Host-mediated effects on the reproductive phenological asynchrony of a generalist mistletoe in China

Aims Host-mediated effects on hemiparasitic mistletoes were hypothesized to contribute to mistletoes reproductive phenological asynchrony, thus providing a longer period of food supply to its mutualistic pollinators and dispersers. However, studies with empirical data interrogating this hypothesis are lacking. Methods Weekly monitoring of flowering and fruiting patterns on a generalist mistletoe Dendrophthoe pentandra (Loranthaceae) was conducted for two consecutive years in tropical Xishuangbanna, Southwest China. We examined whether flowering and fruiting patterns were seasonal, quantified the degree of stagger within D. pentandra populations, and determined the factors influencing the first flowering date of D. pentandra. Furthermore, the effect of change in the number of host species on reproductive phenological asynchrony of mistletoe was examined. Important Findings We found that (i) both flowering and fruiting exhibited unimodal peaks in the two consecutive years of the study; (ii) the first flowering date was significantly influenced by crown area of mistletoe and light, such that clump with larger crown and more light exposure had an earlier first flowering date and longer flowering and fruiting durations; (iii) different host species had a significant impact on the phenology of mistletoes. However, contrary to our hypothesis, the number of host species did not significantly change the asynchrony of reproductive phenology of mistletoe. Therefore, these results suggest that alternative hypotheses are needed to interpret the ecological significance of the number of host species and phenological asynchrony of generalist mistletoes.

For everything there was a season: phenological shifts in the Tetons

Around the world, phenology — the timing of ecological events — is shifting as the climate warms. This can lead to a variety of consequences for individual species and entire ecological communities. Grand Teton National Park biologists have identified this topic (“effect of earlier plant flowering on pollinators and wildlife”) as one of their priority research needs. We assembled phenological observations of first flowering dates for 49 species collected by Frank Craighead, Jr. in the 1970s, before significant warming occurred. In 2016 we began standardized phenological observations of these same species, plus an additional 61 for a total of 110 species, in the same locations. First flowering date for 65% of the species with historic records correlated significantly with mean spring temperature; these species are therefore expected to flower earlier now than in the 1970s. Early spring flowers had the largest shifts in phenology, emerging an average of 21 days earlier now relative to the 1970s. Yet not all species are emerging earlier. In particular, phenology of late summer/early fall flowering plants was largely unchanged. In 2017, we initiated pollinator collections at our key phenology sites. Additional years of observations will allow us to better understand plant-pollinator interactions and identify potential phenological mismatches. Featured photo by Shawna Wolf, taken from the AMK Ranch photo collection.

For everything there was a season: phenological shifts within the flora of the Tetons

Around the world, phenology — the timing of ecological events — is shifting as the climate warms. This can lead to a variety of consequences for individual species and entire ecological communities, most notably when asynchronies develop between plants and animals that depend upon each other (e.g. nectar-consuming pollinators). Grand Teton National Park biologists have identified this topic (“effect of earlier plant flowering on pollinators and wildlife”) as one of their priority research needs. We have gathered, digitized, and quality-controlled phenological observations of first flowering dates collected by Frank Craighead, Jr. in the 1970s, before significant warming occurred. First flowering date for 87% of a 72-species data set correlates significantly with spring temperatures in the 1970s, suggesting that these plants should now be flowering earlier and will continue to flower earlier in the future. This year we began standardized phenological observations of these 72 species in the same location and initiated a citizen science program. Our proposed next steps are to: (1) gather and analyze further historical records of plant phenology; (2) conduct 3-5 additional years of contemporary observations; (3) link plant phenological changes with potential cascading impacts on pollinators and foragers; (4) model phenology under future climate change scenarios; and (5) implement a long-term citizen science program in the Tetons. Featured photo by Shawna Wolf, taken from the AMK Ranch photo collection.

The influence of experimental warming on flowering phenology of Moss Campion, Silene acaulis / Experimentel hiting ávirkar blóming hjá leggstuttari túvublómu (Silene acaulis)

<p><strong>Úrtak</strong></p><p>Í níggju ár kannaðu vit, á hvønn hátt experimentel hiting ávirkar tey ymisku stigini í blómingini hjá leggstuttari túvublómu, <em>Silene acaulis </em>í Føroyum. Hitin varð experimentelt øktur við smáum sekshyrntum vakstrarhúsum, ið eru gjørd úr polycarbonate. Tey eru opin í erva og tí navnið „Open top Champers“ (OTC). Kanningarnar vórðu gjørdar í fjallaøki í 600 m hædd, har blómustigini hjá leggstuttari túvublómu regluliga vórðu mátað í vakstrartíðini frá mai til juli mánað í tíggju OTC og tíggju kontrollum. Kanningarnar, ið vit skriva um í hesi grein, eru frá 2001 og hvørt ár frá 2007­2010. Vit skrivaðu upp tíðarskeiðið, tá fyrsti blómuknubbin var sjónligur, tíðarskeiðið tá fyrsta blóman var útsprungin, tá fyrsta og seinasta krúnublað følnaði. Kanningarnar eru ein partur av altjóða samstarvinum „International Tundra Experiment“ ITEX, ið er eitt samstarv millum fleiri støð serliga á norðraru hálvu, har kanningar verða gjørdar. Kanningarnar hava til endamáls at granska árinið av veðurlagsbroytingum á plantuvøkstur. Úrslitini frá hesari kanning vísa greiðar munir millum OTC og kontrollarnar. Sum heild komu øll stigini í blómingini umleið eina viku fyrr í OTC enn í kontrollunum. Longdin á øllum blómingartíðarskeiðinum var ikki ymisk í OTC og kontrollunum. Okkara OTC øktu bara hitan umleið 1°C um summarið og broyttu neyvan vetrarhitan. Hetta og ymisk onnur viðurskifti gera, at úrslitini ikki siga okkum alla søguna um broytingarnar í føroyskum plantuvøkstri, sum fara at koma av globalu upphitingini.</p><p> </p><p><strong>A</strong><strong>bstract</strong></p><p>Over a period of nine years we studied the influence of experimental warming on the flowering phenology of Moss Campion<strong>, </strong><em>Silene acaulis </em>in the Faroes. The temperature was experimentally elevated with hexagonal greenhouses called open top chambers (OTC´s) made by polycarbonate. The experiment was conducted in an alpine area at 600 m a.s.l. where the flowering stage of <em>Silene acaulis </em>was measured regularly during the growing season from May to July in ten OTC´s and ten control plots. In this paper, we present observations from 2001 and every year from 2007 to 2010. We measured four events in the flowering stage: first visible bud (FB), first flowering date (FO), first petal drop (FPD) and last petal drop (LPD). This experiment is a part of „The International Tundra Experiment“ (ITEX) that is a collaborative, multisite experiment using a common temperature manipulation to examine the influence of climate change on vegetation. The results from our experiment showed statistically significant changes between the OTC´s and the control plots for all four events. Typically, the events occurred about one week earlier in the OTC´s. The length of the flowering period from FB to LPD was not significally different in the OTC´s from the control plots. The warming induced by the OTC´s in our experiment was only about 1oC in the summer and less than that in the winter. This and other confounding effects such as sheltering imply that care should be taken when using our results to predict phenological in the Faroes changes induced by global warming.</p>