Intensive Browsing Research Articles

Analysis of a multivariate model for detecting browsing pressure by goats in the arid zone of Northern Chile. Application to Bridgesia incisifolia (Bert. ex Cambess) shrublands

A statistical methodology for the analysis of the effect of caprine browsing pressure in Bridgesia incisifolia (Bert. ex Cambess) shrublands is elaborated. This procedure is based on the assumption that shrubs modify parameters such as twig length (TL), twig weight (TW), number of leaves on the twig (NL) and leaf weight (LW) due to the stress caused by browsing. A classification function (F) of a discriminant analysis (DA) using six indexes based on these variables was tested. The three treatments of browsing used in the DA were: non-browsed areas during a period of 13 years (F=0), moderate browsing with exclusion of 4 and 5 years (F=1) and intensive browsing without exclusion periods (F=2). All the indexes show significant differences between treatments. The first function of DA shows a percentage of explained variability of 83·99%. This function permits us to quantify the grade of browsing of B. incisifolia, the most palatable and therefore the most vulnerable of browsing shrub in the semi-arid region of Northern Chile.

Establishment and Control of Hay-scented Fern: A Native Invasive Species

Hay-scented fern (Dennstaedtia punctilobula (Michx.) Moore) is a native forest understory species that behaves as an invasive plant under certain conditions. Previous work has shown that both increased understory light intensity following overstory thinning and removal of competing plants by herbivores can lead to accelerated growth of hay-scented fern, allowing it to develop dense, nearly monospecific understories that inhibit tree seedling regeneration. To study the relationship between these two factors, we sampled 28 forest stands thinned at different times and subjected to different levels of browsing by white-tailed deer (Odocoileus virginianus), and concluded that more than 15 years of intensive browsing following thinning was necessary for ferns to form closed understory canopies with densities of >90 fronds/m2 and canopy heights of 60–80 cm; thinning alone or intensive browsing alone was not sufficient to cause this level of fern invasion. We applied three treatments to dense fern understories to determine the relative importance of the fern canopy and the dense mat of roots, rhizomes, and dead fronds in the inhibition of tree seedling establishment. Results after two years were: (1) complete removal of the organic mat produced a large germination response of woody and herbaceous species; (2) mixing the organic mat into the mineral soil produced an initial germination response but poor seedling survivorship, as the fern canopy regrew to near pretreatment density; (3) repeatedly clipping the ferns for two years without disturbing the organic mat resulted in a lower germination response than the removal treatment, but rapid growth of seedlings.

Dietary overlap of three ungulate species in the Palava Biosphere Reserve

The Palava Biosphere Reserve (South Moravia, Czech Republic) contains a vaiety of habitat types and maintains a high diversity of plant and animal species. Within this unique region is situated a game reserve for ungulate species. This paper presents the results of dietary similarity and dietary overlap of three ungulate species: the wild goat ( Capra aegagrus) the mouflon ( Ovis musimon) and roe deer ( Capreolus capreolus) within the reserve, including competition and coexistence of these species. The qualitative and quantitative similarity of diet of all three animal species varies between 20 and 96%. The greatest similarity was found for the goat and mouflon diet and lowest for the roe deer and mouflon. There was marked competition for food during the winter months, as all three species consume large amounts of broad-leaved sprouts. This intensive browsing has had a considerable negative impact on the vegetation.

Population ecology of Cirsium pitcheri on Lake Huron sand dunes I. Impact of white-tailed deer

Cirsium pitcheri is a monocarpic perennial endemic to the shorelines of the Great Lakes, primarily Lakes Huron and Michigan. Its populations are being reduced by anthropogenic impact and deer grazing throughout much of its range. Several of its once abundant populations at some locations have been extirpated. The species is listed as threatened and endangered in Canada and the United States, respectively. Greenhouse studies were conducted to determine the effects of simulated herbivory by white-tailed deer on the survival, growth, and compensatory ability of plants. We found mat Cirsium pitcheri possessed good ability to compensate for tissue loss. However, simulated intensive browsing resulted in significant reductions in root dry weight. Since the flowering ability of monocarpic perennials such as Cirsium pitcheri is dictated by the amount of stored root reserves, such reductions in root biomass may delay the onset of flowering, reduce overwinter survival, and affect the future growth and survival of this threatened species. Keywords: white-tailed deer, browsing, defoliation, compensation, Cirsium pitcheri, Pitcher's thistle.

