An Assessment of Invertebrates Diversity within Woodland and Grassland Habitats in Selected Nature Reserves

| July 31, 2017

Abstract

This report assesses the differences between two major types of habitats, woodland and grassland habitats. The emphasis is on the evaluation of invertebrates diversity within woodland and grassland habitats in selected nature reserves. For that purpose, three methods of collecting invertebrates are suggested to include pitfalls, beating and sweeping. It is concluded that the comparison between biodiversity issues in woodland and grassland habitats might contribute to more efficient management of those habitats in the future.

 

Key Words: woodland habitats, grassland habitats, invertebrates, ecosystems

 

Introduction

The exploration of different habitats enables individuals with a significant opportunity to focus on specific features of diversity exhibited in particular places, either in woodland or grassland habitats (Schuster et al., 2015). Woodland habitats tend to demonstrate extensively diverse characteristics across the United Kingdom in terms of subtypes and plants. Multiple factors, such as changes in climate, geology, soils and historical tendencies, turn out to influence the way habitats develop (Palo et al., 2013). The presence of trees emerges as one of the apparent physical characteristics of woodland habitats despite the availability of specific types of forests in different climate conditions across the United Kingdom. Unlike forests where space is limited as a result of the tendency of grouping trees, woodland habitats have an open space. This type of habitats are unique and varied within the United Kingdom, as they turn out to define the local landscape in a distinct manner (Schuster et al., 2015). The history of woodland habitats in the United Kingdom can be traced after the period of the last Ice Age, which represents a significant moment when trees completely recolonised the land. Nonetheless, the degree to which the original forest cover is currently preserved is unclear. It has been identified that approximately 2% of the United Kingdom has woodland habitats existing since the period of the Middle Ages (Corbane et al., 2015).

In comparison, Agate (2002) refers to the specificity of grassland habitats as extremely rich wildlife habitats across the United Kingdom. Most known grassland habitats are actually defined as semi-natural, illustrating a historical tendency of alterations imposed as a result of  different farming practices (Agate, 2002). This type of habitats is widely recognised for the presence of plant and invertebrate life. Another unique feature of grassland habitats is the presence of an extensive range of mammals and birds (Corbane et al., 2015). In this form of habitats, different species of wildlife use the capacities allowed by open spaces to meet their needs for food and cover.

Conducting a comparison of the two habitats is of value because it is important to consider the ecological benefits of such forms of habitats, as indicated by Agate (2002). Performing biodiversity assessments in both woodland and grassland habitats is a well-grounded and researched activity pertaining to an accurate determination of the health status of a particular environment (Sarthou et al., 2014). As a result, a substantial range of taxonomic groups within these habitats might be explored, presenting their ecological characteristics and specific functions. Research shows that the invertebrate community is a relevant indicator of environmental health dimensions (Corbane et al., 2015).

A comparison between woodland and grassland habitats is beneficial for future management of such habitats. The reason why the focus in this research is on invertebrates is because they are closely linked with the maintenance of biodiversity in habitats. Providing a sufficient knowledge of the way these habitats function is crucial in underlining management issues that can be used to guide future research efforts (Corbane et al., 2015). In addition, the proper management of habitats leads to expanding biodiversity and increasing the levels of light (Brambilla and Saporetti, 2014). The dimension of substantial structural diversity also should be considered as one of the management concerns for maintaining an adequate balance within woodland and grassland habitats (Hooftman and Bullock, 2012). Therefore, the current paper aims at exploring the notion of invertebrates diversity within woodland and grassland habitats in selected nature reserves. The focus in this report is on woodland and grassland habitats.

 

Literature Review

This section of the report provides information on habitat types and Simpson’s index of diversity, which is identified in research as a reliable measure of diversity (Wan et al., 2014). In addition, other topics covered in the literature review refer to Shannon and Jaccard similarity indices in the process of analysing biodiversity data, as those indices also present effective measures of diversity (Palo et al., 2013).

