Seral community

About: Seral community is a research topic. Over the lifetime, 618 publications have been published within this topic receiving 21377 citations.

The Evolution of Thallus Form and Survival Strategies in Benthic Marine Macroalgae: Field and Laboratory Tests of a Functional Form Model

Abstract: A synthetic "functional form" paradigm concerning hypothetically important adaptive features of algal structure and function was developed and tested by a costs/benefits strategic approach. Successional manipulations were performed by disturbing mature, environmentally constant intertidal communities; from the array of colonizing macroalgae, Ulva sp. was chosen as an opportunistic representative of pioneer seral stages, Egregia menziesii and Gelidium purpurascens/robustum as intermediate to late seral species, and Pelvetia fastigiata and Corallina officinalis as characteristic of more mature climax communities. The ranking from high to low primary producers (Ulva > Gelidium > Egregia > Pelvetia > Corallina) indicates that selection in fluctuating environments has favored opportunistic species having high net productivity, while those species able to persist in benign predictable habitats do so at the cost of lower photosynthetic rates and presumably slower growth. The kilocalories per ash-free gram dry we...

Succession after Fire in the Chaparral of Southern California

Abstract: Extensive sampling of chaparral with 10—m line intercepts in the San Gabriel and San Bernardino Mountains of southern California revealed site—oriented vegetative characteristics and successional patterns. Of the 78 species encountered, few were widespread and abundant; most were local and infrequent. The most widespread and abundant species were long—lived rootcrown sprouters. Adenostoma fasciculatum (chamise), the most frequently encountered shrub, occurred on 71.4% of the sites and composed one—fifth of all shrubs in the study. The second most common species, Quercus dumosa (scrub oak), appeared on 32% of the sites sampled. Many non—sprouting subshrubs and woody species were restricted to elevations below 3,000 ft (ca. 900 m), sunny exposures, and young stands. Chaparral succession, both in composition and rate of change, is influenced most by aspect, particularly north— and south—facing slopes. Next in importance is the influence of coastal and desert exposure. Elevation is a factor that may compensate for coastal—desert exposure or aspect. Percentage of slope is least important. The rate of succession after fire in coastal chaparral is slowest on south—facing slopes below 3,000 ft. Early stages of shrub succession are characterized by a mixture of chaparral seedlings, resprouts, and seedlings of coastal sage subshrubs. Most of the present—day chaparral on south—facing slopes is a coastal sage—chaparral subclimax due to frequent fire. On fire—free sites a chamise—chaparral climax community develops within 30 years after fire. The fastest succession rate is in coastal chaparral on north—facing slopes above 3,000 ft. The profusion of coastal sage subshrubs is missing, and vigorous, tall—growing sprouting species are abundant. The death of large, short—lived species in stands older than 25 years allows pockets of seral species to develop in the climax scrub oak—chaparral. Chaparral succession is not a series of vegetational replacements, but a gradual ascendance of long—lived species present in the pre—fire stand. The pattern of chaparral succession on desert exposures differs from that on coastal exposures. Slope aspect is less important, but proximity to the Pacific Ocean is more important than on coastal exposures. Fire favors the sprouting species of chaparral over woodland and forest communities bordering the chaparral communities. Fewer chaparral species occur on desert exposures than on coastal ones. Seedling and mature shrub mortality rates are lower in desert than in coastal chaparral. Succession after fire in desert chaparral is slow, and the climax community is composed of large shrub specimens with subshrubs clustered around their skirts and a canopy broken by intershrub spaces. Chaparral stands older than 60 years often are decadent, especially chamise—chaparral. Old stands are characterized by a high proportion of dead wood, little annual growth, and no new seedling development. Various phytotoxic substances may account for the loss of vitality and lack of regeneration. Maintenance of vigorous chamise—chaparral is shown to be dependent on fire. A re—evaluation of current fire—exclusion and suppression practices is needed. The present fire—exclusion policy is probably the least desirable one to insure the perpetuation of chamise—chaparral.

Fire and Mammalian Secondary Succession in an Australian Coastal Heath

Abstract: A species—rich small—mammal community on 7 ha of diverse coastal heath in Myall Lakes National Park, New South Wales, Australia, was studied for 7 mo before the area burned in a wildfire (August 1974) and has subsequently been monitored for 5 yr since the fire. Species regularly trapped were the dasyurids Antechinus stuartii and Sminthopsis murina, the peramelid Isoodon macrourus, and the native murids Pseudomys novaehollandiae and P. gradcilicaudatus, together with the introduced Mus musculus. Pseudomys species, M. musculus, and S. murina reached greater abundance on early seral stages, while the abundance there of both Rattus fuscipes and R. lutreolus was much reduced. Species reach peak abundance in an orderly replacement sequence exhibiting a mammalian secondary succession. A habitat accommodation model is proposed with species entering the succession and reaching peak abundance as externally controlled changes in the vegetation fulfil the habitat requirements of each species. Species leave the succession or are greatly reduced in abundance when these local physical conditions move out of the optimal range for the species. This study shows that a major perturbation of a small—mammal community can produce a variety of responses among species, suggesting that regeneration time may represent a resource axis subdivided by community members in this secondary succession. The rapid recovery illustrated by the total number of individuals, as a measure of community response, support the suggestion that fire and fire frequency have been major factors in producing a fire—adapted, species—rich small—mammal community on this heathland.

Sucessional Status and the Palatability of Plants to Generalized Herbivores

Abstract: Theoretical considerations and evidence from the literature suggest that early successional plant species should make a lesser commitment of resources to defense against herbivores, and should then provide better food sources for generalized herbivores than later successional and climax plants. Commitment to defense by plants is estimated by determining short-term palatabilities to two slug species; one native to western Washington, Ariolimax columbianus, and one introduced from Europe, Arion ater. Results of tests with 100 plant species of three growth forms and from different seral stages indicated that early successional annuals were significantly more palatable than early successional perennials which were sig- nificantly more palatable than later successional species. No correlation was found between palatability and evolutionary association of the herbivores with the plant species.