Recovery of browse-sensitive tree species following release from white-tailed deer Odocoileus virginianus zimmerman browsing pressure

Deer browsing encourages the development of a vegetation dominated by non-browse or browse-tolerant species at the expense of those sensitive to browsing. For restoration or management of forests, it is crucial to understand how browse-sensitive species recover following release from browsing. As these species re-establish, or achieve former levels of dominance, they must compete with a newly established vegetation. We examined recovery of eastern hemlock Tsuga canadensis (L.) Carr, a shade-tolerant, browse-sensitive tree species, following release from intensive browsing. To examine patterns of recovery over time we used data collected from three forest sites in northern Wisconsin, USA. In an intensely browsed forest, eastern hemlock was the leading dominant in the tree stratum. However, it was absent from the seedling and sapling strata where sugar maple Acer saccharum Marsh. was the dominant species. Twelve years of protection from white-tailed deer Odocoileus virginianus browsing resulted in establishment of hemlock seedlings not present in adjacent browsed areas. In a 27-year-old exclosure, under a canopy of shade-tolerant species, there was apparent recovery of hemlock to a diameter distribution typical of an all-aged forest. In forests subjected to continuous and intensive browsing pressure from the early part of this century, periods as long as 70 years may be required for shade-tolerant trees to achieve size class distribution characteristic of all-aged forests.

Effects of Goat Browsing on Gambel Oak Communities in Northern Utah

Replicated populations of 5 shrub species were monitored over a 3-year period to assess community responses to intensive browsing by Spanish-type goats. Response variables included stem density, stem-size distribution skewness, stem diameter-stem production relations, and sprout abundance and weight. No species exhibited a density change. Size distribution skewness increased only in browsed oak (Quercus gambelii Nutt.) populations. Sprout weights also increased in browsed oak populations, but declined in comparably browsed serviceberry (Amelanchier alnifolia Nutt.) populations. The only other significant sprouting response was an increase in sprout numbers in browsed snowberry (Symphoricarpos oreophilus Gray) populations. Relationships between basal stem diameter and stem production of 4 species were altered by goat use. The slopes of these relations were consistently lower in browsed populations of oak and serviceberry than in adjacent control populations, indicating that browsing reduced productivity, especially of large stems. Conversely, slopes of rabbit-brush (Chrysothamnus viscidiflorus lanceolatus (Hook.) Nutt.) relations increased in goat-browsed pastures relative to those of control populations; rabbitbrush was avoided by goats. Similarly, big sagebrush (Artemisia tridentata wyomingensis Nutt.) was avoided and its stem production responded positively in communities subjected to goat browsing. Important cumulative effects of goat browsing included declines in productivity of serviceberry and oak, and an increase in that of sagebrush.

Gorse — A resource for goats?

Abstract A 4-year trial in Canterbury showed that gorse (Ulex europaeus L.) can be a year-round maintenance feed for goats. Goats consistently ate more gorse than did sheep, and preferred flowers, green foliage, and bark. When green foliage was sparse, they ate brown stems. Non-lactating feral goats performed just as well on gorse as on pasture. Liveweights peaked in summer and were at a minimum in late winter. Over two spring-summer seasons, gorse produced, on average, 19.5 t dry matter (DM)/ha per year under intensive browsing, 13.5 t DM/ha of which was green material. Production was much greater on gorse which had not been intensively browsed. Gorse did not grow in winter, although standing green gorse was eaten. Gorse digestibility (in vitro) varied from 65% digestible dry matter (DDM) in spring to < 20% DDM in winter. In vivo measurements were higher. Levels of N, Ca, and Mo in gorse foliage were adequate for sheep and goat nutrition, but S, K, Cu, and Mg were low, and P was very low. Ash concentrations averaged 3% of dry matter. More research into goat management is needed to make maximum use of the high growth rates of gorse in spring and summer.

