TRAINING & RESEARCH CENTER

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Twizel New Zealand
Phone 64 3 4353 227 Fax 64 3 4353 227

Email: taneh@watershed.net.nz

Catchment Habitats and Landscape Ecosystems

Haikai Tane

Director
Centre for Catchment Ecology
Watershed Systems Ltd, Waitaki Basin

Adjunct Professor of Sustainable Development
Unitec Institute of Technology, Auckland

About the Author: Haikai Tane is an honors graduate in geography and a law graduate from the Australian National University, Canberra, and a post graduate in science, (ecology and planning) from the University of British Columbia, Canada. Haikai Tane has surveyed, mapped and modeled watershed catchments using geospatial technologies such as remote sensing and GIS since the early 1970ís. Haikaiís expertise researching and developing geospatial systems for watershed catchments has attracted international recognition and awards. In May 2000 Haikai was inaugaurated as Adjunct Professor of Sustainable Development at the Unitec Institute of Technology in Auckland.

1. Overview

Sustainable production of fresh, reliable water supplies is a natural function of watershed catchments. Provided the spatial connectivity and ecological functionality of near surface aquifers, riparian habitats and floodplain ecosystems are maintained, natural biophysical systems ensure reliable water supplies.

The results of recent riparian research and development in Australia and New Zealand indicate bio-hydraulic processes linked to catchment habitats and landscape ecosystems, control critical land and water relationships in watershed catchments. Land and water degradation programs tend to be counter-productive when the symptoms of degradation are the main focus. Before addressing symptoms of land degradation, like gullying, erosion and pollution, it is necessary to identify the dysfunctional structures and processes in catchment ecosystems.

It does not matter whether the landscape is forest, farm or suburban settlement, remote wilderness or urban open space, (or various combinations), the fundamental ecological principles and catchment processes remain the same. Once watershed processes are integrated and functionally linked through appropriate suites of riparian habitats and catchment ecosystems, watershed ecostructures evolve into cybernetic systems.

With hindsight, the concepts are profoundly simple, though difficult to grasp at first. In this short review, the author explains why riparian habitat and landscape ecosystem relationships are necessary prerequisites for sustainable water resource management. Underlying and linking habitats and ecosystems in functional ways (Leopold 1949) are natural networks called ecostructures, (Warshall 1998, Tane 1999).

Ecostructures are well known in traditional Pacific and Aboriginal cultures from long experience. In science, however, they are a new discovery. Mapping and modeling watershed catchments using geospatial technologies, (eg 3D digital orthophotos, remote sensing and GIS), were instrumental in identifying key catchment habitats, watershed ecosystems and their connecting ecostructures.

2. Watershed Perspectives

"There is as yet no social stigma

in the possession of a gullied farm"

Aldo Leopold USA

Water is life according to ancient wisdom. Yet in the industrial societies of the western world, the very watershed processes and catchment ecosystems relied upon to replenish aquifers, streams and rivers are degraded and dysfunctional. Not just a little, horrendously. Clean, fresh water has become polluted, raw water.

In industrial societies, conventional attitudes and perspectives towards watersheds are governed by the plumbing and drainage paradigm (Figure 1). References to the role of biophysical processes, riparian habitats and catchment ecosystems are conspicuous by their superficiality.

Polluted waters and gullied farms are now so common in Australian watershed catchments, they have become part of landscape iconography. Many people and communities now see them as natural, normal conditions.

Similarly in New Zealand, river catchments with braided riverbeds are now so seriously overloaded with gravel and debris, their floodplains more closely resemble gravel quarries than riparian ecosystems. Many people now believe this condition is natural.

In these eco-colonial attitudes and perceptions of catchment habitats and landscape ecosystems lies the dilemma. At odds ecologically and alienated culturally from the environs they inhabit, the dominant Anglo-American industrial societies of Australia and New Zealand are unable to see they are destroying the integrity of their watershed catchments, while spending millions of dollars annually treating the symptoms of degradation.

3. Catchment Habitats

Catchment habitats are the unique building blocks of landscape ecosystems. They are biogeographic units with unique patterns and ecological processes. Catchment habitats are identified by their characteristic topological signatures, described by their landscape identity and image, and inventoried for key biophysical parameters (Tane 1995).

