Showing papers on "Shrub published in 1982"

A phytosociological analysis of woody species in forest communities of a part of Kumaun Himalaya

Abstract: This paper reports on a detailed phytosociological analysis of forests in the NW catchment of the Gola River in Kumaun Himalaya, 29°19′–29°27′N and 79°32′–79°42′E. Fourteen sites and 56 stands at elevations ranging from 1200 to 2523 m and covering the following five forest types were investigated: Pinus roxburghii, mixed, Quercus leucotrichophora, Q. lanuginosa, and Q. floribunda. The basal cover of the forests differed according to slope position and aspect. The three oak forests had more basal cover than the other two, and Q. lanuginosa had the most. The performance of individual tree and shrub species and the number of saplings and seedlings differed according to slope position and aspect. The mixed forest had the greatest tree diversity, and among the others diversity increased with increasing basal cover. The diversity of trees, saplings, and herb layer was greatest on aspects with intermediate temperature and moisture conditions; whereas that of shrubs and seedlings increased towards the cooler (and wetter) and warmer (and drier) exposures. There was a positive relation between the diversity of shrubs plus seedlings and trees plus saplings in P. roxburghii and mixed forests; whereas this relationship was inverse in the three oak forests. In general, the dominance-diversity curves for the tree layer followed a geometric series conforming to the niche pre-emption situation in communities of low diversity. Among the forests, the regeneration was best in Q. lanuginosa and worst in Q. leucotrichophora.

Ecological Effects of Fire in Brazilian Cerrado

Abstract: Cerrado “sensu lato” is a complex of oreadic1 plant formations, formed by campo limpo (a grassland formation), campo sujo, campo cerrado, cerrado “sensu stricto” (intermediate savanna formations) and cerradao (a scleromorphic forest formation). The savanna formations may be considered ecotones between campo limpo and cerradao. Their herbaceous/undershrub and tree/shrub species are respectively common to both of these two extreme types of formation (Figure 1).

A phytosociological analysis of woody species in forest communities of a part of

Abstract: This paper reports on a detailed phytosociological analysis of forests in the NW catchment of the Gola River in Kumaun Himalaya, 29 ° 19'-29 ° 27' N and 79 ° 32'-79 ° 42' E. Fourteen sites and 56 stands at elevations ranging from 1 200 to 2 523 m and covering the following five forest types were investigated: Pinus roxburghii, mixed, Quercus leucotrichophora, Q. lanuginosa, and Q. floribunda. The basal cover of the forests differed according to slope position and aspect. The three oak forests had more basal cover than the other two, and Q. lanuginosa had the most. The performance of individual tree and shrub species and the number of saplings and seedlings differed according to slope position and aspect. The mixed forest had the greatest tree diversity, and among the others diversity increased with increasing basal cover. The diversity of trees, saplings, and herb layer was greatest on aspects with intermediate temperature and moisture conditions; whereas that of shrubs and seedlings increased towards the cooler (and wetter) and warmer (and drier) exposures. There was a positive relation between the diversity of shrubs plus seedlings and trees plus saplings in P. roxburghii and mixed forests; whereas this relationship was inverse in the three oak forests. In general, the dominance-diversity curves for the tree layer followed a geometric series conforming to the niche pre-emption situation in communities of low diversity. Among the forests, the regeneration was best in Q. lanuginosa and worst in Q. leucotrichophora.

Ecology of southeastern shrub bogs (pocosins) and Carolina bays: a community profile

Abstract: Shrub bogs of the Southeast occur in areas of poorly developed internal drainage that typically but not always have highly developed organic or peat soils. Pocosins and Carolina bays are types or subclasses of shrub bogs on the coastal plains of the Carolinas and Georgia. They share roughly the same distribution patterns, soil types, floral and faunal species composition and other community attributes, but differ in geological formation. Carolina bays may contain pocosin as well as other communities, but are defined more by their unique elliptical shape and geomorphometry. The pocosin community is largely defined by its vegetation, a combination of a dense shrub understory and a sparser canopy. The community is part of a complex successional sequence of communities (sedge bogs, savannas, cedar bogs, and bay forests) that may be controlled by such factors as fire, hydroperiod, soil type, and peat depth. Pocosins and Carolina bays harbor a number of animal groups and may be locally important in their ecology. Although few species are endemic to these habitats, they may provide important refuges for a number of species. These communities are simultaneously among the least understood and most rapidly disappearing habitats of the Southeast. Forestry and agricultural clearage aremore » current impacts.« less

Cattle grazing influence on a mountain riparian zone.

Abstract: A combination of management and physical topographic constraints caused cattle to concentrate on the riparian zone early in the grazing season in 1977 and 1978. A large percentage of cattle days and vegetation utilization on the riparfan zone occurred in the first 4 weeks of the grazing period. Utilization on herbaceous vegetation was 76 and 72% in 1977 and 1978, respectively. Impact of grazing on the most prevalent species, Kentucky bluegrass was minimal. Shrub use increased with increased maturity of herbaceous vegetation. Utilization of major shrubs was not excessive in either year, and very likely had no long-term effects on either the abundance or vigor of the shrubs. Riparian zones are those areas associated with streams, lakes, and wet areas where plant communities are predominately influenced by their association with water. They are key areas for a wide variety of uses. Fisheries and wildlife biologists have suggested mountain riparian zones are critical habitats in maintaining viable populations of fish, birds, small and big game animals (Ames 1977, Hubbard 1977). These areas are extremely important in providing forage and water for domestic animals (Phillips 1965, Cook 1966). Watershed specialists have indicated that the riparian zone plays an integral role in water quantity and quality (Horton and Campbell 1977). The U.S. government land management agencies, committed by law to manage for multiple use, have identified riparian zones as critical management areas.

