Restoration s Influence on Aerial Arthropod Diversity Damien Clauson Abstract The arthropod diversity of restored dunes can provide useful measures of restoration progress This study conducted at Fort Funston Golden Gate National Recreation Area provides data on the abundance and diversity of aerial arthropods in two dune conditions restored native plant dominated dunes and unrestored exotic plant dominated dunes Fort Funston is part of the National Park Service and began restoration of native vegetation in 1991 however scientists have not conducted much research regarding aerial arthropod diversity and restoration status at Fort Funston Arthropods were sampled for using yellow colored sticky traps over a period of five days in mid February I evaluated the data with the Simpson s Index of diversity and non parametric tests Results indicated a difference between diversity of the restored and unrestored areas Introduction California s coastal dunes are home to many endemic species of plants and animals giving the dunes an ecological uniqueness Powell 1978 Unfortunately development and human use has impaired the uniqueness of this environment The result as Randall and Hoshovsky 2000 note is that native vegetation of California has been declining in biomass since settlement in 1769 Disturbance of the native ecosystems is a probable cause but also likely is the decline due to the introduction of non native species Species not endemic to the region of California s coastal dunes but from similar climates make likely candidates to compete with natives upon introduction These invasive plants may out compete natives and have altered the ecology of the affected landscapes Randall and Hoshovsky 2000 Now a common tool to reverse these problems is restoration of the native habitat to improve the health of plant and other organism communities While plants are often affected by invasive species so are the other organisms associated with the vegetation Arthropods including the very important insects are no exception In fact arthropods are considered particularly appropriate for assessing habitat quality because they are sensitive to small scale changes in habitat conditions Arthropod monitoring can indicate much about the land they are located in A study by Mattoni et al 2000 and Laborde et al 1993 indicate that arthropod assemblages can be studied to evaluate habitats and monitor restoration projects Also the study of insects provides useful information about an environment because of their importance in the functioning of the natural ecosystems Rosenberg et al 1986 In a study involving butterfly assemblages the species richness varied by either natural exotic or restored Nelson et al 1999 So it is expected that associated with a change in the vegetation is a change in arthropod species composition Restoration can affect a community much like a disturbance Pre restoration disturbances often of anthropogenic origin present potential stresses on the arthropod community and illustrate how succession is important to this health Nordstrom et al 2000 note that human based disturbance leads to landforms existing that normally would not and an overall effect of altering succession Van Aarde et al 1996 studied species richness and found that beetle species richness increased with the increase in age of sites In a study of a tropical forest termite assemblage response to habitat perturbation researchers found that the response of the termites depended on the perturbation Davies et al 1999 The recovery of the termite assemblages illustrate that species will respond differently based on the ecosystem status i e restored recovering etc Essentially altering succession alters the make up of the species composition and restoration alters succession One location where these restoration efforts are apparent is the dunes of Fort Funston Fort Funston comprises a portion of the Golden Gate National Recreation Area GGNRA and is home to a large number of native species of plants and animals Dunes used to stretch far into present day San Francisco Cooper 1967 but have since been greatly altered by human use largely associated with the Army s fortification and construction in the area During the 1930 s the Army constructed coastal defense batteries and in doing so altered the dune topography and destroyed much of the native plant community I intended to investigate the affects of restoration on the aerial arthropods at Fort Fusnton by measuring arthropod diversity in restored and unrestored sites Knowing that the species composition responds to changes in the ecosystem makes it possible to focus on specific taxonomic groups One important study at Fort Funston by Morgan and Dhalsten 1999 addressed the ground dwelling arthropod diversity in relationship to the removal of the nonnative iceplant They found that iceplant removal leads to greater diversity of ground dwelling arthropods In my study I expect to discover a measurable difference between arthropod species diversity in restored and unrestored sites The interaction between insects and vegetation play an important role in the ecology of dunes My study aims to provide a partial answer on the affects of restoration on the aerial arthropod diversity Methods Fort Funston GGNRA spans approximately 230 acres along the coastal region of the northern San Francisco peninsula It lies south of Ocean Beach and north of Pacifica bordered to the west by the Pacific Ocean and to the east by a primary coastal highway figure 1 The non native plant Carpobrotus edulis iceplant covers much of Fort Funston creating extensive amount of monoculture Originally control planted iceplant for has erosion succeeded tremendously at establishing itself Iceplant is a perennial shrub of the fig family Aizoaceae native to South Africa Non native grasses are also present in the park Native plant species occupy a much smaller portion of the park Some of the native species found at Fort Funston include coastal sage scrub plants such as silver sagewort Atemesia Figure 1 Map showing location of Fort Funston sp coyote bush Baccharis sp and Lupinus sp Restoration efforts began in 1991 and consisted of the replacement of non native vegetation notably the iceplant with native vegetation in a portion of the park NPS 2000 GGNRA began this restoration of native vegetation in approximately 23 acres of the northern portion of the park My study sites include both the iceplant inundated and restored areas of the
View Full Document
Unlocking...