Proposal
for Network-level Research Initiative: Understanding the Causes and Consequences
of Changes in Biodiversity
M.D. Smith, NCEAS and Konza Prairie LTER
D.R. Foster,
Rather than provide an overview of our workshop we have
highlighted the major ideas that we feel will be useful to the LTER program as
we begin to plan and think critically about network level research and
synthesis. Our charge was to address the following issues: What are the key emerging questions regarding
our specific topic—Biodiversity Losses? What is the unique and special role
that the LTER network can play in addressing this topic today? And 3) What can
the LTER network do in the future that other science efforts have not done or cannot
do to address this topic?
1) The Need
There is little argument that the loss of biotic
diversity represents a major environmental challenge (NRC 2001, 2003). In our
consideration of the implications of biodiversity loss, however, we suggest
that the scope should be expanded to understanding the causes and consequences
of changes in biodiversity. In doing so, this includes
consideration of not only reassortment of species and
changes in composition through loss and gain (invasion) of species, but importantly,
also through alteration in their abundances.
All of these can have important implications for different dimensions of
diversity, spanning multiple hierarchical and organizational levels.
Altered biodiversity may
have profound impacts on community and ecosystem structure and functioning, and
ultimately the provisioning of ecosystem services (Figure 1). Drivers of
changes in biodiversity can be linked directly or indirectly to human
activities, which pervade and impact ecosystems globally (Vitousek
et al. 1997). Thus, it is critical that biotic changes are studied holistically
by linking human and ecological systems, in terms of key drivers, responses and
feedbacks. By this we mean that it will be most productive to think about a
biodiversity changes in relation to other key research themes:
invasions/extinctions, coupled human and natural systems, altered water and
nutrient cycles, climate change, forecasting landscape change, and engineered
systems. For example, the study of coupled human and natural systems relates
directly to the drivers of biodiversity shifts, as well as feedback between
science and society response. We do recognize the need for separate research
programs focusing on biodiversity losses and invasions/extinctions, but strongly
suggest that the topics not be considered in isolation as invasions and
extinctions are drivers, manifestations and part of the response to
biodiversity loss.
2)
Research Challenges
Recent research suggests
that changes in biodiversity can impact a suite of community and ecosystem
processes, such as invasibility, productivity, carbon storage and disease
incidence, as well as stability of ecosystems (e.g., Naeem
et al. 1996, Hector et al. 1999, Tilman et al. 2001, Loreau et al. 2001). Few studies
have assessed the role of different drivers in biodiversity changes. Rather,
most studies simulate species loss or gain, with little attention given to
compositional shifts or changes in abundance. Moreover, most studies have been
small-scale, of short duration, and focused on particular community types
(grasslands) and taxonomic groups (plants). Thus, it remains unclear how generalizable results from these studies are or how they
might scale across multiple sites or trophic levels and over longer time
periods. This
is particularly important because the causes and consequences of biotic change
occur and are manifest at multiple spatial and temporal scales.
Much
remains unknown about changes in biodiversity. Specific research challenges
include understanding: 1) background (natural) rates and drivers of
biodiversity change against which human drivers can be compared, 2) how drivers
differ within and across ecosystems, 3) which aspects of diversity (genetic,
richness, abundance, dominance, composition) are most impacted and which groups
(e.g., microbes, plants, animals) and systems (e.g., desert, grassland, stream,
lake) are more profoundly influenced, 3) the consequences of changes in
richness, shifts in dominance or altered composition for community and
ecosystem structure and function and sustainability of ecosystem services, 4)
the feedbacks of these impacts on biodiversity and drivers of change, 5) how
society responds to the perception or reality of changes in biodiversity, 6)
how we should manage changes in biodiversity, and 7) how we can retain, augment
or restore ecosystem services that accompany these changes. These are just a
few of the many research challenges discussed during the ASM workshop.
Comprehensively
addressing these and related challenges requires a research program that is
broad-scale, interdisciplinary, and integrative. It demands research that
incorporates a multi-pronged approach that includes long-term observation,
large-scale experimentation, and synthesis. Other scientific efforts may have strengths
in each of these approaches. However, the LTER network is uniquely poised to
incorporate all three of these with unprecedented breadth and integration.