Community Structure and Productivity in Ceanothus Chaparral and Coastal Sage Scrub of Southern California

Abstract: Adjacent, 22—yr—old stands of evergreen chaparral and drought—deciduous coastal sages scrub at a low—elevation site near the ocean in the Santa Monica Mountains of California were analyzed. The chaparral is a pure stand of Ceanothus megacarpus and has an aboveground live biomass of 6482 g/m². The coastal sage scrub is co—dominated by Salvia leucophylla and Artemisia californica and has an aboveground live biomass of 925 g/m². Attached and standing dead wood comprise 15% and 21% of the total live and dead biomass in the chaparral and coastal sage scrub, respectively, Mean annual aboveground primary production in Ceanothus chaparral is 1056 g°m— ²°yr— ¹, while litterfall is 801 g°m— ²°yr— ¹. In the coastal sage scrub, mean annual primary production is 355 g°m— ²°yr— ¹ and litterfall, 199 g°m— ²°yr— ¹. The drought—deciduous shrubs begin leaf production 1—3 wk after the initial winter rains and continue for 5—7 mo; thereafter, the shrubs lose most of their leaves in the summer. Twig and flower/fruit production continues for several months after leaf growth has ceased. Artemisia and Salvia have no measurable growth for 2 and 4 mo, respectively. In Ceanothus, leaf production begins 3—4 mo after the first rains of winter, and may or may not continue through the summer. Wood production and flowering/fruiting coincide with foliage production. Ceanothus may show measurable aboveground growth for up to 11 mo of the year. Flower production does not occur each year; however, in a flowering year, the production of all reproductive structures is very high (151 g°m— ²°yr— ¹). The length of the measurable aboveground growing season in the two growth forms does not fully account for the great differences in their annual net primary production. The high net primary production in the Ceanothus chaparral is much greater than other evergreen, mediterranean—type ecosystems and most temperate shrub communities. This high productivity is attributed to a tolerance of low water potentials, high photosynthetic rates, and an efficient use of nutrients in C. megacarpus. The high production in Ceanothus chaparral and the potential for reproduction in the coastal sage scrub suggest that the commonly ascribed senscence of mature shrub stands may not occur in these communities.

Herb and shrub dynamics in a mature oak forest: a thirty-year study

Abstract: DAVISON, S.E., and R.T.T. FORMAN (Dept. Botany, Rutgers Univ., New Brunswick, NJ 08903). Herb and shrub dynamics in a mature oak forest: a thirty-year study. Bull. Torrey Bot. Club 109: 64-73. 1982-Cover and frequency of forest herbs and shrubs were measured in permanent plots of a mature mixed-oak woods (Hutcheson Memorial Forest, New Jersey). Plots previously measured in 1950 and 1969 were remeasured in 1979. During this 30-year period, herb layer cover increased seven fold with all predominant species increasing in cover and frequency. Meanwhile herb species diversity declined, with rare herbs decreasing or disappearing. In contrast, shrub layer cover remained about constant, and shrub diversity increased. A major increase in vine cover occurred in both the herb and shrub layers. These changes correlate with an increase in understory light intensity during the 30-year period. Therefore, herb and shrub layer changes are dramatic in this mature uncut forest, indicating that relatively stable or climax communities may have highly dynamic subcommunities.

Ceanothus megacarpus chaparral: A synthesis of ecosystem processes during development and annual growth

Abstract: The evergreen sclerophyll shrub,Ceanothus megacarpus, dominates the chaparral in many areas of the Santa Ynez Mountains, Santa Barbara County, California, USA. Often occurring in pure stands,C. megacarpus chaparral accumulates large amounts of aboveground live biomass during growth after fire as a result of high rates of net primary productivity (850 g/m2/yr) compared to other chaparral areas and Mediterranean scrublands of the world. Populations ofC. megacarpus are even-aged, growing from buried seed which requires heat treatment for germination. During the early years of stand development after fire, competition for water among the shrubs results in mortalities of up to 50% of the initial population. This competition is evident by changes in the population size-structure and dispersion pattern of the living shrubs. Water potential measurements during the summer drought show that smaller individuals are more severely stressed than larger individuals. Similarly, shrubs in younger stands develop lower water potentials than shrubs in older stands. There is little mortality after 15 to 20 years of growth; competition for water is alleviated in older stands presumably because the surviving shrubs have developed more extensive root systems. Leaf area reaches a steady-state of 1.6 m2/m2 in 20-year-old stands. At this stage of development, competition for light is manifest in shrub physiognomy, particularly in the death of lower branches.

Environmental and vegetational variation across a snow accumulation area in montane tundra in central Alaska

Abstract: Several environmental factors were measured in a transect across a snow accumulation area in order to indicate (1) possible controls of arctic vegetation patterns; (2) water, carbon, and nutrient budgets of different vegetation types; and (3) relationships of Eriophorum vaginatum tussock tundra to other vegetation types. The results indicate that the vegetation zones are largely associated with different levels of nitrogen and phosphorus availability rather than length of the snowfree season, water availability, and soil pH. Nitrogen uptake was highest in the forb-grass and lower deciduous shrub zones and lowest in the lichen-heath. Phosphorus uptake was highest in the lower deciduous shrub zone and lowest in the lichen-heath. On the basis of several floristic and environmental factors tussock tundra has the lowest affinities to the lower deciduous shrub zone.

Seed Reserves in Soils of Successional Stages of Pinyon Woodlands

Abstract: Seedlings emerging from soil, duff and litter samples from four microsites (duff, transition, interspace, shrub) and four successional stages (grass-forb, shrub-tree, tree-shrub, tree) were recorded for 6 weeks. Seed reserves in soils decreased in number and species diversity from early to late successional stages. Of seedlings emerging, 890% were annuals. The shrub microsite from the shrub-tree stage had the highest total and perennial seed reserves. As shrub cover decreased, the transition microsite between the duff and interspace became the most important source of total seed reserves, and the duff microsite became the most important source of perennial seed reserves. INTRODUCTION The temporal and spatial variation in seed reserves in soils is an important component in modeling succession (Major and Pyott, 1966; Livingston and Allessio, 1968; Kellman, 1970). Previous studies found that seed reserves decline from early to late stages of succession (Oosting and Humphreys, 1940; Olmsted and Curtis, 1947; Quick, 1956; Livingston and Allessio, 1968). In southwestern shruband grasslands, seed reserves are concentrated under or around shrubs and grasses, with few seeds in the barren area in between (Knipe and Springfield, 1972; Nelson and Chew, 1977). Seed reserves also vary with soil depth, with most of the reserves concentrated in the top 2-3 cm of soil (Floyd, 1966; Wesson and Wareing, 1969; Childs and Goodall, 1973; Strickler and Edgerton, 1976). The objective of this study was to determine variation in amounts and species of seed reserves in the soils from various stages of pinyon woodland succession. The most commonly identified stages of pinyon-juniper succession are: (1) annual grass-annual forb stage; (2) perennial grass-perennial forb stage; (3) shrub-perennial grass-perennial forb stage; (4) shrub-perennial grass-perennial forb-young tree stage; (5) mature treeshrub stage, and (6) climax tree stage (Arnold et al., 1964; Erdman, 1970; Barney and Frischknecht, 1974; Stager, 1977; Tausch and Tueller, 1977). In addition, distribution of seed reserves among seedbed components of the woodlands was examined. This seedbed consists of a mosaic of shrub litter, pinyon duff, bare ground (interspace) and transition microsites. SITE DESCRIPTION The study was conducted in April 1979 on the N-facing foothill slopes of the Sweetwater Mountains, 0.5 km SE of Walker, California (T. 8 N., R. 23 E., Sec. 27). The study area has a slope of 15 % and an elevation of approximately 1890 m. Average annual precipitation is 250 mm and mean annual temperature is 9.8 C. The soils are well-drained typic torripsamments of granitic parent material. The area is characterized by variations in understory and pinyon (Pinus monophylla) cover resulting from a combination of past use of wood products, livestock grazing, wildfires and disease or insect attacks. Within a recent burn and adjacent woodland area, four sites in different successional stages were identified as grass-forb, shrub-tree, tree-shrub and tree. The grassforb site is located on the 1973 Rock Creek burn. The burn was aerial-seeded in the 1Stationed at the Renewable Resources Center, University of Nevada, Reno 89512.

