Vertebrate Biodiversity Assignment Caitlyn Kavanagh PDF

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How Eucalypt woodland forest maturity influences the abundance, richness and composition of bird communities in the Hawkesbury Forest (2019). Caitlyn Kavanagh 18346969

Abstract This study aims to investigate the influence habitat has on species richness, abundance and composition. Specifically, it looks at how the age of eucalypt forest plantations in the Hawkesbury Forest Experiment, NSW, Australia, affects the bird populations. Previous studies have shown that older forests are host to higher rates of biodiversity, mainly due to more ecological niches and microhabitats. Biodiversity is an indicator of the functionality of an ecosystem, and birds are a good indicator of biodiversity as they are easy to observe are characteristically significant to forest ecosystems. The study was conducted by observing the species that were in, or immediately surrounding the chosen sample area. A comparison of young (2011) verse old (2006/7) sites was conducted using 4 main plantations, and taking 6 randomly-selected subsamples as each (4 x 6). Results found that the abundance and species richness was not significantly different between treatments, however there was significance in the composition of diversity in treatments. The older plantations were dominated by less social birds, while young plantations were host to a more diverse population of feeding behaviours. Possible explanations for this relate to the competitive nature of species found in old plantation as well as ‘exploitation’ vs ‘conservation’ stage theories.

Key words: BEF, Noss’s biodiversity model, bird behaviour, forest maturity, life-stage biodiversity, richness, abundance, composition, associational susceptibility, intermediate disturbance theory, plantation

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Table of Contents Abstract............................................................................................................................2 1. Introduction..................................................................................................................4 2. Methods.........................................................................................................................7 2.1 Site and survey method.........................................................................................................7 2.2 Classification of birds............................................................................................................8 2.3 Statistical analysis.................................................................................................................8

3. Results...........................................................................................................................9 3.1 Bird Abundance and Richness..............................................................................................9 3.2 Statistical Analysis of Bird Community Composition..........................................................9

4. Discussion....................................................................................................................12 5. References...................................................................................................................14

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1. Introduction Biodiversity means the variability among living organisms, and the ecological complexes of which they are apart, including diversity within species and of ecosystems (Lundstrom,

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2008). It is an essential factor in determining the survival of an ecosystem. Noss (1990) categorised biodiversity into compositional, structural and functional diversity (See fig 1). Compositional diversity is what the ecosystem consists of in terms of species and gene pool diversity. Structural diversity refers to how the species and components are organised. Functional diversity reflects how the components work together in processes such as nutrient cycling or during disturbances. Figure 1. Noss’s (1990) balance of the three components of biodiversity; (1) compositional, (2) structural and (3) functional.

This study aims to observe the functionality of ecosystems in young plantations in contrast to older plantations. Birds are common and widely distributed, making them an important biological marker of ecosystems. Birds are sensitive to change and quick to respond to environmental stressors, are ecologically meaningful and previous studies allow us to differentiate between natural fluctuations and anthropogenic impact (Cook 1976, Ferris and Humphrey 1999; Munn 1989, Noss 1990). According to Calvino-Cancela, (2013), bird communities are, “good indicators of the ability of modified habitats to harbour biodiversity as they constitute a diverse group relying on a variety of food resources, habitats and microhabitats.” Bird abundance, richness and the populations composition can indicate how limited or diverse the forest resource availability is, can represent habitat availability and reflect other factors such as the effect urbanisation, fragmentation, disease and climatic changes in the region, etc.

The study was conducted in the Hawkesbury forest plantation, which is considered a drysclerophyll woodland (R.M Cooper, et al 1998), as it consists of smooth and rough barked eucalypts. Species expected to occur include cockatoos, rosellas, cuckoos, frogmouths, tree creepers, wrens, miners, honeyeaters, robins, fantails, butcherbirds and thrush, etc., (R.M Cooper, et al 1998). The Hawkesbury forest plantation was utilised for this study as the age of trees and conditions they have been grown in is known and has been recorded, as well as the species present in the plantation. Tree density is consistent between sectors and the plantation has been maintained so that shrubs and other species do no occur, ensuring the study is a strict comparison between the maturity of each ecosystem.

