Author: ESPM Web Specialist

In a recent paper (Ecological Impacts, Vol. 39, pp. 94-101), Carrie Levine and colleagues describe methods for analyzing long-term monitoring data to evaluate whether current monitoring programs are as efficient and effective as possible. This can allow researchers to maximize information gained relative to resources required for data collection. In the paper, the authors describe methods for analyzing data from four types of monitoring schemes: long-term records from a single site, one-time surveys at multiple sites, plot-level sampling, and time-series data from multiple sites. Evaluating long-term monitoring data at regular intervals throughout the monitoring program can help researchers determine whether sampling should be reallocated in space or time to optimize the use of financial and human resources.

Read the full article

In Reconstructing Disturbances and Their Biogeochemical Consequences over Multiple Timescales, Kendra McLauchlan and colleagues, including John Battles, overview how disturbances are reconstructed using natural records. Here is the abstract:

Ongoing changes in disturbance regimes are predicted to cause acute changes in ecosystem structure and function in the coming decades, but many aspects of these predictions are uncertain. A key challenge is to improve the predictability of postdisturbance biogeochemical trajectories at the ecosystem level. Ecosystem ecologists and paleoecologists have generated complementary data sets about disturbance (type, severity, frequency) and ecosystem response (net primary productivity, nutrient cycling) spanning decadal to millennial timescales. Here, we take the first steps toward a full integration of these data sets by reviewing how disturbances are reconstructed using dendrochronological and sedimentary archives and by summarizing the conceptual frameworks for carbon, nitrogen, and hydrologic responses to disturbances. Key research priorities include further development of paleoecological techniques that reconstruct both disturbances and terrestrial ecosystem dynamics. In addition, mechanistic detail from disturbance experiments, long-term observations, and chronosequences can help increase the understanding of ecosystem resilience.

Read the full article at BioScience

Acid deposition has depleted calcium in forest soils throughout the northeastern US, a pattern tied to forest declines in the region. But through a fifteen year experiment at Hubbard Brook Experimental Forest that restores this lost calcium, John Battles and colleagues have shown that forests can recover from the damaging impacts of acid rain. The study compares forest growth and productivity in a pair of watersheds. The experimental addition of more than 40 tons of calcium silicate to one watershed allowed comparison of the forests’ responses: the restored forest showed higher aboveground NPP, increased photosynthetic surface area, and a rebound in tree biomass increment. It was also faster to recover from a severe ice storm that affected the area in 1998.

• Read the article in Environmental Science and Technology Letters
  
• Read this article on the UC Berkeley News Service

A big “Thank you!” goes out to our summer research assistants, Natalie Holt and Alex Javier. From May through August Natalie and Alex lent their talents to our research crew, completing lab projects throughout the Sierra Nevada at Baker Forest, Blodgett Forest Research Station, and in Sequoia National Park. Leading the work were Carrie Levine, Flora Krivak-Tetley, and Stella Cousins. Joe Battles was also a big help during our studies at Blodgett. Together we measured thousands of trees, mapped forest plots, built snazzy seed traps, dissected snags, compared swimming holes, and much, much, more. Thanks to everyone involved for the hard work! This summer’s efforts are sure to keep us busy for months (years?) to come.

In the latest issue of the Journal of Forestry (Vol 110, Issue 8, pg. 448-456), Ruth Yanai, Carrie Levine, Mark Green, and John Campbell describe methods for quantifying uncertainties in forest nutrient pools and fluxes. Nutrient budgets of forest ecosystems have not historically included error analysis, in spite of the importance of uncertainty to interpretation and extrapolation of the results. Uncertainty in ecosystem budgets derives from natural variability, such as spatial and temporal uncertainty, as well as knowledge uncertainty, such as model and analytical errors. For example, in the case of nutrient content of forest biomass, the overall uncertainty would be comprised of measurement uncertainty (variation between plots), analytic uncertainty (detection limits of analytical instruments), within-model uncertainty (error in allometric equations), and between-model uncertainty (choosing which allometric equations to use). This paper uses the Hubbard Brook Experimental Forest as an example and describes approaches for quantifying uncertainty in biomass, soils, and hydrologic inputs and outputs. The results suggest that change over time may have less uncertainty than a single measurement if the measures are consistently biased, for example the use of inaccurate allometric equations or soil sampling techniques. These methods can be adapted to many other ecosystems and can have important forest management applications. Identifying the largest uncertainties in nutrient budgets allows us to direct research efforts where the need for information is greatest.

In October, the Battles Lab participated in the 2nd Annual STEMposium as a part of the Youth Speaks Inc Life is Living Festival in West Oakland, CA. The purpose of the event was to engage the community at large, with an emphasis on youth, in discussions about how science, technology, engineering, and math (STEM) impacts their community and can be used to make changes in their community.The event engaged and encouraged youth in STEM research through hands on activities and career exploration, with a special emphasis in areas such as environmental science, urban gardening and agriculture, transportation and urban design. Our exhibit showcased a career as a forest ecologist, with examples of the types of questions we try to answer about the environment. We demonstrated how dendrochronology can be used as a tool to answer environmental questions ranging from climate change, historical disturbances (fire, land slides, hurricanes), to effects of air pollution on forest health. Both kids and adults were fascinated with tree rings and how trees grow, particularly when they got to practice coring a real tree trunk and looking at tree cores under the microscope! We also interacted with educators from local schools, sparking discussion and ideas for classroom activities. Click to learn more about the Life is Living Festival, and the STEMposium.

