Introduction to Vegetation Classification and the Biogeoclimatic Ecosystem Classification System FRST 211: Forest Classification and Silvics

Purpose of Lecture Module Understand the basic principals of classification Introduce examples of classification across a range of spatial scales Understand the basic concepts of the Biogeoclimatic Ecosystem Classification (BEC) system Become familiar with the BEC framework

What is classification? Grouping together of a set observational units on the basis of common attributes Vegetation classification: unit of observation is the ‘stand’ or ‘community unit’, which is homogenous in species composition, structure and function Ecosystem classification, unit of observation is the ‘ecosystem unit’

Why classify? increase our knowledge of ecological units of ecosystems being managed increase our ability to communicate about ecosystems provides a framework for planning and management improves our ability to predict outcome of management practices on specific sites

Relevance for wildlife management and studies

Relevance for land management and conservation

Practical examples of Ecosystem Classification use in forestry Foundation for Forest Practices Code Ecosystem mapping Vegetation inventories (e.g., AAC) Silviculture prescriptions Silviculture surveys

Community Units To understand ‘community unit’ concept, need to understand basic community and succession models Clements versus Gleason dissent: community unit concept versus individualistic concept

Clements view of ecosystems Pioneered holistic view of ecosystems: Ecosystems develop and behave as ‘super- organisms ( ) Frederic E. Clements American Botanist Also interested in Communities and Succession Communities replace one another There are physiological processes involved in succession. Succession moves toward climatic climax The Development and Structure of Vegetation (1904)

Clements view is similar to Relay Floristics model of succession Communities represent different seral stages over time since disturbance. Each seral stage prepares for the next stage. Fits well with primary succession. Bare rock > Lichens, mosses > herbs > shrubs > trees > climax

Abundance lichens mosses herbs grasses herbs shrubs tall shrubs Decid trees Shade Intolerant conifer trees Climax shade tolerant conifer trees Time Processes: disturbance, migration, reaction, germination, competition, stabilization Assumptions: Species differ in dispersal abilities Species differ in physiognomic requirements Pioneers modify the site Later successional species outcompete earlier successional species A stage is reached where the environment is steady All ecosystems progress toward climatic climax Clements:

Clements: all ecosystems progress toward climatic climax xerarchmesarchhydrarch Abundance Moisture Gradient

Gleason’s and Egler’s view of ecosystems Individualistic view: communities are merely functions of populations, and are not organized in any way Henry Gleason ( ) American botanist Frank Egler (1911–1996) American Ecologist Distribution of species independent of one another Don’t require pioneer species for second species to invade bare rock (e.g., spruce on terminal moraine) Both primary and secondary succession species co- occur

Gleason’s and Egler’s view of ecosystems (cont..) All species except a few are present after a disturbance Not a turn-over in species but a change in dominance over time Presence or absence of species is more accidental Views more in line with the Initial Floristics model of succession (Egler, 1954)

Despite polarized view, there are widely recognized features of communities: Similar species combinations often recur Species combinations are correlated with their environment Species are continuously distributed (barring shopping malls etc..) Species combinations (assemblages) tend to change continuously over a wide area

Terrestrial Ecosystem Classifications Focus on the biogeocoenose = portion of landscape and life on it that is relatively uniform in composition, structure and properties of both the biotic and abiotic environments, and their interactions Terrestrial ecosystems have geographical bounds that are gradual, therefore there is variation Terrestrial classification schemes deal mainly with climate, plant communities and soils for simplicity (ecosystem function=CLORPT)

Climate Most important determinant of nature of terrestrial ecosystems (regional climate) Best represented by temperature and precipitation

Global pattern of plants species richness Kier et al. (2005)

Status of World’s Forests (2009)

Climate data is scarce for the range of ecosystems, so zonal ecosystem concept links climate and ecosystem (concept of zonal ecosystems)

Zonal ecosystem Best reflects regional climate of an area Integrated influence of climate on an ecosystem is most strongly expressed in ecosystems least influenced by local relief and soil parent material –Middle slope position in meso-slope –Slope position, gradient, aspect, location that does not result in strong modifying influence of climate –Gentle slope (5-30%) –Soils deep, loamy, freely drained, no restricting horizon Because zonal ecosystems are characteristic of regional climate, they are used to characterize biogeoclimatic units

Climax and Succession Succession: Progressive development of ecosystems through time following a disturbance Sere/seral stage: One in a sequence of successional stages Climatic Climax: dynamic equilibrium with climate; members are in dynamic balance; pant species self- perpetuating (shade tolerant) and in all stages of development Many of BC forests have escaped large-scale disturbances and therefore are at climatic climax Some frequently disturbed and never reach climax

Ecological Equivalence The same climax vegetation can occur over a range of sites because of the compensating effects of environmental factors on plants Therefore, a climax plant association may represent ecosystems in different regional climates with different soils Also, plant communities within an ecosystem can vary due to chance, site, disturbance, time