Amount and Distribution of Dry Matter, Nit- rogen, and Organic Carbon in Soil-Plant Systems of Mesquite and Palo Verde

Abstract: Over a 3-year period, soil-plant systems of velvet mesquite and palo verde from the Sonoran Desert were sampled by standing crop, litter, and soil components and analyzed to describe the amount and distribution of dry matter, nitrogen, and carbon in the systems. Honey mesquite was sampled on a limited basis in southern New Mexico. Velvet mesquite averaged about one-third larger in crown area and weight than palo verde, but the two shrubs were similar in the distribution of dry matter, N, and C. Honey mesquite was much smaller and differed in distribution of dry matter, N, and C. Regression analysis showed that dry matter, N, and C in components of shrub systems of velvet mesquite and palo verde varied in a predictable manner and can be estimated with good precision using height, average crown diameter, or crown area of shrubs as the independent variable. Functional analysis showed that soil under palo verde did not accumulate N or C with increase in shrub size, whereas that under velvet mesquite accumulated N at the rate of 11.2 g/m2 per meter of height and C at the rate of 0.11 kg/M2 per meter of height. Shrubs dominate the vegetation on over 200 million hectares of land in the conterminous United States, mostly in the Southwest and the Intermountain Basin. Many authorities consider shrubs the climax vegetation on about one-half this area, while on the remaining 100 million hectares shrubs now dominate where grasses were once the climax dominants. Man has been using shrublands since prehistoric times, but until recently little management has been applied. When used, management usually has been directed at eliminating shrubs. Because shrubs play an important role in terrestrial ecosystems, we should understand their ecological role. This is especially important in arid areas where shrubs are an important component of the vegetation. This paper reports on a study to determine how dry matter, nitrogen, and carbon were accumulated and distributed in soil-plant systems of two desert shrubs: velvet mesquite (Prosopisjuliflora) and palo verde (Cerdicium floridum). Limited data on honey mesquite (Prosopis juliflora var. glandulosa) are included as an adjunct to the main study.

Analysis of forest vegetation at and around Naini Tal in Kumaun Himalaya

Abstract: Certain forests at and around Naini Tal were quantitatively analysed. On the basis of IVI, a total of five forest types, viz., Pinus roxburghii, Quercus floribunda, Q. lanuginosa, Q. leucotricltophora and Q. semecarpifolia were recognized. The total tree basal cover ranged from 2686.7 to 6045.8 cm2 100 m-2. The composition of tree and shrub layers differed markedly among various types of forest. Q. floribunda forest supported the largest shrub population, while P. roxburghii and Q. semecarpifolia were the poorest in this regard. P. roxburghii forest indicated zero diversity, whereas Q. floribunda forest on basal cover basis and Q. leucotricltophora forest on density basis, had maximum diversity. Among the oak forests, Q. floribunda forest (indicated relatively greater equitable share of resources among the various species. Generally, a total of four tree strata and a shrub stratum sheltering, in turn, a layer of herbs were recognizable in the present forests. The forests could be graded, as follows, in a decreasing order of soil protection potential: Q. floribunda (site 2) > Q. leucotricltophora > Q. floribunda (site 3) > Q. lanuginosa > Q. semecar pifolia > P. roxburghii. The trees in the oak forest were more wind stable, while in P. roxburghii they were specially susceptible to wind effect. With the exception of Q. leucotrichophora and Q. semecarpifolia in their respective forest types, the dominant species in all the forests had a stable population indicating good regeneration.