A floodplain bog-flush, swale habitat for example, implies both geophysical structure and biophysical performance. It is worthy of note that catchment audits in New Zealand and Australia show that the performance of riparian habitats depends largely on the integrity of landscape ecostructures, (Tane 1996, Woodward-Clyde 1999).

By industrial logic, catchment habitats have become economic resources whose integral parts are valued separately in monetary costs and benefits. These separate parts are licensed and sold off like individual products: soil, water, minerals, vegetation, animals, and sites. Instead of integrated resource management, industrial society in Australia and New Zealand has achieved ecological disintegration of watershed catchments.

This is not a new scientific discovery. Since the realization that soil erosion, water pollution and landscape degradation are related to land use and other cultural activities, many writers have described the problem.

One of the more influential writers in this field is Aldo Leopold, a wildlife ecologist from America with a profound appreciation of habitats and ecosystems. In The Land Ethic he described the interactive energies flowing through a circuit of soils, plants and animals.

Using his words, "soils and landscapes are Ösustained by circuits. When a change occurs in one part of the circuit, many other parts must adjust themselves to it. Evolution is a series of self-induced changes, the net result of which has been to elaborate the flow and to lengthen the circuit." (Leopold 1949).

These circuits linking sites, habitats and ecosystems, are environmental infrastructure network systems called landscape ecostructures (Warshall 1998). They are complex networks connecting land and water systems both above and below the landscape (Tane 1999).

Finding watershed catchments with intact and healthy ecostructures is a challenge. Diagnosing the underlying causes of catchment degradation and working out what happened ecologically under varying human impacts is an even more challenging exercise. The main methods used include geospatial mapping and modeling using remote sensing GIS in conjunction with establishing benchmark transects.

Ecography, an integrated landscape assessment method of mapping habitats and modeling landscape ecosystems (Tane 1995) provided the key insights. First developed and tested for the New Zealand Land Inventory during the 1970ís, ecographic methods are now, in one form or another, integral to the modern science of landscape ecology.

Waitaki Basin Case Study

Preparations and team training commenced in 1976, for a comprehensive habitat audit of the Waitaki Basin, a watershed catchment bordering the NZ Southern Alps. Catchment habitats were mapped and their attributes recorded in one of the largest coordinated, integrated resource assessments of a catchment undertaken in New Zealand. Covering an area of 9770 square kilometers, the Waitaki Basin contains the highest mountain in the south pacific, Mauka Aoraki (Mt Cook), substantial glaciers and one of its largest rivers, the Waitaki.

Comprehensive field surveys corroborated earlier research recording widespread damage to soils and vegetation ecosystems. Moreover, it showed that key catchment habitats and watershed ecosystems had been virtually eliminated from semi-arid areas by successive waves of cultural activities, including fire, grazing, draining and in recent decades using herbicides, pesticides and other industrial chemicals.

The catchment audit included traditional thematic mapping of soils and geology. Several land capability assessments were undertaken, for nature conservation and wildlife management, outdoor recreation, pastoral farming, irrigated agriculture, farm forestry and tree crops. Key insights from the audit however, came from the ecographic inventory of catchment habitats and land use systems. The methodís potential lies in identifying and diagnosing the conditions and trends in catchment ecosystems.

The Watershed Systems Centre for Catchment Ecology is planning to repeat the catchment audit to coincide with the 25th anniversary of the original survey.

4. Landscape Ecosystems

The connectivity and spatial patterns of catchment habitats help create landscape ecosystems. They are multi-dimensional biogeographic units adapting and evolving over time to all environmental influences, including human settlement. Their role and function within stream catchments depends on linkages between sites, habitats and land use activities. Their sustainability depends on the status and condition of natural environmental networks called ecostructures (Warshall 1998, Tane 1996, 1999).

The mapping of landscape ecosystems requires yet another level of integration through progressive ecosynthesis, one that includes the infrastructures and landuse activities of human settlement. In other words, shifting from catchment habitats to landscape ecosystems involves integration through geospatial systems. Usually, though not necessarily, this takes place in a GIS, (Goodchild et al 1996).

