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openCC (other)Jan 2023View details →

Urbanization and fragmentation have opposing effects on soil nitrogen availability in temperate forest ecosystems.

Nitrogen (N) availability relative to plant demand has been declining in recent years in terrestrial ecosystems throughout the world, a phenomenon known as N oligotrophication. The temperate forests of the northeastern U.S. have experienced a particularly steep decline in bioavailable N, which is expected to be exacerbated by climate change. This region has also experienced rapid urban expansion in recent decades that leads to forest fragmentation, and it is unknown whether and how these changes affect N availability and uptake by forest trees. Many studies have examined the impact of either urbanization or forest fragmentation on nitrogen (N) cycling, but none to our knowledge have focused on the combined effects of these co-occurring environmental changes. We examined the effects of urbanization and fragmentation on oak-dominated (Quercus spp.) forests along an urban to rural gradient from Boston to central Massachusetts (MA). At eight study sites along the urbanization gradient, plant and soil measurements were made along a 90 m transect from a developed edge to an intact forest interior. Rates of net ammonification, net mineralization, and foliar N concentrations were significantly higher in urban than rural sites, while net nitrification and foliar C:N were not different between urban and rural forests. At urban sites, foliar N and net ammonification and mineralization were higher at forest interiors compared to edges, while net nitrification and foliar C:N were higher at rural forest edges than interiors. These results indicate that urban forests in the northeastern U.S. have greater soil N availability and N uptake by trees compared to rural forests, counteracting the trend for widespread N oligotrophication in temperate forests around the globe. Such increases in available N are diminished at forest edges, however, demonstrating that forest fragmentation has the opposite effect of urbanization on coupled N availability and demand by trees.

Effects of permafrost thaw on nitrogen availability and plant-soil interactions in a boreal Alaskan lowland: I - Percent Cover Data 2013

This dataset examines shifts in plant community structure along a lowland boreal permafrost thaw chronosequence. Data was collected in 2013 at the APEX Beta and forested study plots, located adjacent to the BNZ experimental forest. Percent cover data was collected for subcanopy vascular and nonvascualr vegetation in July 2013.

Effects of permafrost thaw on nitrogen availability and plant-soil interactions in a boreal Alaskan lowland: II - Nitrogen Data 2013

This dataset examines shifts in extractable soil pore water chemistry along a lowland boreal permafrost thaw chronosequence. Data was collected in 2013 at the APEX Beta and forested study plots, located adjacent to the BNZ experimental forest. Measured parameters include: dissolved inorganic N (DIN), dissolved organic N (DON), free amino acids, total dissolved N (TDN), soil temp. at 10 cm, seasonal ice depth, and volumetric soil moisture at 10 cm. Soil pore water samples and environmental variables were collected every three to four weeks from late June to late September, 2013 for a total of five sampling events.

Effects of permafrost thaw on nitrogen availability and plant-soil interactions in a boreal Alaskan lowland: III - Root Abundance 2013

This dataset examines shifts in rooting along a lowland boreal permafrost thaw chronosequence. Data was collected in 2013 at the APEX Beta and forested study plots, located adjacent to the BNZ experimental forest.

Effects of permafrost thaw on nitrogen availability and plant-soil interactions in a boreal Alaskan lowland: IV - Plant vs Nitrogen Data 2013

This dataset examines shifts in soil and plant characteristics, and extractable soil pore water chemistry along a lowland boreal permafrost thaw chronosequence. Data was collected in 2013 at the APEX Beta and forested study plots, located adjacent to the BNZ experimental forest. Data includes mean DIN, DON, free amino acids, and TDN from seasonal pore water measurements as well as aboveground vegetation C and N concentrations, and summertime, litterfall % N, and resorption efficiency for C. calyculata.

Effects of permafrost thaw on nitrogen availability and plant-soil interactions in a boreal Alaskan lowland: V - Isotape Data 2013

This dataset examines shifts in foliar del N 15 concentations for three plant species found across a lowland boreal permafrost thaw chronosequence. Data was collected in 2013 at the APEX Beta and forested study plots, located adjacent to the BNZ experimental forest.