An Evaluation of Dimension Analysis for Predicting Shrub Biomass

Abstract: Fifteen independent variables consisting of circumference, surface area, and volume for various assumed shapes were derived from simple diameter and height measurements. These variables were used in seven models to predict aboveground biomass of leaves, different sizes of live and dead twigs, and combinations of fractions for threetip sagebrush, gray horsebrush, green rabbitbrush, and broom snakeweed. In addition, models based on height and circumference were tested on each species and fraction. A simple linear model with surface area or volume as independent variables and height X circumference models gave the best biomass predictions for these species. Land managers and researchers require reliable estimates of shrub weights to assess site productivity, food abundance, treatment effects, and fuel loading. With increased emphasis on prescription burning to improve range shrublands, techniques are needed to rapidly determine the weight of various live and dead plant fractions. Established techniques, such as harvesting, are slow and expensive. Uresk et al. (1977) estimated that clipping big sagebrush (Artemisia tridentata) phytomass was 120 times more expensive than using dimension analysis. Using the weight estimate technique (Pechanec and Pickford 1937) requires a considerable training and clipping to check estimates. A technique that is rapid, relatively accurate, and requires little training is desirable. Tufts (1919) found a high correlation between trunk circumference and weight of the top of fruit trees. Since this early beginning, many others including Kittredge (1944), Attiwill (1962), Baskerville (1965), and Brown (1978) have used combinations of trunk diameter, total height, live crown length, ratios of live crown length to total height, and crown widths to estimate tree biomass. In most cases, very successful relationships were developed from these simple measurements. Similarly, biomass estimates of various shrub species and plant fractions have been developed using stem diameters (Telfer 1969, Brown 1976), crown diameter axes (Rittenhouse and Sneva 1977), crown volume (Chew and Chew 1965, Lyon 1968, Mack 1971, Burk and Dick-Peddie 1973, Ludwig et al. 1975, Rittenhouse and Sneva 1977, and Wakimoto and Menke 1978), crown cover (Ludwig et al. 1975), and height X circumference (Harniss and Murray 1976) as independent variables. Various crown shapes have been assumed. Most models were of the form Y= a + bX, Y=axb, or Y = a + bX1 + cX2. Harniss and Murray (1976) found that the model Y aHCb predicted leaf biomass of big sagebrush quite well. A large number of variables could be used to predict biomass. However, variables that express the size of the crown appear to be most useful. We sought a technique that was rapid, easy to use in the field, and produced reliable results. Therefore, our objectives were: (I) to develop equations for biomass prediction that were based on easily measured crown diameters and height, (2) to compare different shapes and their circumferences, surface areas, and volumes calculated from the measurements in (1), (3) to monitor plant size and dead to live ratio per plant, parameters that are useful in predicting rate of fire spread, and (4) to test easily comAuthors are range scientist, USDA Agr. Res. Serv., U.S. Sheep Exp. Sta., Dubois, Ida. 83423; and range management specialist, University of Idaho. U.S. Sheep Exp. Sta., Dubois, Id. 83423. Manuscript received January 7. 1981. puted regression models. Four species common to sagebrush rangeland were selected for study: threetip sagebrush (A. tripartita: gray horsebrusth (Tetradymia canescens); green rabbitbrush (Chrysothamnus viscidiflorus); and broom snakeweed (Gutierrezia sarothrae). Study Area and Methods The U.S. Sheep Experiment Station consists of ( 10360 ha) 25600 acres of sagebrush-grass rangeland located in Clark County, (90 km) 56 mi north of Idaho Falls, Ida. The area is used annually as spring-fall range for sheep. Vegetation is predominantly shrubs with an understory of perennial grasses and forbs. All sites from which shrubs were measured and collected lay within a threetip sagebrush (A. tripartita) bluebunch wheatgrass (Agropyron spicatum) vegetative type. Surrounding topography is undulating and marked by pronounced lava outcrops. Climatic conditions are characterized by hot summers and cold, harsh winters, with an average annual precipitation of 292 mm (11.5 in.). Most of the moisture falls as rain with May and June receiving the highest precipitation. Twenty threetip sagebrush and 20 gray horsebrush plants were selected from each of 5 sites during May, 1979. In addition, 50 green rabbitbrush and 50 broom snakeweed plants were selected from a 10-ha area in August, 1979. Plants were selected to encompass the size range of plants normally found on the Station, with the exception of very small, young, or seedlings. On each selected plant, four diameters were measured across the crown at 45? angles. The height from ground level to the tallest nonflowering stem was also measured (Fig. 1). Many plants have multiple stems arising from below ground level. These were counted for use as an additional variable. Each plant was then severed at ground level and air-dried to a moisture content between 5-10%. Threetip sagebrush and gray horsebrush plants were separated individually into the following fractions: (I) leaves, (2) live twigs 2.5 cm, (5) dead floral twigs (threetip sagebrush), (6) dead twigs 2.5 cm. For additional predictions the above were combined into: (9) leaves and live twigs 2.5 (1.00 in) represent size classes used to characterize the time-lag constant i.e., their ability to respond to humidity by absorbing and desorbing moisture (Fosberg, 1970). The size classes, in the order above, are called the I hour (h), lOh, and lOOh classes. JOURNAL OF RANGE MANAGEMENT 35(4), July 1982 451 This content downloaded from 207.46.13.24 on Mon, 12 Sep 2016 04:12:15 UTC All use subject to http://about.jstor.org/terms Table 1. Numbering system used to identify the independent variable. Shape Circumfernce' Surface area2 Volume3 Right cylinder 1 6 11 Elliptical cylinder 2 7 12

Effects of pine-produced chemicals on selected understory species in aPinus ponderosa community.

Abstract: Pinus ponderosa accounted for more than 98% of all tree and shrub stratum stems in a climax community with low herb coverage and aboveground biomass, 35% and 60 g/m(2), respectively. Because of our previous report that nitrification and nitrifying bacteria in the same community were allelopathically inhibited, we speculated that the pine-produced allelochemics might also directly influence the development and growth of the herb stratum. In most cases decaying needles, needle leachate, and field soils significantly reduced germination and radicle growth ofAndropogon gerardii andA. scoparius, pine-associated herbaceous species. Additionally, growth ofAndropogon scoparius seedling radicles was reduced 28-56% by pine needle extracts, 33% by pine bark extracts, and 67% by soil hydrolysate extracts.Andropogon seed germination was reduced 20-25% by pine needles and soil. Phytotoxins identified in various plant parts and associated soils were caffeic acid, chlorogenic acid, quercetin, and condensed tannins. Pine needle water and soil hydrolysate extracts were most inhibitory to the radicle growth of the test species. Thus it appears that the limited growth of the herbaceous stratum in the pine community may be accounted for, in part, by allelopathy. Such allelopathic interactions may have an adaptive ecological significance in various forest and other plant communities.

Photosynthetic and respiratory responses to temperature and light of three Alaskan tundra growth forms

Abstract: Photosynthetic and respiratory response of four Alaskan tundra species comprising three growth forms were investigated in the laboratory using an infrared gas analysis system. Vaccinium vitis-idaea, a dwarf evergreen shrub, demonstrated a low photosynthetic capacity: P max = 1 mg CO2 g dry wt-1 h-'; Topt < 100C. Betula nana, a deciduous shrub, had a high relatively photosynthetic capacity: Pmax = 14 mg CO2 g dry wt-' h-'; Topt 170C. Two graminoid (sedge) species, Carex aquatilis and Eriophorum vaginatum, showed different responses. Carex showed a high photosynthetic capacity: Pmax = 20 mg CO2 g dry wt-1 h-I; Topt 220C. Eriophorum vaginatum demonstrated an intermediate photosynthetic capacity of 4 mg CO2 g dry wt-1 h-1 at saturated light levels. Leaf dark respiration, up to 200C, was approximately the same for all species. The patterns of root respiration among species was opposite to the trend in photosynthesis. Vaccinium vitis-idaea had the highest rate of root respiration and B. nana the lowest (C. aquatilis was not measured). Correlation between leaf nitrogen content (%) and photosynthetic capacity was high. Hypothesized growth form relationships explained differences in photosynthetic capacity between the deciduous shrub and evergreen shrub, but did little to account for differences between the two sedges. Differences in rooting patterns between species may affect tissue nutrient content, carbon flux rates, and carbon balance.

