2009_rnr_384_rangeland_management_lecture_notes

2009_rnr_384_rangeland_management_lecture_notes - RNR 384:...

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Unformatted text preview: RNR 384: Spring 2009 Principles of Natural Resource Management Rangeland Management Practices Mitch McClaran Professor of Range Management 112 Biological Sciences East, 621-1673 mcclaran@u.arizona.edu Office Hours 1-2PM Tuesdays and 9-10 Thursdays or by appointment Lecture Schedule 13 Feb Fri Rangelands A. ecosystem components B. concerns C. management practices D. rangeland management discipline 16 Feb Mon Rangeland Plant Response to Herbivory A. growth patterns and meristems B. intensity, season, kind of defoliator, and neighboring plants 18 Feb Wed Rangeland Herbivore Production A. forage quantity and the animal unit concept B. forage quality and diet selection 20 Feb Fri Rangeland Herbivore Management A. principles B. distribution tools C. estimating stocking rate and grazing capacity 23 Feb Mon Monitoring and Evaluating Rangeland Condition A. goals and system design B. traditional monitoring and evaluation design C. new approaches Obtain LECTURE NOTES (including 2008 exam) from Library Course Reserves, using password “rangelands” Lecture 1. Rangelands a. ecosystem components b. concerns c. management practices d. range management discipline Ecosystem Components: atmosphere: greenhouse gases soils: generally low fertility and shallow, plants: generally herbaceous and/or shrubby, few trees (<20ft3/acre/yr) herbivores: wild and domestic carnivores: wild and domestic humans: private, communal and/or public based-decisions about allocation of resources Extent of Rangelands: about 50% of land surface, and about 50% of that is grazed by livestock Table from from Asner et al. 2004. Biome statistics of land area, managed grazing, and climatology Percent of global land area Area grazed (M km2) Percent biome grazed Mean grazing area AET Mean biome AET Grazing: biome AET Grazing: biome MAPb Grazing: biome MAT 15 9.48 49.1 595 781 0.76 0.69 0.90 14.22 11 7.68 54.0 321 401 0.80 0.75 0.59 Desert 15.45 12 1.97 12.8 71 88 0.81 0.82 0.95 Dense shrubland 5 2.73 45.4 314 339 0.93 0.90 0.96 13 1.72 9.9 1114 1141 0.98 0.97 0.87 Temperate broadleaf evergreen forest/woodlands 1.26 1 0.71 56.0 821 818 1.00 1.00 1.00 Tropical deciduous forest/woodland 5.96 5 1.20 20.2 935 859 1.09 1.04 1.04 Boreal evergreen forest/woodland 6.36 5 0.08 1.2 424 354 1.20 0.78 3.03 Open shrubland 9 3.98 32.9 297 243 1.22 1.22 1.26 2.18 2 0.02 1.1 435 352 1.24 1.45 0.45 Temperate deciduous forest/woodland 5.10 4 1.49 29.1 793 611 1.30 1.62 1.32 Temperate needleleaf evergreen forest/woodland 3.62 3 0.76 20.9 689 463 1.49 1.59 2.23 15.68 12 1.26 8.0 642 369 1.74 1.50 1.67 7.32 6 0.17 2.3 431 247 1.75 1.74 0.01 Evergreen/deciduous forest/woodland Tundra Biomes are ordered by the ratio of actual evapotranspiration (AET) in grazed portions of each biome compared to the biome mean AET. Source data: Ramankutty & Foley (160), Hearn et al. (8), and Goldewijk et al. (1). b Other abbreviations are MAP, mean annual precipitation, and MAT, mean annual temperature. P1: GCE a LaTeX2e(2002/01/18) 12.09 Boreal deciduous forest/woodland AR227-EG29-08.sgm 6.01 17.43 Tropical evergreen forest/woodland AR227-EG29-08.tex 19.31 Grassland/steppe AR Savanna ASNER ET AL. Biomea Total area (M km2) 266 TABLE 1 16 Oct 2004 10:42 Annu. Rev. Environ. Resourc. 2004.29:261-299. Downloaded from arjournals.annualreviews.org by STEWARD OBSERVATORY on 11/25/08. For personal use only. Rangeland Concerns: Atmosphere - temperature - precipitation Soil - basis for primary production - erosion is source of water pollution Plants - basis for herbivores - supports human needs and desires Herbivores - basis for carnivores - supports human needs and desires Carnivores - some herbivore control - supports human needs and desires Humans - health - security - wealth and equity Livestock use of low productivity (arid) and high productivity (mesic) lands differes between developed and developing countries (Table 4 and Map 4 from FAO 2006). Implications for future land uses as mesic areas are converted to cropland. 328 1 200 – 1 600 1 600 – 2 000 0 – 400 400 – 800 National boundaries Other dominant land use type Source: Estimated net primary productivity (Prince and Goward, 1995) is displayed in cells for which at least one-third of the area is used as pasture (FAO,2006f). 