Causes and consequences of exotic plant invasions

Photo by Tiffany Knight Why are some exotic plant species able to become dominant in a community while others remain minor constituents?
To date, research presents mixed and contradictory results of the relationship between phylogenetic novelty and invasiveness. We aim to resolve some of this variation with a synthetic approach that explicitly considers spatial scale, environmental gradients and stage of invasion. We conduct field experiments that examine multiple mechanisms of invasion and their interactions on exotic plant population dynamics. In addition, we are synthesizing the effects that natural enemy introductions have on the fitness and population dynamics of exotic weeds.

• Community assembly and macroecology of islands
• Role of functional traits in explaining highly invaded Hawaiian ecosystems
• Synthesis of biocontrol agent effects on focal and non-target plants

Pollination Ecology

Recent global reports such as the IPBES have documented that pollinators are declining in abundance and diversity at local, regional, and global spatial scales due to human changes to the landscapes. How will these pollinator declines change the structure of plant-pollinator interactions and the function of pollination?

We collect plant-pollinator network data and conduct pollination experiments in grassland ecosystems along elevation, latitudinal and land use gradients. We have developed collaborations in understudied regions of Europe that have high densities of traditionally managed meadows. We use hands-on summer schools to grow our database while training the next generation of pollination ecologists. We synthesize the causes and consequence of pollen limitation for plant species. We examine the history of science for this rapidly changing field of study.

• Plant-pollinator networks in European meadows
• History of the field of pollination ecology
• Meta-analysis of pollen limitation
• Changes in plant-pollinator networks across long time intervals
• Plant-pollinator networks in agroecosystems
• Plant-pollinator networks in the Arctic

Restoration of degraded habitats

Grassland and coastal ecosystems provide valuable ecosystem services, including large contributions to global biogeochemical cycles and flood mitigation. However, many of these ecosystems have become heavily degraded by human activities. We examine the effects of habitat size, shape, exotic plant invasions, and dispersal limitation on plant community assembly. We study how to best optimize our monitoring efforts to identify at-risk species and their threats. We study the responses of rare plant species to large-scale habitat restoration.

• Experimental restoration of grassland ecosystems
• How do we prioritize species for conservation?
• Restoration of coastal sand dunes

Climate Change Photo: Tricklabor / Service Drohne

Present and future climate change is a major driver of change in world´s ecosystems. How will changes in temperature and precipitation influence plant demography and population dynamics and plant biodiversity?

We are synthesizing the state of our knowledge on how climate change effects plant populations using COMPADRE, a global database of plant matric models and in collaboration with the sApropos working group. We are synthesizing the state of our knowledge on how climate change effects plant biodiversity using studies that experimentally manipulate temperature and precipitation. Further, we have initiated our own research to fill in gaps in our knowledge for certain plant species and regions of the world.

Projects:

• Effects of climate change on plant population dynamics and biodiversity ( sApropos )
  
• Range limits and demography of Carpobrotus edulis
• Effects of climate change on plant demography in the Global Change Environmental Facility (GCEF)

Forest community dynamics

Forest ecosystems have economic and cultural value, and provide vital ecosystem services. The loss of forests in developing countries is a globally recognized environmental crisis. There is an urgent need to synthesize the state of our knowledge on patterns of tree species distributions and their threats.

We contribute to global efforts to understand the macroecological patterns of tree species, and assess the threat to these species. We collaborate with the Foundation for Ecological Security (FES) in India to identify important tree species, model their species distribution and assess threats to their populations by collecting demographic data.