3)
Unique Role of the LTER Network
The
LTER network provides an unparalleled platform to comprehensively examine the
causes (both natural and human-caused) and consequences of changes in
biodiversity and to implement an integrative, broad-scale research program. Sites within the network are arrayed along multiple
gradients – environmental, cultural and biological – and include multiple
ecological scales – organism (or lower) to region. Ecosystem types are
replicated across sites, e.g., desert, grassland, forests, and often there are
commonalities in drivers among sites.
In
addition to these important attributes, the LTER network has a number of
existing strengths that will feed directly into a multi-pronged research
approach:
A)
Long-term observation
Many
LTER sites have historical datasets on community and ecosystem processes,
including species composition of different taxonomic groups, productivity,
nutrient cycling, as well as a number of abiotic
variables (climate, atmospheric nutrient deposition). The datasets can be
leveraged to examine changes in different aspects of diversity over time and
space and in relationship to environment, disturbance, and regional processes.
B)
Large-scale experimentation
Many
sites have manipulations of species, nutrients, climate, disturbance regimes,
and land-use. These experiments – many of which are long-term and ongoing – can
be used to evaluate multiple drivers and their interactions, the process of
diversity changes, and the consequences of biotic change. Importantly, these
experiments can be used to inform and facilitate creation of new, innovative
experiments at regional and continental (network-wide) scales. Existing close intersite relationships and collaborations with other
scientists, sites and regions within the LTER network will play a critical role
in facilitating larger-scale research as well.
C)
Modeling and synthesis
Both
A) and B) feed directly into modeling efforts and synthesis activities. These
are vital for testing generalizations, prediction, study
design and for forecasting. We encourage LTER scientists to take the lead in synthesizing existing data and ideas and expanding
collaborations within and outside the LTER network. This will encourage
diversity of approaches, sites, and perspectives to capture new thinking.
4) Planning Grant
Directives and Considerations
We propose the following
activities for the planning grant:
I)
Identify the compelling research questions and challenges
and thematic linkages
II)
Develop a information matrix of LTER and relevant non-LTER
data from permanent plots, experiments, and monitoring efforts
III)
Conduct post-hoc syntheses
a. Identify those
questions that can be addressed with existing data and knowledge
b. Highlight
information gaps and data needs
IV)
Base on I) and III) design network-level research to address
the most compelling research questions that demand large-scale, integrative
research
We
suggest the planning activities attempt to incorporate all of these steps. We
believe these steps will feed directly into planning and implementation of a
multi-pronged research program to broadly address the drivers, process and
consequences of changes in biodiversity.
Several points to consider in the
planning process:
1) Synthesis in
LTER will be most exciting if it addresses many of the proposed (and other)
themes (e.g., climate change, coupled human and natural systems, changes in
biodiversity, invasions) simultaneously and in an integrated fashion;
2) There is a
strong argument to be made that synthesis will be most productive if carried
out simultaneously at many sites including those with little prior
background or disciplinary strength on the particular topic. Adding new
strengths to sites that may have focused resources elsewhere and bringing data from new sites and
systems to bear on key topics may well lead to more rapid advancements in
synthesis and ecological understanding.
Importantly, this consideration argues for network-wide equity through
inclusion in synthetic activities and the disbursement of funding;
3) The development
of this next evolutionary phase in the LTER program may require new thinking
concerning the way that site, intersite,
network-wide, and extra-network science are conducted, as well as new thinking
regarding the role and optimal organization of the Network Office in order to
facilitate this new activity.
5) References
Chapin III FS, BH Walker, RJ
Hobbs, DU Hooper, JH Lawton, OE Sala and D Tilman. 1997. Biotic control over the functioning of
ecosystems. Science 277:500-503.
Hector et
al. 1999.
Plant diversity and productivity experiments in European
grasslands. Science 286:1123-1127.
Loreau et al. 2001. Biodiversity and ecosystem
functioning: current knowledge and future challenges. Science 294:804-808.
NRC. 2001. Grand challenges in
environmental sciences.
NRC. 2003. NEON: Addressing the
nation’s environmental challenges.
Naeem S, K Hakansson, JH
Lawton, MJ Crawley, and LJ Thompson. 1996. Biodiversity and plant productivity in a
model assemblage of plant species. Oikos 76:259-264.
Tilman D, PB Reich, JMH Knops, D Wedin, T Mielke and C Lehman. 2001. Diversity and
productivity in a long-term grassland experiment. Science 294:843-845.
Vitousek PM, HA Mooney, J Lubchenco
and JM Melillo. 1997. Human domination of earth’s
ecosystems. Science 277:494-499.