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1. Altered precipitation has asymmetric impacts on annual plant communities in warm and cool growing seasons

   https://doi.org/10.1525/elementa.2021.00014  

   Spasojevic, Marko J.; Homyak, Peter M.; Jenerette, G. Darrel; Goulden, Mike L.; McFaul, Shane; Madsen-McQueen, Tesa; Schauer, Lisa; Solis, Miguel (January 2022, Elementa: Science of the Anthropocene)

   While altered precipitation regimes can greatly impact biodiversity and ecosystem functioning, we lack a comprehensive view of how these impacts are mediated by changes to the seasonality of precipitation (i.e., whether it rains more/less in one season relative to another). Over 2 years, we examined how altered seasonal precipitation influenced annual plant biomass and species richness, Simpson’s diversity, and community composition of annual plant communities in a dryland ecosystem that receives both winter and summer rainfall and has distinct annual plant communities in each season. Using a rainfall exclusion, collection, and distribution system, we excluded precipitation and added water during each season individually and compared responses to control plots which received ambient summer and winter precipitation. In control plots, we found five times greater annual plant biomass, twice as many species, and higher diversity in winter relative to summer. Adding water increased annual plant biomass in summer only, did not change richness or diversity in either summer or winter, and modestly shifted community composition. Excluding precipitation in either season reduced annual plant biomass, richness, and Simpson’s diversity. However, in the second winter season, biomass was higher in the plots where precipitation was excluded in the previous summer seasons suggesting that reduced productivity in the summer may facilitate biomass in the winter. Our results suggest that increased precipitation in summer may have stronger short-term impacts on annual plant biodiversity and ecosystem function relative to increased winter precipitation. In contrast, decreasing precipitation may have ubiquitous negative effects on annual plants across both summer and winter but may lead to increased biomass in the following off-seasons. These patterns suggest that annual plant communities exhibit asymmetries in their community and ecosystem responses to altered seasonal precipitation and that considering the seasonality of precipitation is important for predicting the effects of altered precipitation regimes. 

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2. Distinct communities under the snow: describing characteristics of subnivium arthropod communities

   https://doi.org/10.1093/ee/nvae017  

   Ziadeh, Christopher P; Ziadeh, Shayleigh B; Aflague, Breanne H; Townley, Mark A; Ayres, Matthew P; Contosta, Alexandra R; Garnas, Jeff R (April 2024, Environmental Entomology)

   Trotter, Talbot (Ed.)

   Arthropods are active during the winter in temperate regions. Many use the seasonal snowpack as a buffer against harsh ambient conditions and are active in a refugium known as the subnivium. While the use of the subnivium by arthropods is well established, far less is known about subnivium community composition, abundance, biomass, and diversity and how these characteristics compare with the community in the summer. Understanding subnivium communities is especially important given the observed and anticipated changes in snowpack depth and duration due to the changing climate. We compared subnivium arthropod communities with those active during the summer using pitfall trapping in northern New Hampshire. We found that compositions of ground-active arthropod communities in the subnivium differed from those in the summer. The subnivium arthropod community featured moderate levels of richness and other measures of diversity that tended to be lower than the summer community. More strikingly, the subnivium community was much lower in overall abundance and biomass. Interestingly, some arthropods were dominant in the subnivium but either rare or absent in summer collections. These putative “subnivium specialists” included the spider Cicurina brevis (Emerton 1890) (Araneae: Hahniidae) and 3 rove beetles (Coleoptera: Staphylinidae): Arpedium cribratum Fauvel, 1878, Lesteva pallipes LeConte, 1863, and Porrhodites inflatus (Hatch, 1957). This study provides a detailed account of the subnivium arthropod community, establishes baseline information on arthropod communities in temperate forests of northeastern North America, and explores the idea of subnivium specialist taxa that are highly active in winter and might be especially vulnerable to climate change. 

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3. Arthropod communities in the Second College Grant, NH ver 1

   https://doi.org/10.6073/pasta/7333f727fc8396555d18913d6e8e6d52  

   Ziadeh, Christopher P; Ziadeh, Shayleigh B; Aflague, Breanne H; Townley, Mark A; Ayres, Matthew P; Garnas, Jeffrey R (January 2023, Environmental Data Initiative)

