An investigation of the hydrological requirements of River Red Gum (Eucalyptus camaldulensis) Forest, using Classification and Regression Tree modelling

Abstract

River Red Gum (Eucalyptus camaldulensis) is widely distributed throughout many water courses and floodplains within inland Australia. In recent years, accelerated decline of River Red Gum condition has been observed in many locations, and field observations of the degradation are consistent with the reduction of flooding. However, there are few publications that quantitatively investigate the relationships between River Red Gum condition and flooding history. We applied Classification and Regression Tree (CART) to model the minimum flooding requirement of River Red Gum forest/woodland in Yanga National Park, located on the Lower Murrumbidgee Floodplain, southeast Australia, using crown conditions derived from historical aerial photographs spanning more than 40 years. The model produced has a moderate reliability with an overall accuracy of 64Ð1% and a Kappa index of 0Ð543. The model brings in important insights about the relationship between River Red Gum community type, flood frequency and flood duration. Our results demonstrated that (1) CART analysis is a simple yet powerful technique with significant potential for application in river and environmental flow management; (2) River Red Gum communities on the Lower Murrumbidgee Floodplain require periodic inundation (3-5 years) for a duration of up to 64 days to be in moderate to good conditions; (3) Although the crown conditions of different community types displayed similar degradation trends, they have distinct flooding requirements; and (4) The River Red Gum community in Yanga National Park may be managed as hydrological units given limited environmental water allocations.

Linking local ecological outcomes with basin-wide water planning: a case study of Yanga National Park, an important Australian inland forested wetland

“…The ERM for this species was verified with historical canopy condition data (Wen et al 2009a) using the modelled "actual" wetland hydrological time series. However, two fundamental limitations in the LYNC needed to be considered.…”

“…With an area of about 80 000 ha, the park is renowned for its wetlands as critical fish and water bird habitats and refuge for biodiversity in arid and semi-arid Australia (Kingsford and Thomas 2004, Wen et al 2009a, 2009b. The park is an essential part of the Lowbidgee floodplain, which is listed in the Directory of Important Wetlands in Australia (Environment Australia 2001).…”

“…We adjusted the curves using site-specific data collected within the Yanga National Park whenever such data are available. For example, we used the historical vegetation condition maps (Wen et al 2009a) to update the optimal inter-flood dry duration of river red gum forest to 5 months (Fig. 3).…”

Modelación matemática de la interacción entre la vegetación de ribera y el régimen hídrico del río en condiciones semiáridas

“…Kappa se ha usado mucho para pruebas de diagnóstico médico y psiquiátrico (Cohen, 1960;Landis y Koch, 1977) y, más recientemente, para evaluar modelos de distribución de comunidades vegetales utilizando sensores remotos (Chen et al, 2010;Franz et al, 2010;Kokaly et al, 2003;Liu et al, 2009;Niclòs Corts et al, 2010), para mapeo de humedales (Biondini y Kandus, 2006;Nielsen et al, 2008;Peters et al, 2008) e incluso para evaluar un modelo de riberas enfocado en los efectos de las inundaciones sobre la vegetación (Wen et al, 2009). …”

“…Arreglando la información de salida del RibAV en el formato descrito (Tabla 7.23) es posible generar los índices "CCI" y "Kappa" de los TFV; de esta manera el modelo permite generar dos indicadores de eficiencia útiles para su sólida calibración, y se suma a los recientes esfuerzos por evaluar la bondad de las predicciones sobre distribución vegetal "presencia/ausencia" (Biondini y Kandus, 2006;Chen et al, 2010;Franz et al, 2010;Kokaly et al, 2003;Liu et al, 2009;Niclòs Corts et al, 2010;Nielsen et al, 2008;Peters et al, 2008;Wen et al, 2009). …”