Incorporating reindeer grazing and damage by ozone in LPJ-GUESS for the BioDiv-Support project

This model code was developed for the BioDiv-Support project (https://www.smhi.se/en/research/research-departments/meteorology/biodiv-support-1.145930), which studied the impact of climate change and air pollutions on the vegetation in mountain regions in Europe. Reindeer browsing and grazing functionality was added in a new function, grazebrowse, in management.cpp. Plant killing from reindeer trampling was added in the mortality_guess function in vegdynam.cpp. Functionality of ozone stress was added in a new function, ozone_stress, that was called by the function canopy_exchange in canexch.cpp. With the new functions there are five new plant functional type (PFT) specific parameters:

browse_pref   preference value for browsing 0-10

tramp_frac     trampling value for mortality from browsers 0-10

PODy            O₃ deposition threshold for toxicity

PODy_k        slope in the effect of exceeding PODy

PODy_m       constant in the effect of exceeding PODy

There are also six general settings for the reindeer browsing and trampling:

herbivore_int                     Intensity of grazing browsing and trampling

visit_int                              Years between visits by grazers for a patch

first_graze_yr                    First calendar year with grazing, browsing and trampling

last_graze_yr                    Year to stop herbivory, for simulation of exclosure

h_max_reach                    Maximum height of a cohort for the herbivore to be able to reach its canopy

N_browseharvest_scale   Factor to reduce removal of N relative to C during grazing or browsing

All relevant information for LPJ-GUESS can be found on the model's website: https://web.nateko.lu.se/lpj-guess/. In this model, version 4.1 of LPJ-GUESS is used. Unless specifically aiming to reproduce results in the study referenced above, it is recommended to use the latest release of LPJ-GUESS, which includes the most recent developments and bug fixes. To obtain the latest release of LPJ-GUESS, understand how the version archived here relates to it and connect to the user community for the latest updates, please also refer to https://web.nateko.lu.se/lpj-guess/.