FORMICA INTEGROIDES OF SWAKUM MOUNTAIN: A Qualitative and Quantitative Assessment and Narrative of Formica mounding behaviors influencing litter decomposition in a dry, interior Douglas-fir forest in British Columbia by Adolpho J. Pati A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in The Faculty of Graduate and Postdoctoral Studies (Forestry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) September 2014 © Adolpho J. Pati, 2014 Abstract Formica spp. mound construction is fundamental to northern forests as their activities govern and shape forest floor dynamics and litter decomposition. The interior Douglas-fir forest at Swakum Mountain contains a super colony of Formica integroides whose presence and monolithic structures dramatically demonstrate their impact on the landscape. Through a series of observations, natural and controlled experiments I examine the effects of Formica mounding on litter decomposition. The basic measurements of temperature, moisture, evolved CO2, and mass loss reveal that Formica mounds buffer litter decomposition as Douglas-fir needles are carefully stacked, stockpiled, and assembled into thatch, where at the depth of ~ 8 cm thatch mass loss minimizes and begins to stabilize. The function of Formica mounding further exacerbates the prevailing arid conditions endemic to this forest type. Cotrufo's Microbial Efficiency-Matrix Stabilization (MEMS) framework sets forth a conceptual model where labile plant constituents are efficiently utilized by microbes and stabilized into soil organic matter (SOM). I integrate my findings within this framework while conceptualizing aspects of complexity theory as potential ecological drivers contributing to soil organic matter formation relating to Formica mounds. Through natural and controlled experiments my overall objective is to describe and explain litter decomposition involving Formica spp. within an interior Douglas-fir forest. I have included descriptive observations, sketches, and photographs involving the forest floor and Formica spp. behaviors and ecology to provide a holistic perspective describing litter decomposition within this local forest type. The framework of scientific methodology combined with a novel approach, provides further empirical and qualitative support for the findings of my research. ii Preface This dissertation, all poetry, figures and sketches are original, unpublished, independent work by the author, Adolpho Pati, under the guidance, support and supervision of Cindy Prescott. iii Table of Contents Abstract .................................................................................................................................................... ii Preface ................................................................................................................................................... iii Table of Contents ................................................................................................................................... iv List of Tables .......................................................................................................................................... vi List of Figures ........................................................................................................................................ vii Acknowledgements ................................................................................................................................ ix Dedication ............................................................................................................................................... x 1 Introduction ........................................................................................................................................ 1 1.1 Overview ...................................................................................................................................... 1 1.2 The Conundrum: Humus and Soil Organic Matter - An Evolving Conceptual Overview ............. 2 1.3 The Components .......................................................................................................................... 4 1.3.1 Soil Attributes - The Physical Framework .............................................................................. 4 1.3.2 Plant Community Contributions: The Forest Floor, Roots, and Rhizosphere ........................ 4 1.3.3 The Microbes and Fauna ....................................................................................................... 6 1.4 Literature Review ......................................................................................................................... 7 1.4.1 Overview................................................................................................................................. 8 1.4.2 Decomposition in Northern Forests ........................................................................................ 9 1.4.3 Red Wood Ants and Decomposition .................................................................................... 12 1.4.4 Significance of Red Wood Ants ............................................................................................ 16 1.5 Soil Organic Matter, Wood Ants, and Their Dwellings ............................................................... 17 1.6 Formica Mounds: Structure and Composition ............................................................................ 33 1.7 Field Observations ..................................................................................................................... 38 1.7.1 Summer / Fall 2008, Summer 2009 ..................................................................................... 38 1.7.2 Fall 2009 ............................................................................................................................... 45 1.7.3 Spring 2010 .......................................................................................................................... 52 1.8 Thesis Objective ......................................................................................................................... 59 2 Methods ........................................................................................................................................... 60 2.1 Site Description .......................................................................................................................... 60 2.2 Observation Methods ................................................................................................................. 62 2.3 Mound Locations and Measurements ........................................................................................ 62 2.3.1 Study Area Survey and Mapping ......................................................................................... 62 2.3.2 Mound Size and Area of Influence ....................................................................................... 62 2.3.3 Large Woody Debris Measurements .................................................................................... 63 2.3.4 Ambient, Forest Floor, and Mound Temperatures ............................................................... 63 2.4 Specimen and Material Collection.............................................................................................. 63 2.4.1 Formica sp. and Invertebrate Collection .............................................................................. 63 2.4.2 Material Collection ................................................................................................................ 63 iv 2.4.3 100 Needles Collection for Mass Loss Studies .................................................................... 64 2.5 Laboratory Procedures ............................................................................................................... 67 2.5.1 Sample Drying ...................................................................................................................... 67 2.5.2 100 Needles Weight and Volume for Decomposition Sequence ......................................... 67 2.5.3 Carbon and Nitrogen Analysis of 100 Needles .................................................................... 68 2.5.4 Elemental Analyzer Procedure ............................................................................................. 68 2.5.5 CO2 Evolution Sample Preparation and Incubation ............................................................. 69 2.5.6 Gas Chromatograph Procedure ........................................................................................... 70 2.5.7 Internal Standards and Samples .......................................................................................... 71 2.6 Calculations ................................................................................................................................ 71 3 Results ............................................................................................................................................. 74 3.1 Temperature ............................................................................................................................... 74 3.2 Moisture ...................................................................................................................................... 81 3.3 CO2 Evolution ............................................................................................................................