There is an interesting and important discovery of profound importance to integrated catchment planning and management behind this methodology. It makes an interesting story, one that builds on the landmark results of a Bankers Trust privately funded R&D program initiated by a visionary farmer at Tarwyn Park in the Bylong Valley in Australia (Tane 1996, Woodward-Clyde 1997).

Bylong Creek Case Study

The Tarwyn Park R&D project investigated the nature, flows and storage capacities of floodplain aquifers and their recharge cycles trough natural sequences of flooding. Hydrogeological investigations were linked through ortho image based GIS to soil and vegetation surveys, catchment habitat mapping and land use systems.

In the 1970ís, soil erosion, salinity and serious gullying characterized Bylong Valley at Tarwyn Park. Bylong Creek was deeply entrenched, ephemeral and prone to damaging floods and debris. Farming became unprofitable and Tarwyn Park, an historic thoroughbred horse stud, went into liquidation. Before the introduction of environmental engineering programs that dismantled flood control works and reestablished landscape ecostructure, the Tarwyn Park floodplain was in a serious state of degradation.

The discrete roles and functions of the catchment habitats and landscape ecosystems on the floodplain were restored through adaptive strategies that simulated natural seasonal flooding, notably stalling and storing floodwaters through induced recharge. Suites of seepage weirs and infusion swales discouraged accelerated runoff and flood drainage. The floodplain at Tarwyn Park was restored from a water drainage dominated system with a low water table and annual water deficit, to a floodwater storage system with high water tables and annual water surplus.

In addition, upward and lateral aquifer pressure at discharge sites, generally located above natural headlands on the floodplain, helped ensure positive movement of groundwaters and near surface aquifers, maintaining their freshness while preventing water logging problems normally associated with stagnant waters. The performance of the dryland pastures under these conditions is similar to bog-flush meadows, rich in species and productive throughout the dry summer season.

Given that Tarwyn Park is in a low rainfall zone prone to soil and water degradation, it came as a surprise to those involved in the project, that the restoration of the floodplain habitats and landscape ecosystems corrected the land degradation problems and converted Bylong Creek into a perennial stream. Essentially the restoration strategy was based on reestablishing floodplain habitats and landscape ecosystems, and letting natural processes rebuild landscape ecostructures, (Figure 2).

5 Landscape Ecostructures

Landscape ecostructures are natural networks of habitats and ecosystems. They are natural phenomena recognized by Pacific cultures for millennia. Industrial science has only recently discovered their existence and has yet to fathom their full meaning.

In the Pacific region serpent mythologies, paintings and sculptures are commonly used to describe landscape ecostructures. Among the Melanesians and Polynesians, mythological Taniwhas, (serpent spirits and demons living in the landscape) are the diligent spiritual protectors guarding the integrity of land and water systems. In indigenous societies, myth and taboo can serve the role and function of policy and regulation.

The Watershed Systems Centre for Catchment Ecology is situated in Ruataniwha country, the native name for the Ohau-Pukaki locality in the Waitaki Basin. The rua (two) taniwhas (spirits) governing the landscape were represented by raised mounds about 50 metres long covered in boulders, situated at strategic sites in the landscape.

Until destroyed by industrial infrastructure in the 1970ís, for hundreds of years the two taniwha mounds were constant reminders of the terraqueous networks of catchment habitats and landscape ecosystems. Among the indigenous inhabitants of Oceania they come complete with landscape taboos and resource rules taught through songs and stories, dancing, painting and carving (Tane 1996).

The Australian Aborigines use a combination of sand painting, song lines and ceremonial dance to represent habitats, ecosystems and their network ecostructures. The sand painting showing floodplain ecography including ecostructures in figure 1 was immensely helpful in interpreting the results of R&D at Tarwyn Park and Billabong Creek.

The scientific nature and role of landscape ecostructures is probably best illustrated by a recent practical example. In 1998, the author undertook to audit the Upper Billabong Creek catchment and assess land degradation (Woodward-Clyde 1999).

Billabong Creek Catchment

The Upper Billabong is a watershed catchment perched on the western slopes and foothills of the Great Dividing Range, in southeast Australia. The catchment has been occupied for millennia by Aborigines and settled by Europeans in the nineteenth century. Both cultures employed practices with major impacts on environmental systems and catchment processes. Both cultures burnt and cleared vegetation to such an extent, that the landscape was often devoid of vegetation cover at critical times, exposing the unprotected soils and streams to the full strength of summer solar radiation or winter exposure. Fragile organic compounds in the soils, like humus, worms castings and manures, oxidized and volatilized when exposed to intense solar radiation including extreme UV rays.