Effects of permafrost thaw on nitrogen availability and plant-soil interactions in a boreal Alaskan lowland: VI - Soil Nitrogen Pools

This dataset examines shifts in soil N and extractable soil pore water chemistry along a lowland boreal permafrost thaw chronosequence. Data was collected in 2013 at the APEX Beta and forested study plots, located adjacent to the BNZ experimental forest. Measured parameters include: dissolved inorganic N, dissolved organic N, free amino acids, total dissolved N, C:N of soil material, soil bulk density, soil N concentration, soil C concentrations, volumetric soil moisture. Soil pore water samples were collected every three to four weeks from late June to late September, 2013 for a total of five sampling events, while soil cores were collected in late July 2013 for physical characterstics and soil C and N concentrations.

openCC (other)Oct 2021View details →

Climate Change Across Seasons Experiment (CCASE) at the Hubbard Brook Experimental Soil Solution Resin Available Nitrogen

Resin available soil solution nitrogen was measured during seasonal incubations in 2014 and 2015 on all Climate Change Across Seasons Experiment (CCASE) plots. Reference (or control) plots are shared with the collaborating Northern Forest DroughtNet experiment. There are six plots total (each 11 x 14m). Two are warmed 5 degrees C throughout the growing season (Plots 3 and 4). Two others are warmed 5 degrees C in the growing season and have snow removed during winter to induce soil freeze/thaw cycles (Plots 5 and 6). Four kilometers (2.5 mi) of heating cable are buried in the soil to warm these four plots. Two additional plots serve as controls for our experiment (Plots 1 and 2). Analysis and results from these data are presented in Sanders-DeMott 2018. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. Sanders-DeMott, R., Sorensen, P.O., Reinmann, A.B. et al. Growing season warming and winter freeze–thaw cycles reduce root nitrogen uptake capacity and increase soil solution nitrogen in a northern forest ecosystem. Biogeochemistry 137, 337–349 (2018). https://doi.org/10.1007/s10533-018-0422-5

openCC (other)Apr 2020View details →

Microarthropod and nematode effects on soil nitrogen availability in fluffgrass mesocosms at the Jornada Basin LTER site, 1986-1987

This data package contains soil nitrogen measurements taken over a 12-week interval in soils treated to exclude microarthropods and nematodes. The purpose of this study was to test if changing densities of soil microarthropods and nematodes results in changes in soil nitrogen availability. In 1986 and 1987, 110 fluff grass (Dasyochloa pulchella) plants were collected from the Jornada Basin College Ranch and transplanted into pots, which contained 5 replicates of each treatment. The 4 treatments include 1) control, 2) NEMACUR (to exclude nematodes), 3) chlordane (to exclude mites) and 4) NEMACUR + Chlordane. Each was sampled 5 times during a 12-week interval after the initial treatment. Pots were watered weekly to maintain conditions at field capacity. Samples were taken from the rhizosphere and analyzed for NO3(-)- N, NH4(+)-N, Inorganic-N, microbial-N, % H20, % organic matter, root biomass, and nematode density. This study was completed in 1987.

openCC0Dec 2019View details →

Effects of Altered Precipitation on Biological Soil Crusts, Fungi, and Soil Nitrogen Availability at the Monsoon Rainfall Manipulation Experiment (MRME) in the Sevilleta National Wildlife Refuge, New Mexico (2016)

Microbial activity in drylands is mediated by the magnitude and frequency of growing season rain events that will shift as climate change progresses. Nitrogen is often co-limiting with water availability to dryland plants, and thus we investigated how microbes important to the nitrogen (N) cycle and soil N availability varied temporally and spatially in the context of a long-term rainfall variability experiment in the northern Chihuahuan Desert. Specifically, we assessed biological soil crust (biocrust) chlorophyll content, fungal abundance, and inorganic N in soils adjacent to individuals of the grassland foundation species, Bouteloua eriopoda, and in the unvegetated interspace at multiple time points associated with an experimental monsoon rain treatment. Treatments included small weekly (5 mm) or large monthly (20 mm) rain events, which had been applied during the summer monsoon for nine years prior to our sampling. Additionally, we evaluated target plant C:N ratios and added 15 N-glutamate to biocrusts to determine potential for nutrient transport to B. eriopoda. Biocrust chlorophyll was up to 67% higher in the small weekly or large monthly rainfall regimes compared to ambient controls. Fungal biomass was 57% lower in soil interspaces than adjacent to plants but did not respond to rainfall regime treatments. Ammonium and nitrate concentrations near plants declined through the sampling period but varied little in soil interspaces. There was limited movement of 15 N from interspace biocrusts to leaves but high 15 N retention in the soils even after additional ambient and experimental rain events. Plant C:N ratio was unaffected by rainfall treatments. The long-term alteration in rainfall regime in this experiment did not change how short-term microbial abundance or N availability responded to the magnitude or frequency of events, suggesting a limited response of N availability to future climate change.

