Dryland Salinity in Western Australia as a Complex Adaptive System Assignment Sample

• Subject Name : Environmental Science

Executive Summary

Dryland salinity is one of the major concerns that surround Western Australia. The environmental problem of dryland salinity has been visualised and analysed as a complex adaptive system in this report with the notion of fast and slow variables dictating the regime shift to be the water table and hydrology and the vegetation on the land respectively. Further, discussion on how strengthening the resilience in this complex adaptive ecological system has been provided with a notion to restore the natural state of vegetation in the ecosystem to manage the rising permanent infertility in soil. Several recommendations like us of halophytes, leeching, and vegetation change as triggers of regime shift have been evaluated to consider a shift to a more sustainable and managed ecosystem.

Table of Contents

Introduction

Discussion

Complex Adaptive Systems 

Dryland salinity in Western Australia as a complex adaptive system

Resilience

Sustainability through resilience

Recommendations

Conclusion

References

Appendix: List of dryland salinity management initiatives in western Australia

Introduction

Dryland salinity in Australia is a major environmental concern and is defined as excessive salt concentration in soil hampering with the plant and vegetation growth that generally arises with poor water quality and damaged infrastructure (O'Brien et al., 2019). Dryland salinity is a cause of major concern as it directly impacts the productivity of land in terms of its agriculture, water quality, as well as biodiversity(Harper et al., 2017). According to the government of Australia, more than 1 million hectares of fertile land has been directly affected by dryland salinity in Western Australia and costs more than $500 million in the annual revenue (Government of Australia, 2020). Therefore, the management of dryland salinity in Western Australia has been a priority. The resilience of this ecosystem is important to be analysed as it will open frontiers for the management and ensuring sustainability in the region (McFarlane et al., 2016). This report is focussed on the case study of “Dryland salinity in Western Australia” through the lens of complex adaptive systems and identifies how altering the resilience of the natural ecosystem of western Australia’s drylands can help in achieving sustainability in the system.

Discussion

The focus of this discussion is to analyse the dryland systems of Western Australia as a complex adaptive system and to measure how alterations in its resilience can impact sustainability.

Complex Adaptive Systems

A complex adaptive system can be defined as an integrated networked system where the focus on an independent sector does not provide a vision and understanding for the holistic perspective of the behaviour of the system (Phillips & Ritala, 2019). The systems are considered complex when the emergent behaviour is an amalgamation of multiple components with networked action and parallel function. The science of complex adaptive systems is particularly important as they help in the understanding, prediction, and prevention of the problems that are persistent in the system (Walker & Salt, 2012). The characteristics of complex adaptive systems include a high degree of adaptive capacity, resilience, homeostasis, organisation, and intricate networking. Natural ecosystems, hence, serve as a prominent example of complex adaptive systems with self-organised local interactions (Phillips & Ritala, 2019).

An appealing feature of the complex adaptive system is their non-linearity making them develop in to flexible and diverse. A complex adaptive system is formulated with a range of variables that are either fast or the dependent variables and the slow or independent variables (Phillips & Ritala, 2019). The course of resilience and inclination of these ecosystems is heavily dependent on the social interactions and gives rise to social ecological systems. When a minimum threshold is crossed in the systematic interaction in a complex adaptive system, a regime shift is observed where the course for succession in the system changes (Wang et al., 2020). Therefore, it becomes important to identify the minimum basal thresholds of a system and monitor its discourse to ensure sustainability and balance in the system.

Dryland Salinity in Western Australia as A Complex Adaptive System

The dryland salinity in Western Australia can be seen as a complex adaptive socio-ecological system with interactions from natural as well as the anthropogenic environment. From nature and the anthropogenic interactions. The salt carried via rainfall has been depositing in Western Australia for about 13000 years (Resilience Alliance and Santa Fe Institute, 2004). This deposited salt is stored in underground water. Before the anthropogenic activities and land occupation through settlements, this water was utilised by the perennial shrubs that limited the water table rise and prevented salinity of the top soil. However, with the mass clearings, this has not been possible and with current scenario, two alternative regimes can be seen as a possibility for this system. First, a productive, non-saline soil ecosystem with deep-rooted perennial vegetation, and, secondly, an unproductive a salt and waterlogged shallow rooted vegetation ecosystem (Resilience Alliance and Santa Fe Institute, 2004).

