Nudos en el nudo del desarrollo

The seed bank was assessed by taking haphazard soil samples. The first set was taken on the 29th of March, 2012, and the second on the 31st of October, 2012. These samples were refrigerated for 19 days at 4 oC (as used in Fountain and Outred, 1991; cited by Standish et al. 2001). The samples were then spread out over potting mix and dolomite, and watered daily for three months. Any seedlings that did grow were identified and recorded.

Statistics

Minitab version 16 (Minitab Inc., 2010) and Microsoft® Office Excel® version 12 (Microsoft Corporation, 2006) was used to perform statistical analyses. Digital Sampling Method version 1.00 (Landcare Research Ltd, 2003) was used to estimate tradescantia cover.

Results

Existing vegetation

A table (Table 3) containing all species found in the plots was created. It is not intended to be a complete list of all species present in Monro’s but a list of what was present in the plots surveyed. Elder (Sambucusnigra) and bindweed (Calystegia sylvatica) were new additions, these species not being present in the list compiled by Esler in 1962 (and therefore, supposedly not in Monro’s at that time). Both are exotic.

Pearson’s correlations were performed between the tradescantia biomass and the vegetation groups defined by Allen and McLennan (1983), except the tree fern group which had no individuals measured. There was no relationship (r<0.1) between the lianes/vines group (n=4, r=-0.0189) and tradescantia biomass. There was a weak (0.1<r<0.3) positive relationship between tradescantia biomass and the seedling/small plant group (n=4, r=0.1216). Moderate positive relationships (0.3<r<0.7) were

indicated between tradescantia biomass and the saplings group (n=4, r=0.6809), the epiphyte group (n=4, r=0.5817), and the tree group (n=4, r=0.0498).

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Table 3: List of plant species found in Munro's Bush by the author.

Species with an asterisk are exotic species

A Pearson’s correlation was also done to examine any potential relationship between kawakawa (Macropiper excelsum) and the tradescantia biomass. There were no relationships (r<0.1) between biomass and kawakawa overall (shrubs and saplings, n=4, r=-0.0499) and kawakawa shrubs (n=4, r=0.0931), and a moderate positive relationship with kawakawa saplings (n=4, r=-0.3014).

Pearson’s correlations were also performed to examine the relationship of tradescantia biomass to total (native and exotic) species richness, native species richness and exotic species richness. Total species richness and exotic species richness had strong positive relationships(r>0.7) with biomass; total species richness (n=4, r=0.8174) and exotic numbers (n=4, r=0.7468). Native species richness had a moderate relationship (n=4, r=06809).

In the permanent plots, the numbers of individuals in each vegetation group were recorded, as well as the percentage of cover and the biomass of tradescantia (Table 4). This list shows the different amounts of trees, saplings, lianes/vines, epiphytes, tree ferns and small plants/seedlings in each plot, as well as the biomass and percentage cover of tradescantia in each plot.

Trees Shrubs Vines and

Lianes

Ferns and Fern Allies

Herbaceous Plants

Alectyron excelsus Macropiper

excelsum Calystegia silvatica* Asplenium flaccidum Collospermum hastatum

Beilschemiedia tawa Streblus

heterophyllus Calystegia tuguriorum Microsorum scandens Tradescantia fluminensis*

Coprosma robusta Metrosideros

perforata Corynocarpus

laevigatus

Muehlenbeckia australis

Laurelia nova-zelandiae Ripogonum

scandens

Melicytus ramiflorus Parsonsia

heterophylla Pittosporum

eugeniodides Sambucus nigra*

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Photo 11: Photo Three, after grazing.

The tradescantia has been reduced to stalks averaging 3cm in height.

Table 4: Numbers of individuals in vegetation groups and tradescantia details

This table presents the raw data without identification of species. Seedlings and small plants are not common, and tree ferns are totally absent. This does not represent the forest as a whole.

Two months after the plots were set up, it was discovered that stock had entered Monro’s and grazed on the tradescantia of the ‘South’ bank (Appendix Three) where Plot Three was located (Photo 11). This plot was deemed unusable for later work; the grazing had reduced the tradescantia to 3cm in height in some places and soil had been churned up in many places; this could affect the presence of seedlings and saplings later on. There also appeared to be grazing on some karaka saplings. The marker pegs for the plot were removed and the plot abandoned. Figures 12, 13 and 14 show the graphs of species and individuals in each vegetation groups, for the three Plot Trees Saplings Lianes

and Vines Epiphytes Tree Ferns Seedlings & small plants Average estimated Biomass m2 of tradescantia Average Proportion Cover of tradescantia One 12 2 4 0 0 0 122.8 0.300226 Two 5 2 6 1 0 0 408.5 0.8525 Three 3 0 6 0 0 0 345.1 0.1275 Four 17 2 0 2 0 2 150.3 0.5025

48 remaining plots.

Plot one (Fig. 10) was notable because it had the lowest amount of vegetation groups recorded. Only trees, saplings and lianes/vines were recorded as present, and no seedlings were recorded. An invasive weed was present; Elder.

Plot two (Fig. 11) had the highest amount of species present despite having the highest tradescantia biomass of all the plots assessed (408.5 g/m2). However, two of the nine species graphed were introduced species; elder was present, as well as the exotic bindweed. It also lacked kawakawa, the most prevalent species in the other two plots. The number of kahakaha (Collospermum hastatum) individuals was given as one, because the height at which the plant was located made it difficult to accurately assess numbers.

Figure 10: Species in vegetation groups of Plot One

49 Plot Four (Fig. 12) contained the only ferns (living as epiphytes) recorded in this census, and the most trees. Over half of the trees were kawakawa, and no weed species were recorded in this plot.

Figure 12: Species in vegetation groups of Plot Four.

Graph showing the species present in Plot Four, and the number of individuals in each vegetation group.

Figure 11: Species in vegetation groups of Plot Two

Graph showing the species present in Plot Two, and the numbers of individuals in each group 0 0.51 1.52 2.53 3.5 Indi vi dua l Numbers Species

Plot Two

Lianes and Vines Epiphytes

50

Photo 12: Two large Brassica species in seed-bank sample

Potential vegetation: Seed bank

This experiment returned mixed results. Out of the eight total samples, only two (both March samples) grew seedlings. Four of the seven seedlings grown were not natives or normal weed species, but were horticultural species; three Brassica sp. Plants (Photo 12) and one chard (Beta vulgaris subsp. cicla) or spinach plant (Spinacia oleracea). The other three were identified as mahoe. These results are not indicative of anything beyond the paucity of quick-growing species in the seed bank.

Discussion