Environmental Pest Plants
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12.3 Land use Spatial Pattern Catchment size: 36,930 ha. Catchment location: North and east across the Whakamarama and Mamaku plateaus from Hiwiroa to Tauranga Harbour. Predominant land uses (account for 97% of catchment): - Indigenous forest covers 20,909 ha (56.6%) of catchment, primarily on plateau country in the upper and middle catchments and along the steeps sides of gullies in the middle reaches of all catchments. - Pasture grassland covers 9,905 ha (26.6% of catchment), primarily in the lower and middle catchments on land of low to moderate relief. - Exotic plantation forest covers 4,605 ha (12.4%) on plateau country in middle catchments. Urban landforms: 82 ha (0.2% of catchment) Wetlands: 28.7 ha (0.07% of catchment), primarily herbaceous saline wetlands along the Wairoa estuary margins. Most modified: The lower parts of the Wairoa catchment have been heavily modified by conversion of forests to pasture grassland, orcharding and urban land uses. Least modified: The upper catchment retains indigenous vegetation on flats and in gullies of the dissected Whakamarama plateau, though this has been modified by logging during the late 19th and early 20th centuries, and clearfelling of broadleaf forest on the plateau and replacement with pine plantations during the late 20th century. Table 12.2: Land use within the Wairoa catchment. % of LCDB2 Classification Area (ha) Catchment Broadleaved indigenous hardwoods 127.0 Indigenous forest 20,908.7 Manuka and/or kanuka 219.4 Indigenous Forest 21,255.1 57.6% Coastal sand and gravel Estuarine open water 0.5 Herbaceous freshwater vegetation Herbaceous saline vegetation 28.2 Lake and pond 44.3 Mangrove River 85.9 Wetland Systems 158.9 0.4% Afforestation (imaged, post LCDB 1) 42.1 © Crown Copyright 2010 331 Contract Report No. 2075 % of LCDB2 Classification Area (ha) Catchment Afforestation (not imaged) Forest harvested 160.1 Other exotic forest 311.9 Pine forest - closed canopy 3,845.2 Pine forest - open canopy 159.8 Exotic Plantation Forest 4,518.9 12.2% Orchard and other perennial crops 699.8 Short-rotation cropland Orchards and Crops 699.8 1.9% High producing exotic grassland 9,838.0 Low producing grassland 67.1 Pastoral Lands 9,905.2 26.8% Deciduous hardwoods 22.4 Major shelterbelts 55.2 Mixed exotic shrubland Gorse and broom 231.4 Other Exotic Vegetation 309.0 0.8% Built-up area 68.9 Transport infrastructure 1.9 Urban parkland/Open space 11.0 Urban Landforms 81.8 0.2% Not Classified 0.3 ,0.1% Grand Total 36,930.3 100.0% Legal Protection This section provides an overview of the areas protected by legal statute and covenants, for the purpose of biodiversity protection. Department of Conservation The Department of Conservation administers ha within the Wairoa catchment for conservation purposes. Reserves to protect indigenous ecosystems, vegetation, habitats, or species comprises 13,559.4 ha (99.1%). Reserves that have other primary aims, which could conflict with protection of natural values, comprises 121.9ha (0.9%). Table 12.3: Department of Conservation administered lands within the Wairoa catchment. Reserve Type (DOC Legal Description) Area (ha) Conservation Park - S.19 Conservation Act 1987 10,248.9 Fixed Marginal Strip - S.24(3) Conservation Act 1987 23.7 Local Purpose Reserve - S.23 Reserves Act 1977 96.8 Recreation Reserve - S.17 Reserves Act 1977 1.4 Scenic Reserve - S.19(1)(a) Reserves Act 1977 49.6 Stewardship Area - S.25 Conservation Act 1987 3,260.9 Grand Total 13,681.3 © Crown Copyright 2010 332 Contract Report No. 2075 The upper Wairoa catchment includes 1,902 ha of the Opuiaki Ecological Area, 168 ha of the Mangapapa Ecological Area, and 1,741 ha of the Waiteariki Ecological Area. Nga Whenua Rahui There are no Nga Whenua Rahui kawenata within the Wairoa catchment. QEII There are seventeen QEII covenants totalling 110.6 ha within the Wairoa catchment. Table 12.4: QEII covenants within the Wairoa catchment. Covenant Area (ha) 5/03/020 7.0 5/03/021 28.0 5/03/021B 0.5 5/03/125 4.8 5/03/151 8.4 5/03/160 6.0 5/03/250B 0.0 5/03/288.1 8.2 5/03/288.2 1.3 5/03/288.3 0.9 5/03/322 0.0 5/03/332.1 2.0 5/03/332.2 1.2 5/03/332.3 0.6 5/03/332.4 0.9 5/03/375 33.5 5/03/379 7.4 110.6 Grand Total (0.3%) Western Bay of Plenty District Council Covenants Within the Wairoa catchment there are 21 Western Bay of Plenty Covenants, with a total area of 155.7 ha (1.2%). Table 12.5: Western Bay of Plenty District Council Covenants within the Wairoa catchment. WBOP Covenants Area (ha) Cov6309 3.89 Cov6395 12.09 Cov6910 1.73 Cov6985 23.49 Cov7068 13.15 Cov7351 25.87 Cov7433 4.16 Cov7532 2.55 Cov7675 22.79 Cov8584 17.19 © Crown Copyright 2010 333 Contract Report No. 2075 WBOP Covenants Area (ha) Cov9276 80.44 Cov9622 5.56 Cov9729 6.69 CovFE313 746.51 966.1 Grand Total (2.6%) 12.4 Indigenous vegetation and flora Vegetation Pattern Approximately two-thirds (65%) of the 20,909 ha of indigenous forest is