   Arthropods are active during the winter in temperate regions. Many use the seasonal snowpack as a buffer against harsh ambient conditions and remain active in a refugium known as the subnivium. While the use of the subnivium by insects and other arthropods is well-established, far less is known about winter community composition, abundance, biomass, and diversity and how these characteristics compare with the community in the summer. Understanding subnivean communities is especially important given observed and anticipated changes in snowpack depth and duration with changing climate. We studied winter and summer insects and other arthropods using pitfall trapping in northern New Hampshire, where snowpack is still relatively intact. We found that compositions of the subnivium and summer arthropod communities differed. The subnivium arthropod community featured moderate levels of richness and other measures of diversity that tended to be lower than in the summer community. More striking, the subnivium community was much lower in overall abundance and biomass than the summer community. Interestingly, some groups and species of arthropods were dominant in the subnivium but either rare or absent in summer collections. These putative “subnivium specialists” included one spider (order: Araneae), Cicurina brevis (Emerton, 1890), and three rove beetles (order: Coleoptera, family: Staphylinidae) Arpedium cribratum Fauvel, 1878, Lesteva pallipes LeConte, 1863, and Porrhodites inflatus (Hatch, 1957). This study provides a detailed account of the subnivium arthropod community, presents novel concepts, and establishes baseline information on arthropod communities in the North American northeastern temperate forest. 

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4. Changes in climate drive recent monarch butterfly dynamics

   https://doi.org/10.1038/s41559-021-01504-1  

   Zylstra, Erin R.; Ries, Leslie; Neupane, Naresh; Saunders, Sarah P.; Ramírez, M. Isabel; Rendón-Salinas, Eduardo; Oberhauser, Karen S.; Farr, Matthew T.; Zipkin, Elise F. (July 2021, Nature Ecology & Evolution)

   null (Ed.)

   Declines in the abundance and diversity of insects pose a substantial threat to terrestrial ecosystems worldwide. Yet, identifying the causes of these declines has proved difficult, even for well-studied species like monarch butterflies, whose eastern North American population has decreased markedly over the last three decades. Three hypotheses have been proposed to explain the changes observed in the eastern monarch population: loss of milkweed host plants from increased herbicide use, mortality during autumn migration and/or early-winter resettlement and changes in breeding-season climate. Here, we use a hierarchical modelling approach, combining data from >18,000 systematic surveys to evaluate support for each of these hypotheses over a 25-yr period. Between 2004 and 2018, breeding-season weather was nearly seven times more important than other factors in explaining variation in summer population size, which was positively associated with the size of the subsequent overwintering population. Although data limitations prevent definitive evaluation of the factors governing population size between 1994 and 2003 (the period of the steepest monarch decline coinciding with a widespread increase in herbicide use), breeding-season weather was similarly identified as an important driver of monarch population size. If observed changes in spring and summer climate continue, portions of the current breeding range may become inhospitable for monarchs. Our results highlight the increasingly important contribution of a changing climate to insect declines. 

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5. Benefits of protected areas for nonbreeding waterbirds adjusting their distributions under climate warming

   https://doi.org/10.1111/cobi.13648  

   Gaget, Elie; Pavón‐Jordán, Diego; Johnston, Alison; Lehikoinen, Aleksi; Hochachka, Wesley M.; Sandercock, Brett K.; Soultan, Alaaeldin; Azafzaf, Hichem; Bendjedda, Nadjiba; Bino, Taulant; et al (January 2021, Conservation Biology)

   null (Ed.)

   Climate warming is driving changes in species distributions and community composition. Many species have a so-called climatic debt, that is, shifts in range lag behind shifts in temperature isoclines. Inside protected areas (PAs), community changes in response to climate warming can be facilitated by greater colonization rates by warm-dwelling species, but also mitigated by lowering extirpation rates of cold-dwelling species. An evaluation of the relative importance of colonization-extirpation processes is important to inform conservation strategies that aim for both climate debt reduction and species conservation. We assessed the colonization-extirpation dynamics involved in community changes in response to climate inside and outside PAs. To do so, we used 25 years of occurrence data of nonbreeding waterbirds in the western Palearctic (97 species, 7071 sites, 39 countries, 1993–2017). We used a community temperature index (CTI) framework based on species thermal affinities to investigate species turnover induced by temperature increase. We determined whether thermal community adjustment was associated with colonization by warm-dwelling species or extirpation of cold-dwelling species by modeling change in standard deviation of the CTI (CTISD). Using linear mixed-effects models, we investigated whether communities in PAs had lower climatic debt and different patterns of community change than communities outside PAs. For CTI and CTISD combined, communities inside PAs had more species, higher colonization, lower extirpation, and lower climatic debt (16%) than communities outside PAs. Thus, our results suggest that PAs facilitate 2 independent processes that shape community dynamics and maintain biodiversity. The community adjustment was, however, not sufficiently fast to keep pace with the large temperature increases in the central and northeastern western Palearctic. Our results underline the potential of combining CTI and CTISD metrics to improve understanding of the colonization-extirpation patterns driven by climate warming. 

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