TN021
Soil solution chemistry in Detrital Input and Removal Treatments (DIRT) from the Andrews Experimental Forest, 1999-2011

CREATOR(S): Kate Lajtha

PRINCIPAL INVESTIGATOR(S): Kate Lajtha

ORIGINATOR(S): Kate Lajtha

OTHER RESEARCHER(S): Derek Pierson, Phillip Sollins, Hayley Peter-Contesse, April Strid, Fox Sparky Peterson, Jennifer Dawn Wig, Kim Townsend

DATA SET CONTACT PERSON: Fox Sparky Peterson

DATA SET CREDIT:

DIRT is funded under the DEB-12570372.

METADATA CREATION DATE:

4 Jan 2013

MOST RECENT METADATA REVIEW DATE:

29 Oct 2019

KEYWORDS:

biogeochemistry, decomposition, carbon cycling, litterfall, nutrients, terrestrial ecosystems

PURPOSE:

Soil organic matter (SOM) is the terrestrial biosphere's largest pool of organic carbon and is an integral part of the global C cycle. Therefore, changes in SOM formation and decomposition due to climate change, land management, disturbance or other factors can feed back to the climate system to either sequester CO2 into organic forms or release it to the atmosphere. Despite its pivotal role in the global C cycle, the relative importance and linkages of the various biological, chemical and physical processes regulating SOM balances are not well understood. Although forests contain more than 3x the soil C (575 x 1015 g) of agricultural lands (180 x 1015 g), forest SOM dynamics and their relation to detrital inputs and soil biotic processing remain poorly understood. Even fundamental relationships, such as between mean annual temperature and SOM turnover rates, are controversial. A major challenge for environmental science is to develop a predictive understanding of how climate and vegetation interact to determine how detritus and soil biota affect SOM formation and stability. Over the years, our informal group of ecologists, biogeochemists and ecosystem modelers has been using a common set of experimental manipulations, referred to collectively as DIRT (Detritus Input and Removal Treatments), to assess how rates and sources of plant inputs control the accumulation and dynamics of SOM and nutrients in forest soils over decadal time scales. The original DIRT treatments consist of chronically altering plant inputs to forest soils by regularly removing surface litter from permanent plots and adding it to others. Our network of DIRT sites now includes four operational temperate forest sites. The central goal of the DIRT project is to assess how rates and sources of plant litter inputs control the accumulation and dynamics of organic matter and nutrients in forest soils over decadal time scales. The project examines processes at multiple levels, across decades and centuries, exploring the intricate interconnections of biology and chemistry that lead to the formation of humic materials over these hitherto unexplored long time spans. Our plots are part of an informal network of similar experimental treatments that span a significant climatic gradient and that encompass both coniferous and deciduous forests, and that vary widely in anthropogenic N loading. Current DIRT sites include Harvard Forest, MA (oak forest, established 1991); Bousson Experimental Research Reserve, PA (deciduous forest, established 1992); Sikfokut Forest, Hungary (turkey oak forest, established 2001), and the Michigan Biological Station, MI (pine forest, established 2004).

METHODS:

Experimental Design - TN021:

Description:

DIRT plots were established at the HJ Andrews Experimental forest in 1997 with USDA support. There are 15 plots on the forest, 2 for each treatment, as well as some "split plots" to address dynamics at a finer scale. The plots are about 10m - 15m (about 100 m squared) to account for the extreme forest floor heterogeneity. Unlike other DIRT sites, HJ Andrews Experimental forest adds a location that is wetter and has much lower inputs of atmospheric N and much larger inputs of coarse woody debris than the other sites. Plots are sited in the low-elevation Douglas-fir/western hemlock zone on Andic soils of volcanic origin. These soils are of low density and highly sorptive, potentially leading to different nutrient dynamics than other DIRT sites. Additionally, the "double wood" treatment is implemented on Andrews, using mulch to simulate increased woody debris.

Instrumentation: Prenart lysimeters and LICOR soil respiration

Field Methods - TN021:

Description: The DIRT plots consist of 15 plots of 100 square meters located in a flat area on the H.J. Andrews experimental forest. 6 treatments are used for detrital inputs and removal: control, no litter, double litter, double wood, no roots, and no inputs. To create double litter plots, litter is removed annually from the "no litter" plots and put on the double litter plots. To create double wood, mulch is added to the system. To create no roots, the plot is trenched around the outside so that roots cannot penetrate. To create no inputs, trenching and removal are conducted. On each plot are five lysimeters which are collected with rain events when the weather permits. Soil respiration chambers also exist. Bulk soil for CHN analysis is collected from a nearby location using Oakfield corers.

SITE DESCRIPTION:

Unlike other DIRT sites, AND adds a location that is wetter and has much lower inputs of atmospheric N and much larger inputs of coarse woody debris than the other sites. Plots are sited in the low-elevation Douglas-fir/western hemlock zone on Andic soils of volcanic origin. These soils are of low density and highly sorptive, potentially leading to different nutrient dynamics than other DIRT sites. Additionally, the "double wood" treatment is implemented on Andrews, using mulch to simulate increased woody debris.

TAXONOMIC SYSTEM:

Garrison et al., 1976

MEASUREMENT FREQUENCY:

annually

PROGRESS DESCRIPTION:

Complete

UPDATE FREQUENCY DESCRIPTION:

irregular

CURRENTNESS REFERENCE:

Observed

RELATED MATERIAL:

Harvard Forest DIRT plots: http://harvardforest.fas.harvard.edu/dirt-detritus-input-and-removal-treatments

University of Michigan Biological Station DIRT plots: http://umbs.lsa.umich.edu/research/researchsite/umbs-dirt-plots.htm