Biology of Invertebrates Done at Nielsen Park - Research Paper Example

Field Trip Report on Biology of Invertebrates Done at Nielsen Park Client Inserts His/her Name Client Inserts Grade Course Client Inserts Tutor’s Name 27/09/2011 Field Trip Report on Biology of Invertebrates Done at Nielsen Park Abstract The survey was done at Nielsen Park which is a section of Sydney Harbour National Park. The main objective of the study was to survey the diversity of terrestrial invertebrate fauna within the park and contrast the fauna of areas with differing history of fire. Several different sampling methods were used so as to collect many species as possible. Different habitats were also sampled to achieve the same. Direct search techniques and nets to sweep vegetation were used to sample the invertebrate associated with trees and shrubs. Visually attractive traps were used to sample flying insects. Those flying insects that are normally attracted to odour were sampled by use of odour traps. Ground-dwelling invertebrates were sampled by use of direct searching methods and Barlese funnels. Replicate samples from each main vegetation type in areas that were unburnt and in areas that had been subjected to prescribe burning by the management were collected. It was found that there was no significant difference between the vegetation types, thus woodlands and heath lands had the same effects to the species composition and abundance. It was also found that there was a significant difference to burn types with regards to species compositions and abundance Introduction Nielsen Park preserves the largest area of foreshore bush land south of the harbour. Even though there have been surveys of some of the vertebrates known to use the park, there have been no previous surveys of the terrestrial invertebrates fauna. The fauna of the bush remnants in the park is threatened predominantly by changes to the vegetation they use as habitat. The native vegetation is threatened by weed invasion, excess nutrients, dieback of trees due to Phytophthora, inappropriate fire regimes and physical trampling by visitors. Over 180 species of native plants have been recorded in Nielsen Park. This includes the endangered Nielsen Park she-oak that is only found in this location. The park supports two major plant communities, the coastal sandstone woodland and coastal sandstone heath. Over 120 weed species have also been recorded and the area is the focus of bush regeneration efforts by many volunteer groups. Prescribed burning of sections of the park has been used to promote regeneration of native plants. The goal of the field trip was to come up with a complete species list of invertebrate that would be collected during the survey. The abundance and composition of these species in the habitats sampled were to be measured. Some invertebrates could be identified with the help of the literature that had been provided, while others which could not be identified were sorted into the “morphospecies” group which simply means groups of individuals that we considered being different species based on gross morphology. Even though the main aim of the study was to survey the diversity of terrestrial invertebrate fauna within the park and contrast the fauna of areas with differing history of fire, these specific objectives were to be achieved after the survey; to establish the diversity of terrestrial invertebrates, examining species in their natural habitats, the study was also to contrast the diversity and composition of invertebrates in two habitats that differ in their history of fire. The study was also to help the students gain experience in identifying terrestrial invertebrates, and lastly, the study was objected to examine the relationship between habitat and structure, function and/or reproduction. The study was aimed at addressing the questions about the following; the diversity of the vertebrates collected from the survey, the differences in fauna sampled by the different techniques, and the differences in fauna found between habitats differing in fire history. Methods The sampling design involved collecting samples from each of the main vegetation types (woodland and heath), in areas that were unburnt and in areas that had been subjected to prescribed burning by the management. This was done for each sampling technique. The sampling was designed as follows: Habitat Woodland Heath Burn history Burnt n replicate samples n replicate samples Unburnt n replicate samples n replicate samples Different sampling methods were used to sample invertebrates depending on their habitat. This was done so as to collect as many species as possible from the already identified habitats. The habitats included; invertebrates of vegetation which included those species associated with trees and shrubs, those flying invertebrates that are normally attracted to bright colour, those invertebrates that are attracted to odour, and lastly those ground-dwelling invertebrate species. Two sampling techniques were used to sample invertebrates of vegetation. Timed sweeps with a butterfly net were used. This took five minutes in duration and 6-8 replicates per combination of vegetation type and burn type were collected. Direct searching was also employed for this case. This also took five minutes in duration as 2 replicates per combination of vegetation type and burn type were collected. For the case of those insects which are attracted to bright colours and visual traps were used, two sampling techniques were also employed for this case. First, yellow plastic bowls filled with water to attract flying insects were set up. Detergents were added to the water to reduce the surface tension and increase the likelihood of retaining insects that had flown into the water. Intervals of 60 minutes in duration were allowed whereas 6-8 replicates per combination of vegetation type and burn type were collected. Malaise traps were also set up in each habitat type to help sample the flying insects. However, enough time was not taken to replicate so the collected samples were not included in the formal analysis of the study. Those flying insects that are normally attracted to odour were sampled by use of odour traps. This involved two sampling techniques. First, hanging traps were used. The traps were baited with canned tuna. However, those that were baited with banana were not effective and thus were removed from the analysis. The exercise took intervals of 90 minutes in duration while 3 replicates per combination of vegetation type and burn type were collected. Pitfall traps were also set up. These were baited with a mixture of peanuts and rolled oats. Each interval took 3 hours 15 minutes in duration. 5 replicates per combination of vegetation type and burn type were collected. For those ground-dwelling invertebrates, two sampling techniques were also used to collect the samples. Direct searches of leaf litter on the ground were made. 1 × 1 meter quadrats were used to sample the habitats. The searches took intervals of 15 minutes and 3 replicates per combination of vegetation type and burn type were collected. Berlese funnels were also used in sampling. Here, ¾ of a 20 litre bucket of soil and leaf litter of the top 5 cm of soil from 2 m2 area was collected. Half of the sample was put into the funnels. They were left overnight to extract animals and 2 replicates per combination of vegetation type and burn type were collected. The sampling exercise was designed to be analysed by a two factor analysis of variance (ANOVA). These statistical tests are appropriate for data with a single continuous dependent variable (Y, in our case, total abundance or the number of species), and categorical predictor variables (X, in our case, vegetation type and burn history). Two analyses were obtained from each sampling technique, one for the total abundance (number of individuals per sample) and one for species richness (the number of species per sample). The ANOVA table has tests of the three hypotheses: Do the vegetation types differ? Do the burn types differ? Do these two factors interact? (Does the effect of burn type depend on vegetation type? Results After the raw data was collected and analyses (ANOVA) made, tables with results were generated. Samples of the results in the various habitats were used to come up with various conclusions about the study (Not all tables are used in the report). One sampling technique in each habitat was selected at random to come up with the conclusion. From the tables obtained, if P > 0.05, then the probability that the differences observed are due to chance is high. Here, it can be concluded that there is no significant difference. If P Read More