Both native and non-native grasslands occur within the city.

Native Grassland

Native grassland is characterized by perennial bunch grasses such as needlegrass and herbaceous annuals and perennials such as Cleveland's shooting star, blue-eyed grass, fascicled tarweed, sanicles, and mariposa lily. This habitat type is often associated with clay soils and frequently occurs as open patches within coastal sage scrub. Native grassland is considered a sensitive habitat due to its limited distribution in California, potential to support sensitive species, use as raptor foraging habitat, and continuing decline as a result of development and agricultural practices. In Carlsbad, native grassland is extremely limited. Existing patches are too small to be mapped at the scale used for the HMP vegetation database.

Non-Native Grassland

Non-native grassland is characterized by non-native grasses such as wild oats, bromes, and others. Other species present in this habitat type include invasive natives such as telegraph weed, fascicled tarweed, doveweed, and invasive non-native species such as Russian-thistle, black mustard, and tocalote.

Coastal Sage Scrub

Coastal sage scrub is home to the federally threatened coastal California gnatcatcher. Coastal sage scrub types within Carlsbad include maritime succulent scrub, Diegan coastal sage scrub, and coastal sage scrub-chaparral scrub, and all three are considered sensitive habitats.

Maritime Succulent Scrub

Maritime succulent scrub includes a variety of succulents, such as fish-hook cactus, coast cholla, shore cactus, california desert thorn, cliff-spurge, bladder-pod, and several species of dudleya, mixed with typical Deigan coastal sage scrub species.

Diegan Coastal Sage Scrub

Diegan coastal sage scrub is a drought-deciduous community comprised of aromatic shrubs with a diverse understory of annual and perennial forbs and grasses. This habitat occurs primarily on dry south-facing slopes or hillsides or on clay-rich soils adjacent to chaparral. Characteristic plant species include California sagebrush, California buckwheat, black sage, white sage, lemonadeberry, laurel sumac, and purple needlegrass. It also supports a variety of sensitive plants such as California adolphia and Del Mar mesa sand-aster. In Carlsbad the largest remaining tracts of Diegan coastal sage scrub are found in the Calavera Hills area, southeast of Agua Hedionda Lagoon, and near Rancho Santa Fe Road.

Coastal Sage Scrub-chaparral Scrub

Coastal sage scrub-chaparral scrub is a transitional community between coastal sage scrub and chaparral types. Within the context of the MHCP, it is categorized as a sub-type of coastal sage scrub and is considered to be a sensitive habitat.

Chaparral habitat in the city has been grouped into two categories: undifferentiated (including southern mixed and chamise chaparral) and southern maritime chaparral.

Southern Mixed & Chamise Chaparral

Southern mixed chaparral is a fire- and drought-adapted plant community composed of a variety of woody shrubs, many of which are "stump sprouters" that regenerate rapidly from undamaged underground tissues following fires or other ecological perturbations. The dominant shrubs vary from site to site. In most situations the dominants include chamise, Nuttall's scrub oak, mission manzanita, laurel sumac, lemonadeberry, and toyon. Understory plants may include rush-rose, deerweed, wreathplant, and a variety of aster and daisy relatives.

Chamise chaparral is a community dominated by chamise, which may comprise up to 90 percent of the relative cover. The remaining species include shrubs and understory plants common in other types of chaparral.

These chaparral types have a patchy distribution throughout Carlsbad, occurring on wetter north- and west-facing slopes, alternating with coastal sage scrub, grasslands, and oak woodlands.

Southern Maritime Chaparral

Southern maritime chaparral is similar to southern mixed chaparral, but occurs on sandstone. It is the most limited type of chaparral in Carlsbad, and is characterized by several endemic shrubs, including Del Mar manzanita, wart-stemmed ceanothus, coast spice bush, and Nuttall's scrub oak. Summer holly is also associated with this habitat type. Other dominant shrubs are the same as those listed for the other two types of chaparral. Southern maritime chaparral is considered a sensitive habitat.

Two woodland types occur in Carlsbad: oak woodland and eucalyptus woodland.

Oak Woodland

Oak woodland is dominated by coast live oak, with scattered individuals of other tree species.

