B: Impacts of invasive species on ecosystem processes and structures
Key listener: Chelcy Ford Miniat
Note taker: Tara Haan Karel
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FOCUS QUESTIONS
1) What are the critical scientific issues?
Is there something that science can do to help prioritize the management of known invaders versus
preventing new invasions?
What controls the invasability of systems? Why are some systems more invadable than others?
We need to have host-specific information on the role in system function that is scalable
Evaluating cumulative and interactive impacts of multiple invaders eliminating native species from an
ecosystem (water, C, and replacement species)
Compounding effects and lower species diversity in an ecosystem; when you lose species diversity, you
typically lose productivity and resiliency.
And how do IS and species change in general affect resiliency?
Per capita effects of IS on process changes - Is there a threshold? Is it a linear relationship? What are
other drivers? Does it differ by taxonomic group?
How do broad scale drivers (N deposition, climate change) affect per capita effects on
processes? (ties into other stressors)
Is there a framework (functional traits) that we can develop to help predict/scale IS (and host) effects on
ecosystem processes?
**Ecosystem engineer (IS) effects on ecosystem processes
How do IS change fire regimes and how do they interact with other stressors to impact ecosystem
processes?
2) What are the critical management and policy issues?
How do we motivate policy?
What is the social acceptance of change to ecosystem processes, function, and structure? Some people
won’t care if the impact is visual, and some may care more.
How do we prioritize multiple policies – for example, TES vs IS
The role of federally managed lands will become increasingly important, especially with population
growth and spread into the WUI. Understanding the importance of public lands and land use and
potential for increasing demands on those lands
There is increasing pressure on public lands to mitigate for private lands
Fragmentation
Natural systems are reservoirs for what we can use for restoration and important for building
resilience in the landscape
The prioritization of policy needs to be science-driven (especially important when continually facing
decreased funding)
Management also needs to be influenced by science
Temporal: Hysteresis and legacy effects – how long after restoration will we see a change in
process/pool/flux?
Spatial: How much of the system do we have to manipulate to change function?
How much do we have to take into account IS effects on process in our restoration process? How does
management of non-invasives influence invasability? Sometimes IS may be already present but not
problematic. Specifically, when we’re trying to restore a process (ex- beavers in west and Nutria habitat)
What is success? When would we be done with an action when we have limited funds? Performancebased outcomes? It might be useful to link to a process
We need more funding to facilitate research on using IS as products (ex: biofuel)
Nitrogen deposition affects invasion success (both positively and negatively)
3) Which scientific data, models, and syntheses are available to inform this topic?
Potential for using data and models that we already have in novel ways for management implications
There are existing meta-analyses to inform this topic, but there is not a lot. It is much more
straightforward to quantify the effects of invaders on populations, but it is difficult to quantify the
impacts on things like hydrologic cycles, nutrient cycling, and C budgets. It may be easiest to start with
species with very profound effects on ecosystems.
We are getting better at systems analysis (Matt Reeves S-T work, food web models), however we don’t
have a lot at the landscape scale
FIA data can play a huge role
Lovett et al paper
USGS/NRCS soil maps – opportunity for connection? This is also a gap because they are very targeted to
agriculture
NEON data/network
LTER
Experimental forests network
NPS has a good inventory and monitory program
There are increasing amounts of databases for IS and functional traits
NIDRM (FHP product that assesses risk to a species to species by pests – EAB, gypsy moth, laurel wilt)
Ghandi and Herms 2010
Literature and studies predicting BG effects of plant invasives
Work by Christine Hawkes, D’Antonio, Sykes
LiDAR
MODIS products, NDVI
Do FACE experiments include invasive species?
LANDIS II
4) Which issues are likely to become increasingly important by 2040 and beyond?
Invasion debt – how many of these invaders are weak invaders now but have the potential for strong
invasion? When will that ‘switch’ turn? Understanding the tipping point for conversion
Climate change will be affecting resources and processes independently of invaders – how will invasion
interact? When does it make sense to address IS with all of these other things going on and shifting
priorities in the face of climate change? IS may alter community function more quickly than climate
change. Restoration targets will be shifting due to climate change.
Climate change may predispose communities to invasion and make them more vulnerable.
TES responses to accumulating stresses related to IS
Water quality and quantity with growing populations and IS
Connecting ecosystem services to human health (ex: pollen from cedar in TX)
Honeysuckle and ticks (structure)
Other insects carrying diseases and health of animals/livestock/crops, in addition to humans
(malaria, dengue, white nose syndrome, rabies)
Some sort of invasive tax? Something policy relevant and measureable that an industry could set for
themselves for reducing impact (ex: number of new introductions, number of acres affected)
Relates back to performance-based outcomes/metrics
As IS continue to put pressure on harvest of plants for protein, needs will shift somewhere else (food
security)
Ex: Invasion impacts on cattle production
With the increase in urbanization and population growth, scientific literacy will decline
5) How does this topic potentially connect with other topics in the chapter outline?
Consequences of process change for native species and communities
A causes B – changes in species and landscapes is related to and leads to changes in ecosystem
processes
There is an important connection to economics and identifying impacts on ecosystem processes with
impacts and valuation of ecosystem services
What is an invasive species? Define early
Ecosystem process change can also affect social values (ex: cultural heritage sites, erosion, change in fire
regimes)
EAB -> black ash -> Native American impacts (relation to social dimensions?)
What are the effects of IS on ecosystem processes?
6) What are the gaps in knowledge and current research?
To what extent do invaders irreversibly change ecosystem processes? When an IS changes an ecosystem
process, how quickly is it reversible? Can we get back to ‘Kansas’ with the process? Are we talking about
reversible through management or over time on its own? Ex- the microbial community
What triggers weak invaders to become strong invaders? When/why? Is there something about the
invasion biology that would help predict this?
How is this related to management actions? And time succession
Which hosts will become susceptible?
How does changing atmospheric C influence palatability and defense of hosts?
Below-ground processes and invasions by soil-dwelling organisms (earthworms, ground beetles)
Mychorrhizae and microbial communities
We need to value ecosystem service change from IS
Scalable information on ecosystem services (we need to put into a landscape context)
We need basic studies and information on IS impacts on ecosystem processes
Longitudinal studies of IS effect on ecosystem processes and function are needed
Being able to predict alternate stable states in ecosystems could help to predict impacts; what are the
thresholds of transitioning from one stable state to another? What are the processes associated with
those stable states?
Cross-ecosystem effects? A process in one system may affect another system; terrestrial-aquatic
connections in particular may be of interest
Belowground change from IS might change efficacy of restoration actions (ex: knapweed, cogongrass
and mycorrhizae)
**What is the effect of IS on ecosystem processes? When it comes to actual processes, the tools and
models available don’t quantify ecosystem processes
Ties to Chapter 1 – explain up front
We need to tie change in ecosystem processes to public values
The effect and impact of an IS may change over time; we need long-term monitoring of systems
Gaps might be biome or system dependent. For instance, we may have more information available for
impacts of aquatic IS than impacts in terrestrial systems