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In forests adapted to infrequent (> 100-year) stand-replacing fires, novel short-interval (< 30- year) fires burn young forests before they recover from previous burns. Postfire tree regeneration is reduced, plant communities shift, soils are hotter and drier, but effects on biogeochemical cycling are unresolved. We asked how postfire nitrogen (N) stocks, N availability and N fixation varied in lodgepole pine (Pinus contorta var. latifolia) forests burned at long and short intervals in Grand Teton National Park (Wyoming, USA). In 2021 and 2022, we sampled 0.25-ha plots that burned as long-interval (> 130-year) stand-replacing fire in 2000 (n = 3) or 2016 (n = 3) and nearby plots of shortinterval (16-year) fire that burned as stand-replacing fire in both years (n = 6 ‘reburns’). Five years postfire, aboveground N stocks were 31% lower in short- versus long-interval fire (77 vs. 109 kg N ha-1, respectively) and 76% lower than 21-year-old stands that did not reburn (323 kg N ha-1). However, soil total N averaged 1,072 kg N ha-1 and dominated ecosystem N stocks, which averaged 1,235 kg N ha-1 and did not vary among burn categories. Annual resinsorbed nitrate was highest in reburns and positively correlated with understory species richness and biomass. Lupinus argenteus was sparse, and asymbiotic N fixation rates were modest in all plots (< 0.1 kg N ha-1 y-1). Although ecosystem N stocks were unaffected, high-severity short-interval fire reduced and repartitioned aboveground N stocks and increased N availability. These shifts in N pools and fluxes suggest reburns can markedly alter N cycling in subalpine forests. 

Summary Leaf dark respiration (R_dark), an important yet rarely quantified component of carbon cycling in forest ecosystems, is often simulated from leaf traits such as the maximum carboxylation capacity (V_cmax), leaf mass per area (LMA), nitrogen (N) and phosphorus (P) concentrations, in terrestrial biosphere models. However, the validity of these relationships across forest types remains to be thoroughly assessed.Here, we analyzedR_darkvariability and its associations withV_cmaxand other leaf traits across three temperate, subtropical and tropical forests in China, evaluating the effectiveness of leaf spectroscopy as a superior monitoring alternative.We found that leaf magnesium and calcium concentrations were more significant in explaining cross‐siteR_darkthan commonly used traits like LMA, N and P concentrations, but univariate trait–R_darkrelationships were always weak (r² ≤ 0.15) and forest‐specific. Although multivariate relationships of leaf traits improved the model performance, leaf spectroscopy outperformed trait–R_darkrelationships, accurately predicted cross‐siteR_dark(r² = 0.65) and pinpointed the factors contributing toR_darkvariability.Our findings reveal a few novel traits with greater cross‐site scalability regardingR_dark, challenging the use of empirical trait–R_darkrelationships in process models and emphasize the potential of leaf spectroscopy as a promising alternative for estimatingR_dark, which could ultimately improve process modeling of terrestrial plant respiration. 

Let [Formula: see text] be an integer and [Formula: see text] be a finite field with [Formula: see text] elements. We prove several results on the distribution in short intervals of polynomials in [Formula: see text] that are not divisible by the [Formula: see text]th power of any non-constant polynomial. Our main result generalizes a recent theorem by Carmon and Entin on the distribution of squarefree polynomials to all [Formula: see text]. We also develop polynomial versions of the classical techniques used to study gaps between [Formula: see text]-free integers in [Formula: see text]. We apply these techniques to obtain analogs in [Formula: see text] of some classical theorems on the distribution of [Formula: see text]-free integers. The latter results complement the main theorem in the case when the degrees of the polynomials are of moderate size. 

ABSTRACT Reef-building corals depend on symbiosis with photosynthetic algae that reside within their cells. As important as this relationship is for maintaining healthy reefs, it is strikingly delicate. When ocean temperatures briefly exceed the average summer maximum, corals can bleach, losing their endosymbionts. Although the mechanisms governing bleaching are unknown, studies implicate uncoupling of coral and algal cell divisions at high temperatures. Still, little is known regarding the coordination of host and algal cell divisions. Control of nutrient exchange is one likely mechanism. Both nitrogen and phosphate are necessary for dividing cells, and although nitrogen enrichment is known to increase symbiont density in the host, the consequences of phosphate enrichment are poorly understood. Here, we examined the effects of phosphate depletion on symbiont growth in culture and compared the physiology of phosphate-starved symbionts in culture to symbionts that were freshly isolated from a host. We found that available phosphate is as low in freshly isolated symbionts as it is in phosphate-starved cultures. Furthermore, RNAseq revealed that phosphate-limited and freshly isolated symbionts have similar patterns of gene expression for phosphate-dependent genes, most notably upregulation of phosphatases, which is consistent with phosphate recycling. Similarly, lipid profiling revealed a substantial decrease in phospholipid abundance in both phosphate-starved cultures and freshly isolated symbionts. These findings are important because they suggest that limited access to phosphate controls algal cell divisions within a host. IMPORTANCEThe corals responsible for building tropical reefs are disappearing at an alarming rate as elevated sea temperatures cause them to bleach and lose the algal symbionts they rely on. Without these symbionts, corals are unable to harvest energy from sunlight and, therefore, struggle to thrive or even survive in the nutrient-poor waters of the tropics. To devise solutions to address the threat to coral reefs, it is necessary to understand the cellular events underpinning the bleaching process. One model for bleaching proposes that heat stress impairs algal photosynthesis and transfer of sugar to the host. Consequently, the host’s demands for nitrogen decrease, increasing nitrogen availability to the symbionts, which leads to an increase in algal proliferation that overwhelms the host. Our work suggests that phosphate may play a similar role to nitrogen in this feedback loop.