Peer-reviewed publications

Temperate grasslands are a highly threatened global biome. Complicating management and conservation strategy development, modern grasslands can be difficult to characterize across landscapes since they range from native and semi-native to completely non-native species compositions such as those found in heavily managed pastures. Similar to methods used to differentiate C3 and C4 grasses, we investigate the ability of using temporal variations in growth characteristics as an alternative pathway to predicting native versus introduced species composition across grassland landscapes. To do this, we conducted an exploratory analysis using a time-series of Normalized Difference Vegetation Index values as a measure of vegetation greenness with Landsat 5 TM imagery across a growing season and performed an unsupervised classification. Results from the classification were compared with field observation to determine if we can differentiate between native and introduced grassland types in the Northwest Glaciated Plains subecoregion of northeastern Montana. Our results indicated that we predicted grassland cover with 81% accuracy within our 200 km2 study area and 71% accuracy in our 5000 km2 secondary study area. Further extrapolation of our methodology, combined with the refinement of vegetation indices of time-series imagery, classification algorithms and the availability of data from planned Landsat and Sentinel missions, may provide the spatial detail necessary to improve grassland monitoring and rangeland management over large areas.

Assessments of programs offering payments for forest conservation have largely focused on their contribution to avoiding deforestation but have overlooked degradation. We integrated remotely-sensed forest cover images, georeferenced landscape information, field-level forest inventories and face-to-face landowner surveys to quantify avoided deforestation and degradation within the context of Ecuador's Socio Bosque Program (PSB). We found the PSB prevented 9% of enrolled forest area in Ecuador's Amazon Basin from being deforested over the 2008-2014 period. This value is higher than previous assessments conducted in other Latin American nations. Inventory data suggest that forests within PSB-enrolled areas exhibited less evidence of degradation although statistical differences were only marginally significant On average, PSB-enrolled forests had between one and two more tree species per hectare than non-enrolled forests. These additional tree species were twice as likely to be of commercial timber value and at greater threat of extinction.

Conversion of grassland to cropland has accelerated over the past decade due to high crop prices, government incentives and a growing global human population. Conversion of grasslands leads to loss of habitat and threatens the ability of the land to provide ecosystem services, such as carbon sequestration, water filtration and reduced erosion. We developed a method for identifying remaining intact habitat across the Mississippi River Basin-Great Plains geography by stacking subsequent years of the Cropland Data Layer (United States) and Annual Crop Inventory (Canada). We call the resulting cumulative plowed lands the “plowprint”. The total size of the plowprint increased by 27,159,278 ha from 2009-2013. As of 2013, approximately one-third of the study area had been plowed. We conclude that developing the ability to monitor cumulative change over time will allow disparate agencies and organizations to align their goals, strategies and activities, and measure progress in a uniform way.

The Missouri River Basin (MRB) functions as the “life zone” for the larger Mississippi River Basin, providing grassland habitat that infiltrates precipitation and recharges groundwater, reduces sediment erosion, filters nutrients, stores carbon, and provides critical habitat for wildlife. The role of this region as a producer of food and fuel, both nationally and internationally, creates unique challenges for conservation. To support conservation efforts and sustainable management of this invaluable resource, a large-scale, screening-level evaluation of the water quantity and quality benefits of land conservation efforts in the MRB was performed. This paper describes the development and application of a Soil and Water Assessment Tool (SWAT) model to the MRB study area to provide estimates of water quantity and quality (sediment, total phosphorus, total nitrogen) benefits from the avoided conversion of intact grassland to cultivated cropland. The results of this study indicate that the avoided conversion of grassland to cropland could potentially prevent more than 1.7 trillion gallons of surface runoff as well as prevent the export of approximately 46 million tons of sediment, 87 million pounds of total phosphorus, and 427 million pounds of total nitrogen from the MRB study area landscape every year.

Sufficiently rigorous monitoring and evaluation can assess the effectiveness of management actions to conserve natural resources. However, costs of monitoring can be high in relation to program budgets, so it is critical to design monitoring efforts to ensure a high return on investment. To assess the relative contribution of different monitoring strategies to yield information for management decisions, we examine the evolution of a multi-year monitoring program across several MPAs in West Papua, Indonesia. Three monitoring strategies were implemented: external expert, science practitioner, and community monitoring staff. We place the monitoring objectives in a decision science framework, with six explicit fundamental objectives for monitoring to evaluate performance of marine protected areas. We examine each strategy in light of the six objectives to evaluate: 1) power to detect change, 2) extent of local capacity development, and 3) cost effectiveness. Over time, costs were reduced and scientific value increased through clear communication of science objectives, outcome-driven experimental design, adequately resourced monitoring programs, and a long-term view that anticipates phasing out outside consultants and transitioning monitoring responsibilities fully to locally-based staff. Investments to develop capacity of staff living locally to perform data management, analysis, interpretation, and science communication proved the most cost-effective approach in the long-term. With many globally important ecosystems in developing countries, developing local scientific capacity for the full cycle of monitoring is key to informed decision-making and ensuring long-term sustainability of efforts to conserve biodiversity.

Improving water quality and other ecosystem services in agriculturally dominated watersheds is an important policy objective in many regions of the world. A major challenge is overcoming the associated costs to agricultural producers. We integrate spatially-explicit models of ecosystem processes with agricultural commodity production models to analyze the biophysical and economic consequences of alternative land use and land management patterns to achieve Total Maximum Daily Loads targets in a proto-typical agricultural watershed. We apply these models to find patterns that maximize water quality objectives for given levels of foregone agricultural profit. We find it is possible to reduce baseline watershed phosphorus loads by ~ 20% and sediment loads by ~ 18% without any reduction in agricultural profits. Our results indicate that meeting more stringent targets will result in substantial economic loss. However, when we add the social benefits from water quality improvement and carbon sequestration to private agricultural net returns we find that water quality improvements up to 50% can be obtained at no loss to societal returns. The cost of meeting water quality targets will vary over time as commodity and ecosystem service prices fluctuate. If crop prices drop or the value of ecosystem services increase, then achieving higher water quality goals will be less costly.