 

Habitat Types

In the habitat classification system pertaining to the categorisation and grouping of different forms of habitats (Corbane et al., 2015), researchers include numerous broad categories, such as woodland and scrub, grassland, mire, tall herb and fen, heathland, open water spaces, swamp, coastland, exposure and waste, and other categories. It is essential to note that amongst the mentioned broad habitat types, more specific habitat types are recognised, each represented by its own name, code and unique description (Palo et al., 2013). Corbane et al. (2015) indicate that the proper classification of habitat types is useful in recording different aspects of semi-natural vegetation as well as specific forms of wildlife habitats. The classification technique used in the mentioned system aims to cover substantial areas of countryside, which provides a sufficient basis for comparison among different habitats. The accurate assessment of habitat types contributes to more relevant practices used for nature conservation (Komonen and Kouki, 2011).

Although trees are the dominant plant form in woodland habitats, other forms can be found, such as mosses, ferns and lichens, and different types of grasses (Villemey et al., 2015). A significant rule pertaining to the specificity of woodland habitats is that the extensive diversity of plants determines the animal diversity within this type of habitats. The variations of woodland habitats are determined by the dominant tree species presenting the wood and the spacing available between separate trees. Such factors are considered fundamental in determining the precise amount of light that enters into the main leaf canopy and reaches the woodland floor (Suurkuukka et al., 2014). Tree spacing is determined in a natural way in woodland habitats because the focus is on the competition occurring between individual trees in terms of light, space and water.

Nature in woodland habitats emerges with its ultimate recycling qualities (Corbane et al., 2015). For instance, dead rotting wood has the capacity for a rich hunting ground (Palo et al., 2013). Woodland habitats are characterised with a solid amount of invertebrates, especially in the United Kingdom where their number accounts to more than 1,700 different kinds (Agate, 2002). Two major types of woodland habitats are identified, such as coniferous woodland and broadleaf woodland in selected nature reserves across the United Kingdom. Coniferous woodland habitats mostly consist of conifers, which are described as trees with needle-like leaves. Another characteristic of those trees is that they are commonly evergreen; they also produce their seeds inside specific cones. Broadleaf woodland habitats consist of trees with a huge variety of leaf shapes (de Noronha and Vaz, 2015). Yet both subtypes of woodland habitats are adapted to various climate conditions. Conifers are usually present in quite cold climates, while broadleaf trees are adapted to either cold or mild winter temperatures.

As the name of grassland habitats suggests, this type of habitats is dominated by lands covered in grasses and grass-like plants. It has been indicated that grassland habitats tend to support a quite high density of grazing animals. However, grassland ecosystems have the disadvantage of being fragile as a result of the scarce availability of water (Knudson et al., 2015). It appears that grassland habitats are commonly targeted for human development, but such processes are usually associated with harmful outcomes, which should be considered in the process of managing those habitats (Palo et al., 2013). In the United Kingdom, a widespread type of grassland habitats is identified as chalk grassland, which can be mainly found in southern England (Natural History Museum, 2015). Numerous flowering plants and insect life are present in chalk grassland. A traditional management method of chalk grassland identified in history is sheep grazing. Nonetheless, the intensive use of agriculture in such places had led to a declined quality of chalk grassland since the 1940s.

 

Simpson’s Index of Diversity

The notion of biodiversity is important for the simple existence of habitats, which increases the need to use accurate indices of biodiversity data analysis. Simpson’s index of diversity is a uniform measure of diversity (Wan et al., 2014). In ecological terms, the respective index is used to quantify the biodiversity characteristics of different habitats. The precise number of species present in those habitats should be appropriately determined (Wan et al., 2014). Another significant criterion used for the classification of species in Simpson’s index of diversity relates to the abundance of each of those species, which might be beneficial in determining or forecasting certain diversity trends in the future. It is emphasised that the increase of the richness and evenness of species corresponds to expanded values of diversity over time (Zhang and Zhou, 2010). The most important objective of Simpson’s index of diversity is to represent an accurate quantitative estimate of biological variability in habitats, which will further facilitate efforts to compare the qualities of different biological entities.