• Global tree synthesis
• India tree distributions and demography

Prof. Tiffany Knight
Alexander von Humboldt Professorship Spatial Interaction Ecology
phone +49 341 9733198
fax +49 341 9739360
E-mail tiffany.knight@idiv.de

Anne-Kathrin Thomas
Assistant Spatial Interaction Ecology
phone +49 341 9733198
fax +49 341 9739360
E-mail anne-kathrin.thomas@idiv.de

Nina Becker
Scientific Manager
phone +49 341 9733159
fax +49 341 9739360
E-mail Nina.Becker@idiv.de

Valentin Stefan
Scientific Programmer
phone +49 341 9733210
E-mail Valentin.Stefan@idiv.de

Sarah Passonneau
Research Officer for bibliometrics, bibliographic management and research in ecology
phone +49 341 9733231
E-mail Sarah.Passonneau@idiv.de

Dr. Demetra Rakosy
Research Officer - Postdoc
E-mail demetra.rakosy@ufz.de

Elena Motivans
Research Officer - PhD
E-mail elena.motivans@idiv.de

Lara-Pauline Sittel
Student Research Assistant
lara-pauline.sittel@ufz.de

Esther Sossai
Student Research Assistant
E-mail esther.sossai@idiv.de

Aizhan Ilyassova
Student Research Assistant
E-mail

Christian Savona
Student Research Assistant
E-mail

Miguel de Guinea
Student Research Assistant
E-mail

Members from Martin Luther University:

Dr. Joanne Bennett
Research Officer - Postdoc
phone +49 341 9733155
E-mail Joanne.Bennett@idiv.de

Dr. Lotte Korell
Research Officer - Postdoc
phone: +49 345 5585308
E-mail lotte.korell@ufz.de

Michael Wohlwend
Research Officer – PhD
E-mail michael.wohlwend@idiv.de

Sarah Passonneau
Research Officer - Library Scientist
phone +49 341 9733231
E-mail sarah.passonneau@idiv.de

Dr. Aldo Compagnoni
Research Officer - Postdoc
phone +49 341 973323155
E-mail aldo.compagnoni@idiv.de

Amibeth Thompson
Research Officer - PhD
phone +49 341 9733224
E-mail Amibeth.Thompson@idiv.de

Sam Levin
Research Officer - PhD
phone +49 341 9733224
E-mail Sam.Levin@idiv.de

Neeraja Venkataraman
Research Officer - PhD
E-mail neeraja.venkataraman@idiv.de

Leana Zoller
Research Officer - PhD
E-mail leana.zoller@idiv.de

Martin Andrzejak
Research Officer - PhD
E-mail martin.andrzejak@idiv.de

Dr. Jeroen Everaars
Research Officer
E-mail jeroen.everaars@idiv.de

Esther Sossai
Student Research Assistant
E-mail esther.sossai@idiv.de

Johanna Pieplow
Student Research Assistant
E-mail johanna.pieplow@idiv.de

Index:

You could use our publication index for further requests.

2019 (10)

