SOIL COLLEMBOLA UNDER DIFFERENT CONIFER SPECIES ON SOUTHERN VANCOUVER ISLAND, BRITISH COLUMBIA by B. BAUMBROUGH B. Sc., The University of British Columbia, 1990 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Department of Soil Science) We accept this thesis as conforming |R5N{he required standard/ THE UNIVERSITY OF BRITISH COLUMBIA 1998 © B. Baumbrough, 1998 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia Vancouver, Canada DE-6 (2/88) ABSTRACT Three separate but related studies examined collembolan populations under single- species forest stands and how these forest covers might influence feeding in Collembola. In November 1993, a preliminary investigation examined the effects of single-species conifer stands on the density and species diversity of soil collembola on southern Vancouver Island, British Columbia. The top 3 cm of 4.4 cm diameter soil cores, sampled from experimental plots of western redcedar, Douglas-fir, western hemlock, and Sitka spruce, were extracted for collembola using a high gradient extractor. Average linkage cluster analysis of Renkonen's percentage similarity and Morisita's similarity indices did not indicate distinct collembolan communities under each conifer species. However, the density and species richness of collembola under the four conifer species were sufficiently different to imply that further investigation was warranted. A second study was conducted in November 1995 and in May 1996. Soil cores were collected and extracted from two replicate plots of the four conifer species at three different sites located on southern Vancouver Island. Results of this study reflected those ofthe preliminary investigation. Distinct collembolan communities among each ofthe conifer species were not clearly demonstrated using Morisita's similarity index and average linkage clustering. However, significant differences in collembolan density and species richness among conifer species were found using the GLIMMEX procedure in SAS. Collembolan density and species richness was lowest under the western redcedar plots and highest under the Sitka spruce plots. The Modified Simpson's and the Modified Shannon-Wiener indices demonstrated that the structure of the collembolan communities varied only slightly under the different conifer species and was most often characterized by one or two dominant collembolan species and several rare species. Percent moisture content, bulk density and pH were determined from each ii soil core extracted for collembola. Statistical analysis of these data revealed no significant differences among conifer species. In the third investigation, the feeding attributes of collembola species, sampled in the previous investigation from Sitka spruce, Douglas-fir, and western redcedar, were assessed by analysis of the gut contents of mounted specimens. Statistical analysis of the results from five common species found no significant differences in the feeding habits within a collembolan species and between collembolan species among the three conifer species. In November 1993, a preliminary investigation examined the effects of single species conifer stands on the abundance and species diversity of soil collembola on southern Vancouver Island, British Columbia. The top 3 cm of 4.4 cm diameter soil cores, sampled from experimental plots of western redcedar, Douglas-fir, western hemlock, and Sitka spruce, were extracted for collembola using a high gradient extractor. Average linkage cluster analysis of Renkonen's percentage similarity and Morisita's similarity indices did not indicate distinct collembolan communities under each conifer species. However, the density and species richness of collembola under the four conifer species were sufficiently different to imply that further investigation was warranted. A second study was conducted in November 1995 and in May 1996. Soil cores were collected and extracted from two replicate plots of the four conifer species at three different sites located on southern Vancouver Island. Results of this study reflected those of the preliminary investigation. Distinct collembolan communities among each of the conifer species were not clearly demonstrated using Morisita's similarity index and average linkage clustering. However, significant differences in collembolan abundance and species richness among conifer species were found using the GLIMMEX procedure in SAS. Collembolan density and species richness was lowest under the western redcedar plots and highest under the Sitka spruce plots. iii The Modified Simpson's and the Modified Shannon-Wiener indices demonstrated that the structure ofthe collembolan communities varied only slightly under the different conifer species and was most often characterized by one or two dominant