Development of a Riparian Condition Assessment Protocol for Northern Gulf Rivers using Remote Sensing and Ground Survey

superuser — Tue, 21 Jul 2009 06:57:15 +0000

The primary focus of this study was to establish the riparian condition baseline against which future condition trends could be measured; and the development of a robust, repeatable method of analysis.
However, during the course of the study, researchers found that the dramatic changes in woody vegetation in both the channel zone and across floodplains warranted much more detailed investigation to establish:

IDs and People

Program:

Tropical Rivers Research and Development

LWA Project Code:

GRU38

Host Organisation:

Land and Water Australia

Subjects

Subjects:

Rivers and Wetlands

Keywords:

Riparian

condition

Northern

gulf

Rivers

remote

sensing

ground

survey

woody

Vegetation

protocol

floodplains

Current Activities

Status:

Complete

Land use effects on soil nutrient enrichment: Risks for weed invasion

Mon, 18 Aug 2008 02:01:58 +0000

IDs and People

Program:

Defeating the Weed Menace R&D Program

Program Theme:

Land use change impacts on weed incursion

Research Type:

Research Project

Legacy (KMS) Project ID:

CEN9

Host Organisation:

CSIRO Entomology

Researchers:

Elizabeth Lindsay

Dr Saul Cunningham

Subjects

Subjects:

Data and Information

Landscape Management

Weeds

Keywords:

Soil

Weeds

Vegetation

weed

nutrient enrichment

bungendore

murrumbateman

boorowa

young

Project Information

Summary:

This project examined various soil and vegetation properties of remnant eucalypt grassy woodlands under different livestock grazing regimes within agricultural landscapes on the southern tablelands and south west slopes of N.S.W. All woodlands contained a minimum of two exotic plant species and there was up to 94% exotic plant cover in the understorey.

The most common invasive exotic plants were annual exotic grasses, most of which were introduced in the past to surrounding areas as pasture grasses. The top soil was generally enriched in various forms of nitrogen and phosphorous compared to published information on woodlands with a low disturbance history. There was no difference in the soil nutrient status between sites with livestock grazing excluded and those with low to high intensity grazing. This indicates that soil nutrient levels within woodlands will take a long time to decline to original levels once a major source, livestock, has been removed.

Exotic plant cover and diversity in the understorey increased as soil nutrient concentrations increased, whereas native plant diversity decreased as soil nutrient levels increased. Exotic plant cover increased as native plant cover decreased. Managing for a low soil nutrient status and high native plant understorey diversity and cover could assist in controlling exotic plants in woodlands.

A rotational grazing scheme rather than a setstock grazing regime would also help to maintain the native plant understorey. Land use intensity appears to alter the soil seed bank, soil properties and the weed community in woodland remnants. The land use history of a site appears just as important as the current property or landscape use; however this information is not always available.

The understorey of remnants in a grazing landscape are likely to be easier to restore and protect than those in the higher intensity cropping and grazing landscapes. When restoring the woodland understorey through native grass seedbaddition, there will be greater success if seeds are sown in areas of low soil ammonium and close to mature eucalypt trees. Weed invasion and nutrient enrichment are two major problems affecting the longevity of remnant grassy woodlands in agricultural landscapes. Minimising nutrient inputs and exotic grass dominance will assist in maintaining small remnants in highly modified landscapes.

Outcomes:

Results show that though remnant woodlands have been affected by agricultural practices, they are remarkably resilient. Minimising grazing pressure can improve the functioning of invertebrate communities and ecosystem processes within remnant woodlands. Livestock exclusion won’t improve all sites, and for some, additional remediation work will be required. With careful management, remnant vegetation can still be part of the production system within a livestock grazing property, with fencing making strategic grazing easier. Woodland vegetation needs to be rested from grazing and stock camping in woodlands should be minimised to stop further nutrient enrichment.

Current Activities

Status:

Complete

Background

Project Background:

Most of the eucalypt woodlands in south eastern Australia exist as remnants in highly modified agricultural landscapes, commonly on private land (McIntyre et al., 2002). In order to preserve the remaining woodlands we need to better understand the disturbances they face (e.g. land clearing, edge effects, livestock grazing, nutrient enrichment, weed invasion) and how to balance the conservation and production needs of these landscapes.

Aims:

This study aimed to understand the impacts of productive land use (livestock grazing and cropping) on soil nutrient enrichment and the understorey vegetation in small remnant grassy woodlands in agricultural landscapes. Sites were on the southern tablelands and south west slopes of N.S.W near the towns of Bungendore, Murrumbateman, Boorowa and Young (Appendix Fig. A1).

The main objectives of this project were to determine;

what exotic plants are common in woodlands?
the relationship between weed diversity and abundance and soil nutrient levels,
the impacts of weed invasion and nutrient enrichment on the understorey vegetation,
if there are native plant seeds in the soil seed bank that are not present as adults, and if there are
native plant species that are rare as adults but with a large seed reserve in the soil
how nutrient enrichment, weed invasion and the seed bank change with the current grazing regime
and land use intensity
what is inhibiting native grass germination and establishment in exotic grass dominated woodlands?

All in Vegetation

Development of a Riparian Condition Assessment Protocol for Northern Gulf Rivers using Remote Sensing and Ground Survey

Land use effects on soil nutrient enrichment: Risks for weed invasion