Long-term effects of wild ungulates on the structure, composition and succession of temperate forests

Ramirez, Juan Ignacio; Jansen, Patrick A.; Ouden, J. den; Goudzwaard, L.; Poorter, Lourens

doi:10.1016/j.foreco.2018.09.049

Cited by 69 publications

(51 citation statements)

References 53 publications

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“…Large herbivores steer temperate forest composition in two major ways: Preferential browsing and grazing of more palatable species such as broadleaved tree species, and intense physical disturbance such as trampling or uprooting, which can eliminate entire cohorts of seedlings and samplings from forest stands [44]. Our study confirmed the protective function of the thorny shrubs.…”

Section: Discussionsupporting

confidence: 75%

Thorny Shrubs Limit the Browsing Pressure of Large Herbivores on Tree Regeneration in Temperate Lowland Forested Landscapes

et al. 2019

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Thorny shrubs are considered as an important driver in the natural development of temperate forest structures, particularly in European lowland forests. We assessed the current role of thorny shrubs in the regeneration of deciduous tree species under heavy browsing pressure in a central European temperate forested landscape. The study’s military training area offered a unique opportunity to investigate the processes in which deciduous tree seedlings grew under thorny shrubs and in the close vicinity of thorny shrubs in a landscape with a high density of large herbivores (red deer and sika deer). We assessed the number of seedlings, species composition, seedling height, and degree of browsing damage, and their relationship to study plots elevation, thorny shrub species, coverage, and height. The regenerated tree seedlings were mostly detected as common ash (Fraxinus excelsior) and wild cherry (Cerasus avium). The species of thorny shrubs were blackthorn (Prunus spinosa), hawthorn (Crataegus sp.), and wild rose (Rosa sp.). We found that the thorny shrubs protected the tree seedlings from browsers to a large extent. However, the effects of thorny shrubs on the tree seedlings' characteristics varied among the shrub species. While results revealed significant effects of hawthorn and wild rose on the tree seedlings' abundance and survival, blackthorn’s negative effect of shading the tree seedlings outweighed its protective role. These results indicated a possible mechanism that enabled the regeneration of deciduous tree species under large herbivore pressure. These results can be applied in the landscape planning and forest management of deciduous tree regeneration and forest restoration in temperate forested lowland landscapes, where high densities of large herbivores (without the presence of large predators) usually occur.

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Section: Discussionsupporting

confidence: 75%

Thorny Shrubs Limit the Browsing Pressure of Large Herbivores on Tree Regeneration in Temperate Lowland Forested Landscapes

et al. 2019

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“…Although our study was only conducted in Michigan, northern hardwood forests cover millions of hectares from Minnesota to the Canadian Maritimes. Furthermore, many temperate mesic forests worldwide are similarly characterized by high ungulate populations and reduced tree recruitment [60,61]. Even larger extents of forest may be affected by insects and pathogens, that are often introduced and that create widespread overstory mortality and a dense regeneration layer with little chance of overstory recruitment.…”

Section: Management Implicationsmentioning

confidence: 99%

Tree Regeneration Structure Following Beech Bark Disease-Motivated Harvests: Factors Associated with Patterns and Management Implications