collembolan species and several rare species. Percent moisture content, bulk density and pH were determined from each soil core extracted for collembola. Multivariate analysis of this data revealed no significant differences among conifer species. In the third investigation, the feeding attributes of collembola species, sampled in the previous investigation from Sitka spruce, Douglas-fir, and western redcedar, were assessed by analysis ofthe gut contents of mounted specimens. Statistical analysis of the results from five common species found no significant differences in the feeding habits within a collembolan species and between collembolan species among the three conifer species. IV TABLE OF CONTENTS Abstract ii Table of Contents v List of Tables vj List of Figures vii Acknowledgements viii CHAPTER 1: Genera! Introduction 1 CHAPTER 2: Preliminary assessment ofthe density and species diversity of soil Collembola under different conifer species 2.0 Introduction 9 2.1 Study site 10 2.2 Methods 11 2.2.1 Data Analyses 12 2.3 Results 12 2.3.1 Similarity indices and cluster analysis 18 2.4 Discussion 22 CHAPTER 3: Assessment of the density and species diversity of soil Collembola under different conifer species 3.0 Introduction 26 3.1 Study sites 29 3.2 Methods 31 3.2.1 Data Analysis 33 3.3 Results 34 3.3.1 Abundance data 3 4 3.3.2 Species diversity 34 3.3.3 Time of sampling 58 3.3.4 Soil moisture, bulk density, and pH 58 3.4 Discussion 60 CHAPTER 4: Gut content analysis of Collembola collected from different conifer species. 4.0 Introduction 69 4.1 Study Sites 71 4.2 Methods 71 4.2.1 Data analysis 72 4.3 Results 72 4.3.1 Feeding attributes of individual species 77 4.3.2 Tree species effect 85 4.3.3 Time of sampling 86 4.3.4 Parasites 86 4.4 Discussion 91 CHAPTER 5: General Conclusions 98 Literature Cited 100 V LIST OF TABLES Table 2.1. Forest floor collembolan species found in soil core samples taken from 35 year 13 old plantations on south Vancouver Island. Collembola sampled from four conifer species each planted at three different spacings. Table 2.2. Comparison of collembolan mean density (individuals m"2) and diversity 20 under four forest covers. Table 3.1. Analysis of collembolan density data using Log Linear model. 37 Table 3.2. Least square means of the log of the expected count and standard error of 37 collembolan density data. Table 3.3. P-values from pair-wise comparisons of collembolan density under conifer 37 species. Table 3.4. Collembolan species identified from three installations of EP571 in November 38 1995 and May 1996. Table 3.5. Analysis of collembolan species richness data using Log Linear model. 45 Table 3.6. Least square means of the log of the expected count and standard error of 45 collembolan species richness data. Table 3.7. P-values from pair-wise comparisons of collembolan species richness under 45 conifer species. Table 3.8 Comparison of Richness and Evenness of collembolan species collected 46 November 1995. Table 3.9 Comparison of Richness and Evenness of collembolan species collected May 47 1996. Table 3.10. Mean density and percentage of the total abundance of common and/or 53 dominant collembolan species collected in November 1995. Table 3.11. Mean density and percentage of the total abundance of common and/or 55 dominant collembolan species collected in May 1996. Table 3.12. Analysis of moisture content, bulk density, and pH data. 59 Table 3.13. Least square means of moisture content, bulk density, and pH. 59 Table 4.1. Percentage of individuals of all species which contain various gut components. 73 Table 4.2. Analysis of gut content data to test for differences among five 83 collembolan species. Table 4.3. Analysis of collembolan gut content data to test for differences among conifer 87 species. /. notabilis, I. uniens, M. achromata, N. minimus, and T. yosii analysed separately. Table 4.4. Comparison of the quantity of fungal hyphae in gut contents of five species of 88 collembolans collected in November 1995 from three different conifer species. Percentage of individuals with gut contents at least 50% hyaline or darkly pigmented hyphae. Table 4.5. Comparison of the quantity of fungal hyphae in gut contents of five species of 89 collembolans collected in May 1996 from three different conifer species. Percentage of individuals with gut contents at least 50% hyaline or darkly pigmented hyphae. VI LIST OF FIGURES Figure 2.1. Tree diagram resulting from average linkage cluster analysis of Renkonen's 21 index of percent similarity of Collembola species data. Figure 3.1 Map of location of sampling sites. 31 Figure 3.2 Relative mean density (individuals m"2) of Collembola collected from four 36 conifer species at three different installations and two different sampling times.