Forest Research Institute

About: Forest Research Institute is a facility organization based out in Dehra Dūn, India. It is known for research contribution in the topics: Population & Forest management. The organization has 5320 authors who have published 7625 publications receiving 185876 citations.

Seasonal acclimation of photosystem II in Pinus sylvestris. II. Using the rate constants of sustained thermal energy dissipation and photochemistry to study the effect of the light environment.

Abstract: Photosynthesis in evergreen conifers is characterized by down-regulation in autumn and rapid up-regulation in spring. This seasonal pattern is largely driven by temperature, but the light environment also plays a role. In overwintering Scots pine (Pinus sylvestris L.) trees, PSII is less down-regulated and recovers faster from winter stress in shaded needles than in needles exposed to full sunlight. Because the effect of light on the seasonal acclimation of PSII has not been quantitatively studied under field conditions, we used the rate constants for sustained thermal energy dissipation and photochemistry to investigate the dynamics and kinetics of the seasonal acclimation of PSII in needles exposed to different light environments. We monitored chlorophyll fluorescence and needle pigment concentration during the winter and spring in Scots pine seedlings growing in the field in different shading treatments, and within the crowns of mature trees. The results indicated that differences in acclimation of PSII in overwintering Scots pine among needles exposed to different light environments can be chiefly attributed to sustained thermal dissipation. We also present field evidence that zeaxanthin-facilitated thermal dissipation and aggregation of thylakoid membrane proteins are key mechanisms in the regulation of sustained thermal dissipation in Scots pine trees in the field.

Effect of species composition, stand density and site index on the basal area increment of oak trees (Quercus sp.) in mixed stands with beech (Fagus sylvatica L.) in northern France

Abstract: We investigated the relationship between tree size and radial growth of oak in mixed oak-beech stands where beech basal area ranged from 0.0 to 98.2%. We analysed 30 long-term permanent oak-beech plots in northern France with a total of 167 growth periods between 1904 and 2000. The study was based on a nonlinear segmented model of individual tree basal area increment as a function of diameter at breast height, which is implemented in the French forest growth simulator Fagacees. We investigated variations of slope γ from the linear branch of the segmented model for oak. We found stand density, species composition, and site index to have a significant influence. The basal area increment of oak decreased with rising admixture of beech and increased with site quality and lower stand density. The effect of beech admixture found in the present study corresponds with findings from tree physiology on below- and aboveground competition. Our results underline differences in competitiveness and long-term species dynamics in mixed oak-beech stands.

Classification of European beech forests: a Gordian knot?

Abstract: Questions: What are the main floristic patterns in European beech forests? Which classification at the alliance and suballiance level is the most convincing? - Location: Europe and Asia Minor. - Methods: We applied a TWINSPAN classification to a data set of 24605 releves covering the whole range of Fagus sylvatica forests and the western part of Fagus orientalis forests. We identified 24 operational phytosociological units' (OPUs), which were used for further analysis. The position of each OPU along the soil pH and temperature gradient was evaluated using Ellenberg Indicator Values. Fidelity of species to OPUs was calculated using the phi coefficient and constancy ratio. We compared alternative alliance concepts, corresponding to groups of OPUs, in terms of number and frequency of diagnostic species. We also established formal definitions for the various alliance concepts based on comparison of the total cover of the diagnostic species groups, and evaluated alternative geographical subdivisions of beech forests. - Results: The first and second division levels of TWINSPAN followed the temperature and soil pH gradients, while lower divisions were mainly geographical. We grouped the 22 OPUs of Fagus sylvatica forests into acidophytic, meso-basiphytic and thermo-basiphytic beech forests, and separated two OPUs of F.orientalis forests. However, a solution with only two ecologically defined alliances of F.sylvatica forests (acidophytic vs basiphytic) was clearly superior with regard to number and frequency of diagnostic species. In contrast, when comparing groupings with three to six geographical alliances of basiphytic beech forests, respectively, we did not find a strongly superior solution. - Conclusions: We propose to classify F.sylvatica forests into 15 suballiances - three acidophytic and 12 basiphytic ones. Separating these two groups at alliance or order level was clearly supported by our results. Concerning the grouping of the 12 basiphytic suballiances into ecological or geographical alliances, as advocated by many authors, we failed to find an optimal solution. Therefore, we propose a multi-dimensional classification of basiphytic beech forests, including both ecological and geographical groups as equally valid concepts which may be used alternatively depending on the purpose and context of the classification.