Association with mature plants protects seedlings from predation in an arid grassland shrub, Gutierrezia microcephala.

Abstract: Survivorship of Gutierrezia microcephala (Compositae) seedlings was studied in an undisturbed arid grassland and in experimental plots where various components of the natural vegetation were removed following seed germination The major causes of seedling mortality were herbivore damage from the specialist grasshopper, Hesperotettix viridis, and drought stress associated with competition from established plants The relative intensity of these mortality factors varied strongly with seedling size Large seedlings had higher overall survivorship but were most likely to be killed by defoliation; most small seedlings died of drought stress In plots where all perennial grasses were removed (leaving established G microcephala plants), seedling survivorship was 5 times greater than in undisturbed vegetation Surviorship in plots where both grasses and mature G microcephala were removed was slightly poorer than in undisturbed vegetation due to a large increase in mortality from defoliation From May–August, when the herbivore H viridis was abundant, seedling survivorship was better in the immediate vicinity of mature conspecific plants than in plots lacking mature G microcephala, both in the presence and absence of perennial grasses These results provide a counter example to theories predicting that the impact of specialist herbivores on seedling recruitment is greatest in the vicinity of parent plants

Comparative Phenology and Growth in Three Chaparral Shrubs

Abstract: The seasonality of Mediterranean-climate shrublands in California is reflected in the progression of physiological and phenological characteristics of the dominant shrub species. The progression of phenological stages and plant water stress was followed for 2 yr in three dominant chaparral shrubs, Adenostoma fasciculatum, Ceanothus cuneatus, and Arctostaphylos viscida, in the foothills of Sequoia National Park. Ceanothus has a simultaneous progression of phenological stages; branch elongation, leaf initiation, and flowering occur together. In Adenostoma, vegetative and reproductive growth are sequential. Arctostaphylos has a protracted sequence of reproductive development with flower buds forming in late spring of the season before flowering. Physiological plant functions also have seasonal cycles in which some stages are more vulnerable to environmental perturbations than others.

Nitrogen utilization efficiencies in mediterranean-climate shrubs of California and Chile.

Abstract: Comparative studies of nitrogen utilization efficiencies (g assimilation mg-1 leaf nitrogen expended) for dominant chaparral shrubs of California and matorral shrubs of central Chile indicate varying relationships of these efficiencies to total shrub productivity and community dominance. In California where nitrogen is limiting for shrub growth, increasing nitrogen utilization efficiency is correlated with increased productivity, and species with the highest values are dominant on polar (north-facing) slopes. In Chile where soil nutrients are not strongly limiting, increased nitrogen utilization efficiency beyond a low threshold has little or no effect on productivity. This may be an important aspect of the relative ecological success of deciduous shrubs in Chile. High nitrogen utilization efficiency in Chile is associated with broad ecological amplitude rather than increased competitive ability through higher productivity.

Forage Yield and Quality in a Great Basin Shrub, Grass, and Legume Pasture Experiment.

Abstract: A study was conducted in central Utah to determine the forage and protein yield relationships among the components of grassshrub-legume plantings in a semiarid rangeland pasture. Forage and protein yields of crested wheatgrass (Agropyron cristatum) and total herbage increased when fourwing saltbush shrubs (Atripkx canescens) or legumes (Astragalus cicer, A. fakatus, or Medicage sativa) were grown in association. The shrub and legume species directly contributed to the increase in these yields and to more rapid regrowth of crested wheatgrass. Rehabilitation of depleted rangelands in the United States has received much research attention since the mid 1930’s. This has guided successful seeding of several million hectares throughout the West. Seeding emphasis was on grasses and only a little attention was given to forbs and almost none to shrubs (Blaisdelll972). The two crested wheatgrasses, standard crested wheatgrass (Agropyron desertorum) and ‘Fairway’ crested wheatgrass (Agropyron cristarum), were most commonly seeded. Fairway crested wheatgrass can grow on dry sites where few other grasses survive (Plummer et al. 1968). It isa preferred species for inclusion in mixtures with other grasses, forbs, and shrubs. Dubbs (1966) found that Fairway crested wheatgrass was more palatable than standard crested wheatgrass over a longer part of the year. Neither sheep nor heifers liked standard crested wheatgrass after heading. Fairway was leafier than standard crested wheatgrass but no higher in protein content. Fourwing saltbush (Atriplex canescens) is a native, dioecious shrub that occurs on desert and foothill ranges in western America and has been included in some range plantings. It grows to heights of 60 to 180 cm with most of the seasonal growth in midsummer. This shrub was reported to be one of the most abundant producers of forage and seed tested on Utah game ranges (Plummer et al. 1968). Springfield (1966) considered it to be a useful shrub for ranges of southwestern United States. Palatability of fourwing saltbush forage to sheep was intermediate between prostrate summer cypress (Kochia prostrata) and Artemisia herba alba in Iran where it was considered a promising forage plant for large scale plantings (Nemati 1977). Monsen (1980) successfully interseeded fourwing saltbush and crested wheatgrass into southern Idaho rangelands dominated by sagebrush (Artemisia spp.)and an annual grass. The presence of the saltbush shrubs did not reduce the grass density or herbage yields. Cattle readily accepted the saltbush as a forage species and utilized approximately 50% of the annual growth. A number of legume species have been suggested for use in range renovation programs. Townsend et al. (1975) tested 14 legumes and concluded that cicer chickpea milkvetch (Astragalus cicer), sicklepod milkvetch (Astragalus falcatus), and alfalfa (Medicugo sutiva) merited additional evaluation for potential use under dryland or range conditions. Cicer milkvetch was considered adapted