To see this is a complex adaptive system, the vegetation cover can be seen as a fast or dependent variable that is linked with the independent variable or the slow variable of hydrology and water table depth. The disturbance in this system and the threshold triggers can be the removal of the deep rooted perennial vegetation and replacing it with shallow rooted annual vegetation (Walker & Salt, 2012). This can, therefore, impact the ecological niche and water uptake cycles of the plan resulting in a direct impact on the soil salinity and fertility of the system. The threshold of the ecosystem in this complex adaptive system is linked with the clearing of deep rooted native vegetation of the land and its replacement with annual, shallow rooted plants with anthropogenic intervention (O’Brein et al., 2019). Several external factors like changes in the water regulation, industrialisation, and nature of plants in vegetation can also be seen as the external factors that can be associated with the regime shift in the dryland saline ecosystem of western Australia.

Figure 1: Dryland salinity in Western Australia as a complex adaptive system 

Resilience

Resilience in an ecosystem can be defined as the robustness of the system with its ability to resist change and bounce back to its natural state (Walker, 2020). Ecological resilience has, therefore, also been defined as the ability of an ecosystem to respond to the disturbances and restore to its natural state. The resilience of a system is directly associated with the slow and fast variables that help in the determination of the ecological threshold. In the given system, it can be analysed that the natural state of the drylands of western Australia was inclusive of deep rooted perennial vegetation that was consequently replaced by the shallow rooted annual vegetation (Falk et al., 2017).

As a consequence, the water table rise was observed and the salinity in the water due to deposited salts from the rains resulted in affecting the top layer of the soil making it unproductive and infertile. The perennial plants in the natural vegetation had emerged in a consequent succession of the niche and were able to survive as they influenced the water table by reducing the groundwater reach to the fertile layer. However, when these plants were replaced by the settlements, the rise in water levels resulted in salinity of the soil. When the salt accumulates in the root zones of the vegetation, the plant growth is negatively affected (Harper et al., 2017). A condition of “physiological drought” is experienced by the plant where the salt rich water in its absorption zone is poor for the plant growth (Laban et al., 2018). Therefore, strengthening the resilience, that is the ability of this ecosystem to bounce back to its natural state must be ensured to shift the regime to a more sustainable and ecologically productive system.

Sustainability Through Resilience

Resilience is important in the sustainable systems as it helps in building a cushion for a regime shift and helps the complex adaptive system to return to its natural state. However, once the minimum threshold is lost, this change is less probable and an alternate regime is observed. Sustainability is, therefore, an integral component of resilience. A sustainable system can better absorb, recover, and adapt to the disturbances in the system. Resilience is often considered complementary to sustainability as it helps in building endurance in a system and prevent catastrophic regime shifts. In consideration of the case study of dryland salinity in Western Australia, the strengthening of the natural ecological habitat with deep rooted vegetation to restore the ground levels will provide increased resilience and help in preventing further damage. A major consideration in this case study is to acknowledge that the land and soil damage that is caused by the saline water is permanent and renders the soil highly infertile and damaged (Yirdaw wt al., 2017).

Therefore, strengthening of resilience to ensure sustainability is even more important to prevent further damage and land loss. Salinity in an ecosystem has been classified into primary and secondary salinity. Primary salinity arises through the discourse of natural development whereas, secondary salinity is a consequence of the anthropogenic intervention (Li et al., 2020). In the saline drylands of Western Australia, a natural salinity persists with precipitation and water runoff but is ecologically managed through plant cover and vegetation that helps in keeping the water levels of the table deep seated (Li et al., 2020). However, this primary salinity has been aggravated to secondary salinity by the settlements that resulted in a change of vegetation cover. Sustainable management of the drylands of western Australia is, therefore, an ecological priority and must be ensured to save the ecosystem and prevent further damage.

Recommendations

Multiple strategies have been employed to ensure the wellbeing of the rising salinity in the drylands of western Australia however, limited success has been obtained. Walker and Holling discuss that the four essential aspects of resilience are resistance, panarchy, latitude, and precariousness (Walker, 2020). Therefore, strengthening of these components is critical to ensure resilience and sustainability in the ecological system of drylands of western Australia. To ensure the salinity management in the drylands of western Australia, the following strategies can help in the restoration and ensuring sustainability:

1. Cultivation of halophytes: Halophytes are a class of plants that thrive and survive in soils that have high salt concentration (Malik & Ravindran, 2018). These plants are used for remediation of soils and help in reclamation of land. Some plants that have been successful in land restoration and soil fertility management in highly dry and salt rich environments like that of western Australia include the Suaeda maritima (Figure 2a) and Sesuvium portulacastrum (Figure 2b) that have demonstrated to remove about 504 kgs and 474 kgs of salt from saline soils of 1ha land respectively, over the time period of four months (Vårhammar et al., 2019).

