Savannas occur where trees and grasses interact to create a biome that is neither grassland nor forest. Woody and gramineous plants interact by many mechanisms, some negative (competition) and some positive (facilitation). The strength and sign of the interaction varies in both time and space, allowing a rich array of possible outcomes but no universal predictive model. Simple models of coexistence of trees and grasses, based on separation in rooting depth, are theoretically and experimentally inadequate. Explanation of the widely observed increase in tree biomass following introduction of commercial ranching into savannas requires inclusion of interactions among browsers, grazers, and fires, and their effects on tree recruitment. Prediction of the consequences of manipulating tree biomass through clearing further requires an understanding of how trees modify light, water, and nutrient environments of grasses. Understanding the nature of coexistence between trees and grass, which under other circumstances...

Tree-grass interactions in Savannas

The Analysis of Variance.

____________________________________ Brown, James K.; Smith, Jane Kapler, eds. 2000. Wildland fire in ecosystems: effects of fire on flora. Gen. Tech. Rep. RMRS-GTR-42-vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 257 p. This state-of-knowledge review about the effects of fire on flora and fuels can assist land managers with ecosystem and fire management planning and in their efforts to inform others about the ecological role of fire. Chapter topics include fire regime classification, autecological effects of fire, fire regime characteristics and postfire plant community developments in ecosystems throughout the United States and Canada, global climate change, ecological principles of fire regimes, and practical considerations for managing fire in an ecosytem context.

/pdf/wildland-fire-in-ecosystems-effects-of-fire-on-flora-3u9thcsxty.pdf

Wildland fire in ecosystems: effects of fire on flora

Post-fire vegetative dynamics as drivers of microbial community structure and function in forest soils

Intake and digestion of leaves of Quercus calliprinos, Pistacia lentiscus, and Ceratonia siliqua, with and without supplementation of various amounts of polyethylene glycol (PEG), were examined. The tannin contents in these species exerted a substantial negative effect on feed intake and digestion. The effects were species specific and related to tannin content. Once-daily Supplementation with PEG efficiently neutralized the negative effects of tannins. The amount of PEG needed to produce a maximal increase in feed intake was lower than the amount required to produce a maximal increase in digestibility. The intake of digestible crude protein and metabolizable energy was raised in PEGsupplemented animals from a submaintenance level to levels considerably exceeding the maintenance requirement of goats. The response was related to the tannin content of the plant.

/pdf/effect-of-a-daily-supplementation-of-polyethylene-glycol-on-5fiqqrf5es.pdf

Effect of a Daily Supplementation of Polyethylene Glycol on Intake and Digestion of Tannin-Containing Leaves (Quercus calliprinos, Pistacia lentiscus, and Ceratonia siliqua) by Goats

The key to managing Arizona chaparral depends on creating and maintaining brush-free or savanna-like habitats. Brush control using fire, chemicals, and mechanical methods has been tested previously; but limited information is available on goats. This study evaluated the effect of 4 goat-stocking levels in a short duration grazing system and mechanical brush crushing on chaparral shrubs, herbaceous vegetation, litter, and soils. After 4-1/2 years, percent total shrub cover was lower (P<0.05) on paddocks stocked at 1.4, 2.4, and 4.2 Spanish goats/ha (35, 39, and 38%, respectively) compared to unstocked controls (51%). Crushing brush increased the effectiveness of goats; mean total shrub cover was lower (P<0.05) on paddocks where brush was crushed vs not crushed (33 and 50%, respectively). Shrubs least preferred by goats were not affected, while preferred browse was impacted at all stocking levels. Goat stocking and brush treatments did not affect perennial herbs, while annuals were generally increased by soil disturbance. Less litter (P<0.05) accumulated under shrubs subjected to heavy stocking levels compared to unbrowsed paddocks. Concentrations of N and P in the soil were also affected (P<0.05) under desert ceanothus (Ceanothus greggii Gray) where the soil bulk density was also increased (P<0.05). While goats can reduce total shrub cover, problems may result. Perennial herbaceous vegetation did not respond. Shrubs preferred by goats were also preferred by native deer. Reduced forage diversity and nutritional stress could result if these species were eliminated from the stand. Also, trampling disturbance by goats affected nitrogen accumulation in the litter and soil, but more importantly heavy browsing may eliminate nitrogen-fixing shrubs.