Elenitsky

Walters

Farinosi

2020

Forests

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In the northern Appalachian region of North America, mortality of mature American beech (Fagus grandifolia Ehrh.) via the introduced beech bark disease (BBD) can result in dense thickets of beech saplings that inhibit the regeneration of other species. It is unknown if similar structures characterize more recently infested managed forests in the Great Lakes region. If these dense beech sapling layers do exist, management would be aided by knowing which site/regional factors they are associated with and by identifying particular sapling structures that may threaten the sustainability of these forests under current management paradigms. To examine these patterns, we used a natural experiment with sample plots in 69 unevenly aged, selection silviculture-managed, maple (Acer spp.)-dominated northern hardwood stands. Our stands were dispersed across northern Michigan, USA and had undergone BBD-motivated partial harvests favoring beech removal (mean = 5.5 years before measurement). In each stand, we quantified tree regeneration structure in relation to winter deer use (fecal pellet count density), site quality (habitat type), geographic region (Eastern Upper Peninsula and Northern Lower Peninsula), and multiple measures of overstory stand density. We also examined the density effects of taller regeneration strata on subordinate strata. Across sites, the small sapling recruit class (i.e., >137 cm tall and <5 cm diameter at 137 cm tall) was dominated by beech and was often dense (44% of subplots > 2000 stems ha−1 and 16% of subplots > 5000 ha−1) but never exceeded the > 10,000 stems ha−1 reported in the northern Appalachian region. Beech sapling density was higher in the Northern Lower Peninsula, on lower quality sites, at lower postharvest overstory densities, and on sites with higher densities of preharvest overstory beech. In contrast to the beech-dominated small sapling recruit class, seedlings (i.e., <25 cm tall) were generally more species diverse than sapling strata and were dominated by maple species. Although generally dense, seedling density was negatively related to small sapling recruit density, suggesting that saplings may suppress the seedling stratum. The general pattern for the small sapling recruit layer of browsing-insensitive beech (and ironwood, Ostrya virginiana Mill. K. Koch) dominance and low representation of browsing-sensitive species (e.g., Acer spp.) circumstantially supports the notion that regeneration structure is heavily influenced by deer. However, current deer use was generally low in our stands, and relationships with tree regeneration structure were weak. Instead, regeneration structure is likely shaped by a combination of factors operating at long time scales (i.e., legacies of deer browsing pressure, selection silviculture (given beech and ironwood are shade tolerant), overstory composition, and site quality) and by those effects that are more proximal, such as postharvest overstory density. Minimum stocking criteria for species considered desirable for management (e.g., sugar maple and Acer saccharum Marshall) suggest many stands are inadequately stocked in the sapling recruit classes. Although future regeneration dynamics are unclear, current patterns suggest that many stands with high beech/ironwood small sapling recruit densities may require management intervention to overcome insufficient recruitment of species targeted for management.

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“…Exlosures of these Guam ungulates have revealed restoration can be rapid [38,39], and soil chemical traits are among the important ecological processes that are restored following ungulate exclosure [40,41]. Physical disturbance of the litter and soil is one means by which non-native ungulates damage ecosystem processes such as nutrient cycling [42][43][44][45][46]. Moreover, the Integrated Natural Resources Management Plan (INRMP) that was guiding all DoN activities at this time was published in 2012 [47], and stated that an ecosystem approach would guide management to "restore and maintain ecological processes" that included "nutrient cycles."…”

Section: Case 5 Multiple Approved Practitioners Accessing the Same Cmentioning

confidence: 99%

Tree conservation can be constrained by agents from conservation permitting and funding agencies

Marler

2019

Communicative & Integrative Biology

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Recent conservation actions for Serianthes nelsonii Merr. and Cycas micronesica K.D. Hill in the Mariana Islands have illuminated some negative consequences associated with ill-informed agents representing permitting and funding agencies. Several cases from the islands of Guam and Tinian are discussed as ineffective conservation examples, and these are countered with two examples of successful conservation approaches. When biologists that act as points of contact for federal permitting and funding agencies do not possess education, knowledge, and experience that is germane to federally listed species, sound science may be marginalized from the conservation agenda. When rapid turnover of federal conservation agents introduces dysfunction, discontinuities in collaborations may thwart success. When lapses in conservation contracts are allowed, short-term extemporary contracting approaches are utilized, and conservation practitioners that lack the ability to include an experimental approach to conservation actions are employed, the co-production of new knowledge to enable decision support tools for future decision-makers may be hindered.

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Long-term effects of wild ungulates on the structure, composition and succession of temperate forests

Cited by 69 publications

References 53 publications

Thorny Shrubs Limit the Browsing Pressure of Large Herbivores on Tree Regeneration in Temperate Lowland Forested Landscapes

Thorny Shrubs Limit the Browsing Pressure of Large Herbivores on Tree Regeneration in Temperate Lowland Forested Landscapes

Tree Regeneration Structure Following Beech Bark Disease-Motivated Harvests: Factors Associated with Patterns and Management Implications

Tree conservation can be constrained by agents from conservation permitting and funding agencies

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