• Arceo-Gómez, G., Schroeder, A., Albor, C., Ashman, T.-L., Knight, T., (2019):
  Global geographic patterns of heterospecific pollen receipt help uncover potential ecological and evolutionary impacts across plant communities worldwide
  Sci. Rep. 9 , art. 8086
  full text (url)
• Bennett, J.M., Steets, J.A., Burns, J.H., Durka, W., Vamosi, J.C., Arceo-Gómez, G., Burd, M., Burkle, L.A., Ellis, A.G., Freitas, L., Li, J., Rodger, J.G., Wolowski, M., Xia, J., Ashman, T.-L., Knight, T.M., (2019):
  Publisher Correction: GloPL, a global data base on pollen limitation of plant reproduction
  Sci. Data 6 , art. 2
  full text (url)
• Bernardo, H.L., Vitt, P., Goad, R., Masi, S., Knight, T.M., (2019):
  Using long-term population monitoring data to prioritize conservation action among rare plant species
  Nat. Areas J. 39 (2), 169 - 181
  full text (url)
• Burns, J.H., Bennett, J.M., Li, J., Xia, J., Arceo-Gómez, G., Burd, M., Burkle, L.A., Durka, W., Ellis, A.G., Freitas, L., Rodger, J.G., Vamosi, J.C., Wolowski, M., Ashman, T.-L., Knight, T., Steets, J.A., (2019):
  Plant traits moderate pollen limitation of introduced and native plants: a phylogenetic meta‐analysis of global scale
  New Phytol.
  full text (url)
• Chase, J.M., Gooriah, L., May, F., Ryberg, W.A., Schuler, M.S., Craven, D., Knight, T.M., (2019):
  A framework for disentangling ecological mechanisms underlying the island species–area relationship
  Front. Biogeogr. 11 (1), e40844
  full text (url)
• Fill, J.M., Pearson, E., Knight, T.M., Crandall, R.M., (2019):
  An invasive legume increases perennial grass biomass: An indirect pathway for plant community change
  PLOS One 14 (1), e0211295
  full text (url)
• Havens, K., Jolls, C.L., Knight, T.M., Vitt, P., (2019):
  Risks and rewards: Assessing the effectiveness and safety of classical invasive plant biocontrol by arthropods
  Bioscience 69 (4), 247 - 258
  full text (url)
• Levin, S.C., Crandall, R.M., Knight, T.M., (2019):
  Population projection models for 14 alien plant species in the presence and absence of above‐ground competition
  Ecology 100 (6), e02681
  full text (url)
• McGlinn, D.J., Xiao, X., May, F., Gotelli, N.J., Engel, T., Blowes, S.A., Knight, T.M., Purschke, O., Chase, J.M., McGill, B.J., (2019):
  Measurement of Biodiversity (MoB): A method to separate the scale‐dependent effects of species abundance distribution, density, and aggregation on diversity change
  Methods Ecol. Evol. 10 (2), 258 - 269
  full text (url)
• Westerband, A.C., Kagawa-Viviani, A.K., Bogner, K.K., Beilman, D.W., Knight, T.M., Barton, K.E., (2019):
  Seedling drought tolerance and functional traits vary in response to the timing of water availability in a keystone Hawaiian tree species
  Plant Ecol. 220 (3), 321 - 344
  full text (url)

2018 (10)

• Bennett, J.M., Steets, J.A., Burns, J.H., Durka, W., Vamosi, J.C., Arceo-Gómez, G., Burd, M., Burkle, L.A., Ellis, A.G., Freitas, L., Li, J., Rodger, J.G., Wolowski, M., Xia, J., Ashman, T.-L., Knight, T.M., (2018):
  GloPL, a global data base on pollen limitation of plant reproduction
  Sci. Data 5 , art. 180249
  full text (url)
• Bennett, J.M., Thompson, A., Goia, I., Feldmann, R., Ştefan, V., Bogdan, A., Rakosy, D., Beloiu, M., Biro, I.-B., Bluemel, S., Filip, M., Madaj, A.-M., Martin, A., Passonneau, S., Kalisch, D.P., Scherer, G., Knight, T.M., (2018):
  A review of European studies on pollination networks and pollen limitation, and a case study designed to fill in a gap
  AoB Plants 10 (6), ply068
  full text (url)
• Bernardo, H.L., Vitt, P., Goad, R., Masi, S., Knight, T.M., (2018):
  Count population viability analysis finds that interacting local and regional threats affect the viability of a rare plant
  Ecol. Indic. 93 , 822 - 829
  full text (url)
• Bialic-Murphy, L., Gaoue, O.G., Knight, T., (2018):
  Using Transfer Function Analysis to develop biologically and economically efficient restoration strategies
  Sci. Rep. 8 , art. 2094
  full text (url)
• Chase, J.M., McGill, B.J., McGlinn, D.J., May, F., Blowes, S.A., Xiao, X., Knight, T.M., Purschke, O., Gotelli, N.J., Adler, F., (2018):
  Embracing scale‐dependence to achieve a deeper understanding of biodiversity and its change across communities
  Ecol. Lett. 21 (11), 1737 - 1751
  full text (url)
• Crandall, R.M., Knight, T.M., (2018):
  Role of multiple invasion mechanisms and their interaction in regulating the population dynamics of an exotic tree
  J. Appl. Ecol. 52 (2), 885 - 894
  full text (url)
• Craven, D., Knight, T.M., Barton, K.E., Bialic-Murphy, L., Cordell, S., Giardina, C.P., Gillespie, T.W., Ostertag, R., Sack, L., Chase, J.M., (2018):
  OpenNahele: the open Hawaiian forest plot database
  Biodiver. Data J. 6 , art. e28406
  full text (url)
• Knight, T.M., Ashman, T.-L., Bennett, J.M., Burns, J.H., Passonneau, S., Steets, J.A., (2018):
  Reflections on, and visions for, the changing field of pollination ecology
  Ecol. Lett. 21 (8), 1282 - 1295
  full text (url)
• Pardini, E.A., Parsons, L.S., Ştefan, V., Knight, T.M., (2018):
  GLMM BACI environmental impact analysis shows coastal dune restoration reduces seed predation on an endangered plant
  Restor. Ecol. 26 (6), 1190 - 1194
  final draft (pdf)
• Thompson, A.H., Knight, T.M., (2018):
  Exotic plant species receive adequate pollinator service despite variable integration into plant–pollinator networks
  Oecologia 187 (1), 135 - 142
  full text (url)