Heathland management in the New Forest, Hampshire, England

Heathland in the New Forest, Hampshire, England, is subject to systematic controlled burning, the main intention of which is to maintain and enhance the quality of the grazing for commoners' animals. Mature heathland vegetation is richer in bird, reptile and invertebrate life than younger age classes. However, a survey has confirmed that despite a recent reduction in the area burnt annually, burning had produced an imbalance in favour of young age classes of heather Calluna vulgaris and Erica spp., and that intensive browsing after fire was severely inhibiting the regeneration of gorse Ulex europaeus. The data obtained made it possible to recommend management policies which attempted to correct the imbalance in vegetation age structure and also satisfied the requirements of the grazier.

Plant Characteristics Related to Feeding Preference by Black-Tailed Deer

Six plant species of known preference by black-tailed deer (Odocoileus hemionus columbianus) were used to evaluate several factors thought to influence preference. Factors studied included chemical composition, in vitro fermentation of dry matter and cellulose, and effects of essential oils and water and methanol extracts on rumen microbial activity in vitro. Chemical analyses revealed considerable differences among species in all constituents; but, with the exception of moisture which was generally higher in the more preferred species, tissue components did not show any consistent relationship to preference. Fermentations of cellulose but not of dry matter were more closely related to preference than chemical composition and provided a good general indication of species preference. Similarly, the overall effects of oils and extracts on rumen activity suggested different preference ratings for the species, but results of the water extracts most closely approximated the established preference order. J. WILDL. MANAGE. 38(1):32-41 Like other herbivores, black-tailed deer show definite selectivity in their feeding. Thus, the animals have often been observed to prefer different parts of plants (Brown 1961:68-69, Oh et al. 1970:24) and to discriminate among and within species (Cowan 1945:131-137, Brown 1961:63-76, Crouch 1966, Miller 1968:144-148, Oh et al. 1970: 24). In addition, preference has been shown to vary by location and even on the same area during different seasons (Miller 1968:144-148, Brown 1961:69, Crouch 1966: 472-474, Crouch 1968:548, Oh et al. 1970: 24). Studies designed to identify factors influencing relative preference of animals for plants can provide information for formulating better management programs for both animal and plant resources. Many workers, therefore, have attempted to identify such factors by studying chemical composition and digestibilities of deer foods (Hellmers 1940, Einarsen 1946, Gastler et al. 1951, Bissell et al. 1955, Bissell and Strong 1955, Taber and Dasmann 1958:84-107, Brown 1961:83-89, Dietz et al. 1962, Short et al. 1966). Other investigators have studied effects on deer microbial activity of essential oils and individual terpenes isolated from pla ts (Nagy et al. 1964, Oh et al. 1967). Most investigations, however, were primarily concerned with the nutritive value f deer foods and included only proximate analyses which did not allow for determination of many individual chemical compounds. Much detailed work, therefore, is still needed to better understand factors influencing forage preferences of deer. In the Pacific Northwest, Douglas fir (Pseudotsuga menziesii) is utilized by deer, and in many areas intensive browsing seriously retards reforestation. Efforts to control browsing require an understanding of the role of Douglas fir in deer diets and its relative preference among associated species. In this study, therefore, we evaluated several factors suspected to affect preference using Douglas fir and five associated species of known preference to black-tailed deer during the dormant season. We determined concentrations of nutritional and nonnutritional chemical compounds and studied fermentabilities of the tissues and effects of their essential oils and extracts on rumen microbial activity in vitro. We gratefully acknowledge the coopera32 J. Wildl. Manage. 38 (1):1974 This content downloaded from 157.55.39.139 on Sat, 26 Nov 2016 04:17:01 UTC All use subject to http://about.jstor.org/terms PLANT CHARACTERISTICS AND DEER FEEDING PREFERENCE ? Radwan and Crouch 33 tion of personnel of the Oregon Game Commission, Corvallis, Oregon, for use of the Cedar Creek deer enclosure at the Tillamook Burn to obtain the necessary plant material and deer. MATERIALS AND METHODS Plants and deer were obtained during February 1969 in or near a 340-acre deer enclosure at the Tillamook Burn in northwest Oregon. The area has been previously described by Crouch (1968:543).