opencc-by-4.0Sep 2021View details →

Assessing Nitrogen Availability in Biobased Fertilizers: Effect of Vegetation on Mineralization Patterns

Biobased nitrogen (N) fertilizers derived from animal manure can substitute synthetic mineral N fertilizer and contribute to more sustainable agriculture. Practitioners need to obtain a reliable estimation of the biobased fertilizers’ N value. This study compared the estimates for pig slurry (PS) and liquid fraction of digestate (LFD) using laboratory incubation and plant-growing experiments. A no-N treatment was used as control and calcium ammonium nitrate (CAN) as synthetic mineral fertilizer. After 100 days of incubation, the addition of PS and LFD resulted in a net N mineralization rate of 10.6 ± 0.3% and 20.6 ± 0.4% of the total applied N, respectively. The addition of CAN showed no significant net mineralization or immobilization (net N release 96 ± 6%). In the pot experiment under vegetation, all fertilized treatments caused N immobilization with a negative net N mineralization rate of −51 ± 11%, −9 ± 4%, and −27 ± 10% of the total applied N in CAN, PS, and LFD treatments, respectively. Compared to the pot experiment, the laboratory incubation without vegetation may have overestimated the N value of biobased fertilizers. Vegetation resulted in a lower estimation of available N from fertilizers, probably due to intensified competition with soil microbes or increased N loss via denitrification.

dryad40/100

Nitrogen availability determines ecosystem productivity in response to climate warming

One of the major uncertainties for carbon-climate feedback predictions is an inadequate understanding of the mechanisms governing variations in ecosystem productivity response to warming. Temperature and water availability are regarded as the primary controls over the direction and magnitude of warming effects, but some unexplained results signal that our understanding is incomplete. Using two complementary meta-analyses, we present evidence that soil nitrogen (N) availability drives the warming effects on ecosystem productivity more strongly than thermal and hydrological factors over a broad geographical scale. First, by synthesizing temperature manipulation experiments, meta-regression model analysis showed that the warming effect on productivity is mainly driven by its effect on soil N availability. Sites with higher warming-induced increase in N availability were characterized by stronger productivity enhancement and vice versa, suggesting that N is a limiting factor across sites. Second, a synthesis of full-factorial warming×N addition experiments demonstrated that N addition significantly weakened the positive warming effect, because the additional N induced by warming may not further benefit plant growth when N limitation is relieved, providing experimental evidence that N regulates the warming effect. Further, we demonstrated that warming effects on soil N availability were modulated by changes in dissolved organic N and soil microbes. Overall, our findings enrich a new mechanistic understanding of the varying magnitudes of observed productivity response to warming, and the N scaling of warming effects may help constrain climate projections.

opencc-zeroJun 2022View details →

opencc-by-4.0Dec 2022View details →

Figure 1 in Effects of nitrogen and phosphorus availability on the early growth of two congeneric pairs of savanna and forest species

Figure 1. On that figure are the logarithms of root-to-shoot ratio square root in two pairs of congeneric species. The forest houses data from two species (E. contortisiliquum and S. grandiflorum), as do the savanna (E. gummiferum and S. lycocarpum). The complete solution is represented by Com; The solution without N by -N; The solution without P by -P; The solution without both nutrients by -NP.

opencc-by-4.0Sep 2024View details →

Data and analyses for Perkowski et al. (2024) manuscript accepted to AoB Plants: "Symbiotic nitrogen fixation reduces belowground biomass carbon costs of nitrogen acquisition under low, but not high, nitrogen availability"

This repository contains data and scripts for analyses and plots in Perkowski et al. (2024), titled "Symbiotic nitrogen fixation reduces belowground biomass carbon costs of nitrogen acquisition under low, but not high, nitrogen availability". v2.0 updates code and scripts per reviewer comments and is the final release prior to manuscript proofing.