Measuring the density of species is important for the conduct of a complete assessment of habitats. The major aspect behind the use of Simpson’s index of diversity is the dimension of probability that two specimens might be identified as belonging to the same types of species (Wan et al., 2014). There are two major degrees of diversity based on this index, in particular low diversity (0) and high diversity (0.9999). This indicates the use of a simple mathematical formula to provide relevant information about the diversity within habitats.

 

Shannon and Jaccard Similarity Indices

The analysis of biodiversity data is often facilitated with the use of Shannon and Jaccard similarity indices. Values presented on Shannon-Weiner index might range from 0 to 4, implying the presence of a substantial number of types of species within particular habitats, including woodland and grassland habitats (Zhang and Zhou, 2010). The values on the mentioned index are usually represented by the variable H. Similar to Shannon-Weiner’s index, Simpson’s index of diversity demonstrates an extensive range of organisms within different habitats, as these are represented by the variable D. Moreover, Jaccard’s index of similarity refers to the measurement of the precise way in which two different sample sets are represented (Magurran, 2003). Yet it is important to ensure that Jaccard’s index of similarity tends to ignore the abundance of different species. This means that Jaccard’s index is solely based on the comparison between the presence and absence of certain species (Wan et al., 2014).

 

 Methodology

A primary research was performed by the researcher, as the research approach and strategy selected for this study referred to quantitative methodology. It has been identified that quantitative approach might provide more accurate, specific and measurable outcomes compared to the qualitative approach (Zhang and Zhou, 2010). The study used pitfalls, beating and sweeping to collect invertebrates in both woodland and grassland habitats. The major research question identified in the study refers to the prediction of significant differences in diversity between habitats and across sites. The mentioned techniques are useful in monitoring invertebrates living on foliage and represented in low vegetation. The method of pitfalls is used for catching significant numbers of invertebrates with minimum efforts (Zhang and Zhou, 2010). Yet an emerging disadvantage of pitfalls refers to their insufficiency in comparing different numbers over time and across sites. This is because catch rates vary with the specific structure of surrounding vegetation in both habitats. The utilisation of the beating technique involves tapping branches using a special stick, as invertebrates are trapped into a beating tray where they are held securely for further assessment and analysis (Magurran, 2003). Sweeping relates to a process of using a sweep net with back and forth movements to catch invertebrates. The use of multiple techniques to collect invertebrates promises to yield objective results regarding the richness and density of species found in both habitats.

 

Conclusion

This report focused on the importance of differentiating between two major types of habitats, woodland and grassland habitats. It has been argued that a comparison between the two habitats is important for maintaining an adequate balance of habitat ecosystems and guiding more efficient management of those habitats. The paper included a literature review in which different concepts related to the differences in woodland and grassland habitats were examined (Agate, 2002). Other aspects included in the literature review section referred to a description of Simpson’s index of diversity as well as an overview of Shannon and Jaccard similarity indices. These indices are preferred over other indices in analysing biodiversity data because they represent quite accurate and objective formulas of assessing the richness and abundance of particular species in both woodland and grassland habitats (Zhang and Zhou, 2010). In terms of methodology, the researcher focused on the use of three common techniques of collecting invertebrates, such as pitfalls, beating and sweeping, which were identified as effective in catching a substantial amount of invertebrates for research purposes. In conclusion, an assessment of biodiversity issues in woodland and grassland habitats might help researchers in the field present adequate insights into the emergence of different species and development of flexible ecosystem trends in those habitats.

 

References

Agate, E. (2002). The Urban Handbook. Doncaster: British Trust for Conservation Volunteers.

 

Brambilla, M. and Saporetti, F. (2014). ‘Modelling Distribution of Habitats Required for Different Uses by the Same Species: Implications for Conservation at the Regional Scale’. Biological Conservation, 174, pp. 39-46.

