Disturbance Assessment Methods

URI: http://linked.data.gov.au/def/corveg-cv/191d0612-455b-41a9-98ac-5e10cd984fbd

Date created: 2019-07-19
Date modified: 2020-07-17

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Definition

Purpose

The method is carried out to assess the evidence of disturbances which have occurred previously within the sampling unit.

Abstract

Synopsis

The observer visually assesses the evidence of disturbances which have occurred prior to the visit to the study location. The type of disturbance, the time elapsed since the disturbance are recorded as well as the severity of the disturbance within the sampling unit.

Key Features

    • Method: visual identification of disturbance evidence
    • Target: vegetation and soil within the sampling unit

Procedure

The method is carried out to assess the evidence of disturbances which have occurred previously within the sampling unit.

Pre-conditions

The study location has been established applying the Survey Site Selection and Establishment Method.

Technique

The observer determines the type of disturbance events that have occurred by visual assessment of the persistent evidence available within vegetation and soil of the sampling unit. For each observed evidence type the time elapsed since the event as well as its severity are recorded. The severity of the disturbance event is determined by either recording the proportion of the sampling unit affected by a disturbance type, the number of individual plants affected by a disturbance, or by assigning a severity type describing the severity qualitatively.

      • Storm damage: Storm damage is usually identified by the presence of broken branches in the crowns. The severity os recorded by the proportion of the sampling unit affected.
      • Logging: The observer records the number of stumps in the site.
      • Ringbarking: The observer records the number of stems in the sampling unit that have been treating by ringbarking, thinning or poisoning.
      • Grazing: The observer assesses if the sampling unit has been previously grazed by domestic stock, feral animals and native animals. This is usually evident in damage to the ground layer plants and/or presence of animal faeces or tracks. This information is recorded as either 'not apparent', 'present' or 'severe' (Enough to make major impact on ground cover abundance or composition).
      • Extensive clearing: The observer records if the site has been previously cleared/thinned and regrown. This information is recorded as either 'not apparent', 'present' (i.e. most of the vegetation is regrowth from a previous clearing/thinning event).
      • Animal diggings: The observer records if animal diggings are present at the sampling unit or not.
      • Roadworks: The observer assesses the proportion of the sampling unit affected by old snig tracks and other tracks.
      • Salinity: The proportion of the site affected by severe anthropogenic salinity is recorded.
      • Fire: If evidence of a fire event is observed, the age as well as the height of the tallest vegetation impacted by the fire are recorded.
      • Weeds: The percentage cover of exotic species at the site is estimated. In the case of secondary sites this figure is derived by adding the cover of weed species from the comprehensive species list (the cover values are added ignoring any overlap between strata).
      • Erosion: The type and severity of an erosion event are assessed following McDonald, Isbell and Speight (2009).

Technique

The following categories are applied to describe the proportion of a study location affected by a disturbance event.

Hierarchy
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source

Neldner, V.J., Wilson, B.A., Dillewaard, H.A., Ryan, T.S., Butler, D.W., McDonald, W.J.F, Addicott, E.P. and Appelman, C.N. (2020) Methodology for survey and mapping of regional ecosystems and vegetation communities in Queensland. Version 5.1. Updated March 2020. Page 72 - 73. Queensland Herbarium, Queensland Department of Environment and Science, Brisbane.

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