Incremental soil mineralization over large areas was the inevitable result, followed by soil erosion, salinity and sedimentation.

There are so few habitats unaffected by land degradation remaining in the Upper Billabong Creek catchment that it is little wonder the local community have trouble conceiving what healthy landscape ecosystems look like. The few sites found and recorded in the study showing robust health, ecosystem resilience, biological productivity and restored ecostructures were regarded by many as infested with environmental weeds.

The overall results presented a bleak picture. Active stream and gully erosion affects 500 kilometres of watercourses in the Upper Billabong catchment. There is hardly a stream left in the Upper Billabong that is not degraded by gullying in some way. Over 10% of the catchment is actively eroding. Far greater areas are still recovering from previous erosion events. Degraded landscapes with dissected regoliths are now perceived as normal.

The catchment audit found that human activities transformed the normally aggrading streams and floodplains in the Upper Billabong into actively eroding landscapes. The combined affects of exposing soils and young plants to extreme solar radiation in summer and winter winds and frosts, are lost in detailed surveys and analysis of land degradation symptoms. In particular, accelerated runoff and soil drainage resulting from poor vegetative cover have seriously damaged landscape ecostructures and catchment processes which manage the flows, yields, reliability and quality of water resources.

Confining drainage, channeling streams and clearing riparian areas of wetland vegetation has increased storm water velocities and flood flows. As a result, gullying, streambed and bank erosion, are commonplace. The gullies rapidly drain surrounding landscapes, depleting their soils, drying out near surface aquifers and cracking confining clay bands. The soils have become surfaces and the resulting gullies have become in effect storm water and groundwater drains.

The situation is unstable and unsustainable. Extensive areas of degrading regoliths (the mantle covering bedrock) and their soils are discharging sediment, salts and nutrients into the channel system for transport downstream. Previously they were integrated in the regolith, in the saturated clay bands beneath meadow and wetland soils, in the micro-organisms and humus matter of the soil, and in the above ground biomass.

Before extensive gullying and accelerated land drainage became the norm, sediments, minerals and nutrients were intercepted and stored, converted in biomass and recycled through catchment ecosystems. The networks of riparian sites, habitats and landscape ecosystems that made it all possible, are being destroyed. Ignorance and neglect are decommissioning landscape ecostructures.

6. Catchment Ecology

In the technical jargon of landscape ecologists, the inter-montane valleys of the New Zealand high country are catchment ecosystems with aggrading floodplains and distributary river systems. Left to Nature they develop into highly productive landscape ecosystems with levels of habitat diversity matched by abundant biota. Characteristic habitat suites of terraqueous meadows and marshes, bog flushes and seepage swales, probably accounted for a third of the total landscape. Today they are mostly less than 10% of the total due to land drainage and degradation.

The way landscape ecosystems operate in watershed catchments is usually determined culturally. In the watershed catchments of both the Upper Billabong and Waitaki Basin, Quaternary basins operating as natural aggradational systems for millennia have been converted to degradational systems by cultural activities.

Healthy, distributary river systems have braided floodplains with a rich tapestry of forests, woodlands, shrublands, bogs and flushes. Their aquifers, discharge springs, surface streams, pools and riffles are only some of the myriad habitats that are now memories. Sand and gravel-choked floodplains and deep unstable, drainage channels are replacing them.

River Conservation Myths

At the time of writing, the NZ Department of Conservation is encouraging the elimination of riparian vegetation from high country floodplain rivers to encourage unstable gravel riverbeds (Hepplethwaite 1999). Captured by cultural perceptions that unstable, gravel floodplains are normal, intrinsic parts of the high country, they are preventing ecological restoration of rivers and their floodplains though natural processes of vegetation succession and ecosynthesis.

In simpler terms, their aim is to turn these mighty mountain floodplain rivers, once clothed in habitat mosaics of forests, woodlands, shrublands and wetlands, into industrial gravel beds with drainage channels maintained by combinations of bulldozing, spraying, felling, and burning woody plant communities. Ironically, this Department of Conservation program is heralded as "river recovery".