dominated by tawa, either in combination with rimu and/or beeches. Just under one-quarter (23%) of forest is highland and steepland softwoods-hardwoods. Unlogged rimu- tawa forest occurs within the Opuiaki Ecological Area, along with dense podocarp stands on alluvial terraces. Table 12.6: Indigenous forest types within Wairoa catchment. Forest Type Area (ha) Beeches 96.2 General hardwoods 704.2 Highland and steepland softwoods-hardwoods 4,897.7 Kauri-softwoods-hardwoods 59.7 Rimu-tawa 4,049.1 Rimu-tawa-beeches 258.4 Softwoods 171.6 Tawa 8,876.3 Tawa-beeches 349.3 Unclassified 1,446.2 Total 20,908.7 Species Lists There are at least 10 lists of vascular plants within the catchment. Rare or Threatened Species The Department of Conservation Bioweb database includes the following records: Brachyglottis kirkii var. kirkii (At Risk-Declining) Hymenophyllum atrovirens (At Risk-Naturally Uncommon) Olearia cheesemanii (At Risk-Naturally Uncommon) Peraxilla tetrapetala (At Risk-Declining) Pimelea tomentosa (Threatened, Nationally Vulnerable) Pittosporum kirkii (At Risk-Declining) Syzygium maire © Crown Copyright 2010 334 Contract Report No. 2075 12.5 Pest plants Plant Pest RPMS Status Wairoa Wild kiwifruit Total control present Banana passionfruit Progressive control present Boneseed Progressive control present Bushy asparagus Progressive control present Cathedral bells Progressive control present Heather Progressive control present Lantana Progressive control present Old man's beard Progressive control present Wild ginger Progressive control present Woolly nightshade Progressive control present Yellow flag iris Progressive control present The EBOP RPMS provides lists of species in the following categories: ‗Eradication‘, ‗Total and Progressive Control‘, ‗Boundary Control‘, and ‗Regional Surveillance‘. Explanations for each category are given below: Eradication pest plants (10 species) - pests of low incidence but with a high threat of spread or seriousness of adverse effects. The objective of this category is to eradicate all known populations by 2020 and immediate eradication of any new occurrences. Total control pest plants (1 species) - pests of low incidence but with high threat of spread or seriousness of adverse effects. The objective is the protection of indigenous biodiversity and production values by controlling currently known populations and immediate destruction of new occurrences. Progressive control pest plants (15 species) - Pest of high incidence in parts of the region, and with high threat of spread or seriousness of adverse effect. The objective is to reduce density and/or distribution with priority given to controlling isolated or satellite populations. Boundary control pest plants (3 species) - Pests of high incidence over the region, and with serious effects. The objective is protection of production values by controlling effects. Surveillance pest plants (23 species) - Plants of known threat of adverse effects, which may be established in parts of the region, but about which there is uncertainty of distribution, and/or threat of spread and/or feasibility of control. There are two objectives for these pests. The first is to increase understanding of the distributions, impacts and control options, the second is to have them voluntarily controlled by land occupiers with assistance from EBOP programmes (EBOP 2003). EBOP also maintains a database of 123 pest plant species that are of interest or under active management in the Tauranga Harbour catchment. For more information refer to Environment Bay of Plenty‘s Regional Pest Management Strategy, or to their excellent pest plant resources on the internet at http://www.envbop.govt.nz/ Environment/Pest-Plants-and-Weeds. aspx © Crown Copyright 2010 335 Contract Report No. 2075 The Department of Conservation also maintains a pest plant database and this includes the following records for the Wairoa catchment: Agapanthus praecox Jasminum polyanthum Berberis glaucocarpa Leycesteria formosa Buddleja davidii Pinus spp. Celastrus orbiculatus Pueraria montana Cortaderia selloana Rosa spp. Crocosmia x crocosmiiflora Rubus fruticosus agg. Cupressus lusitanica Selaginella kraussiana Cytisus scoparius Senecio mikanioides Eucalyptus spp. Spartina alterniflora Gladiolus carneus Tradescantia fluminensis Hedychium gardnerianum Ulex europaeus Hydrangea macrophylla Vitis vinifera 12.6 Pest animals Affecting Species Affecting Vegetation Control Underway Indigenous Fauna Possum Goat Red deer Fallow deer Feral pig Ship rat Norway rat Mustelids Cats Mice Hedgehog Wasps Pest fish State of the Vegetation There is a network of foliar browse index lines in the catchment. Foliar Browse Index vegetation monitoring (Willems 2001; Woods 2008) suggests that the overall condition of vegetation not subject to pest control is moderate. Kamahi was found to be in generally poor condition in both surveys, and browse values on the less-preferred mahoe had increased between 2001 and 2008.