35 Result(s)
within
Knute J. Nadelhoffer
-
Article
Old-growth forest carbon sinks overestimated
-
Article
Molecular-level changes in soil organic matter composition after 10 years of litter, root and nitrogen manipulation in a temperate forest
With climate change, forests are expected to receive increased inputs of carbon (C) and nitrogen (N) but it is unclear how this will modify forest C cycling and storage at the molecular-level. To investigate t...
-
Article
Effects of canopy structure and species diversity on primary production in upper Great Lakes forests
Canopy structure and tree species diversity, shaped by succession, disturbance, and community composition, are linked to numerous ecosystem functions, including net primary production (NPP). Understanding of h...
-
Article
What’s to do?
-
Article
Tree taxa and pyrolysis temperature interact to control the efficacy of pyrogenic organic matter formation
We know little about how shifts in tree species distribution and increases in forest fire intensity could affect the formation of pyrogenic organic matter (PyOM) or charcoal, one of the most important and pers...
-
Article
Long-term doubling of litter inputs accelerates soil organic matter degradation and reduces soil carbon stocks
Soil organic matter (SOM) constitutes more than two-thirds of terrestrial carbon stocks yet there are many uncertainties about the fate of soil carbon reserves with global environmental change. Moisture, alter...
-
Article
Exotic earthworm community composition interacts with soil texture to affect redistribution and retention of litter-derived C and N in northern temperate forest soils
Exotic earthworm impacts on temperate forest soils are influenced by earthworm community composition and are likely constrained by the degree of organic matter redistribution following earthworm introductions ...
-
Chapter
Effects and Empirical Critical Loads of Nitrogen for Ecoregions of the United States
Human activity in the last century has increased nitrogen (N) deposition to a level that has caused or is likely to cause alterations to the structure and function of many ecosystems across the United States. ...
-
Article
Nitrogen Uptake by Trees and Mycorrhizal Fungi in a Successional Northern Temperate Forest: Insights from Multiple Isotopic Methods
Forest succession may cause changes in nitrogen (N) availability, vegetation and fungal community composition that affect N uptake by trees and their mycorrhizal symbionts. Understanding how these changes affe...
-
Chapter
Using Nitrogen Isotope Ratios to Assess Terrestrial Ecosystems at Regional and Global Scales
Advances in technology have made extensive surveys of 15N natural abundances in terrestrial ecosystems feasible at the regional and even global scale within the last decade. To date, such surveys have included me...
-
Article
Climate and species affect fine root production with long-term fertilization in acidic tussock tundra near Toolik Lake, Alaska
Long-term fertilization of acidic tussock tundra has led to changes in plant species composition, increases in aboveground production and biomass and substantial losses of soil organic carbon (SOC). Root litte...
-
Chapter
Atmospheric Nitrogen Deposition: Implications for Terrestrial Ecosystem Structure and Functioning
Acid rain research on terrestrial ecosystems has increasingly focused on the effects of inorganic nitrogen (N) deposition, both as nitric acid (HNO3) and ammonium (NH4 +, which can produce ac...
-
Article
The Imprint of Land-use History: Patterns of Carbon and Nitrogen in Downed Woody Debris at the Harvard Forest
-
Article
A synthesis: The role of nutrients as constraints on carbon balances in boreal and arctic regions
As in many ecosystems, carbon (C) cycling in arctic and boreal regions is tightly linked to the cycling of nutrients: nutrients (particularly nitrogen) are mineralized through the process of organic matter dec...
-
Article
Forest nitrogen sinks in large eastern U.S. watersheds: estimates from forest inventory and an ecosystem model
The eastern U.S. receives elevated rates of Ndeposition compared to preindustrial times, yetrelatively little of this N is exported indrainage waters. Net uptake of N into forestbiomass and soils could account...
-
Article
Resource-based niches provide a basis for plant species diversity and dominance in arctic tundra
Ecologists have long been intrigued by the ways co-occurring species divide limiting resources. Such resource partitioning, or niche differentiation, may promote species diversity by reducing competition1,2. Alth...
-
Article
Long-term movement of 15N tracers into fine woody debris under chronically elevated N inputs
Two key questions in the study of large-scale C (carbon) and N (nitrogen) cycling in temperate forests are how N cycling in soil detritus controls ecosystem-level retention of elevated N deposition, and whethe...
-
Chapter
Forest nitrogen sinks in large eastern U.S. watersheds: estimates from forest inventory and an ecosystem model
The eastern U.S. receives elevated rates of N deposition compared to preindustrial times, yet relatively little of this N is exported in drainage waters. Net uptake of N into forest biomass and soils could acc...
-
Article
Long-Term Nitrogen Additions and Nitrogen Saturation in Two Temperate Forests
This article reports responses of two different forest ecosystems to 9 years (1988–96) of chronic nitrogen (N) additions at the Harvard Forest, Petersham, Massachusetts. Ammonium nitrate (NH4NO3) was applied to...
-
Article
Nitrogen Controls on Fine Root Substrate Quality in Temperate Forest Ecosystems
Nitrogen controls on fine root substrate quality (that is, nitrogen and carbon-fraction concentrations) were assessed using nitrogen availability gradients in the Harvard Forest chronic nitrogen addition plot...