In industrial societies depending on scientific mythologies, catchment consciousness is lost when governments carve up the environment into separate administrative empires. Departmentalism is the antithesis of integrated catchment management. Connectivity of catchment ecosystems through landscape ecostructures are unknown or ignored, while drainage schemes imposed on degraded watershed ecosystems cleared of their forests and woodlands, ensure fresh waves of gravel and debris with each flood.

Like engineers and hydrologists, resource scientists preoccupied with specific issues, like soil erosion or endangered species, have forgotten the essential connectivity between river, stream and catchment habitat. They have yet to display an understanding of landscape ecostuctures or catchment ecosystems.

Indigenous and Industrial Mythologies

Animistic, indigenous societies survive by revering landscape habitats and ecosystems. They develop ethical traditions covering their relationships with rivers and catchments. Koori and Maori people have catchment ethics (Tane 1996).

By their nature, catchment ethics are fuzzy externalities, intangible and esoteric. so they are left out of the statistical equations and numerical models of engineers and hydrologists. To the indigenes this is the naïve nescience of ecocolonialists, of a people and society alienated from the environments they occupy (Cox and Elmqvist 1991).

It is a similar situation with catchment hydrology. Stream flow and catchment yields are the treasured measures. They are calculated using the drainage model of engineers, as if catchment ecosystems operate like plumbing infrastructure. The equations have no place for habitats, communities and ecosystem functions.

In industrial societies soils, vegetation and land use are independent variables, not interdependent systems. The dissembled parts are fast becoming resource empires for government agencies and corporate moguls. The connectivity of water and habitat is forgotten. Industrial society has lost catchment consciousness (Tane 1996). The consequences are a host of intractable problems and unexpected externalities with incremental impacts and long time lags characteristic of complex systems.

Take for example, the industrial approach to managing water catchments.

The general aim is to maximize water yields. This even takes precedence over the integrity of landscape ecosystems and healthy rivers. Probably nowhere is this better illustrated than in the crass generalization that "reduction of forest cover increases water yield". This directly reflects industrial attitudes that soil, vegetation, wildlife; land use and landscape ecosystems are dispensable in the interests of maximizing water supplies.

Of course, the removal of all flora and fauna increases water yields too. The illogical conclusion of this line of industrial reasoning is to concrete the whole catchment, like Gibraltar.

The clear message from environmental audits of watershed catchments in Australia and New Zealand is that when catchment habitats and landscape ecosystems are operating efficiently, natural systems replenishing and purifying water operate most effectively. This does not mean excluding people, just eliminating deleterious land use and infrastructure impacts and encouraging ecological land use systems. Following this line of reasoning, land use systems should seek to mimic and enhance catchment habitats and landscape ecosystems. This is the big challenge for the next millenium.

Fortunately, leading research and development groups are already providing the necessary models and methodologies for designing watershed terraquacultures (Ruddle and Zhong 1988).

7. Post-Industrial Imperatives

The specialist is one who rarely makes small mistakes

while moving towards the grand fallacy

Marshall McLuhan Canada

The calamitous results of two hundred years blending bad economics and bad land use in watershed catchments are basically being misinterpreted. Meanwhile, literally millions of dollars are being spent decorating the countryside planting native trees and shrubs for dubious reasons.

The situation is distinctly McCluhanesque. When it comes to contemporary society in Australia and New Zealand, the medium is the message. The medium is our evolving landscape and the message is not good. For deep gullies and gravel riverbeds everywhere are draining the lifeblood from the land. Our upland, watershed catchments are an environmental mess with failing ecostructures.

Environmental programs, regulatory controls, Landcare lotteries and Streamcare grants are more often than not ad hoc attempts at restoring damage to stream catchments. A plethora of projects treating the symptoms of long term degradation of catchment habitats and landscape ecosystems is clear evidence that overall strategies are lacking or inadequate..

Industrial society is commonly defined by the politics of resource exploitation.

Cultural attitudes and perspectives have emerged as the basic problem in industrial societies largely bereft of catchment consciousness and land ethics. We have the collective knowledge, technology and resources to restore watershed catchments to full functionality and productivity. But it seems we do not have the necessary driving force of unified cultural mythology and public policy.