Avian nest densities and nest-site selection in farmstead shelterbelts

Abstract: Farmstead shelterbelts are man-made habitats consisting of parallel rows of trees and shrubs designed to protect farmsteads from damaging winds, drifting snow and blowing soil, and to moderate the effects of wind, thereby reducing heat loss from humans, domestic animals, and farm buildings (Smith and Scholten 1980). These habitats may be viewed as small (generally <1 ha) "wooded islands" surrounded by extensive fields of crops, pastures and natural prairies; however, despite their small size and isolation from other wooded habitats, shelterbelts are a source of food and song perches as well as roosting and nesting sites for a number of bird species (Orendurff 1941, Martin 1978). Avian communities in shelterbelts have been examined during the breeding season (Weiser and Hlavinka 1956; Cassel et al. 1966, 1967; Emmerich 1978; Martin 1978). However, with the exception of studies dealing with Mourning Doves (Zenaida macroura) (see Nelson 1976 for review), Ring-necked Pheasants (Phasianus colchicus) (e.g., Olson and Flake 1975) and Ferruginous Hawks (Buteo regalis) (Lokemoen and Duebbert 1976), little is known about the nesting ecology of many bird species breeding in shelterbelts. A study by Field (1971) represents the only published report giving the total number of nests per bird species. Her study dealt only with a portion of one shelterbelt where tree/shrub species used and height above ground of 75 nests of four bird species were noted. As part of an investigation of breeding-bird diversity in 69 shelterbelts, Martin (1978) examined 185 nests of eight species and noted tree/shrub species used, height above ground, lateral distance of nest from main stem, and distance of nest from top of tree/shrub. However, his study did not attempt to locate total nests per shelterbelt nor total nests per season. A determination of both the number of avian species nesting in farmstead shelterbelts and the abundance of nests per species is an initial and important step in assessing whether or not these small, narrow, agricultural habitats are valuable nesting areas or instead perhaps function to attract predators, hence reducing fledging success (see Gates and Gysel 1978). Moreover, because farmstead shelterbelts are restricted in size, the availability of nest-sites conceivably could be a limiting resource to birds. Thus, a knowledge of factors critical to nest-site selection would give a better understanding of how coexisting nesting species effectively exploit these "wooded islands" (after Pianka 1973, Schoener 1974).

Small mammal populations in an unburned and early fire successional sagebrush community.

Abstract: Species composition and total numbers of small mammals changed little in the unburned sagebrush while individual species capture rates varied considerably. Following spring burning, the number of small mammal species and abundance were slightly. lower than control levels and were near unburned levels after 3 years. Species composition was greatly reduced on the fall bum in the first postburn year. Two years after burning four species were captured, although only two were caught in live-traps. Total small mammal density increased dramatically in the first two postburn years. The large increase in abundance on both bums was due primarily to Peromyscus maniculatus and Spermophilus armatus. Food use patterns on the fall burn were similar to those observed on the spring burn where small mammals utilized their preferred food types in relation to its abundance and availability. National Park. In unburned areas mountain big sagebrush (Artemisia tridentata vaseyana) is the most abundant shrub, forming dense, homogeneous stands. The most common grasses are wheatgrasses (Agropyron spp.), Idaho fescue (Festuca idahoensis), bluegrasses (Poa spp.) and needlegrasses (Stipa spp.). Characteristic forbs include yarrow (Archillea millefolium), wild buckwheat (Eriogonum umbellatum), geranium (Geranium spp.), lupine (Lupinus spp.), and northwest cinquefoil (Potentilla gracilis). Grasses and forbs form a continuous understory with few open areas. The sagebrush is bordered by stands of Douglas-fir (Pseudotsuga menziesii) and aspen (Populus tremuloides).

Response of Chihuahuan Desert mountain shrub vegetation to burning.

Abstract: The effects of fire on vegetation in the desert mountain shrub community were studied on 3 to 7-year-old burned sites near the northern limits of the Chihuahurn Desert. Coverage and frequency of redberry juniper (Juniipcruspinchotii) and frequency of whitebail acacia (Acacia texends) were lower, while frequencies of catclaw mimosa (Mimosa biunc~em) and skeleton goldeneye (Viguiera stenoloba) were higher on burned sites when_compared with unburned paired piants. Lechuguiiia (Agave lecheguil&, sotoi (DasytYrion leiophylbun), and sacahuista (Nor and Texas Tech University. It is a contribution of College of Agricultural Sciences, Publication No. T-9-235. Texas Tech University. Manuscript received March 28, 1980. huan Desert. Bunting and Wright (1977) reported theeffectsof fire on desert mountain shrub vegetation 2 years after burning in the Texas Big Bend country. Kittams (1973) noted that in burned desert mountain shrub communities, catclaw mimosa (Mimosa biuncifera). skunkbush (Rhus aromatica), silver dalea (Dalea argyraea), skeleton goldeneye (Viguiera stenoloba). mountain mahogany (Cercocarpus montanus), scrub oaks (Quercus spp.), redberry juniper (Juniperus pinchotii) and alligator juniper (J. deppeana) usually recovered through some form of vegetative sprouting. He observed that lechuguilla (Agave lecheguilla), datil (Yucca baccata), and mature soto (Dasylirion leiophyllum) were usually killed by fire. ,Bunting and Wright (1977) found that fire reduced shrub cover and total grass cover 43% and 72% respectively in a desert mountain shrub community 2 years after burning. Coverage of forbs and half shrubs increased 650%. The fire significantly reduced the density or cover of sideoats grama (Bouteloua curtipendula), blue three-awn (Aristida glauca), sotol, and lechuguilla, whereas coverage contributed by skeleton goldeneye tripled through vigorous sprouting and seedling establishment on the burned area (Bunting and Wright 1977). Information pertaining to other species common to the Chihuahuan Desert is available from studies conducted elsewhere. Mortality rates for cholla (Opuntia imbricata) and pricklypear (0. phaeacantha) two growing seasons after a prescribed burn on the Texas High Plains averaged 45% and 68%, respectively (Heirman and Wright 1973). Pricklypear mortality was 3270 the first year following a prescribed burn (Cable 1967) and 28% the second growing season after an experimental tire (Reynolds and Bohning 1956), in two separate studies conducted in the Arizona Sonoran Desert. Survival of ocotillo (Fouquieria splendens) following a 62 JOURNAL OF RANGE MANAGEMENT 35(l). January 1999 wildfire in the Sonoran Desert was 33Ycfor heavily damaged plants and 50% for plants only scorched (White 1969). Regeneration occurred primarily through basal sprouting. Algerita (Berberis trifoliolata) sprouted vigorously following a wildfire in south central New Mexico (Dwyer and Pieper 1967). The objective of this study was to document longer term effects of fire on vegetation in the mountain shrub community of the Chihuahuan Desert by examining 3 to ‘I-year-old burned areas.

