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In this study, we tested the efficiency of near infrared reflectance spectroscopy (NIRS) to assess nitrogen content in faeces of free‐living ruminants. Faecal nitrogen (FN) content was analysed in 168 pellet groups from red deer Cervus elaphus and roe deer Capreolus capreolus in the growing season and in winter using both the standard Kjeldahl method and NIRS analysis. Estimates of nitrogen content obtained by the two methods did not differ (P > 0.1), and the correlation between FN values was significant (P < 0.001). FN content ranged within 1.10–4.58% of dry matter and, as anticipated, it was higher in the growing season than in winter in both species (P < 0.01). Faecal nitrogen values were also higher for roe deer than for red deer, although the difference was only significant in the growing season (P = 0.007). Our study confirmed that faecal nitrogen of free‐living ruminants can be accurately determined with NIRS analysis. NIRS represents a low‐cost analytical technique, which could replace conventional labourious methods and is highly promising for analyses of diet quality in free‐living ruminants.

8Determining and characterizing soil organic matter (SOM) cheaply and reliably can help to support 9 decisions concerning sustainable land management and climate policy. Glomalin, a glycoprotein 10 produced by arbuscular mycorrhizal fungi, was recommended as a promising indicator of SOM quality. 11But extracting glomalin from and determining glomalin in soils using classical chemical methods is too 12 complicated and time consuming and therefore limits the use of this parameter in large scale surveys. 13Near infrared spectroscopy (NIRS) is a very rapid, non-destructive analytical technique that can be used 14 to determine many constituents of soil organic matter. 15Representative sets of 84 different soil samples from arable land and grasslands and 75 forest soils were 16 used to develop reliable NIRS calibration models for glomalin. One calibration model was developed for 17 samples with a low content of glomalin (arable land and grasslands), the second for soils with a high 18 content of glomalin (forest soils), and the third calibration model for all combined soil samples. 19Calibrations were validated and optimized by leave-one-sample-out-cross-validation (LOSOCV) and by 20 the external validation using eight soil samples (arable land and grassland), and six soil samples (forest 21 soils) not included in the calibration models. 22Two different calibration models were recommended. One model for arable and grassland soils and the 23 second for forest soils. No statistically significant differences were found between the reference and the SOIL Discuss., doi:10.5194/soil-2016-9, 2016 Manuscript under review for journal SOIL 24

In this paper we address total glomalin‐related soil protein (T‐GRSP) as a possible indicator of differences in forest soils related to reactive nitrogen and forest composition. We focused especially on the relationship between T‐GRSP (g kg−1), soil organic carbon (SOC), and reactive nitrogen (Nr) availability among different categories of temperate forests and different horizons. Our study included 105 sampling sites divided into 5 categories, which vary in elevation and tree species composition (coniferous, deciduous, mixed). We detected significantly higher T‐GRSP and SOC in the F+H horizon under conifers. We assume that this observation might be attributed to suppression of decomposition of T‐GRSP and SOC by nature of coniferous litter. The lack of significant differences in T‐GRSP/SOC among the categories and the positive correlations between T‐GRSP and SOC in most of the categories confirmed the strong relationship of T‐GRSP with SOC. We found a significantly higher content of T‐GRSP in the F+H horizon for all studied forest categories. However, the contribution of T‐GRSP to SOC is significantly higher in the A horizon, which might be caused by stabilization of glomalin by mineral fraction, including clay minerals or by the belowground origin of glomalin. We found the increase of SOC with increasing Nr in the A horizon for most categories of forest. T‐GRSP follows this trend in the case of deciduous forests (decid), mixed forest (mixed), and mountain forests (mount). On the other hand, we detected a decrease of T‐GRSP with increasing Nr in the F+H horizon of coniferous forests (conif). Moreover the T‐GRSP/SOC decreases with the increase of Nr in the A horizon of conif, mixed and mount, which points to the higher sensitivity of forest with prevalence of coniferous trees. Our observations have confirmed an ecosystem‐specific relationship between T‐GRSP, SOC and Nr. We concluded that T‐GRSP in combination with T‐GRSP/SOC has the potential to reveal qualitative changes in soil organic matter (SOM) connected with increasing Nr.

Food quality is an important factor influencing the demography of small rodents. While there have been numerous studies on food supply during small mammal population cycles, studies on quality of food consumed are rare due to technical difficulties in estimating nitrogen in small samples, such as stomachs or faeces. In this study, we use a new method, near infrared reflectance spectroscopy (NIRS), for estimating nitrogenous compounds (NC) in stomachs of common voles (Microtus arvalis). Samples were taken from two populations over two 3-year periods. Vegetation cover (managed alfalfa/set-aside field), and thus also food supply, differed significantly between the two periods. In analysing the effects of food supply and individual attributes (i.e. sex, body size, reproduction) on NC in stomachs, we were able to show that nitrogen varied uniformly and that sex, body size and season had no effect. No significant difference in NC intake was observed between the two study periods, despite individuals being smaller and the population less abundant during the second period. During the peak densities, however, reproducing females consumed food with a significantly higher level of nitrogen than all other individuals. Our results indicate that changes in food supply do not affect the overall quality of food consumed but that maintenance of nutritional quality may require higher energetic release, which may affect body condition. We confirm that NIRS represents a useful new tool opening new possibilities in small-mammal ecology studies.