Understanding the effect of biodiversity on ecosystem functioning (BEF) is foundational to comprehending the stability of an ecosystem. A successful forest biome is required to meet the components of Noss’s biodiversity model (1990), as diversity promotes productivity, reflecting a positive relationship in BEF. Forest biodiversity is the foundation of many ecosystem services, and individual species traits play an important role in determining ecosystem functioning and processes (Pan, et al. 2018). Increasingly complex forest structures enable diversified microclimates, niches and habitats for maintaining biodiversity (Pan, et al. 2018) – forest age is an important indicator for these complex forest features, in terms of both tree height, and biomass, which influence biodiversity respectively. Previous studies have revealed that there is a significant difference in the species composition and structure in young and old forests (Moning, et al. 2008). Forest age is one of the most simple 5

but effective key values that may be controlled by forest management. Plantations may provide habitat for forest biodiversity, which may enhance landscape, connectivity and regional biodiversity, and could potentially provide relief to increased habitat fragmentation if effective. In this study, we would expect the old plantation forest to have higher species richness and abundance, as the ecosystem is more developed and potentially more diverse in all aspects, facilitating to more bird species.

The complexity and variability of forest structures may have a strong influence over the integrity of the ecosystem, which can be measured by recording the richness, abundance and composition of bird communities. Increased complexity in forests promotes overall ecosystem diversity, as it ‘provides a wider diversity of foraging sites and microhabitats,’ (Moning, et al. 2008) allowing organisms to specialise, from lichens growing on trees, to insects harboured in biomass, to birds who contribute to keeping the system in balance and support continuity.

Understanding the key aspects of biodiversity is essential in making a full assessment on an ecosystems strength and weaknesses. Using birds as a biological indicator, this study aims to: 1. Assess the influence of habitat maturity on biodiversity by observing species richness and abundance in plantations regulated under the Hawkesbury Institute for the Environment. 2. Establish how habitat life-stage influences the composition of local bird communities.

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2. Methods 2.1 Site and survey method The Hawkesbury forest institute provides a unique environment where the life stage, plant diversity and density is known. Plots planted during the 2006/2007 planting event are able to be contrasted to the 2011 planting event. The study involved a total of 24 surveys conducted at 4 different plots of eucalypt plantation, considered as either ‘mature’ (2006/2007) or ‘young’ (2011) based on the year the plantation was initiated at the Hawkesbury Forest Institute, labelled Y1, Y2, O1 and O2 (figure 2). The density of O1 and O2 plots was 1000 trees/ha with a spacing of 3.85m between rows, while Y1 and Y2 had a density of 1600 trees/ha, with a spacing of 3.75m between rows. The Y plots were slightly smaller in surface area than the O plots, but the number of trees did not vary significantly as a result of density. The samples were taken at approximately 10am, over 3 different dates with similar weather patterns.

Of these 4 plots, 6 random sites were chosen using a random number generator. The random number generator was used to produce 2 numbers from the range of the x and y axis of each

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plot, which selected the tree in which the survey would be conducted from. The species of eucalypt used in the experiment can be found in appendix A. Once the sites were determined, a resettlement period* of 2 minutes was taken before commencing each survey, which lasted 5 uninterrupted minutes and accounted for birds that landed in trees, on the forest floor, and birds flying over the site. Individual species were recorded, and abundance was tallied. Binoculars were used to identify important details of the birds observed.

Figure 2. Map of the Hawkesbury forest institute plots, with record of the plantation age, and the species in each plot. *Silent period after reaching site

2.2 Classification of birds During the survey, known bird species were recorded, and a description of the appearance and behaviour of unknown birds was taken down to identify after the survey, using “The Australian Bird Guide” written by Peter Menkhorst, et al.

The guide was also used to classify the birds into different functional groups in order to develop an understanding of the composition of each specific community. The classification is based on the criteria used by (Calvino-Cancela, 2013). Bird species were grouped according to:  

Their behaviour in an ecosystem – (a) aggressive/territorial, (b) gregarious/social, (c) lives in breeding pair, (d) solitary species Their main food resources – (a) prey/carrion, grouping predatory birds that hunt vertebrates and those feeding on dead and decaying animals, (b) insects, (c) seeds and (d) fleshy fruits.

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 

Their main habitat – (a) forest specialist (b) forest generalist (c) those typical of shrublands and open habitats and wooded areas (d) ubiquitous species – both open and wooded areas Also, classified by conservation status

2.3 Statistical analysis Richness and abundance To analyse the richness and abundance of bird populations, the data was summarised for each site (4 x 6) into a total population and total no. species, and then calculated into a total population size and total species richness for young vs. old plantations. Two tailed T-tests were used to determine any significance between the sites in terms of richness and abundance.

Composition After classifying the birds as per the criteria in 2.2; -

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Means were calculated to determine at what value we could expect certain characteristics to occur in contrasting sites. This was calculated by no. total birds to give insight to the population structure. Two sample paired tests were conducted to determine the statistical significance of the data. For example, the number of territorial birds per sample in O1 & 2 were compared to the number of territorial birds per sample in Y1 & 2, as well as the number of species of territorial birds. Pearson’s correlation tests were used to determine a statistical correlation between site and community structure.

