Characteristics of Central American brocket deer resting sites in a tropical mountain cloud forest in eastern Mexico

The Central American brocket deer is a vulnerable species. Geographically isolated populations have been affected by poaching and habitat fragmentation, leading to local extinctions. It is therefore important to understand this species’ habitat characteristics, particularly of resting sites, which play a crucial role in survival and fitness. We describe the characteristics and distribution patterns of Central American brocket deer resting sites at the microhabitat and landscape scales in San Bartolo Tutotepec, Hidalgo, México. We conducted eight bimonthly field surveys between November 2017 and March 2019, consisting of 32 transects of 500 m length to search for fecal pellets, footprints, scrapes, and browsed plants. At each resting site we identified, we measured canopy closure, horizontal thermal cover, protection from predators for fawns and adults, escape routes, slope from the ground, presence of scrapes, cumulative importance value of the edible plant species, and distance from the resting site to the nearest water resource to characterize the site at the microhabitat scale. At the landscape scale, we identified the type of biotope, elevation, aspect, and slope. We compared all of these parameters from resting sites with a paired randomly selected site to serve as a control. We performed a multiple logistic regression to identify the parameters associated with the resting sites and a point pattern analysis to describe their distribution. We characterized 43 resting sites and their corresponding control plots. At the microhabitat scale, resting sites were associated with higher vertical thermal cover, more concealment cover, more escape routes, more edible plant species, higher slope from the ground, and closer distance to water resources. At the landscape scale, resting sites were associated with beech forest, oak forest, secondary forest, and ravine biotopes and negatively associated with pine forest, houses, and roads. Resting sites had an aggregated spatial pattern from 0 to 900 m, but their distribution was completely random at larger scales. Our study revealed that Central American brocket deer selected places with specific characteristics to rest, at both microhabitat and landscape scales. We therefore suggest that existing habitat be increased by reforesting with native species—particularly Mexican beech forest and oak forest—to improve the deer’s conservation status in the study area.

Variations of the Oxidative Ratio across Ecosystem Components and Seasons in a Managed Temperate Beech Forest (Leinefelde, Germany)

The oxidative ratio (OR) of organic material integrates the ratio of CO2 sequestered in biomass vs. O2 produced over longer timescales, but the temporal and spatial variability within a single ecosystem has received very limited attention. Between October 2017 and October 2019, we repeatedly sampled leaves, twigs, bark, outer stem wood, understorey vegetation and litter in a temperate beech forest close to Leinefelde (Germany) for OR measurements across a seasonal and spatial gradient. Plant component OR ranged from 1.004 ± 0.010 for fine roots to 1.089 ± 0.002 for leaves. Inter- and intra-annual differences for leaf and twig OR exist, but we found no correlation with sampling height within the canopy. Leaf OR had the highest temporal variability (minimum 1.069 ± 0.007, maximum 1.098 ± 0.002). This was expected, since leaf biomass of deciduous trees only represents the signal of the current growing season, while twig, stem and litter layer OR integrate multiple years. The sampling years 2018 and 2019 were unusually hot and dry, with low water availability in the summer, which could especially affect the August leaf OR. Total above-ground OR is dominated by the extremely stable stem OR and shows little variation (1.070 ± 0.02) throughout the two sampling years, even when facing extreme events.

Survival time and mortality rate of regeneration in the deep shade of a primeval beech forest

Low mortality rates and slow growth differentiate shade-tolerant from shade-intolerant species and define the survival strategy of juvenile trees growing in deep shade. While radial stem growth has been widely used to explain mortality in juvenile trees, the leaf area ratio (LAR), known to be a key component of shade tolerance, has been neglected so far. We assessed the effects of LAR, radial stem growth and tree height on survival time and the age-specific mortality rate of juvenile Fagus sylvatica L. (European beech), Acer pseudoplatanus L. (sycamore maple) and Acer platanoides L. (Norway maple) in a primeval beech forest (Ukraine). Aboveground and belowground biomass and radial stem growth were analysed for 289 living and 179 dead seedlings and saplings. Compared with the other species, F. sylvatica featured higher LAR, slower growth and a lower mortality rate. The average survival time of F. sylvatica juveniles (72 years) allows it to reach the canopy more often than its competitors in forests with low canopy turnover rate. In contrast, a combination of lower LAR, higher growth rate and higher age-specific mortality rate of the two Acer species resulted in their shorter survival times and thus render their presence in the canopy a rare event. Overall, this study suggests that shade tolerance, commonly defined as a relationship between sapling mortality and growth, can alternatively be formulated as a relationship between survival time and the interplay of growth and LAR.

Climate and Management Factors Underlying Changes in Beech Forest Herbaceous Layer Plant Communities in the Polish Eastern Carpathians

The herbaceous vegetation and forest stand characteristics in European beech forests growing in the Polish part of the Eastern Carpathians have changed over the last 40 years. This has been influenced by many factors, including land-use change, forest management and climate change. This study investigates changes in forest cover and structure and the associated changes in herbaceous layer plant communities and seeks to elucidate whether and how beech forest herbaceous layer communities have been affected by climate change. The study used information from archival and current land cover maps, semi-permanent sampling plots, forest management plans for the Forest Districts of Brzozów, Lesko and Ustrzyki Dolne and meteorological weather station data compiled for three study periods of herbaceous vegetation (1970s, 2000s, 2010s). In the study area, the regular shelterwood system was changed to an irregular shelterwood system that produces stands with a complex overstorey structure. The results revealed the important role of light availability in shaping the species composition of the herbaceous layer in semi-natural Carpathian beech forests, which was strongly related to the course of management activities. An overall decrease in the number of species during the 2010s is linked to the ageing of beech forests, increased intensity of management activities in ageing stands, competition from understorey vegetation and lower soil moisture that can be linked to climate change. Our study partially supports the existing findings that more manipulative forest management systems can play an important role in countering the current and expected effects of climate change on the forest ecosystem because of the low degree of spatial differentiation of the stand’s structure (developmental stages). Therefore, foresters managing the structure of stands should strive to create a forest structure with high variability of developmental stages on a regional scale.