Helena and Lewis & Clark National Forests Forest Plan Assessment Chapter 2, Terrestrial Ecosystems 2015 Table of Contents Introduction ................................................................................................................................................................1 Terrestrial Vegetation .................................................................................................................................................1 Introduction ............................................................................................................................................................1 Scale and Methods .............................................................................................................................................2 Broad Scale Context............................................................................................................................................3 Ecosystems and Key Ecosystem Components ....................................................................................................3 Existing Information ...............................................................................................................................................5 Vegetation Drivers ..................................................................................................................................................6 Introduction ........................................................................................................................................................6 Climate ................................................................................................................................................................6 Vegetative Succession ........................................................................................................................................8 Fire ......................................................................................................................................................................9 Forest Insects and Disease .............................................................................................................................. 16 Vegetation Management................................................................................................................................. 31 Invasive Plants ................................................................................................................................................. 40 Potential Vegetation Types ................................................................................................................................. 49 Existing Condition ............................................................................................................................................ 49 Trend ............................................................................................................................................................... 53 Vegetation Composition ...................................................................................................................................... 54 Existing Condition ............................................................................................................................................ 54 Trend ............................................................................................................................................................... 60 Vegetation Structure and Function ..................................................................................................................... 61 Tree Size Class.................................................................................................................................................. 61 Forested Density Class ..................................................................................................................................... 64 Nonforested Density Classes ........................................................................................................................... 66 Forest Vertical Structure Class ........................................................................................................................ 66 Forest Age Class ............................................................................................................................................... 68 Connectivity and Pattern ................................................................................................................................. 70 Information Needs ........................................................................................................................................... 72 Threatened, Endangered, Proposed, and Candidate Plant Species, and Potential Species of Conservation Concern ............................................................................................................................................................... 73 Introduction ..................................................................................................................................................... 73 Threatened, Endangered, Proposed, and Candidate Species: Whitebark pine ............................................. 74 Potential Plant Species of Conservation Concern ........................................................................................... 77 Plant Species of Public Interest ....................................................................................................................... 94 Special Ecosystem Components ........................................................................................................................ 105 Introduction ................................................................................................................................................... 105 Old Growth .................................................................................................................................................... 106 Snags .............................................................................................................................................................. 109 Very Large Live Trees ..................................................................................................................................... 112 Coarse Woody Debris .................................................................................................................................... 113 Ecosystem Diversity: Key Characteristics by Potential Vegetation Type .......................................................... 114 Existing Condition .......................................................................................................................................... 114 Trend ............................................................................................................................................................. 133 Information Needs ......................................................................................................................................... 135 Terrestrial Wildlife ................................................................................................................................................. 136 Introduction ....................................................................................................................................................... 136 Process and Methods .................................................................................................................................... 136 Scale ............................................................................................................................................................... 137 Section Organization ..................................................................................................................................... 137 Existing Information .......................................................................................................................................... 137 Existing Condition .............................................................................................................................................. 139 Habitat Associations ...................................................................................................................................... 139 Threatened, Endangered, Proposed, or Candidate Species (‘At Risk Species’; FSH 1909.12, Chapter 10, 12.5) ....................................................................................................................................................................... 145 Potential Terrestrial Wildlife Species of Conservation Concern ................................................................... 159 Terrestrial Wildlife Species of Interest .......................................................................................................... 174 Information Needs............................................................................................................................................. 193 References ......................................................................................................................................................... 193 Tables Table 2.1 Key terrestrial vegetation characteristics of ecosystems on the HLC NFs ..................................................4