2017 (5)

• Crawford, K.M., Knight, T.M., (2017):
  Competition overwhelms the positive plant–soil feedback generated by an invasive plant
  Oecologia 183 (1), 211 - 220
  full text (url)
• Pardini, E.A., Patten, M.V., Knight, T.M., (2017):
  Effects of seed density and proximity to refuge habitat on seed predation rates for a rare and a common Lupinus species
  Am. J. Bot. 104 (3), 389 - 398
  full text (url)
• Schuler, M.S., Chase, J.M., Knight, T.M., (2017):
  Habitat size modulates the influence of heterogeneity on species richness patterns in a model zooplankton community
  Ecology 98 (6), 1651 - 1659
  full text (url)
• Schuler, M.S., Chase, J.M., Knight, T.M., (2017):
  Habitat patch size alters the importance of dispersal for species diversity in an experimental freshwater community
  Ecol. Evol. 7 (15), 5774 - 5783
  full text (url)
• Vitt, P., Knight, T.M., Schutzenhofer, M., Kleiman, W., Havens, K., Bittner, T., (2017):
  Experimental grazing and grass-specific herbicide application benefit rare forb recruitment
  Nat. Areas J. 37 (2), 161 - 169
  full text (url)

2016 (2)

• Bernardo, H.L., Albrecht, M.A., Knight, T.M., (2016):
  Increased drought frequency alters the optimal management strategy of an endangered plant
  Biol. Conserv. 203 , 243 - 251
  full text (url)
• Guthrie, S.G., Crandall, R.M., Knight, T.M., (2016):
  Fire indirectly benefits fitness in two invasive species
  Biol. Invasions 18 (5), 1265 - 1273
  full text (url)

2015

Crandall, R., and T.M. Knight (2015)
Positive frequency dependence undermines the success of
restoration using historical disturbance regimes. Ecology Letters 18: 883–891.

2013

Burkle, L.A., Marlin, J.C., and T.M. Knight (2013)
Plant-Pollinator Interactions over 120 Years: Loss of Species, Co-Occurrence and Function. Science 339: 1611-1615.

Powell, K.I., J.M. Chase, and T.M. Knight (2013)
Invasive plants have scale-dependent effects on biodiversity by altering the species-area relationship. Science 339: 316-318.

Burns, J.H., E.A. Pardini, M.R. Schutzenhofer, Y.A. Chung, K.J. Seidler, and T.M. Knight (2013)
Greater sexual reproduction contributes to differences in demography of invasive plants and their noninvasive relatives. Ecology 94: 995-1004.
 

Research Gate Profile Tiffany Knight