Eucalyptus Woodland

Eucalyptus woodland is a non-native community. It is dominated by various species of planted eucalyptus that survived around old dwellings, or in entire groves (e.g. the Hosp Grove). the understory is usually poorly developed or absent owing to the toxic effect of the eucalyptus leaves that acts to inhibit the growth of other plants. Although this habitat supports no sensitive plant or animal species, it is often used for nesting by raptors and other birds, or for nesting by bats.

Riparian types within the city include riparian scrub, riparian woodland, and riparian forest. Riparian habitats are located along drainages and streams, where the soil tends to be moist during all or part of the year. In Carlsbad, riparian communities may also be the result of agricultural runoff. All riparian habitats are considered sensitive.

Riparian Scrub

Riparian scrub includes several plant communities, including mulefat scrub, southern willow scrub, and baccharis/tamarisk scrub. Riparian scrub is typically dominated by willows and cottonwood trees, by mulefat, or by broom baccharis or tamarisk, an introduced species. The understory is variable depending on canopy coverage, disturbance history and water availability, and usually includes poison oak, wild grape, western ragweed, rushes, and a variety of other water-loving plants.

Riparian Woodland

Riparian woodland includes sycamore-alder riparian woodland and other riparian woodland. Sycamore-alder woodland is an open to moderately closed, winter-deciduous, broadleafed riparian woodland, dominated by well-spaced western sycamore. The community typically includes individuals of several other tree species, including willow, coast live oak, Mexican elderberry, and cottonwood. This community occurs in broad channels of intermittent streams, usually with a cobbly substrate. Sycamore-alder woodland is uncommon in Carlsbad, occurring primarily in the Sunny Creek area and along a narrow drainage south of Lake Calavera.

Riparian Forest

Riparian Forest includes southern coast live oak riparian forest. This community type is dominated by coast live oak with scattered individuals of other tree species, such as western sycamore, willow, and Mexican elderberry. The understory includes toyon, laurel sumac, California wild rose, poison oak, and currants.

Marsh and wetland habitats in Carlsbad include southern coastal salt marsh, freshwater marsh, and cismontane alkali marsh. All marsh habitats are considered sensitive.

Southern Coastal Salt Marsh

Southern coastal salt marsh is a wetland community that develops in low, flat estuaries at the mouths of rivers and streams. Tidal inundation or excessive evaporation results in highly saline conditions around the margins of lagoons, and it is under these conditions that salt marshes develop. The community is characterized by low-growing succulents such as pickleweed, salty-Susan, salt cedar, and other salt-tolerant species.

Freshwater Marsh

Freshwater marsh occurs in drainages, seepages, and other perennially moist, low places. This community is characterized by cattails and bulrushes. Understory species include curly dock, salt marsh fleabane, and a variety of salt-tolerant grasses and herbs. Sensitive plants frequently encountered in the vicinity of this community are spiny rush and San Diego marsh elder.

Cismontane Alkali Marsh

Areas in Carlsbad classified as cismontane alkali marsh are typically disturbed riparian freshwater marsh that have changed in vegetative character due to agriculture or other disturbance. Plant species found in these locations are often those associated with salt marsh, as well as non-native plant species.

Other wetland and aquatic habitat types include estuaries, freshwater/open water, and vernal pools. All wetland habitats are considered sensitive.

Estuaries

Estuarine habitat consists of a semi-enclosed body of water that has a free connection with the open ocean and within which seawater is measurably diluted with freshwater derived from land drainage. Estuarine species include pickleweed, alkali heath, estuary sea blite, and salty-Susan.

Freshwater/Open Water

This aquatic habitat lacks a vascular vegetation, and includes lakes, ponds and reservoirs. The area surrounding open water is almost always characterized by freshwater marsh, salt marsh, or riparian habitats. Excluding the three major coastal lagoons, the largest open water area in the city is Lake Calavera.

Vernal Pools

Vernal pools are a highly restricted, unique wetland habitat type that contains high numbers of endangered, sensitive, and endemic plant and animal species, including San Diego button-celery, little mousetail, spikerush, spreading navarretia, and California Orcutt grass. This type occurs in several scattered locations throughout the city.