• Energy Research

AbstractGlobal change drivers, such as anthropogenic nutrient inputs, are increasing globally. Nutrient deposition simultaneously alters plant biodiversity, species composition and ecosystem processes like aboveground biomass production. These changes are underpinned by species extinction, colonisation and shifting relative abundance. Here, we use the Price equation to quantify and link the contributions of species that are lost, gained or that persist to change in aboveground biomass in 59 experimental grassland sites. Under ambient (control) conditions, compositional and biomass turnover was high, and losses (i.e. local extinctions) were balanced by gains (i.e. colonisation). Under fertilisation, the decline in species richness resulted from increased species loss and decreases in species gained. Biomass increase under fertilisation resulted mostly from species that persist and to a lesser extent from species gained. Drivers of ecological change can interact relatively independently with diversity, composition and ecosystem processes and functions such as aboveground biomass due to the individual contributions of species lost, gained or persisting.

AbstractGlobal change drivers, such as anthropogenic nutrient inputs, are increasing globally. Nutrient deposition simultaneously alters plant biodiversity, species composition and ecosystem processes like aboveground biomass production. These changes are underpinned by species extinction, colonisation and shifting relative abundance. Here, we use the Price equation to quantify and link the contributions of species that are lost, gained or that persist to change in aboveground biomass in 59 experimental grassland sites. Under ambient (control) conditions, compositional and biomass turnover was high, and losses (i.e. local extinctions) were balanced by gains (i.e. colonisation). Under fertilisation, the decline in species richness resulted from increased species loss and decreases in species gained. Biomass increase under fertilisation resulted mostly from species that persist and to a lesser extent from species gained. Drivers of ecological change can interact relatively independently with diversity, composition and ecosystem processes and functions such as aboveground biomass due to the individual contributions of species lost, gained or persisting.

Restoration of degraded drylands is urgently needed to mitigate climate change, reverse desertification and secure livelihoods for the two billion people who live in these areas. Bold global targets have been set for dryland restoration to restore millions of hectares of degraded land. These targets have been questioned as overly ambitious, but without a global evaluation of successes and failures it is impossible to gauge feasibility. Here we examine restoration seeding outcomes across 174 sites on six continents, encompassing 594,065 observations of 671 plant species. Our findings suggest reasons for optimism. Seeding had a positive impact on species presence: in almost a third of all treatments, 100% of species seeded were growing at first monitoring. However, dryland restoration is risky: 17% of projects failed, with no establishment of any seeded species, and consistent declines were found in seeded species as projects matured. Across projects, higher seeding rates and larger seed sizes resulted in a greater probability of recruitment, with further influences on species success including site aridity, taxonomic identity and species life form. Our findings suggest that investigations examining these predictive factors will yield more effective and informed restoration decision-making.

Restoration of degraded drylands is urgently needed to mitigate climate change, reverse desertification and secure livelihoods for the two billion people who live in these areas. Bold global targets have been set for dryland restoration to restore millions of hectares of degraded land. These targets have been questioned as overly ambitious, but without a global evaluation of successes and failures it is impossible to gauge feasibility. Here we examine restoration seeding outcomes across 174 sites on six continents, encompassing 594,065 observations of 671 plant species. Our findings suggest reasons for optimism. Seeding had a positive impact on species presence: in almost a third of all treatments, 100% of species seeded were growing at first monitoring. However, dryland restoration is risky: 17% of projects failed, with no establishment of any seeded species, and consistent declines were found in seeded species as projects matured. Across projects, higher seeding rates and larger seed sizes resulted in a greater probability of recruitment, with further influences on species success including site aridity, taxonomic identity and species life form. Our findings suggest that investigations examining these predictive factors will yield more effective and informed restoration decision-making.

AbstractUnderstanding the combined effects of drought and invasive species on plant community development and soil moisture could provide valuable insight into the mechanisms hindering successful native plant establishment in dryland restoration projects. We implemented a re‐vegetation experiment at two sites in Colorado, USA (one each in the Western Great Plains and Cold Desert ecoregions) to investigate the effects of drought (66% reduction of ambient growing season rainfall), non‐nativeBromus tectorumseed addition (465 seeds/m2), and superabsorbent polymer soil amendment (25 g/m2) on plant community development and soil volumetric water content at 5 and 30 cm depth. Drought resulted in higherB. tectorumcover at the Western Great Plains site but lowerB. tectorumcover at the Cold Desert site. These contrasting results suggest drought may interact with site‐specific precipitation patterns to influenceB. tectorumestablishment. At the Western Great Plains site, drought reduced seeded forb cover andB. tectorumseed addition reduced seeded grass cover, highlighting how the effects of drought and invasive species may vary depending on which functional group is assessed. At the Cold Desert site, drought andB. tectorumseed addition each decreased seeded species cover from approximately 8% to 3%. Superabsorbent polymer effects were limited to slight increases in overall seeded grass cover at the Western Great Plains site from 2.2% to 4.9%. Both drought andB. tectorumseed addition reduced soil volumetric water content but in some cases effects depended on interactions between the two treatments, site, or soil depth. Notably, at the Cold Desert site the reduction in soil volumetric water content resulting fromB. tectorumseed addition with ambient precipitation exceeded that of the drought treatment alone at 5 and 30 cm depth. Our results demonstrate that drought and invasive species both negatively influence native plant establishment and soil moisture, and in some cases may interact. Considering both abiotic and biotic stressors as well as their interactions in restoration planning could improve our understanding of native plant establishment and improve re‐vegetation outcomes.

AbstractUnderstanding the combined effects of drought and invasive species on plant community development and soil moisture could provide valuable insight into the mechanisms hindering successful native plant establishment in dryland restoration projects. We implemented a re‐vegetation experiment at two sites in Colorado, USA (one each in the Western Great Plains and Cold Desert ecoregions) to investigate the effects of drought (66% reduction of ambient growing season rainfall), non‐nativeBromus tectorumseed addition (465 seeds/m2), and superabsorbent polymer soil amendment (25 g/m2) on plant community development and soil volumetric water content at 5 and 30 cm depth. Drought resulted in higherB. tectorumcover at the Western Great Plains site but lowerB. tectorumcover at the Cold Desert site. These contrasting results suggest drought may interact with site‐specific precipitation patterns to influenceB. tectorumestablishment. At the Western Great Plains site, drought reduced seeded forb cover andB. tectorumseed addition reduced seeded grass cover, highlighting how the effects of drought and invasive species may vary depending on which functional group is assessed. At the Cold Desert site, drought andB. tectorumseed addition each decreased seeded species cover from approximately 8% to 3%. Superabsorbent polymer effects were limited to slight increases in overall seeded grass cover at the Western Great Plains site from 2.2% to 4.9%. Both drought andB. tectorumseed addition reduced soil volumetric water content but in some cases effects depended on interactions between the two treatments, site, or soil depth. Notably, at the Cold Desert site the reduction in soil volumetric water content resulting fromB. tectorumseed addition with ambient precipitation exceeded that of the drought treatment alone at 5 and 30 cm depth. Our results demonstrate that drought and invasive species both negatively influence native plant establishment and soil moisture, and in some cases may interact. Considering both abiotic and biotic stressors as well as their interactions in restoration planning could improve our understanding of native plant establishment and improve re‐vegetation outcomes.