Monika Frehner

Modellierung des Einflusses von Wildverbiss auf die Schutzwaldentwicklung an der Rigi-Nordlehne

Modelling the impact of ungulate browsing on the development of the protective forests of the Rigi-Nordlehne Forests on the northern slopes of the Rigi Mountain in central Switzerland (“Rigi-Nordlehne”) have a key protective function against rockfall, erosion, landslides, flooding and debris flows. Forest management endeavours to guarantee that these forests can maintain their role in the long term. Thus multi-story canopies are favored, being resistant and resilient to natural disturbances such as windthrow. In addition, the mixture of tree species should conform to the guidelines of the national project “Sustainability and success monitoring in protection forests” (NaiS). However, at the present time an imbalance in tree species is evident in the regeneration layer, due to the considerable impact of browsing by wild ungulate populations in these beech and fir forests. To predict future mixtures of tree species, the spatially explicit model of forest development Rigfor was developed and applied to simula...

Simulation de la structure optimale des hêtraies de protection contre les chutes de pierres | Simulation of the optimal structure of beech forests protecting against rockfall

Adequate management practices to attain the profiles specified in the Swiss guidelines for the management of mountain protection forests are not always unequivocally clear. This applies among others for beech forests that have a protective function against rockfall. We defined two management scenarios, one of which aims at harvesting trees starting with a minimum diameter at breast height of 40 cm, whereas the other one is focused on the creation of small gaps (area of 500 m2) over a maximum of 10% of the total stand area. These scenarios along with a control scenario characterized by no management were studied using the forest growth model BWINPro. In the control scenario, number of trees, basal area and standing volume were highest. The developments simulated under the two management scenarios were similar, when in scenario thinning harvesting levels corresponded to the growth over a 10-year period. In the other cases, number of trees, basal area and standing volume are lower under scenario gap because ...