 

Corbane, C., Lang, S., Pipkins, K., Alleaume, S., Deshayes, M., Millan, V., Strasser, T., Borre, J., Toon, S. and Michael, F. (2015). ‘Remote Sensing for Mapping Natural Habitats and Their Conservation Status-New Opportunities and Challenges’. International Journal of Applied Earth Observation and Geoinformation, 37, pp. 7-16.

 

de Noronha, T. and Vaz, E. (2015). ‘Framing Urban Habitats: The Small and Medium Towns in the Peripheries’. Habitat International, 45, pp. 147-155.

 

Hooftman, D. A. and Bullock, J. M. (2012). ‘Mapping to Inform Conservation: A Case Study of Changes in Semi-Natural Habitats and Their Connectivity over 70 Years’. Biological Conservation, 145(1), pp. 30-38.

 

Knudson, M. D., VanLooy, J. A. and Hill, M. J. (2015). ‘A Habitat Suitability Index (HSI) for the Western Prairie Fringed Orchid (Platanthera praeclara) on the Sheyenne National Grassland, North Dakota, USA’. Ecological Indicators, 57, pp. 536-545.

 

Komonen, A. and Kouki, J. (2011). ‘Do Woodland Key Habitats Really Support the Functionality of Reserve Networks?’ Biological Conservation, 144(2), pp. 1-667.

 

Magurran, A. E. (2003). Measuring Biological Diversity. New York: Wiley-Blackwell.

 

Natural History Museum (2015). ‘Chalk Grassland’ [online]. Available at: http://nhm.ac.uk/nature-online/british-natural-history/british-habitats/chalk-downland/index.html [Accessed on: 16 July 2015].

 

Palo, A., Ivask, M. and Liira, J. (2013). ‘Biodiversity Composition Reflects the History of Ancient Semi-Natural Woodland and Forest Habitats-Compilation of an Indicator Complex for Restoration Practice’. Ecological Indicators, 34, pp. 336-344.

 

Sarthou, J. P., Badoz, A., Vaissiere, B., Chevallier, A. and Rusch, A. (2014). ‘Local More than Landscape Parameters Structure Natural Enemy Communities during Their Overwintering in Semi-Natural Habitats’. Agriculture Ecosystems & Environment, 194, pp. 17-28.

 

Schuster, C., Schmidt, T., Conrad, C., Kleinschmit, B. and Forster, M. (2015). ‘Grassland Habitat Mapping by Intra-Annual Time Series Analysis-Comparison of RapidEye and TerraSAR-X Satellite Data’. International Journal of Applied Earth Observation and Geoinformation, 34, pp. 25-34.

 

Suurkuukka, H., Virtanen, R., Suorsa, V., Soininen, J., Paasivirta, L. and Muotka, T. (2014). ‘Woodland Key Habitats and Stream Biodiversity: Does Small-Scale Terrestrial Conservation Enhance the Protection of Stream Biota?’ Biological Conservation, 170, pp. 10-19.

 

Villemey, A., van Halder, I., Ouin, A., Barbaro, L., Chenot, J., Tessier, P., Calatayud, F., Martin, H., Roche, P. and Archaux, F. (2015). ‘Mosaic of Grasslands and Woodlands Is More Effective than Habitat Connectivity to Conserve Butterflies in French Farmland’. Biological Conservation, 191, pp. 206-215.

 

Wan, N. F., Gu, X. J., Ji, X. Y., Jiang, J. X., Wu, J. H. and Li, B. (2014). ‘Ecological Engineering of Ground Cover Vegetation Enhances the Diversity and Stability of Peach Orchard Canopy Arthropod Communities’. Ecological Engineering, 70, pp. 175-182.

 

Zhang, Z. and Zhou, J. (2010). ‘Re-Parameterization of Multinominal Distributions and Diversity Indices’. Journal of Statistical Planning and Inference, 140(7), pp. 1731-1738.

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