Shaping land use change (LUC) and ecosystem restoration in a water-stressed agricultural landscape to achieve multiple benefits, Bryant et al. 2020

In spite of its obvious benefits, agriculture, which covers one third of the Earth’s land surface, damages biodiversity and ecosystem services. In some regions, land degradation and depletion of water resources from irrigation have been so great that historical levels of food production in these regions risk decline. Some areas of previously productive farmland will likely need to be retired from use. Within this context, maintaining and enhancing natural corridors and promoting semi-natural, multifunctional landscapes can significantly contribute to recovering biodiversity and mitigating air and water pollution.

Using California’s San Joaquin Valley (SJV) as a case study, this paper illustrates a pragmatic approach to incorporating ecological corridors into working landscapes. The authors offer a new analytical approach that simultaneously incorporates resource-constrained (water, in this case) land-use change (LUC) modeling within the planning and optimization process. The goals are to simultaneously:

• Meet water-use-reduction policy goals for the area under study within the next two decades
• Identify lands for retirement that are (1) likely to be retired anyways and (2) offer high-value habitat for native species and biodiversity.

Over the past century, SJV has been transformed into one of the largest agricultural economies in the world. However, this economic success has been costly to the SJV in several ways, including:

• Damaged infrastructure: high rates of groundwater extraction in the SJV have led to groundwater overdraft and unreplenished aquifers, resulting in large-scale land subsidence. Most of the subbasins in the SJV are categorized as critically overdrawn, and some regions have sunk over 8 meters since the early 20th century; this land subsidence further imperils water availability and quality by impacting water storage and delivery infrastructure.
• Decreased human health, as a result of impaired air and water quality, leading to chronic health problems
• Threats to wildlife and biodiversity; for example, some species have lost up to 98% of their habitat range, and over 35 native species are listed as threatened or endangered

“In response to these challenges, and amid significant drought-driven fallowing, California passed the Sustainable Groundwater Management Act (SGMA), which … obligates locally governed groundwater subbasins to develop plans that will achieve sustainable groundwater use over the next two decades” [Bryant 2020: 2]. To meet these requirements, many subbasins will meet with severe groundwater pumping restrictions. If these areas are not able to coordinate their pumping activities and augment water supplies, the SGMA may require a reduction in cultivation area through fallowing or permanent retirement.

Given the likely retirement of 86,000 ha of irrigated agricultural land, the authors explore spatial optimization of retired land for conservation efforts. They find that a key strategy is the identification of areas that were destined for retirement from cropping which could be shifted to restoration and habitat enhancement, as well as possibly shifting some areas destined for retirement that have “low habitat value” with regards to wildlife for areas with “high habitat value.” Priority restoration areas identified in this analysis include many that are contiguous and located near designated wildlife areas.

Importantly, the analysis presented here is “explicitly organized to help inform engagement between conservation actors and agricultural land managers about how habitat goals can be achieved in ways that benefit communities in the SJV” [Bryant 2020: 3]. The potential positive futures indicated by such analysis can be used to identify opportunities for collaboration between the conservation and agricultural communities, with a goal of guiding land use change toward achieving multiple benefits, such as recovery of imperiled natural communities, resilient agricultural production, and improved public health outcomes.

While it poses a great challenge, the impending transformation in the SJV also presents an opportunity to proactively shape the landscape in ways that not only ensure agricultural and water sustainability, but also achieve many other socio-ecological goals, such as biodiversity protection and improved human health. However, given that achievement of many of these objectives is determined by where things happen on the landscape (rather than simply the aggregate amounts of cultivation, retirement, or restoration), stakeholders need a systematic way to integrate these objectives to inform multi-benefit spatial planning [Bryant 2020: 4].