/pdf/influence-of-spanish-goats-on-vegetation-and-soils-in-li9o7lf555.pdf

Influence of Spanish goats on vegetation and soils in Arizona chaparral

The objective of this study was to test the hypothesis that there are no differences in understory produc- tion, by species, due to stocking levels of Pinus ponderosa (ponderosa pine). Understory production was estimated, by species, on 3 replicates each of 8 growing stock levels, ranging from clearcuts to unthinned stands, in both sapling- and pole-sized pine stands (48 plots) over 3 nonconsecutive years. All stands were approximately 70 yr old when thinning treatments were applied. Production of many herbaceous species, especially Agropyron spp. (wheatgrasses) and Carex spp. (sedges), declined as growing stock levels (measured in terms of basal area) of ponderosa pine increased. While trends in total production were similar, there were specific differences between sapling and pole stands. Sedges and Oryzopsis asperfolia (roughleaf ricegrass) produced more in sapling stands, whereas Danthonia intermedia (timber oat- grass) was more abundant in pole stands. Shrub production, dominated by Arctostaphylos uva-ursi (bearberry), was rela- tively consistent across all stocking levels except unthinned. Although the total number of species declined as pine basal area increased, a few species, such as Linnaea borealis (twinflower) and Shepherdia canadensis (buffaloberry), were found only under relatively dense pine canopies. While floristic species richness was greater at lower stocking levels of ponderosa pine, the total number of species would be greater if all stocking levels were present.

/pdf/response-of-understory-species-to-changes-in-ponderosa-pine-14w2jqx55l.pdf

Response of understory species to changes in ponderosa pine stocking levels in the black hills

/pdf/waterfowl-and-shorebird-use-of-surface-mined-and-livestock-5bmevt6wxp.pdf

Waterfowl and shorebird use of surface-mined and livestock water impoundments on the Northern Great Plains

Forty-two white-tailed deer fawns ( Odocuileus virginianus dakotensis ) were captured and fitted with radio transmitters and observed from June through September 1991 and 1992 to determine diurnal bed site use in the Black Hills of South Dakota. Fawns were monitored biweekly during daylight hours and 259 bed sites were located. In addition, 301 random sites were measured for comparison. Of 31 habitat variables measured, 8 were significant to determine use by fawns for a bed site when compared with random sites. Sites used by fawns were in relatively open stands of ponderosa pine ( Pinus ponderosa ) with mean basal area of approximately 11 m 2 /ha compared to 16 m 2 /ha in random sites. Fawn bed sites had greater mean vegetation cover, which ranged from 28.1% to 36.0%, compared with 19.9% and 33.8% at random sites in 1991 and 1992, respectively. Mean vegetation height was 101 cm at bed sites compared to 75 cm at random sites. Current timber harvest standards for stocking levels of pine range from 14 m 2 /ha to 18 2 /ha in the Black Hills, which are similar to our random sites. These levels preclude adequate development of understory characteristics used by white-tailed deer fawns for bed sites.

https://www.fs.fed.us/rm/pubs_other/rmrs_1999_uresk_d001.pdf

Characteristics of white-tailed deer fawn beds, Black Hills, South Dakota

Forty-two white-tailed deer fawns (Odocoileus virginianus dakotensis) were captured and fitted with radio transmitters and observed from June through September 1991 and 1992 to determine diurnal bed site use in the Black Hills of South Dakota. Fawns were monitored biweekly during daylight hours and 259 bed sites were located. In addition, 301 random sites were measured for comparison. Of 31 habitat variables measured, 8 were significant to deter- mine use by fawns for a bed site when compared with random sites. Sites used by fawns were in relatively open stands of ponderosa pine ( Pinus ponderosa) with mean basal area of approximately 11 m2/ha compared to 16 m2/ha in random sites. Fawn bed sites had greater mean vegetation cover, which ranged from 28.1% to 36.0%, compared with 19.9% and 33.8% at random sites in 1991 and 1992, respectively. Mean vegetation height was 101 cm at bed sites compared to 75 cm at random sites. Current timber harvest standards for stocking levels of pine range from 14 m2/ha to 18 m2/ha in the Black Hills, which are similar to our random sites. These levels preclude adequate development of understory charac- teristics used by white-tailed deer fawns for bed sites.

https://www.jstor.org/stable/pdfplus/41713135.pdf

Characteristics of white-tailed deer fawn beds,

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