6 research outputs found
First results from an experiment excluding three sizes classes of herbivores from tundra vegetation in southern Yamal, Russia
Plant-herbivore relationships are important for the functioning of tundra ecosystems. Here, we report the first results from an exclosure experiment that, something very few studies have done, separated the impact of three sizes of herbivores (small, medium and large) on nine functional groups of plants in the low arctic tundra of the Yamal Peninsula (Russia). Herbivore faeces counts in the exclosures and pictures from automatic cameras proved that the experimental setup worked. The majority of plant groups did not respond to exclusion of herbivores, supporting our expectation that vegetation responses in tundra are generally too slow to be measured during one growing season. The plant groups with highest growth rates and palatability (forbs and grasses) increased their biomass in meadows associated to tall willow shrubs when reindeer were excluded. This result was expected based on studies from other arctic regions. Our results also suggested that willow meadows and forb tundra, which are focal habitat for herbivores, are resilient and have the capacity to increase their biomass over a short term. We expect this experiment to provide valuable information on how different plant functional types and habitats with different growing conditions and importance to herbivores respond to relaxed grazing pressure from a variety of tundra herbivores
Hiding in the background: community-level patterns in invertebrate herbivory across the tundra biome
Invertebrate
herbivores depend on external temperature for growth and metabolism.
Continued warming in tundra ecosystems is proposed to result in
increased invertebrate herbivory. However, empirical data about how
current levels of invertebrate herbivory vary across the Arctic is
limited and generally restricted to a single host plant or a small group
of species, so predicting future change remains challenging. We
investigated large-scale patterns of invertebrate herbivory across the
tundra biome at the community level and explored how these patterns are
related to long-term climatic conditions and year-of-sampling weather,
habitat characteristics, and aboveground biomass production. Utilizing a
standardized protocol, we collected samples from 92 plots nested within
20 tundra sites during summer 2015. We estimated the community-weighted
biomass lost based on the total leaf area consumed by invertebrates for
the most common plant species within each plot. Overall, invertebrate
herbivory was prevalent at low intensities across the tundra, with
estimates averaging 0.94% and ranging between 0.02 and 5.69% of plant
biomass. Our results suggest that mid-summer temperature influences the
intensity of invertebrate herbivory at the community level, consistent
with the hypothesis that climate warming should increase plant losses to
invertebrates in the tundra. However, most of the observed variation in
herbivory was associated with other site level characteristics,
indicating that other local ecological factors also play an important
role. More details about the local drivers of invertebrate herbivory are
necessary to predict the consequences for rapidly changing tundra
ecosystems.KeywordsBackground herbivory Biomass loss Climate change Community-weighted average Invertebrate Insects Tundra </div
The impact of different size herbivores on plant biomass in Yamal (Russia)
Tundra ecosystems are changing environments that are greatly affected by plant-herbivore
relationships. Many herbivores of different sizes eat, trample or clip plants. However they can
also act as support through nutrient addition by faeces. In this study I look at the impact of
three sizes of herbivores (large, medium and small) on ten functional groups of plants
(nitrogen-fixing forbs, erect willows, birch bushes, evergreen ericoids, nitrogen-non-fixing
forbs, grasses, sedges, deciduous shrubs, semi-evergreen shrubs and toxic plants) in three
habitats of differing productivity and importance for herbivores on the Yamal Peninsula in
Russia. My research question is: “is the impact of herbivores cumulative on palatable plants
and complementary on less palatable plants?”. To answer this question, I investigated the first
year data from an exclosure experiment that was set up in 2014. There were tendencies
suggesting that herbivores do not always have a cumulative impact on palatable plants and
that the impact on less palatable plants is not always complementary. However, based on
plant traits, herbivores’ preferences and previous studies I conclude that the fastest growing
plants usually show responses already after a very short time of herbivore exclusion. Further
research during the next years will shed light on persistence of these results
Diversity and Differentiation of Duckweed Species from Israel