Forage Availability in Relation to Browsing of Douglas-Fir Seedlings by Black-Tailed Deer

Relationships between forage availability and browsing of planted Douglas fir (Pseudotsuga menziesii) by black-tailed deer (Odocoileus hemionus columbianus) were studied between June, 1961, and February, 1964, in a 340-acre enclosure occupied by known numbers of deer. The study area, in the Tillamook Burn of northwest Oregon, was burned by three wildfires between 1933 and 1945 which destroyed virtually all conifers. Since 1945, much of the enclosure has been highly disturbed by salvage logging and subsequent erosion, and vegetation consists mainly of seral species of six plant communities. Overstory plant cover averaged 12 percent and understory cover 77 percent in the summer of 1963. Green weights of summer forage averaged about 2,600 lb/acre and forage available for the following winter about 640 lb/acre at the end of the growing season. By midwinter, weathering losses and deer utilization had greatly reduced this amount. Winter growth of herbaceous forage produced about 90 lb/ acre of green feed in March, and by May, forage was again abundant. Leaves of trailing blackberry (Rubus ursinus) were highly preferred forage during winter. Salal (Gaultheria shallon) ranked high but was limited in distribution and abundance. Red huckleberry (Vaccinium parvifolium) and cascara (Rhamnus purshiana) were preferred among common woody plants, but red alder (Alnus rubra), hazel (Corylus cornuta), and vine maple (Acer circinatum) were browsed only when green herbage was unavailable. Green herbage was highly important in winter and early spring. Leaves of forbs and woody plants supplied most summer forage and were utilized in all seasons when available. Planted Douglasfir seedlings ranked higher in preference than most common woody species. Browsing on Douglas fir began with the first snowfall and continued through the winter. It is evident that browsing of Douglas fir will continue until seedlings grow out of reach of deer, because this species is an important food source during winter when preferred green forage is least available. It has long been recognized that deer feed on Douglas fir but until the advent of intensive forest management, this browsing was of little consequence. Foresters have now learned that intensive browsing may result in poor survival and decreased height growth of tree seedlings. Economic losses attributed to browsing have focused attention on an age-old relationship since it is likely that deer have always fed upon seedlings when they had the opportunity. Continuing expansion of tree seeding and planting, and increasing awareness of reforestation failures have focused attention on deer damage in the Pacific Northwest (Lightfoot and Hines 1960, Homing 1962, Heacox and Lawrence 1962). 1 A contribution of the Division of Wildlife Research, Oregon State Game Commission, PittmanRobertson Project W-51-R, and Range Management, Oregon State University. 2 Present address: U. S. Forest Service, Forestry Sciences Laboratory, Olympia, Washington. 542 Nearly all reports of damage indicate browsing takes place either during winter when forage supplies are low, or in spring and early summer when new growth on trees appears to be the most attractive forage available. In 1958, the Oregon State Game Commission, in cooperation with the Oregon State Board of Forestry, initiated the Cedar Creek Black-tailed Deer Study to investigate effects of browsing on Douglas fir planted to reforest the 340,000-acre Tillamook Burn in northwest Oregon (Oregon State Board of Forestry 1962). Progress in reforestation was slowed by a number of factors, including winter deer damage to Douglas-fir plantations (Kallander 1953, Lightfoot and Hines 1960). The present study, carried out as a thesis project in Range Management at Oregon State University, had three objectives: (1) to determine forage availability, This content downloaded from 157.55.39.186 on Sun, 09 Oct 2016 04:13:05 UTC All use subject to http://about.jstor.org/terms AVAILABLE FORAGE AND BROWSING OF DOUGLAS FIR * Crouch (2) to study forage utilization by a controlled number of deer, and (3) to identify factors influencing browsing on tree seedlings. The study was conducted over a 3year period from June, 1961, through June, 1964. I acknowledge the advice and assistance of Drs. D. W. Hedrick and C. E. Poulton of the Range Management Staff, and Dr. H. J. Rayner, W. C. Lightfoot, and W. W. Hines of the Oregon State Game Commission, Research Division. Special thanks are extended to Dr. Hedrick for guidance during the study and assistance in preparing this paper. Appreciation is also extended to Dr. W. H. Lawrence, Weyerhaeuser Co., Centralia, Washington, for help with manuscript revision.

