Californian Chaparral

Chaparral, a type of evergreen woody shrubland, extends over most of the hills and lower slopes of California. Like all Mediterranean type vegetation, it has winter active and summer dormant phases, but the principle genera, Adenostoma, Arctostaphylos, Ceanothus, Heteromeles and Rhus are absent from other regions having a Mediterranean climate.  It has been postulated therefore that the Californian chaparral evolved in situ, and has over the period of its development given rise to over 24 endemic species.  Chaparral can be divided into about eight vegetation types. The main type is often composed of dense thickets of chamise Adenostoma fasciculatum. Associated endemics may include Elymus condensatus (Poaceae) and Erigonum fasciculatum (Polygonaceae).  Ceanothus chapparral is often the climax formation in northern California and may be dominated by several Ceanothus species such as C. crassifolius, C. oliganthus or C. thysiflorus. In the areas between Ceanothus shrubs, endemic species such as Artemisia californica (Asteraceae) may be present. On the many slopes, scrub oak chaparral is often conspicuous usually dominated by Quercus dumosa.  It is one of the most species rich forms of chaparral often supporting a large variety of associates such as Ceanothus leucodermis, Cercocarpus betuloides, Heteromeles artutifolia and the endemic Rhamnus californica (Rhamnaceae). A less extensive chaparral is dominated by manzanita (Arctostaphylos species), which tends to be restricted to deeper soils especially at higher elevations. The characteristic species include Arctostaphylos manzanita and various endemics of this genus such as A. canescens, A. stanfordiana, A. tomentosa and A. viscida (Ericaceae). At higher altitudes, a ground-hugging, compact form of chaparral can be found supporting species such as Arctostaphylos nevadensis, Castanopsis sempervirens, Cercocarpus ledifolius, Chrysothamnus nauseous, Prunus virginiana and a variety of Ceanothus species. In the north this can extend up to the ponderosa pine forest where endemic such as Ceanothus fresnensis and C. prostratus (Rhamnaceae) occur, while in more southern areas the endemic Fremontia californica (Malvaceae) is more likely to be encountered. A less common form of chaparral is dominated by the endemic red shanks Adenostoma sparsifolium (Rosaceae). This is often regarded as the most attractive form of chaparral, but is confined to just four locations in southern California and Baja California. Associated taxa include Adenostoma fasciculatum, Rhus ovata and several Ceanothus species. On the serpentine soils such as in the Coast Range and the foothills of the northern Sierra Nevada, a special type of chaparral can be found supporting a variety of localised endemics such as Arctostaphylos viscida (Ericaceae) and Ceanothus jepsonii (Rhamnaceae). Finally in desert chaparral the dominant species often include endemics such as Juniperous californica (Cupressaceae) and Quercus turbinella var. californica (Fagaceae). Other endemics associated with Californian chaparral include Apiastrum angustifolium, Arctostaphylos elegans, Bloomeria clevelandii, Bloomeria crocea, Ceanothus dentatus, Chorizanthe californica, Chlorogalum pomeridianum, Corethrogyne filaginifolia var. bernardini, Cryptantha torreyana, Delphinium californicum, Dendromecon rigida, Emmenanthe penduliflora, Encelia californica, Eriophyllum lanatum var. achillaeoides, Eriophyllum confertiflorum, Filago californica, Garrya congdoni, Gilia capitata, Gilia clivorum, Gnaphalium californicum, Leptodactylon californicum, Lomatium lucidum, Madia gracilis, Marah fabaceus, Paeonia californica, Papaver californicum, Perezia microcephala, Phacelia imbricata subsp. patula, Pickeringia montana, Rafinesquia californica,  Romneya coulteri, Sanicula crassicaulis, Scrophularia californica and Silene californica.            

 

Californian Lowland Oak Forests

In the Central Valley and surrounding foothills there are extensive oak forests dominated by endemic trees such as Quercus duglasii, Q. labata (Fagaceae), and Pinus sabiniana (Pinaceae) making this an exclusively Californian community. Other associated endemic trees include Aesculus californica (Sapindaceae), Arbutus menziesii (Ericaceae), Juglans californica (Juglandaceae), Pinus coulteri (Pinaceae), Quercus agrifolia (Fagaceae) and Umbellularia californica (Lauraceae), while associated shrubs include Ceanothus cuneatus, Ribes quercetorum, Toxicodendron diversilobum and endemics such as Artemisia tridentata (Asteraceae) and Eriodictyon californicum (Boraginaceae). In places the trees become more widely spaced forming a type of woodland savanna with a grassy ground cover of annual species such as Avena barbata and A. fatua.

 

Californian Closed-Cone Pines and Cypress Forests

These forests form a unique series of plant communities scattered the length of California’s coast, mountains and islands. Many of the characteristic species are relict endemics such as Cupressus abramsiana, C. bakeri, C. forbesii, C. goveniana, C. macnabiana, C. macrocarpa, C. nevadensis, C. pigmaea, C. sagentii, C. stephensonii (Cupressaceae), Pinus muricata, P. radiata and P. torreyana (Pinaceae). In fact of California’s ten native cypress species eight are endemic.  Most of these are highly adapted to fire and their cones remain sealed after maturity, usually accumulating on the tree and only opening when heated by fire. Cypress species tend to occur in groves often within other communities such as chaparral, although no native species occur in the Central Valley or on the offshore islands. These groves support a variety of endemics some of which are confined to just one or a few groves. For example, Arctostaphylos otayensis (Ericaceae), Ceanothus otayensis (Rhamnaceae) and Lepechinia ganderi (Lamiaceae) are confined to the Otay Mountain grove; Nolina parryi (Ruscaceae) is confined to the Sierra Peak grove; Arctostaphylos hookeri (Ericaceae), and Haplopappus eastwoodae (Asteraceae) are confined to the Monterey Peninsula; Arctostaphylos silvicola (Ericaceae) is confined to the sandy soils of the Santa Cruz Mountains and Arctostaphylos pungens var. montana (Ericaceae) is largely confined to groves on serpentine soils. In other cypress groves endemics include Arctostaphylos nummularia (Ericaceae), Baccharis pilularis (Asteraceae), Chamaebatia australis (Rosaceae), Cneoridium dumosum (Rutaceae), Dudleya farinose (Crassulaceae), Eriodictyon californicum (Boraginaceae), Lathyrus splendens (Fabaceae), Lepechinia cardiophylla (Lamiaceae), Lithocarpus densiflorus (Fagaceae), Myrica gale (Myricaceae), Pseudotsuga macrocarpa (Pinaceae), Rosa californica (Rosaceae) and Xerophyllum tenax (Melanthiaceae).