The use of these halophytes in the regions with damaged soil conditions can help in the restoration of the land and prepare it for further management by replacement with deep rooted shrubs for long term management of the land and help in the restoration of the natural habitat (Kumar et al., 2019). This will also help in strengthening the resilience as use of plants on the saline soil of drylands of western Australia help in the mitigation of water table levels and prevent further increment in the water salinity. Management of this vegetation will help via interaction with the slow drivers of the regime shift, that is water table levels and the hydrology of the ecosystem and thereby assist in reaching a sustainable alternative for the regime shift.

Figure 2: Halophytes for land restoration (a) Suaeda maritima (b) Sesuvium portulacastrum

2. Leaching: Leaching is one of the most conventional methods that is used to reduce the soil contents in the soils with effective drainage (Starr et al., 2017). The water with low salt concentration is applied to the roots of the vegetation to promote their growth and minimise the damage caused by the excessive salt levels present around the roots. This will help in the management of the fast variable of the complex adaptive system and thus help in strengthening the resilience by providing immediate management (Costa et al., 2019). Leaching will help in enhancing resilience as it will aid in improving the immediate ecological landscape and provide for scope for management of the slow variables that can eventually affect the hydrology of the condition. Soil assessment and treatment: The build up of salt in the soil can result in the development of three kinds of soils. These are saline, saline-sodic, and sodic soils (Starr et al., 2017).

Each of these kinds of soil has different properties and requires a precise management strategy. Therefore, soil assessment and treatment is important in the management of the ecological condition and insurance of resilience strengthening. assessment and treatment of the soil will be beneficial for both, the slow and the fast variables (Zlotopolski, 2017). The hydrology and water table of the soil and land can be managed if the kind of salinity is assessed and a specific treatment option is laid for the management of ten drylands of western Australia. In conjunction, since the kind of salt and nature of salinity will be assessed an improvised and detailed management plan can be established.

3. Promotion of growth of perennial deep rooted shrubs and trees: Growth of perennial plants must be promoted to restore the natural system prior to anthropogenic intervention (Ploschuk et al., 2017). The deep rooted plants will help in the management of land hydrology and therefore help in enhancing the resilience by impacting the slow variable of the system and directly affect the regime shift towards a sustainable future. This will help in the restoration of the fertile land and prevent further damage by maintaining the water table levels below and thus prevent the salinity of the deposits from affecting the land (Nery et al., 2019).

4. Government and regularised action to prevent further damage: With multitudes of ecological and environmental actions that are required to generate awareness and prevent further exploitation of land and promote restoration. A range of measures have been taken and are listed by the government for dryland salinity management in western Australia (Appendix 1) (Government of Australia, 2020), however, a rigorous participatory approach and stricter actions are required for effective management to enhance resilience and to sustain the ecosystem.

Conclusion

Through this report, it can be concluded that salinity in the drylands of Western Australia can be seen as a Complex Adaptive System with a range of variables playing a role in the discourse of its regime shift. The slow variable of this system can be identified as the hydrology and the water table content in the system that possesses the ability to direct the shift of regime from a productive and fertile land to an unproductive saline dry land in the region. The salinity in the soil is caused by excessive accumulation of salt with rainwater runoff that was submerged in the low lying water table maintained by the deep rooted vegetation native to the ecosystem. However, with the anthropogenic intervention, this vegetation has been lost and has been replaced by the annual shallow rooted plants resulting in an observed rise in the water table.

Due to this rise, the salinity of the water has reached the top soil and has rendered it infertile. The vegetation can, therefore, be seen as a fast variable and its change as a trigger for the regime shift. To ensure sustainability, strengthening of resilience is required in this ecosystem. This can be achieved by promoting halophytes, leeching, and planting deep rooted perennial shrubs for the restoration of saline land and prevention from further salinity in the soil. To have a strong impact and ensure that the principles to strengthen salinity are applied, a formative regularised action of government is also required.

References

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