Abstract
Abstract Ungulate grazing and trampling strongly affect pastures and ecosystems throughout the world. Ecological population models are used for studying these systems and determining the guidelines for sustainable and economically viable management. However, the effect of trampling and other resource wastage is either not taken into account or quantified with data in earlier models. Also, the ability of models to describe the herbivore impact on pastures is usually not validated. We used a detailed model and data to study the level of winter‐ and summertime lichen wastage by reindeer and the effects of wastage on population sizes and management. We also validated the model with respect to its ability of predicting changes in lichen biomass and compared the actual management in herding districts with model results. The modeling efficiency value (0.75) and visual comparison between the model predictions and data showed that the model was able to describe the changes in lichen pastures caused by reindeer grazing and trampling. At the current lichen biomass levels in the northernmost Finland, the lichen wastage varied from 0 to 1 times the lichen intake during winter and from 6 to 10 times the intake during summer. With a higher value for wastage, reindeer numbers and net revenues were lower in the economically optimal solutions. Higher wastage also favored the use of supplementary feeding in the optimal steady state. Actual reindeer numbers in the districts were higher than in the optimal steady‐state solutions for the model in 18 herding districts out of 20. Synthesis and applications . We show that a complex model can be used for analyzing ungulate‐pasture dynamics and sustainable management if the model is parameterized and validated for the system. Wastage levels caused by trampling and other causes should be quantified with data as they strongly affect the results and management recommendations. Summertime lichen wastage caused by reindeer is higher than expected, which suggests that seasonal pasture rotation should be used to prevent the heavy trampling of winter lichen pastures during summer. In the present situation, reindeer numbers in northernmost Finland are in most cases higher than in the management solutions given by the model.
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Claims 8
Claim · model-written summary
The model described changes in lichen pastures caused by reindeer grazing and trampling with modeling efficiency 0.75.
- Taxon
- lichene0
- Interactor
- reindeer
Rangifer taranduse0herbivore - Outcome
- changes in lichen pasturese0
- Value
- 0.75e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The modeling efficiency value (0.75) and visual comparison between the model predictions and data showed that the model was able to describe the changes in lichen pastures caused by reindeer grazing and trampling.”
Claim · model-written summary
At current biomass in northernmost Finland, winter lichen wastage ranged from zero to once lichen intake.
Verbatim
e0“At the current lichen biomass levels in the northernmost Finland, the lichen wastage varied from 0 to 1 times the lichen intake during winter and from 6 to 10 times the intake during summer.”
Claim · model-written summary
At current biomass in northernmost Finland, summer lichen wastage ranged from six to ten times lichen intake.
Verbatim
e0“At the current lichen biomass levels in the northernmost Finland, the lichen wastage varied from 0 to 1 times the lichen intake during winter and from 6 to 10 times the intake during summer.”
Claim · model-written summary
Higher wastage yielded lower optimal reindeer numbers and net revenues.
- Taxon
- reindeerRangifer taranduse0
- Outcome
- reindeer numbers and net revenuese0
- Direction
- lowere0
- Qualifier
- higher value for wastagee0
- Setting
- economically optimal solutionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With a higher value for wastage, reindeer numbers and net revenues were lower in the economically optimal solutions.”
Claim · model-written summary
Higher wastage favored supplementary feeding in the optimal steady state.
- Taxon
- reindeerRangifer taranduse1
- Outcome
- use of supplementary feedinge0
- Direction
- favorede0
- Qualifier
- Higher wastagee0
- Setting
- optimal steady statee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Higher wastage also favored the use of supplementary feeding in the optimal steady state.”
e1“reindeer numbers and net revenues were lower in the economically optimal solutions”
Claim · model-written summary
Actual reindeer numbers exceeded model optimal steady-state numbers in 18 of 20 districts.
- Taxon
- reindeerRangifer taranduse0
- Outcome
- reindeer numberse0
- Direction
- highere0
- Value
- 18 herding districts out of 20e0
- Comparator
- optimal steady‐state solutionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Actual reindeer numbers in the districts were higher than in the optimal steady‐state solutions for the model in 18 herding districts out of 20.”
Claim · model-written summary
Wastage from trampling and other causes should be quantified with data for management recommendations.
Verbatim
e0“Wastage levels caused by trampling and other causes should be quantified with data as they strongly affect the results and management recommendations.”
e1“changes in lichen biomass”
Claim · model-written summary
Seasonal pasture rotation should prevent heavy trampling of winter lichen pastures in summer.
- Taxon
- lichene0
- Interactor
- reindeerRangifer taranduse0herbivore
- Outcome
- seasonal pasture rotatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Summertime lichen wastage caused by reindeer is higher than expected, which suggests that seasonal pasture rotation should be used to prevent the heavy trampling of winter lichen pastures during summer.”