Integrated Catchment Management

Forest harvesting effects

 Research Status: Ongoing
Steepland forest harvesting Richmond Range

Steepland forest harvesting Richmond Range


The potential for erosion and sediment generation within forests is one of the major environmental effects facing the forest industry in New Zealand. In particular, the harvesting phase has the potential to cause a range of environmental impacts many of which are manifested off-site in streams and estuaries.

One of the most significant potential effects arises from operations associated with either construction of roads or infrastructure related to harvesting. These effects are usually related to erosion or the products of erosion, i.e. sediment.

Erosion has the potential to reduce on-site productivity and cause loss or damage to the forest infrastructure. Sediment has two main impacts. Firstly, it can increase the turbidity of stream water (= decrease clarity), and secondly, it can clog stream beds and downstream receiving environments such as estuaries and lakes. Both of these impacts affect the biological community and health of an ecosystem.

The measurement of sediment production is both costly and difficult. Sediment generation is often random in both a spatial and a temporal sense. Erosion is generally caused by a climatic event exceeding some threshold for an erosion process. While the prediction of such an event is often possible and is of a stochastic nature, the prediction of the exact location at which a particular erosion process occurs (e.g. a landslide) is extremely difficult.

Research Approach

While not an explicit part of the ICM programme, Chris Phillips & Michael Marden are determining how forestry operations, particularly those associated with harvesting, affect sediment generation and delivery to streams. They have been measuring sediment generation at a number of localities in North Island plantation forests using a variety of runoff plots and collectors. Their current efforts are focused at Whangapoua Forest in the Coromandel where they are looking at sediment generation and delivery to sterams at a range of scales.

They have also been investigating the rate at which vegetation recovers on harvested cutover in these forests, because there is a strong relationship between sediment generation or surface erosion and the amount of ground-cover vegetation. Conversely, there is a strong relationship between the degree of soil disturbance and vegetation recovery, with the sites of deepest disturbance taking the longest time to recover. Overall, however, ground-cover vegetation recovery is rapid in most environments.

Elements of current and future work will focus on the granite and Moutere gravels in the Nelson-Motueka region as part of the sediment generation and delivery research project and the sediment learning group.

Research Results

Some relevant publications from this work:

Phillips CJ, Weir P, Quinn J, Marden M, Nelson C 2007. Riparian buffers in the New Zealand Forestry context: are they effective? (Abstract) Conference: Riparian Management in Headwater Catchments: Translating Science into Management Vancouver, Canada, 19-21 Feb 2007.

Phillips CJ, Marden M 2006. Sediment generation and sediment yield following harvesting on the Coromandel: implications for management. (Abstract) p 91 in Proceedings of ôResource management under stormy skies: water allocation @ the crossroads? Conference programme and abstracts. November 20-23, 2006, Christchurch.

Marden M, Rowan D, Phillips C 2006. Sediment sources and delivery following plantation harvesting in a weathered volcanic terrain, Coromandel Peninsula, North Island, New Zealand. Australian Journal of Soil Research 44: 219-232.

Phillips CJ, Marden M 2005. Reforestation schemes to manage regional landslide risk. Chapter 18 in Landslide Hazard and Risk Edited by Glade T, Anderson M and Crozier MJ p517-547. 2004 John Wiley & Sons Ltd.

Phillips CJ, Marden M, Rowan D 2005. Sediment yield following plantation harvesting, Coromandel Peninsula, North Island, New Zealand. Journal of Hydrology (NZ) 44(1):29-44.

Phillips CJ, Marden M 2003. Erosion and stormwater control in the Forest industry: past, present and future? Paper to be presented at The 3rd South Pacific Conference on Stormwater and Aquatic Resource Protection. 14-16 May 2003, Auckland, New Zealand.

Phillips CJ Marden M, Rowan D, Garrett L 2002. Soil loss, vegetation recovery, and sediment delivery to streams following plantation harvesting, Coromandel. Programme abstracts from "All the easy water has gone". New Zealand Hydrological Society annual conference, Blenheim, December 3-6, 2002.

Fahey BD, Marden M, Phillips CJ 2003. Sediment yield associated with plantation forestry, coastal Hawke's Bay, North Island, New Zealand. Submitted to Journal of Hydrology (NZ).

Marden M, Phillips CJ, Rowan D 2002. "Soil loss, vegetation recovery, and sediment yield following plantation harvesting, Coromandel - interim results" Programme abstracts from the Soil Quality/ NZ Association of Resource Management Conference in Palmerston North, April 2-5, 2002.

Fransen PJB, Phillips CJ, Fahey BD 2001. Forest road erosion in New Zealand: overview. Earth Surface Processes and Landforms 26: 165-174.

Phillips C 2000. [Poster abstract] Sediment generation following harvesting of Pinus radiata in New Zealand : a variable story. In: Jandl, R.; Devall, M.; Khorchidi, M.; Schimpf, E.; Wolfrum, G.; Krishnapillay, B. eds. XXI IUFRO World Congress 2000 7-12 August 2000, Kuala Lumpur : Forests and society : the role of research : poster abstracts Vol.3. Vienna, IUFRO. P. 458.

Weedy regrowth following harvesting Plantations on Moutere Gravels

Weedy regrowth following harvesting

Plantations on Moutere Gravels

Recent Publications

Year Title File Size
2012 A Summary of Outcomes and selected formal publications from the Integrated Catchment Management (ICM)research programme:2000 – 2011
pdf       1.08MB
2011 Integrated Catchment Management – Special Issue of the NZ Journal of Marine & Freshwater Research  
2010 The Sherry River Story – Improving Water Quality through Whole Catchment Planning. pdf       3.71MB
2009 Motueka Forest sediment study: data report July 2006 to June 2008 and analysis of sediment yield pdf       1.32MB
More publications on this topic »
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BMPs, BEPs and Guidelines

Title Description
Standards and Guidelines for Sustainable Management of Indigenous Forests From guide:
MAF Standards and Guidelines for sustainable management of New Zealand indigenous ...More »  
The National Standard for Environmental Certification of well–managed Plantation Forests in New Zealand Outlines the National Standard for environmental certification of plantation forests. It provides f...More »  
New Zealand Environmental Code of Practice for Plantation Forestry The E CoP is an essential tool for anyone involved in forest management. Developed by the NZFOA, and...More »  
Managing Your Bush Block:A guide to looking after indigenous forest remnants in the Wellington region Tips and techniques of managing bush blocks....More »  
All BMPs, BEPs & Guidelines »

Primary Contacts:

Image - Michael Marden Michael Marden  EmailSend email to Mardenm
Phone: 06 8631345
Fax: 06 8631346
More details»
Landcare Research
Geology/Earth Sciences/Geomorphology/Erosion processes
Image - Chris Phillips Chris Phillips  EmailSend email to phillipsc
Phone: +64 3 321 9775
More details»
Landcare Research
Erosion processes, slope stability, effects of forestry, catchment management, knowledge management
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Page last updated Monday, 23 February 2009

Related areas

Fine sediment: bringing the geomorphology and biology together Sediment generation, delivery and impacts