Energy Biomass from Large Rangeland Shrubs of the Intermountain United States

Abstract: Large individual plants within a few species of rangeland shrubs were studied in several Intermountain States for their potential use in establishing biomass fuel energy plantations Their locations were based on reports in the literature, suggestions from various range researchers, and personal knowledge Biomass and other shrub physical characteristics plus site data were recorded for big sagebrush (Artemisia tridentata), fourwing saltbush (A triplex canescens), big saltbush (A lentiformis), greasewood (Sarcobatus vermiculatus), rubber rabbitbrush (Chrysothamnus nauseosus), and spreading rabbitbrush (C linifolius) in 34 locations Samples of current year's growth and woody tissue were analyzed for burning qualities (heat of combustion, sulfur, moisture, and ash content) Greatest biomass per plant of the individuals sampled was found in greasewood with fourwing saltbush, rubber rabbitbrush, and sagebrush following in decreasing order Burning qualities varied among the species analyzed The heat of combustion of the woody material from all shrubs was approximately 4500 Kcal/kg, but current year's growth varied considerably among species

Growth and Nonstructural Carbohydrate Content of Southern Browse Species and Influenced by Light Intensity

Abstract: Three species of palatable deer browse (flowering dogwood, yaupon, and Japanese honeysuckle) were grown under 3 levels of light intensity: 100, 45, and 8% of full sunlight. After 4 growing seasons, dogwood and yaupon under 45% light were significantly taller, contained more growing points, and produced a larger foliar, stem, and root biomass than plants under other light regimes. Twig growth and biomass were generally poorest in full sunlight, whereas foliar and root biomass were poorest in deep shade. Leaves of all species were smallest on plants in full sunlight. The dry weight per unit of leaf area and the concentration of total nonstructural carbohydrates in leaves declined for all species as light intensity declined. Of the environmental parameters affecting the growth of deer and livestock forage in the understory of forest stands, light is generally recognized as the most influential. With sufficient understanding of the influence of light on the survival, growth, and regeneration of palatable forages, silvicultural guidelines can be developed for objectively sustaining desirable light intensities in the understory with the least infringement on wood production. Currently, the production of forage is little more than a chance by-product of stand silvics. The research reported here explored the effects of 3 levels of light intensity on the leaf, stem, and root growth and the total nonstructural carbohydrate levels in the leaves of 3 species of palatable deer browse that commonly occur in the understory of southern pinehardwood forests. Data were collected from 1974 through 1977 in conjunction with a study evaluating the influence of light intensity on the nutrient quality and digestibility of browse leaves (Blair et al. 1982, unpublished manuscript). Study Area and Methods The study was conducted within the loblolly-shortleaf pine forest type on the Stephen F. Austin Experimental Forest near Nacogdoches, Texas. The principal tree species in the forest type are loblolly pine (Pinus taeda) and shortleaf pine (Pinus echinata) in association with assorted hardwoods. Characteristically, stands consist of a multitiered midstory of pines, hardwoods, and shrubs beneath a pine-hardwood overstory. The stand structure and composition generally result in heavy shading in the forage stratum. The open and relatively flat study site supports well-drained sandy loam soils with a heavy clay subsoil. The soils are acid in reaction and contain moderate amounts of organic matter and natural plant nutrients. Summers are hot and humid and winters are generally mild. The frost-free season averages about 243 days from mid-March to mid-November. A mean annual precipitation of 122 cm is generAuthor is research ecologist, Wildlife Habitat and Silvicultural Laboratory maintained at Nacogdoches, Texas 75962, by the Southern Forest Experiment Station, Forest Service, USDA, in cooperation with the School of Forestry, Stephen F. Austin State University. Manuscript received March 18, 1981. ally well distributed throughout the year. Spring growth of woody plants begins in late March or early April and twig elongation is nearly completed on most species in June (Halls and Alcaniz 1965). Limited growth also occurs on some species following summer rains, particularly after a prolonged dry spell, and on some broadleaf evergreens during warm winter periods. The study site was plowed and leveled to reduce competing vegetation and 127.3by 26.5-m plots were established in a 3 treatment by 4 replication design, each separated by a 1 5-m buffer. Light intensities of 100, 45, and 8% of full sunlight were randomly assigned to treatment plots. Each intensity was replicated 4 times in a completely randomized design. For treatments designated as less than full sun, polypropylene fabric, woven to provide the prescribed light reduction was placed over a 2.4-m high wood frame covering each treatment plot. The bottom 0.3 m on the sides and the top 1.0 m on the end walls were left open to facilitate air movement. Light entry at the upper end-wall openings was controlled by a fabric-covered overhang. Shading was placed over the frames immediately before planting. Browse species studied were flowering dogwood (Cornus florida), a deciduous small tree, and yaupon (Ilex vomitoria), a broadleaf evergreen shrub, both endemic, and Japanese honeysuckle (Lonicera japonica), a common and widespread vine of Asiatic origin that is generally evergreen in the Gulf Coast Plain. These species are considered moderate in shade tolerance, with flowering dogwood the most tolerant. Dogwood and yaupon plants were 2-year-old container-grown nursery stock and honeysuckle plants consisted of young rooted leaders lifted from an extensive open area adjacent to the study site. In February 1974, 1 16-plant row of each species was outplanted on each treatment plot. Species row assignments were random. Plants were spaced 1.5 m within a row and 2.4 m between rows. The long axes of plots were oriented northeast by southwest so all plants would receive approximately equal exposure to solar radiation. Honeysuckle growth was supported on 1-m high woven-wire trellises extending the full length of each row. To eliminate gross differences in soil moisture, gypsum soil blocks were buried on each plot and water needs were monitored by periodic readings with a Bouyoucos soil moisture meter. Water was applied when a meter readout dropped to 45% available soil moisture at either a 6or 12-inch depth. More frequent water was needed on plots in full sunlight and under 45% light than on plots under 8% light. Plants used for growth measurements and chemical determinations were randomly selected. Beginning in the spring of 1976, after plants had grown 2 years under their prescribed light regime, and again in 1977, leaf samples were collected at mid-month of April, May, June, July, August, September, and December, to evaluate differences in the content of total nonstructural carbohydrates. Current leaf tissues were collected only from the terminal 10.2 cm or less of dogwood and yaupon twigs and 20.4 cm or less of honeysuckle leaders. Each month the leaf sample was obtained 756 JOURNAL OF RANGE MANAGEMENT 35(6), November 1982 This content downloaded from 157.55.39.103 on Tue, 27 Jun 2017 18:03:08 UTC All use subject to http://about.jstor.org/terms from I plant within a species row and individual plants were sampled only once yearly. Samples were collected between 10:00 a.m. and 2:00 p.m. to minimize diurnal fluctuations in sugar content of the cell sap. Excised samples were immediately dried to a constant weight in a forced-draft oven at 600 C, ground in a Wiley mill to pass a 1 mm screen, and temporarily stored in a freezer. All leaf tissues were analyzed for total nonstructural carbohydrate (TNC) by the Agronomy Department, Virginia Polytechnic Institute and State University, Blacksburg. Determinations were according to procedures described by Wolf and Ellmore (1975). Reported TNC values are averages of the 1976 and 1977 measurements. In September 1976 and 1977, 10 leaves of flowering dogwood, 15 of honeysuckle, and 20 of yaupon were collected from 1 plant per species on each treatment plot to determine the area and weight of the average size leaf. Selection of sample leaves was based on what appeared to be the typical size for the plant. Excised leaves were temporarily affixed, by species, to a paper backing then photocopied to obtain leaf imprints. The area of each imprinted leaf blade was determined by a polar planimeter. After imprinting, leaf samples were dried at 100? C in weighing bottles, desiccated until cool, then weighed to the nearest 0. 1 mg. Leaf area and weight data were averaged for the 2 years. In September 1974, 1975, and 1977, after 1, 2, and 4 growing seasons, respectively, under the prescribed light regimes the total height growth and the number of growing points (twig tips) were determined on 3 plants of dogwood and yaupon on each treatment plot. In addition, the total linear growth of current twigs was measured on these plants in 1977. In late October 1977, prior to leaf abscission, all leaves were collected from 1 plant of dogwood and I of yaupon on 1 random plot of each light treatment. Leaves were oven-dried to constant weight at 100" C to derive total leaf biomass. During early December 1977 the root systems of these 3 plants of each species were extracted from the ground using a hydrolic water procedure. The maximum diameter of the crown and root system was determined for each extracted plant, after which plants were fractioned into current stems, old wood, and roots. Each root system was dried at 60? C, and ground through the I-mm screen of a Wiley mill, after which a weighed subsampled was removed for a total nonstructural carbohydrate determination. The remaining root and wood fractions were oven-dried to constant weight at 100? C. For honeysuckle only total leaf growth was collected from 1 plant of each treatment as the intertwining leaders could not be removed from the wire trellises and the linear growth measured. From mid-March through mid-November during measurement years, the maximum, minimum, and ambient air temperatures, soil temperature, and relative humidity were determined biweekly on 1 random plot of each light regime. Air temperatures were taken at 76 cm and relative humidity was taken at about 122 cm above ground. Soil temperature was measured by a probe thermometer inserted 7.6 cm below the surface at 2 points per plot. Growth and nonstructural carbohydrate data were subjected to variance analyses to evaluate differences due to light intensity and to test changes in carbohydrate content of leaves across time. When significant differences among treatments occurred, means were compared by Duncan's multiple range test. Testing was at the P<0.05 level.

