High-resolution PVA along large environmental gradients to model the combined effects of climate change and land use timing: lessons from the large marsh grasshopper

Study on the prediction method of grasshopper occurrence risk in Inner Mongolia based on the maximum entropy model during the growing period

Grasshoppers represent a significant biological challenge in Inner Mongolia's grasslands, severely affecting the region's animal husbandry. Thus, dynamic monitoring of grasshopper infestation risk is crucial for sustainable livestock farming. This study employed the Maxent model, along with remote sensing data, to forecast Oedaleus decorus asiaticus occurrence during the growing season, using grasshopper suitability habitats as a base. The Maxent model's predictive accuracy was high, with an AUC of 0.966. The most influential environmental variables for grasshopper distribution were suitable habitat data (34.27%), the temperature-vegetation dryness index during the spawning period (18.81%), and various other meteorological and vegetation factors. The risk index model was applied to calculate the grasshopper distribution across different risk levels for the years 2019-2022. The data indicated that the level 1 risk area primarily spans central, eastern, and southwestern Inner Mongolia. By examining the variable weights, the primary drivers of risk level fluctuation from 2019 to 2022 were identified as accumulated precipitation and land surface temperature anomalies during the overwintering period. This study offers valuable insights for future O. decorus asiaticus monitoring in Inner Mongolia.

Large-scale PVA modeling of insects in cultivated grasslands: The role of dispersal in mitigating the effects of management schedules under climate change

In many species, dispersal is decisive for survival in a changing climate. Simulation models for population dynamics under climate change thus need to account for this factor. Moreover, large numbers of species inhabiting agricultural landscapes are subject to disturbances induced by human land use. We included dispersal in the HiLEG model that we previously developed to study the interaction between climate change and agricultural land use in single populations. Here, the model was parameterized for the large marsh grasshopper (LMG) in cultivated grasslands of North Germany to analyze (1) the species development and dispersal success depending on the severity of climate change in subregions, (2) the additional effect of grassland cover on dispersal success, and (3) the role of dispersal in compensating for detrimental grassland mowing. Our model simulated population dynamics in 60-year periods (2020-2079) on a fine temporal (daily) and high spatial (250 × 250 m2) scale in 107 subregions, altogether encompassing a range of different grassland cover, climate change projections, and mowing schedules. We show that climate change alone would allow the LMG to thrive and expand, while grassland cover played a minor role. Some mowing schedules that were harmful to the LMG nevertheless allowed the species to moderately expand its range. Especially under minor climate change, in many subregions dispersal allowed for mowing early in the year, which is economically beneficial for farmers. More severe climate change could facilitate LMG expansion to uninhabited regions but would require suitable mowing schedules along the path. These insights can be transferred to other species, given that the LMG is considered a representative of grassland communities. For more specific predictions on the dynamics of other species affected by climate change and land use, the publicly available HiLEG model can be easily adapted to the characteristics of their life cycle.

Identifying managerial legacies within conservation corridors using remote sensing and grasshoppers as bioindicators

Biodiversity conservation under global change requires effective management of key biodiversity areas, even areas not under formal protection. Natural grassland conservation corridors between plantation forests are such areas, as they improve landscape connectivity, mitigate the impact of landscape fragmentation, and conserve biodiversity. However, empirical evidence is required to identify the extent to which past management actions promote effectiveness of conservation corridors into the future. We address this issue using grasshoppers, which are well-established indicators of habitat quality. In particular, we assess grasshopper response within corridors to historic grassland photosynthetic activity using a 25-yr normalized difference vegetation index (NDVI) time series. We then use vegetation characteristics measured in the field to understand the potential mechanisms driving grasshopper response. Furthermore, we explore the efficacy of satellite remote sensing for monitoring grasshopper habitat using additive models. We found that grasshopper evenness responded positively to deviation in NDVI within a 3-yr period, whereas assemblage composition responded positively over a shorter time of two years. Grasshopper richness and evenness responded strongly to the local vegetation height and bare ground, whereas grasshopper assemblage composition also responded to plant species richness. We found a major negative impact of the invasive alien bramble (Rubus cuneifolius) on large-sized grasshoppers and species of conservation concern. Overall, the results illustrate the importance of maintaining primary high-quality habitat for maintaining grasshopper diversity, alongside removal of invasive bramble. We recommend prescribed burning to maintain high-quality habitat heterogeneity, with sites burned within three years. Furthermore, high-resolution satellite imagery is effective for monitoring grasshopper richness and assemblage composition response to changes in vegetation within the corridors. Grassland conservation corridors do conserve biodiversity, although effective management and monitoring needs to be in place to ensure biodiversity resembles that of neighbouring protected areas.

A quantitative approach for the design of robust and cost-effective conservation policies under uncertain climate change: The case of grasshopper conservation in Schleswig-Holstein, Germany

Climate is a major determinant of the world's distribution of biodiversity and species ranges are expected to shift as the climate changes. For conservation policies to be cost-effective in the long run these changes need to be taken into account. To some extent, policies can be adapted over time, but transaction costs, lock-in effects and path dependence limit the extent to which such adaptation is possible. Thus it is desirable that conservation policies be designed so that they are cost-effective in the long run even without future adaptations. Given that the future climate change is highly uncertain, the policies need to be robust to climatic uncertainty. In this paper we present an approach for the robustness analysis with regard to the cost-effectiveness of conservation policies in the face of uncertain climate change. The approach is applied to the conservation of a grasshopper species in the German federal state of Schleswig-Holstein. For the assessment of the cost-effectiveness of considered policies we develop a climate-ecological-economic model. We show that in the near future all considered policies have a similar level of robustness, while in the more distant future the policies differ substantially in their robustness and a trade-off emerges between the expected performance and robustness of a policy.