Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

Small wetlands critical for safeguarding rare & threatened plant species

Friday 21 Nov 2014

<em>Drosera arcturii</em>, McKellar Saddle. Image - Sarah Richardson

Drosera arcturii, McKellar Saddle. Image - Sarah Richardson

Rare and threatened species are a common focus of natural area protection but selecting sites to protect them must be balanced against other conservation objectives.

Using a series of wetlands as a case study, Sarah Richardson, at our Lincoln site, and her colleagues investigated whether protecting wetlands with rare and threatened plant species compromises protection of:

  1. the full range of species assemblages found across wetlands
  2. threatened environments, and
  3. large wetlands that are more resilient to degradation and which are important for providing ecosystem services such as regulation of water yield and recreation.

Vascular plant species and species assemblages were assembled for 118 wetlands (66 fens, 35 bogs and 17 marshes) across Southland, and the functional attributes of 29 ‘rare’ and ‘threatened’ species (from 55 of the wetlands) characterised and evaluated.

They found that that the species assemblages in wetlands that have rare and threatened species are different to the assemblages in wetlands without rare or threatened plant species.  Rare and threatened species were not associated with threatened geophysical environments and not related to wetland size. Small wetlands are important for maintaining rare and threatened species and their functional richness.

However, only giving conservation priority to wetlands with rare and threatened plant species will not meet other conservation objectives. Networks of small wetlands will be necessary to safeguard rare and threatened plant species, with other complementary approaches to meet other priorities - for example, safeguarding large wetlands to protect ecosystem services and to maintain populations of other species.

Another interesting finding from the research is that GIS-based exercises such as the LENZ threatened environment layer, do not successfully predict where the most vulnerable plant species occur. This finding is somewhat surprising because many rare and threatened plant species are habitat specialists and, logically, these should be more likely to occur in rare and distinctive environments. However, not directly assessing species composition means species or species groups weakly related to readily-mapped environmental are vulnerable to neglect.

Richardson SJ, Clayton R, Rance BD, Broadbent H, McGlone MS, Wilmshurst JM 2014. Small wetlands are critical for safeguarding rare and threatened plant species. Applied Vegetation Science [early view online].