Duckweeds (Lemnaceae) are tiny plants that float on aquatic surfaces and are typically isolated from temperate and equatorial regions. Yet, duckweed diversity in Mediterranean and arid regions has been seldom explored. To address this gap in knowledge, we surveyed duckweed diversity in Israel, an ecological junction between Mediterranean and arid climates. We searched for duckweeds in the north and center of Israel on the surface of streams, ponds and waterholes. We collected and isolated 27 duckweeds and characterized their morphology, molecular barcodes (atpF-atpH and psbK-psbI) and biochemical features (protein content and fatty acids composition). Six species were identified—Lemna minor, L. gibba and Wolffia arrhiza dominated the duckweed populations, and together with past sightings, are suggested to be native to Israel. The fatty acid profiles and protein content further suggest that diverged functions have attributed to different haplotypes among the identified species. Spirodela polyrhiza, W. globosa and L. minuta were also identified but were rarer. S. polyrhiza was previously reported in our region, thus, its current low abundance should be revisited. However, L. minuta and W. globosa are native to America and Far East Asia, respectively, and are invasive in Europe. We hypothesize that they may be invasive species to our region as well, carried by migratory birds that disperse them through their migration routes. This study indicates that the duckweed population in Israel’s aquatic environments consists of both native and transient species
Hiding in the background: community-level patterns in invertebrate herbivory across the tundra biome
Invertebrate herbivores depend on external temperature for growth and metabolism. Continued warming in tundra ecosystems is proposed to result in increased invertebrate herbivory. However, empirical data about how current levels of invertebrate herbivory vary across the Arctic is limited and generally restricted to a single host plant or a small group of species, so predicting future change remains challenging. We investigated large-scale patterns of invertebrate herbivory across the tundra biome at the community level and explored how these patterns are related to long-term climatic conditions and year-of-sampling weather, habitat characteristics, and aboveground biomass production. Utilizing a standardized protocol, we collected samples from 92 plots nested within 20 tundra sites during summer 2015. We estimated the community-weighted biomass lost based on the total leaf area consumed by invertebrates for the most common plant species within each plot. Overall, invertebrate herbivory was prevalent at low intensities across the tundra, with estimates averaging 0.94% and ranging between 0.02 and 5.69% of plant biomass. Our results suggest that mid-summer temperature influences the intensity of invertebrate herbivory at the community level, consistent with the hypothesis that climate warming should increase plant losses to invertebrates in the tundra. However, most of the observed variation in herbivory was associated with other site level characteristics, indicating that other local ecological factors also play an important role. More details about the local drivers of invertebrate herbivory are necessary to predict the consequences for rapidly changing tundra ecosystems
Hiding in the background: community-level patterns in invertebrate herbivory across the tundra biome
© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. Invertebrate herbivores depend on external temperature for growth and metabolism. Continued warming in tundra ecosystems is proposed to result in increased invertebrate herbivory. However, empirical data about how current levels of invertebrate herbivory vary across the Arctic is limited and generally restricted to a single host plant or a small group of species, so predicting future change remains challenging. We investigated large-scale patterns of invertebrate herbivory across the tundra biome at the community level and explored how these patterns are related to long-term climatic conditions and year-of-sampling weather, habitat characteristics, and aboveground biomass production. Utilizing a standardized protocol, we collected samples from 92 plots nested within 20 tundra sites during summer 2015. We estimated the community-weighted biomass lost based on the total leaf area consumed by invertebrates for the most common plant species within each plot. Overall, invertebrate herbivory was prevalent at low intensities across the tundra, with estimates averaging 0.94% and ranging between 0.02 and 5.69% of plant biomass. Our results suggest that mid-summer temperature influences the intensity of invertebrate herbivory at the community level, consistent with the hypothesis that climate warming should increase plant losses to invertebrates in the tundra. However, most of the observed variation in herbivory was associated with other site level characteristics, indicating that other local ecological factors also play an important role. More details about the local drivers of invertebrate herbivory are necessary to predict the consequences for rapidly changing tundra ecosystems