Friends of The Pinnacle   defeating the weed menace
fotpin's Native Grass Restoration Project
 
  
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Restoring native grasses to the understorey of The Pinnacle
New knowledge that will aid recovery of degraded box-gum grassy woodlands

A Friends of The Pinnacle project funded by:
ACT Environment Grant 2010-11
Caring for Our Country Community Action Grant 2010-2011
Canberra Labor Club 2010-2011


Initial Survey Results

After an outstanding effort by dedicated fotpin volunteers, we have completed our first Weed Menace plant surveys. In all, we estimated the percentage cover of all plant species in four hundred 1 x 1m quadrats that were spread across our ten experimental sites.

I've done some initial analyses and made some simple summaries of the data we collected. We now have a solid baseline against which to compare changes over the coming years as we implement our experimental treatments.

Figure 1 is a multidimensional ordination of each plot (the 5 x 5m treatment areas, with data from the 4 quadrats in each plot pooled), based on the percentage cover of each plant species. The distance between the names for each plot on the figure is proportional to the difference in plant community between those plots. For example, in the mid-left of the figure, s2-10 is very close to s2-11, meaning they have quite similar plant species with similar percentage cover, whereas both of these are very different from s1-2 which is in the bottom-right of the figure. One important pattern is that generally all of the weed sites (W1 to W5) are in the top right-hand area of the ordination space, suggesting that the weed sites are different from our stipa sites (S1 to S5). This is reassuring because that is what we tried to achieve.

Fig 1

Figure 1. Differences among plant communities for each plot at each site. Site numbers include s1 to S5 and W1 to W5. The former were selected because they seemed to have higher native plant cover than the latter, which we regarded as being predominantly weedy. The numbers after each site number refer to the plot number (1 to 10 for most sites).

Another pattern is that generally the plant communities are more similar within each site than they are between sites, which is what you would expect given that the ten plots within a site are next to each other. The interesting exception to this rule is S1, where the plots are widely spaced. S1 is an unusual site because it has the smallest number of species of any site (Figure 2), but has very high cover of native grasses (predominantly Austrostipa).

Fig 2aFig 2b
Fig 2cFig 2d

Figure 2. Summaries of the number of native and exotic species at each site, and summed percent cover (can exceed 100% because of the way we measured them).

The summaries in Figure 2 show that there is quite a lot of variation in number of species of natives and percentage cover of natives and exotics. Interestingly, there is relatively little variation (with S1 as the exception) in the number of exotic species, with all other sites ranging from 20 to 27 species. Although this is more variation than I expected among our sites, our experiment is designed to cope with such variation, since each of our treatments will be present in every site. This is exemplified by our formal statistical analysis (Figure 3), which shows there are no statistically significant differences between treatments. This is as it should be because these data were collected before the treatments were implemented.

Fig 3

Figure 3. Average number of exotic and native species in each fenced and unfenced treatment before the experiment began. Error bars are approximate 95% confidence levels.
Overlapping confidence bars suggest there are no significant differences among our treatment plots at this pre-treatment stage of the experiment.

 


Project funding covers the costs of materials and specialist contractor services only. All other work on the project is carried out by volunteer labour.

If you can help, please contact

 

project home methods & implementation plot map current activities findings full project description
[pdf, 274 kB]

 

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