The most widespread of the pine species is Pinus attenuata occurring nearly the whole length of California, but other species like Pinus radiata are more restricted. When first discovered in 1602 this species was confined to just three small areas near Monterey. All of these closed-cone pines are believed to be relicts of a more widespread Tertiary forest. Some of the endemic species found in these forests include Achillea borealis subsp. californica (Asteraceae), Ceanothus papillosus (Rhamnaceae), Galium angustifolium (Rubiaceae) and the conifer Libocedrus decurrens (Cupressaceae).  On the ultrabasic soils Pinus jeffreyi, P. monticola, P. lambertiana and other conifers occur in varying degrees of dominance, and in some of the more open of these stands, especially in the dryer areas, the associated grasslands include species such as Sitanion jubatum, Stipa lemmoni and the endemic Danthonia californica (Poaceae).

 

Californian Vernal Pools

Vernal pools are small seasonally flooded depressions that usually fill with water during winter. They form mosaics with valley grasslands and as they dry up in spring various annual plant species come in to flower, often in conspicuous concentric rings of showy colours. The associated soils are often extremely ancient, some being dated at over 600,000 years old, and it is their prolonged profile development that has led to the formation of dense impervious hardpans - hence their seasonal flooding. The pools are often isolated from one another forming distinct island habitats with their own assemblages of herbaceous species.  In fact, there are about eight endemic centers. They can be classified into three general type: valley pools, terrace pools and pools of volcanic areas. The valley pools are usually saline and/or alkaline and are usually characterized by endemic species such as Arenaria californica (Caryophyllaceae), Astragalus tener (Fabaceae), Dowinga bella, D. cuspidata (Campanulaceae), and Grindelia camporum (Asteraceae). Terrace pools comprise most of the pools remaining in the Central Valley and are typically neutral or slightly acidic. Their characteristic endemics include Blennosperma nanum (Asteraceae), and the grasses Orcuttia californica and O. pilosa (Poaceae).  Pools in volcanic areas are readily distinguished physiographically, but have similar floras to the terrace pools.  Other endemics associated with vernal pools include Atriplex persistens, Blennosperma bakeri, Brodiaea pallida, Chamaesyce hooveri, Downingia bicornuta, Downingia concolor var. brevior, Downingia ornatissima, Elatine californica, Epilobium cleistogamum, Eryngium constancei, Eryngium aristulatum var. parishii, Gratiola heterosepala, Hemizonia paniculata, Hordeum californicum, Lasthenia burkei, Lasthenia conjugens, Limnanthes bakeri, Limnanthes gracilis subsp. parishii, Limnanthes vinculans, Machaerocarpus californicus, Mimulus tricolor, Muilla clevelandii, Myosotis minimus, Myosurus sessilis, Navarretia fossalis,  Navarretia leucocephala, Navarretia myersii, Neostapfia colusana, Parvisedum leiocarpum,  Pleuropogon californicus var. californicus, Pleuropogon californicus var. davyi, Pogogyne abramsii, Pogogyne douglasii subsp. parviflora, Pogogyne nudiuscula, Tuctoria greenei and Tuctoria mucronata.

 

Californian Coastal Sand Dunes

The dunes of California can be roughly divided into fore dunes, stabilized slopes and ridges, dune scrub and deflation areas (slacks). On the seaward fringes Cakile maritima and/or C. edentula are likely to be the main species, while the pioneer hillocks in front of the dunes include Abronia latifolia, Ambrosia chamissonis, Calystegia soldanella and Elymus mollis. Further up the fore dunes the dominance usually shifts to Ammophila arenaria, together with native species such as Fragaria chiloensis and Lathyrus littoralis and may include endemics such as Croton californicum (Euphorbiaceae)and Poa douglasiii (Poaceae). The dominant specieson some of the more stable slopes and ridges include Haplopappus ericoides, Lotus scoparius and endemics such as Corethrogyne leucophylla (Asteraceae), Dudleya caespitosa (Crassulaceae) and Lotus junceus (Fabaceae), although some of the above mentioned endemics are confined to relatively small areas. Species characteristic of the deflation zones include various Salix species together with Abronia umbellata, Elymus pacificus and Juncus acutus var. sphaerocarpus.

 

Californian Saltmarsh

The saltmarshes of California can be roughly divided into north, central and southern types. However, Salicornia virginica and Spartina foliosa are usually the primary colonists in all three types, and likewise Distichilis spicata is usually the dominant saltmarsh grass in all high marsh zones. Less common species in the upper marsh communities include endemics such as Limonium californicum (Plumbaginaceae) and Suaeda californica (Chenopodiaceae). In the more brackish zones Scirpus acutus and Typha latifolia predominate, while the associated species include the endemic Scirpus californicus (Cyperaceae) and in more southern areas the endemic Anemopsis californicus (Saururaceae) is locally abundant.

Further information required.

 

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