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.

Compound-specific nitrogen, carbon, and hydrogen isotope records from sediments of Sky Pond, an alpine lake in Rocky Mountain National Park (Colorado, United States of America), were used to evaluate factors contributing to changes in diatom assemblages and bulk organic nitrogen isotope records identified in lake sediments across Colorado, Wyoming, and southern Montana. Nitrogen isotopic records of purified algal chlorins indicate a substantial shift in nitrogen cycling in the region over the past ,60 yr. Temporal changes in the growth characteristics of algae, captured in carbon isotope records in and around Sky Pond, as well as a 260% excursion in the hydrogen isotope composition of algal-derived palmitic acid, are coincident with changes in nitrogen cycling. The confluence of these trends is attributed to an increase in biologically available nitrogenous compounds caused by an expansion of anthropogenic influences and temporal changes in catchment hydrology and nutrient delivery associated with meltwater dynamics.

Aim Terrestrial ecosystems sequester about 25% of anthropogenic CO2 emissions annually; however, nitrogen (N) and phosphorus (P) limitation of plant productivity and microbial functioning could curtail this key ecosystem service in the future. Our aim is to address variations in nutrient resupply during decomposition – especially whether the N:P ratio of nutrient recycling via mineralization varies within and across diverse forest biomes. Location Global forest ecosystems. Methods We compiled data on in situ litter decomposition experiments (leaf, wood and root) from the primary literature to examine the relationships between net N and P mineralization across temperate versus tropical forests world‐wide. We define net nutrient mineralization ratios as the average N:P released from decomposing substrates at a given ecosystem site. Results We show that net N and P mineralization are strongly correlated within biomes, suggesting strong coupling between N and P recycling in forest ecosystems. The net N:P of leaf‐litter mineralization is higher in tropical forests than in temperate forests, consistent with latitudinal patterns in foliar and leaf‐litter N:P. At the global scale, the N:P of net mineralization tracks, but tends to be lower than that of litter N:P, pointing to preferential P (versus N) mineralization in forest ecosystems. Main conclusions Our results do not support the view that there is a single, globally consistent mineralization N:P ratio. Instead, our results show that the N:P of net mineralization can be predicted by the N:P of litter, offering a method for incorporating P into global‐scale models of carbon–nutrient–climate interactions. In addition, these results imply that P is scarce relative to microbial decomposer demands in tropical forests, whereas N and P may be more co‐limiting when compared with microbial biomass in the temperate zone.

1Disturbances affect almost all terrestrial ecosystems, but it has been difficult to 2 identify general principles regarding these influences. To improve our understanding of 3 the long-term consequences of disturbance on terrestrial ecosystems, we present a 4 conceptual framework that analyzes disturbances by their biogeochemical impacts. We 5 posit that the ratio of soil and plant nutrient stocks in mature ecosystems represents a 6 characteristic site property. Focusing on nitrogen (N), we hypothesize that this 7 partitioning ratio (soil N: plant N) will undergo a predictable trajectory after disturbance. 8We investigate the nature of this partitioning ratio with three approaches: (1) nutrient 9 stock data from forested ecosystems in North America, (2) a process-based ecosystem 10 model, and (3) conceptual shifts in site nutrient availability with altered disturbance 11 frequency. Partitioning ratios could be applied to a variety of ecosystems and 12 successional states, allowing for improved temporal scaling of disturbance events. The 13 generally short-term empirical evidence for recovery trajectories of nutrient stocks and 14 partitioning ratios suggests two areas for future research. First, we need to recognize and 15 quantify how disturbance effects can be accreting or depleting, depending on whether 16 their net effect is to increase or decrease ecosystem nutrient stocks. Second, we need to 17 test how altered disturbance frequencies from the present state may be constructive or 18 destructive in their effects on biogeochemical cycling and nutrient availability. Long-19 term studies, with repeated sampling of soils and vegetation, will be essential in further 20 developing this framework of biogeochemical response to disturbance. 21 22 4

In the mountainous western border region of Nicaragua andHonduras, a lack of integrated forestry, water, and land-use policies has contributed to a series of interrelated conflicts both within and across country borders. These conflicts are manifested in increases in illegal deforestation, forest fires, and deteriorating surface water resources. Although problems appear most obviously in terms of natural resource shortages, the root of the problems is often the inadequate decision-making process. In this study, we use a problem-oriented approach to describe three natural resource conflicts, analyze the decision-making and social processes contributing to these conflicts, and offer recommendations by describing how a bi-national community-based water monitoring regime could improve data collection and the inclusivity of the decision-making process.