In a recent paper (Ecology, Vol 92, Issue 6), Anne Eschtruth and John Battles investigated the widely held belief that riparian communities are highly invasible to exotic plants. This idea is based primarily on comparisons of the extent of invasion in riparian and upland communities. However, because differences in the extent of invasion may simply result from variation in propagule supply among recipient environments, true comparisons of invasibility require that both invasion success and propagule pressure are quantified. In this study, Eschtruth quantified propagule pressure in order to compare the invasibility of riparian and upland forests and assess the accuracy of using a community’s level of invasion as a surrogate for its invasibility. Extent of invasion was found to be a poor proxy for invasibility. The higher level of invasion in the studied riparian forests resulted from greater propagule availability rather than higher invasibility. Further, this study suggests that failure to account for propagule pressure may confound our understanding of general invasion theories. Ecological theory suggests that species-rich communities should be less invasible. However, Eschtruth and Battles found significant relationships between species diversity and invasion extent, but no diversity–invasibility relationship was detected for any species. Study results demonstrate that using a community’s level of invasion as a surrogate for its invasibility can confound our understanding of invasibility and its determinants.

Natalie van Doorn and colleagues report on a 10-year resurvey of a valley-wide plot network (371 plots across 3,160-ha) in Hubbard Brook Valley, New Hampshire (online in advance of print in the Canadian Journal of Forest Research). The goal of this project was to quantify recent trends in tree biomass and demography. The results from this paper confirm earlier reports that the forest at Hubbard Brook is no longer aggrading. There was no significant change in live tree biomass between 1995/6 and 2005/6. However, there were salient shifts in relative dominance of the canopy species (in particular, significant drop in yellow birch biomass was matched by increases in balsam fir and red spruce). A look into the tree demography revealed that mortality significantly exceeded recruitment for yellow birch and paper birch. For the major tree species, there was no instance of recruitment significantly exceeding mortality. Relative growth rates were greater than 1.5% per year for sugar maple, red spruce, and beech. Although effects of novel disturbances documented on a regional level have not led to directional changes in tree demography at Hubbard Brook, the authors suggest that these novel stressors are depressing the biomass potential of the forest.

Read more about the long-term Hubbard Brook Valley plot network

Maya Hayden and colleagues highlight the conservation importance of abandoned channels as refugia for sustaining pioneer riparian forest ecosystems (online in advance of print in the journal Ecosystems). Recognizing that organisms in disturbance-prone environments often persist in spatial refugia during stressful periods, they explore the importance of abandoned channels as potential refugia for a foundation tree species (Fremont cottonwood, Populus fremontii) within the riparian corridor of a large meandering river (Sacramento River in central California). They quantified the total proportion of cottonwood-dominated forest that initiated as a result of channel abandonment for a 160-km reach of the river via GIS analysis of historical air photos, and found that over 50% of the total extant cottonwood forest area was associated with channel abandonment. Tree-ring evidence showed that cottonwood stands commonly developed immediately following channel abandonment, and the recruitment window was less than 10 years at most sites (4-40 yrs). They connected patterns of tree establishment with floodplain accretion and sedimentation history, showing rates of floodplain rise and fine sediment accumulation to be higher in young sites and decreasing logarithmically over time. These results suggest that abandoned channels are an important refuge for cottonwood recruitment and that sedimentation processes influence the duration of the colonization window for cottonwood trees. They suggest that on rivers where tree recruitment along the active channel is severely limited by hydrologic regulation and/or land management, abandoned channel refugia may play an even more important role in sustaining an ecologically functional riparian corridor. Preserving bank erosion, active meander corridors, and forest regeneration zones created by cutoff events are therefore key conservation measures in shifting rivers.

In February, the Battles Lab participated in the 1st Annual Science, Engineering, Math and Technology (STEM) Career Fair in Oakland, CA, put on by the non-profit SEM Link, Inc. The goal of the event was to expose K-12 youth (particularly underrepresented minorities) to real-world applications of math and science by connecting them to STEM professionals and promoting hands-on learning experiences. The fair brought in over 45 Bay Area youth, mostly middle-school aged and younger, including a large group from Girls Inc. of Alameda County. Our exhibit showcased a career as a forest ecologist, with examples of the types of questions we try to answer about the environment. We demonstrated how dendrochronology can be used as a tool to answer environmental questions ranging from climate change, historical disturbances (fire, land slides, hurricanes), to effects of air pollution on forest health. The kids were really excited to learn about tree rings and how trees grow, particularly when they got to practice coring a real tree trunk and looking at tree cores under the microscope! 

Learn more about SEM Link, Inc