The Javan rhino (Rhinoceros sondaicus) is one of the most threatened mammals on Earth. The only remaining individuals live as part of a small population isolated in a single protected area, Ujung Kulon National Park, Java, Indonesia. Despite almost a century of studies, little is known about the factors that affect Javan rhino demography and distribution. National park officials require such information to identify conservation strategies and track the success and failures of these efforts; translocating selected individuals to establish a second population has been considered, but the risks must be weighed. We show that the 2013 global population of Javan rhinos was 62 individuals, which is likely near the site's carrying capacity. Our analysis of rhino distribution indicates that tsunamis are a significant risk to the species in Ujung Kulon, justifying the risks of establishing additional populations. Continued individual-based monitoring is needed to guide future translocation decisions.

There is growing interest in sustainable intensification of aquaculture production. Yet little economic analysis has been done on farm-level effects of the economic sustainability of production intensification. Data from 83 shrimp farms (43 in Vietnam and 40 in Thailand) were used to identify (through principal component and cluster analyses) 13 clusters of management practices that reflected various scales of production intensity that ranged from 0–1999 kg/ha/crop to 10,000 kg/ha/crop and above, for both Penaeus monodon and Litopenaeus vannamei in Vietnam and Thailand. The clusters identified reflected sets of management practices that resulted in differing yields despite similarities in stocking densities among some clusters. The enterprise budget analysis developed showed that the more intensively managed clusters outperformed the less intensively managed clusters in economic terms. More intensively managed farm clusters had lower costs per metric ton of shrimp produced and were more profitable. The greater yields of shrimp produced per hectare of land and water resources in more intensively managed shrimp farms spread annual fixed costs across a greater volume of shrimp produced and reduced the cost per metric ton of shrimp. Costs per metric ton of shrimp produced decreased from the lowest to the highest intensity level (from US$10,245 at lowest intensity to US$3484 at highest for P. monodon and from US$24,301 to US$5387 for L. vannamei in Vietnam and from US$8184 at the lowest intensity level to US$3817 at the highest intensity level per metric ton for L. vannamei in Thailand). Costs of pond amendments used in shrimp production were particularly high in Vietnam and largely unwarranted, whereas fixed costs associated with the value of land, production facilities, equipment, and labor were sufficiently high in Thailand so that net returns were negative in the long run. Nevertheless, economic losses in Thailand were less at greater levels of intensification. The study demonstrated a clear value proposition for shrimp farmers to use natural resources (such as land) and other inputs in an efficient manner and supports findings from corresponding research on farm-level natural resource use efficiency. Additional research that incorporates economic analysis into on-farm studies of sustainable intensification of aquaculture is needed to provide ongoing guidance related to sustainable management practices for aquaculture.

Marine protected areas (MPAs) are increasingly being used globally to conserve marine resources. However, whether many MPAs are being effectively and equitably managed, and how MPA management influences substantive outcomes remain unknown. We developed a global database of management and fish population data (433 and 218 MPAs, respectively) to assess: MPA management processes; the effects of MPAs on fish populations; and relationships between management processes and ecological effects. Here we report that many MPAs failed to meet thresholds for effective and equitable management processes, with widespread shortfalls in staff and financial resources. Although 71% of MPAs positively influenced fish populations, these conservation impacts were highly variable. Staff and budget capacity were the strongest predictors of conservation impact: MPAs with adequate staff capacity had ecological effects 2.9 times greater than MPAs with inadequate capacity. Thus, continued global expansion of MPAs without adequate investment in human and financial capacity is likely to lead to sub-optimal conservation outcomes.

Overfishing threatens the sustainability of coastal marine biodiversity, especially in tropical developing countries. To counter this problem, about 200 governments worldwide have committed to protecting 10%–20% of national coastal marine areas. However, associated impacts on fisheries productivity are unclear and could weaken the food security of hundreds of millions of people who depend on diverse and largely unregulated fishing activities. Here, we present a systematic theoretic analysis of the ability of reserves to rebuild fisheries under such complex conditions, and we identify maximum reserve coverages for biodiversity conservation that do not impair long-term fisheries productivity. Our analysis assumes that fishers have no viable alternative to fishing, such that total fishing effort remains constant (at best). We find that realistic reserve networks, which protect 10%–30% of fished habitats in 1–20 km wide reserves, should benefit the long-term productivity of almost any complex fishery. We discover a “rule of thumb” to safeguard against the long-term catch depletion of particular species: individual reserves should export 30% or more of locally produced larvae to adjacent fishing grounds. Specifically on coral reefs, where fishers tend to overexploit species whose dispersal distances as larvae exceed the home ranges of adults, decisions on the size of reserves needed to meet the 30% larval export rule are unlikely to compromise the protection of resident adults. Even achieving the modest Aichi Target 11 of 10% “effective protection” can then help rebuild depleted catch. However, strictly protecting 20%–30% of fished habitats is unlikely to diminish catch even if overfishing is not yet a problem while providing greater potential for biodiversity conservation and fishery rebuilding if overfishing is substantial. These findings are important because they suggest that doubling or tripling the only globally enforced marine reserve target will benefit biodiversity conservation and higher fisheries productivity where both are most urgently needed.