slope of the mountains adjoining the Sonoran and Mojave deserts.... Grassland, coastal sage scrub, and chaparral, in which nearly all the burning detectable by Landsat imagery occurs, are divergent in terms of physical appearance, rooting structure, phenology, drought stress, fuel, and fire response.

Chaparral in the American Tradition: Older European Influences

Hanes, T.L. 1971. Succession after fire in the chaparral of southern California. Ecological Monographs 41: 27-52.

There are many misconceptions about the relation between California chaparral and fire. One is that primeval forests were open and park-like, and brushy areas were small and insignificant until white men (sic) settled California (p. 29).
The successional status of chaparral has been debated for years, some botanists even questioning whether chaparral is a climax association. Clements' (1916) early writing considered the California chaparral a deflected or altered vegetation.... Other botanists have rejected the hypothesis that chaparral is a fire subclimax, proposing that it is a true climatic vegetation (Cooper 1922, Bauer 1936, Munz and Keck 1959) (p. 30).
In Clements' later writings (Allred and Clements 1949) he also recognized chaparral as a true climax that persisted after recurrent fires (p. 31).

European Re-evaluation of Human Rôle in Mediterranean Scrublands

Rackham, op. cit.

There is abundant reason why fire should have increased. There is now much more to burn than when the countryside was densely populated and used. Abandoned farmland or neglected pasture turn into forest or shrubland (#increase)....
Foresters are not content with the natural fire risk. Most of the trees planted are pines, which are fire-dependent and fire-promoting. ...In Portugal and other countries, planting eucalypts has had a similar effect, except that they are not killed by fire but sprout, grow up, and generate the fuel for an indefinite succession of future fires. ... Foresters promote fire in another way, when they exclude browsing animals and thus allow native vegetation (especially grasses and shrubs) to grow up and accumulate fuel (#forest).

Quézel, P.; Médail, F.; Loisel, R.; and Barbero, M. 1999. An international review of forestry and forest products. Unasylva 197. Available in the FAO Corporate Document Repository: http://www.fao.org/documents/show_cdr.asp?url_file=/docrep/x1880e/x1880e05.htm.

In countries on the northern Mediterranean basin, the collapse of the age-old agrosilvipastoral system is leading to deep changes in the structure and architecture of forest and pre-forest* communities of plants and animals and, in general terms, to an aging of forest populations …the resulting ecological consequences are very similar: i) disruptions in the natural cycles of disturbances and ecological imbalances, causing large-scale climatic catastrophes; ii) a homogenization of the structure and architecture of plant communities; iii) a marked loss in biological diversity and the banalization of flora; and iv) the spread of immigrant species through "artificialization" of environments that pose competition to indigenous plants in the undergrowth as well as in upper storeys.

Mazzoleni, Stefan; Legg, Colin; and Muetzelfeldt, Robert. 1996. ModMED: Modelling Mediterranean Ecosystem Dynamic. Poster presented at the International Conference on Mediterranean Desertification, Crete (October). Avalable at http://www.homepages.ed.ac.uk/modmed/aims/aims.htm.

The maquis and garrigue vegetation has evolved over thousands of years in an environment of heavy grazing and frequent cutting and burning but agricultural land use in the Mediterranean has changed considerably in the last 20 - 30 years. Records show that grazing of semi-natural Mediterranean vegetation by sheep and goats has virtually ceased in several European countries where marginal land has been abandoned. This has lead (sic) to the rapid succession to woodland and accumulation of biomass. This in turn then affects the frequency and intensity of fires. Abandonment of traditional land management will result in dramatic changes to the landscape.

American Fire Wars: Chaparral Is Dependent on Fire

Hanes, op. cit.

Chaparral fires are both natural and inevitable. A fire-exclusion policy does not prevent fire, it only forestalls fire. In chaparral stands where fire has been excluded for decades, the threat of fire is greatest. ... It is possible that, in terms of preserving the chamise-chaparral of southern California, long-term fire exclusion might be the least desirable practice.

Minnich, op. cit.

Stands as old as 20 years contain little dead fuel and are thus relatively nonflammable ... Chaparral therefore becomes especially flammable after 30 to 50 years, depending on climate and local fuel accumulation rates .The present regime of large, intense conflagrations in southern California chaparral appears to be an artifact of fire suppression. The great achievement of suppression is the extinguishing of small fires.... Thus prevention efforts by a few forest rangers and settlers between 1880 and 1910 may have interrupted burning enough to erase some of the presuppression mosaic. Since 1910, small fires have been replaced by ever-larger ones, with numerous conflagrations since the 1950s despite increased suppression investment.

Rodrigue, Christine M. 1993. Home with a view: Chaparral fire hazard and the social geographies of risk and vulnerability. California Geographer 33: 105-118.

The steady accumulation of fuel is the mechanism by which chaparral creates a condition on which it depends. As a result of this accumulation, the longer the period since a fire, the greater both the probability and the magnitude of the next fire.

American Fire Wars: Chaparral Fire Is Meteorologically Forced

Keeley, Jon E. and Fotheringham, C.J. 2000. Historic fire regime in Southern California. Conservation Biology 15, 6: 1536-1548. Available at: http://www.werc.usgs.gov/seki/pdfs/ConBio1.pdf.

Paleoecological records reveal that these large fires driven by Santa Ana winds were a prominent feature of the landscape long before European settlement. ...The contemporary fire regime in southern California shrublands mirrors the natural fire regime much more closely than is generally credited. ...As is the case today, the natural fire regime was likely characterized by many small fires and a few large fires that consumed the bulk of the landscape. ... The primary change in the fire regime has been the marked increase in fire frequency in areas of high population density such as southern and central coastal California. ... Today, fire suppression is required just to maintain some semblance of the natural fire regime.

Moritz, Max. 2003. Spatiotemporal analysis of controls on shrubland fire regimes: Age dependency and fire hazard. Ecology 84, 2: 351-361.

Large fires in chaparral-dominated shrublands of southern and central California are widely attributed to decades of fire suppression. Prehistoric shrubland landscapes are hypothesized to have exhibited fine-grained age-patch mosaics in which fire spread was limited by the age and spatial pattern of fuels. In contrast, I hypothesize that fires during extreme weather conditions have been capable of burning through all age classes of the vegetation mosaic. ... Exposure to extreme fire weather therefore appears to override the sensitivity of a fire regime to fuels characteristics at the landscape scale. ... Findings contradict the assertion that, in the absence of fire suppression, large fires would be constrained by more complex age-patch mosaics on the landscape.

American Fire Wars: Socialization of Chaparral Fire Hazard Costs

Rodrigue, op. cit.

Consideration of chaparral fire hazard in the Santa Monica Mountains suggests that the benefits of an amenity view are privatized, while the private hazard costs to the household are reduced by the socialization of fire hazard mitigations. Household benefits seem higher than household costs, thus encouraging action on environmentally dysfunctional landscape values if households have the resources to act on them.

American Fire Wars: The Socialization of Costs = Homeowner Irresponsibility

Cohen, Jack, and Saveland, Jim. 1997. Structure ignition assessment can help reduce fire damages in the W-UI. Fire Management Notes 57, 4: 19-23

SIAM (the Structure Ignition Assessment Model) is based on the premise that structure survival is the essence of the W-UI fire problem, but structure ignition is the critical element for survival. ... experiments and model results indicate that flames are an ignition threat only at close distances to a structure. ...This finding suggests that nearby landscape vegetation and neighboring structures are important factors in structure ignitions. … Vegetation management beyond the structure's immediate vicinity has little effect on structure ignitions.