8. Comments and Conclusions

Australia and New Zealand are caught in an intractable cultural dilemma. As a result of believing in industrial mythologies based on ecocolonial knowledge based systems (Cox & Elmqvist 1991), local communities in watershed catchments are starting to believe that the long term degradation of watershed catchments is normal and natural. The degradation of watershed catchments in Australia and New Zealand will continue unabated so long as communities impose activities and infrastructure that destroys ecostructure.

In the hill and high country catchments of southeast Australia and New Zealand, new myths that reinforce local beliefs are in the making. Many people believe symptoms of landscape degradation, like deep tree lined gullies and sand and gravel laden rivers, are unique natural features requiring environmental protection.

Increasingly, landscape restoration through natural regenerative processes operating as self-guiding environmental systems, conflict with policy demands based on industrial performance standards. It seems that key cosmic roles have reversed, for industrial society sets goals like Gods, and Nature becomes its maid and servant.

In these circumstances, the inherent dangers of geospatial technologies for watershed management are clear. They may well become blind machines for determining arbitrary yields of water required and not the intelligent tools for better understanding how watershed catchments operate through integrated habits, ecosystems and ecostructures.

The dynamics of change to post-industrial information society might suggest the prospects are bright. Public concern for the environment is now entrenched, however unrealistic expectations for landscape form and species composition, at the expense of function and community, are undermining the credibility of conservation initiatives.

With the benefit of hindsight we are able to see the manifold failings of industrial society among the many blessings brought by industrial technology. Recognizing the dilemma is only the first step. What post-industrial society urgently needs is a new paradigm for understanding watershed catchments based on the integrity and connectivity of catchment habitats and landscape ecosystems.

References

 

Cox, AC. & T Elmqvist (1991) Ecocolonialism and Indigenous Knowledge Systems, Pacific Conservation Biology Vol.1(1) University of Queenland. Aus.

Curds, Colin (1992) Protozoa in the Water Industry Cambridge University Press, UK.

Goodchild et al (1996) GIS and Environmental Modeling GIS World Books Fort Collins USA.

Hammond, H (1997) Water and Connectivity pp.102-108, in Ecoforestry edited by AR Drengson and DM Taylor.

Hepplethwaite, Simon (1999) Restoring Braided Rivers NZ Forest & Bird No 293, Royal Forest and Bird Society, Wellington NZ.

Leopold, Aldo (1949) A Sand County Almanac Oxford University Press NY 1987

Ruddle, K. & Gongfu Zhong (1988) Integrated Agriculture-Aquaculture in South China Cambridge University Press, UK.

Tane, Haikai (1995) Ecography: Mapping and Modeling Landscape Ecosystems, Technical Manual, River Murray Mapping, Murray Darling Basin Commission Canberra. Aust.

Tane, Haikai (1996) The Case for Integrated River Catchment Management, Keynote address, Proc. International Conference on Multiple Land Use and Integrated Catchment Management, Macauley Land Use Research Institute, Aberdeen. UK.

Tane, Haikai (1999) Landscape Ecostructures for Sustainable Societies in Volume 58(5) NZ Journal of Soil and Health, Auckland NZ.

Warshall, Peter (1998) Modern Landscape Ecology Whole Earth Catalogue, Summer, 1998.

Woodward-Clyde (199) Natural Farming Sequence R&D Joint Venture Tarwyn Park , Canberra, Aus

Woodward-Clyde (1999) Upper Billabong Creek Catchment (Reports 1-4) for Upper Billabong Land and Water Management Plan Working Group, Holbrook, Aus.

The figures for this paper are not available on the Net for commercial copyright reasons. Copies of the figures are available from the Centre for Catchment Ecology free of charge. Please email your name and postal address to taneh@watershed.net.nz, (we would appreciate a paragraph on your particular interests in the information) and you will receive them by regular mail. Haikai Tane, Director

TRAINING & RESEARCH CENTER

PO Box 108 - 11 Mount Cook Street
Twizel New Zealand

Phone 64 3 4353 227 Fax 64 3 4353 227

Email: taneh@watershed.net.nz

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