Ecology of a deciduous and an evergreen dwarf shrub. Vaccinium uliginosum and Vaccinium vitis-idaea in subarctic Fennoscandia.

Abstract: Ecology of a deciduous and an evergreen dwarf shrub. Vaccinium uliginosum and Vaccinium vitis-idaea in subarctic Fennoscandia.

Estimating Browse Production by Deerbrush [Ceanothus integerrimus].

Abstract: This architectural model is designed to significantly refine browse weight estimates for deerbrush (Ceanothus integerrunus). Basal diameter of branches arising from the primary stem (2nd order stems) predicted leaf and branch weights with r2 = 0.97 using an allometric transformation in linear regression. Estimates based on secondary stem basal diameter rather than terminal shoots may be useful in a large number of similar shrub species. Shrubs produce a significant amount of the forage in forests and brushlands. Yet layering, poorly defined shrub canopies, and illdefined current annual growth may make accurate estimates of browse production difficult to achieve. Forage production varies within and among species, with age of the plant, with season of the year, among years, and with site. Developmental response to browsing may be highly variable. For example, chamise (Adenostomafasciculatum) stems resume growth shortly after browsing, whereas deerbrush (Ceanothus integerrimus) stems do not. Animal accessibility to shrub production further complicates estimates of carrying capacity on browse ranges. Attempts to measure shrub browse production have centered on a few basic techniques, including tagged twig methods, ocular estimates, and clip and weight methods. Regression methods have been widely used to estimate total biomass, current annual production, and utilization in shrubs while reducing sampling costs. Several authors have used plant variables such as height, crown volume, and current annual stem diameter and length to predict weights of different species or plant parts within species (Schuster 1965, Lyon 1968, Peek 1970, Ohman et al. 1976). Basile and Hutchings (1966) and Fergus and Marsden (1977) used current annual twig diameter, length and weight relations to predict unbrowsed twig weight as method to estimate utilization in bitterbrush (Purshia tridentata). Regression equations may predict browse production with high precision, but equations generally apply only to specific situations. Research methods have overcome some of the problems associated with accurate browse estimation. Bitterbrush, which has clearly defined growth, exemplifies a species adequately described and measured. We describe a method for predicting stem and leaf biomass in a less easily measured, but important species. Deerbrush is the most important summer browse species for livestock and big game in the 5-million hectare ponderosa pine belt in California (Cronemiller 1953). As an open-crowned deciduous shrub up to 5 m tall, with slender dropping branches and poorly defined annual growth, deerbrush typifies a large group of Authors are with the Department of Forestry and Resource Management, 145 Mulford Hall, University of California, Berkeley 94720. Manuscript received August 30, 1980. difficult-to-measure browse species. Our method proposes a new way of looking at shrub architecture which works to predict leaf and branch biomass in deerbrush. It may have applicability to similarly difficult-to-measure browse species.