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Nature's Notebook observers help pinpoint when to take action against invasive hemlock woolly adelgid
Mon, May 13, 2024
Invasive hemlock woolly adelgid (Adelges tsugae or HWA) has caused widespread decline and mortality in hemlock trees, an important foundation species in the Eastern U.S. One method used for control of this species is the release of specialist predators at two life cycle stages: emergence from summer dormancy in early fall and egg laying in late winter. Authors of this study engaged Nature’s Notebook observers to collect data on HWA. The authors found that emergence of HWA from summer dormancy was consistent, starting at the end of September in each year of the study, while the start of egg laying in late winter was much more variable. Better knowledge of when to take management actions to reduce HWA will help preserve these important trees.
Male and female trees are responding differently to increasing temperatures
Tue, Mar 12, 2024
Dioecy, defined as distinctly male or female individuals in a species, is uncommon in plants, occurring in only about 5% of species. Consequently, our understanding of how this group of plants is being affected by climate change is limited. A group of researchers based at Purdue University in Indiana, USA asked two questions: 1) is the synchronicity in flowering in male and female trees changing? and 2) is the timing of leaf-out and flowering changing at different rates? The researchers found that male trees are advancing their flowering time at a greater rate than female trees. This is potentially bad news for these species; this pattern could reduce pollen transfer from male to female trees and negatively impact reproductive success in these trees. The researchers also found that flowering, which occurs before leaf-out in the species evaluated in this study, is advancing more rapidly than leaf-out. This finding is good news; the increasing temporal gap between flowing and leaf-out means less interference for the transfer of pollen from male to female trees.
Precise, local predictions of grassland bird nest timing
Thu, Nov 30, 2023
Grasslands are among the most disturbed ecosystems globally. In the areas that remain, managers must balance practices such as mowing and burning that maintain natural systems while avoiding nesting periods for grassland birds. The authors of this study used information about nest survival from scientific literature as well as climate information and the USA-NPN’s Spring Bloom Index to develop models to predict the expected nest departure timing for 36 grassland bird species. This information can provide more localized information about nesting timing to better time management actions to avoid this critical period.