3. Results 3.1 Bird Abundance and Richness Overall, both the young and old plantations harboured 12 species each in total across 12 samples each. The total population size of the young plots was 48, while the old plots had a total population of 53, (Table 1).

Table 1. A representation of bird species richness and abundance in the HIE forest experiment plantation, taken between 19.08.19 – 12.09.19.

Site No. Species Y1.1 Y1.2 Y1.3

No. Birds 3 3 1

Site No. Species 6 7 3

O1.1 O1.2 O1.3

No. Birds 3 5 1

7 8 1

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Y1.4 Y1.5 Y1.6 Y2.1 Y2.2 Y2.3 Y2.4 Y2.5 Y2.6 Totals

2 2 3 3 4 0 0 1 0 12

3 8 5 6 9 0 0 1 0 48

2 1 3 1 1 0 2 2 1 12

O1.4 O1.5 O1.6 O2.1 O2.2 O2.3 O2.4 O2.5 O2.6

6 7 10 2 3 0 2 5 2 53

There was little variation in overall species richness and abundance. Both the young and old plantations saw an average of 1.8333 species per sample, resulting in a P value of = 1 and no statistical significance in species richness. The population size was also found to be statistically insignificant by the two-tailed p test (p=0.72), suggesting the life stage of plantation forests has no effect on the richness and abundance of bird populations.

3.2 Statistical Analysis of Bird Community Composition The following birds were observed in the Hawkesbury plantation and were classified based on conservation status, behaviour, habitat and diet (Table 2). All species shared a conservation status of ‘least concern.’ Gregarious or social birds were most common, along with habitat generalists. Diet varied amongst species but was consistent with what the forest plantations had to offer.

Table 2. Characteristics of birds observed in the Hawkesbury Forest Experiment, taken from the BirdLife guide to Australian Birds

Conservation Status Australian Raven least concern

Behaviour

Habitat

Diet

Aggressive

Generalist Generalist

Eastern Rosella least concern

Very aggressive & territorial Gregarious

Generalist

Crusted Pigeons least concern

Gregarious

Generalist

Omnivore/opportu nistic feeders Nectar, fruit and insects Ground feeder, seeds, fruits and buds Seeds

Rainbow least concern Lorikeet

Gregarious

Generalist

Nectar and pollen

Noisy Minor least concern

10

least concern

Gregarious

Specialist

Seeds

least concern

Mostly solitary

Generalist

Carnivore

least concern

Gregarious

Generalist

Carnivore

least concern

Aggressive

Generalist

Carnivore

Fairy Wren least concern

Gregarious

Specialist

Insectivore

Galahs least concern

Gregarious

Generalist

Seeds

Tawny least concern Frogmouth Grey Goshawk least concern

Gregarious

Specialist

Carnivore

Live in mating pairs

Generalist

Carnivore

Aggressive

Generalist

Live in mating pairs

Generalist

Omnivore/opportu nistic Nectar feeder

Aggressive

Generalist

Insectivore

Red-Rumped Parrot Eastern Yellow Robin Grey Shrike Thrush Kookaburra

Indian Minor least concern Little Wattlebird least concern Magpie Lark least concern

Three characteristics of interest were selected and compared amongst young and old populations (Fig 3). This figure shows that there is small difference in habitat and dietary behaviours of birds between treatments. This is confirmed with a Pearsons correlation test which showed that the correlation between habitat specialists in old and young plantations was approximately 0.04, and approximately 0.3 for the occurrence of carnivorous birds, indicating a weak correlation between the factors.

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Comparison of particular characteristics found in birds in Young vs. Old eucalypt plantations 3.5

Average birds per sample

3 2.5 2 1.5 1 0.5 0

No. territorial/aggressive birds

No. specialist birds

No. Carnivorous birds (including omnivores)

Bird species characteristics Young Plantation

Old Plantation

Figure 3. A comparison of the occurrence bird characteristics in young and old plantations to determine which influence the community composition the most significantly. Surveys conducted in the HIE forest experiment between the 19.08.19 – 12.09.19.

Using figure 3 as a guide, further analysis was conducted to determine the statistical significance of the population size of territorial birds on the composition of bird communities in the forest experiment. A two-sampled t-test was used (Table 3). It found that p = 0.01, indicating statistical significance between populations. The Pearsons correlation = 0.62 indicating moderate to strong correlation.

Table 3. T-Test: paired two samples. Number of territorial birds in young plantations vs. old plantations. Mean Variance Observations Pearson Correlation df t Stat

P(T...