Development of a Biotope Quality Index

Bredenhand, Emile (2014-04)

Thesis (PhD)--Stellenbosch University, 2014.

Thesis

ENGLISH ABSTRACT: As the world’s human population increases, more pressure is placed on the management of natural resources. In response, we need an efficient means of monitoring, not only the quantity of these resources but also their quality. No comprehensive standard metric has been developed to assess environmental quality of a biotope, or to define the nature and extent of environmental degradation at this spatial scale. Currently in conservation management, various landscapes are being evaluated for spatial heterogeneity, by making use of species surrogates such as species richness, relative abundance, diversity indices and phylogenetic indices, as well as environmental surrogates. These values are then used towards conservation, where those systems with high intrinsic heterogeneity are usually considered more important than those with low heterogeneity at least when given the choice between the two. Yet, the actual quality of the biotopes within the landscapes is rarely taken into consideration. This study therefore develops and tests a Biotope Quality Index (BQI) to study this point in depth. The BQI makes use of arthropod assemblages as bioindicators of the level of disturbance within a biotope. Firstly, I summarize the literature on the concept of environmental health, and define it as “An ecosystem is healthy, if it can sustain an optimal number of species with optimal population sizes and their ecological processes, thus providing and optimal heterogeneous sustainable system with sufficient resources, and indicated adequate resistance when under perturbational stress, but still allowing natural succession to take place” Against this background, I then review the use of certain Arthropoda as bioindicators, as arthropods are small, mobile, environmentally sensitive, easily sampled, and readily available. These features together make arthropods good subjects for testing the BQI. I then compare the BQI with diversity indices currently used as surrogates of biotope quality. The outcome was that the BQI stood out as a significantly better indicator than the currently available indices for assessing environmental quality of a biotope. Furthermore, during the selection process, I also tested the use of guilds for BQI evaluation, and found that the scavenger (represented by Formicidae) and decomposer (represented by Collembola) guilds were the most significant. The effect of seasonality was also tested. I found the best results with the BQI were when data are pooled from all seasons of the year. A case study, making use of the BQI evaluation, was conducted at a site in the Cape Floristic Region, South Africa (Jonkershoek Valley). BQI results suggested that the agricultural management and tourism within the locality might have an effect on biotope quality. This study has shown that use of the BQI is a useful and practical management tool for evaluating environmental quality of a biotope towards conservation management.

AFRIKAANSE OPSOMMING: Met die vermeerdering van mense op die Aarde, wat meer druk plaas op ons natuurlike hulpbronne en omgewing is daar ‘n aanvraag na doeltrefende maniere wat nie net die kwantiteit maar ook die kwaliteit van die hulbron evalueer. Geen betroubare standard bestaan om biologiese kondisies of die kwaliteit van n omgewing te meet nie. Heidiglik maak wetenskaplikes staat op die bepaling van diversiteit en ander voogde soos spesies rykheid en diversiteit indeksies as voog vir kwaliteit. Die waardes word dan gebruik binne die omgewings bestuur praktyke en bevooroordeel omgewings met ‘n hoë diversiteit, terwyl die kwaliteit van omgewing skaarslik na gekyk word. Hiervolgens, onwikkel ons n Omgewings Kwaliteit Indeks (OKI), wat gebruik maak van Arthropoda saamestellings as bioindikator van die vlak van verval binne ‘n omgewing. Verder sluit die tesis n literatuur studie van die omgesings gesondheid teorie, en die gebruik van arthropoda as bioindikators. As basis van die studie, definieër ons ‘n gesonde omgewings as ‘n omgewing wat’ n optimal hoeveelheid spesies en hulle ekologiese prosesse kan handhaf, en daarom verwys na ‘n diverse onderhoubare sisteem met genoegsame hulpbronne en kan genoegsame weerstand bied onder omgesings stres, maar gee geleentheid vir naturlike suksesie om plaas te vind Ons het verder die OKI getoets teen ander diversiteit’s indeksies, waar ons gevind het dat die OKI evaluering ‘n statistiese beklemtonde verskil toon as bioindikator van omgewings kwaliteit. Verder het ons voorkeer getoets, in gedrags groupe en gevind dat die versamellaars groep (verteeenwoordig deur Formicidae) en die afbrekers groep (verteenwoordig deur Collembola) die beste resultate toon. Seisoene het ook ‘n uitwerking en ons het gevind die groupeering van data ingesamel oor alle seisoene die beste resultate getoon. ‘n Ondersoek studie wat gebruik maak van die OKI evalueering, was gekondakteer in die Jonkershoek valei en het getoon dat die landbou plaagbestuur en toerusme ‘n negatiewe effek het op die omgewing. Verder het die OKI evalueering getoon dat aanplanting van Denne plantasies die kwaliteit van ‘n omgewing verlaag. Die studie het verder getoon dat die OKI evalueering ‘n betroubare evalueerings metode is vir die bestuur van ‘n omgewings, terwyl die diversiteits indeksies nie geskik is as bioindikator van omgewings kwaliteit nie.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/86403
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