Early stages of plant succession following the complete felling and burning of Eucalyptus regnans forest in the Florentine Valley, Tasmania

Permanent milacre quadrats were stsdied on a mnge of sites burnt in vario.;s years. All the recent burns occurred in March. Low herbs, predominantly bryophytes, colonized about 90% of the ground 12 months after burning, and 99 % 6 months later. Marchantia polymorpha was one of the earliest colonizers. On the wetter sites it covered up to 75 % of the ground 14 years after burning, and then declined rapidly. Marchantia growing in exposed places tended to be killed during summer. The fire mosses, Funaria hygrometrica and Ceratodon purpureus, colonized most of the ground not covered by Marchantia and reached peaks of 30-84% cover about 2 years after the fire. After 5 years the fire mosses had almost disappeared. Polytrichum juniperinum succeeded Marchantia and the fire mosses, reaching its peak (38-90 %) about 4 years after burning. Practically all of the low herbs tend to disappear when the taller vegetation becomes dense. The taller vegetation tends to be successively dominated in time by herbaceous fire-weeds, ferns, and woody perennials. Senecio minimus, the most abundant fire-weed, reached up to 79 %cover 2 years after burning, but died suddenly after reaching its peak. The development of ferns depended largely on the abundance of rhizomes surviving the fire (abundance before the fire, nature of fire). Histiopteris incisa and Hypolepis rugulosa were typical of sites which had carried rain-forest understoreys. Pteridium esculentum was initially limited to sites which had carried wet sclerophyll understoreys, but tended to replace the other ferns within 10 years on all but the most sheltered, moist sites. Although patchy at first, the ferns covered 50% of some areas within 4 years. Their expansion and persistence seems to be limited mainly by competition from taller plants. Most of the woody plants germinated within a few months after the fire from seed which was either stored in the ground or shed from nearby trees (depending on the species). Availability of seed and intensity of browsing by native game appear to be the two main factors which determined the abundance of established woody plants. Under favourable conditions the woody plants became dominant so early that the fern stage was by-passed. Intensive browsing was able to delay the dominance of woody plants, often for many years.

Medical Entomology, with Special Reference to the Health and Well-being of Man and Animals

This edition follows essentially the plan of the previous one. The work is divided into chapters corresponding for the most part to the groups of arthropods of medical importance, each chapter with a useful bibliography. Keys, descriptions or figures provide means of identifying most of the important groups at least to genera and in some cases to species. Several sections and keys were prepared by specialists. The text had been brought fairly well up to date at the time the author had completed this revision (the preface is dated April 1949) and includes control measures based on the use of DDT and others of the newer insecticides. A few frank errors, inevitable in a work of this sort, have been spotted during intensive browsing. There are rather few misprints in the scientific names.A great deal of information has been assembled and on the whole this is a good textbook if its rather definite limitations are borne in mind.