800 – 1 200 2 000 – 5 000 Grams of carbon per square meter per year Map 4 Estimated net primary productivity in areas dominated by pasture livestock’s long shadow Annex 2 - Tables Table 3 Grassland area and share of total land covered by grassland in selected regions and countries Region/Country Total area of grassland Percentage of total area as grassland (km2) North America 7 970 811 41.1 Latin America and the Caribbean 7 011 738 34.2 Western Europe 1 216 683 32.5 Eastern Europe 293 178 25.2 Commonwealth of Independent States 6 816 769 31.1 West Asia and North Africa 1 643 563 13.6 Sub-Saharan Africa and South Africa 7 731 638 31.5 661 613 14.9 East and Southeast Asia 5 286 989 32.9 Oceania 5 187 147 58.1 Australia 4 906 962 63.6 China 3 504 907 37.3 371 556 11.7 2 179 466 25.6 Developed Countries 19 803 555 35.4 Developing Countries 18 369 118 24.0 World 38 172 673 28.8 South Asia India Brazil Source: Own calculation. Table 4 Estimated net primary productivity in areas dominated by pasture Region/Country Commonwealth of Independent States Latin America and the Caribbean Mean net Area below 1200 primary (gr Carbon per m2 productivity and year) Area above 1200 (gr Carbon per m2 and year) km2 % km2 % 726.5 3 057 780 96.7 105 498 3.3 1254.6 2 297 740 47.4 2 548 350 52.6 Western Europe 948.8 766 276 72.4 291 848 27.6 West Asia and North Africa 637.0 1 800 730 92.7 142 480 7.3 1226.1 5 066 060 42.8 6 777 050 57.2 Sub-Saharan Africa and South Africa South Asia 708.2 224 012 79.0 59 504 21.0 1158.1 652 412 43.0 863 624 57.0 North America 718.5 4 090 920 90.9 411 074 9.1 Eastern Europe 1080.4 152 280 72.0 59 261 28.0 Oceania 1189.3 143 905 58.3 102 736 41.7 Australia 1065.6 3 895 680 69.4 1 721 570 30.6 Brazil 1637.7 37 424 1.3 2 893 640 98.7 India 385.9 131 927 93.8 8 682 6.2 China 774.5 2 644 020 86.8 402 534 13.2 East and Southeast Asia Developed 871.0 12 473 500 79.8 3 153 290 20.2 Developing 1153.1 12 486 800 48.5 13 233 500 51.5 World 1046.5 24 960 300 60.4 16 386 790 39.6 Note: Summary of Map 4, Annex 1. Source: Own calculation. 363 Livestock’s role in climate change and air pollution Table 3.12 Role of livestock in carbon dioxide, methane and nitrous oxide emissions Gas Source Mainly related to extensive systems (109 tonnes CO2 eq.) Mainly related to intensive systems (109 tonnes CO2 eq.) Percentage contribution to total animal food GHG emissions CO2 Total anthropogenic CO2 emissions Total from livestock activities N fertilizer production 0.04 0.6 on farm fossil fuel, feed ~0.06 0.8 on farm fossil fuel, livestock-related ~0.03 0.4 deforestation (~0.7) 34 cultivated soils, tillage (~0.02) 0.3 cultivated soils, liming (~0.01) 0.1 desertification of pasture processing 0.01 – 0.05 transport ~0.001 24 (~31) ~0.16 (~2.7) (~1.7) (~0.1) 1.4 0.4 CH4 Total anthropogenic CH4 emissions 5.9 Total from livestock activities 2.2 enteric fermentation 1.6 0.20 25 manure management 0.17 0.20 5.2 N2O Total anthropogenic N2O emissions 3.4 Total from livestock activities 2.2 N fertilizer application ~0.1 1.4 indirect fertilizer emission ~0.1 1.4 leguminous feed cropping ~0.2 2.8 manure management 0.24 0.09 4.6 manure application/deposition 0.67 0.17 12 indirect manure emission ~0.48 ~0.14 8.7 Grand total of anthropogenic emissions 33 (~40) Total emissions from livestock activities ~4.6 (~7.1) Total extensive vs. intensive livestock system emissions 3.2 (~5.0) 1.4 (~2.1) Percentage of total anthropogenic emissions 10 (~13%) 4 (~5%) Note: All values are expressed in billion tonnes of CO2 equivalent; values between brackets are or include emission from the land use, land-use change and forestry category; relatively imprecise estimates are preceded by a tilde. Global totals from CAIT, WRI, accessed 02/06. Only CO2, CH4 and N2O emissions are considered in the total greenhouse gas emission. Based on the analyses in this chapter, livestock emissions are attributed to the sides of the production system continuum (from extensive to intensive/industrial) from which they originate. 113 Livestock’s long shadow Table 3.13 Global terrestrial carbon sequestration potential from improved management Carbon sink Potential sequestration (billion tonnes C per year) Arable lands 0.85 – 0.90 Biomass crops for biofuel 0.5 – 0.8 Grassland and rangelands 1.7 Forests 1–2 Source: adapted from Rice (1999). Reversing soil organic carbon losses from degraded pastures Up to 71 percent of the world’s grasslands were reported to be degraded to some extent in 1991 (Dregne et al. 1991) as a result of overgrazing, salinization, alkalinization, acidification, and other processes. Improved grassland management is another major area where soil carbon losses can be reversed leading to net sequestration, by the use of trees, improved species, fertilization and other measures. Since pasture is the largest anthropogenic land use, improved pasture management could potentially sequester more carbon than any other practice (Table 4-1, IPCC, 2000). There would also be additional benefits, particularly preserving or restoring biodiversity. It can yield these benefits in many ecosystems. In the humid tropics silvo-pastoral systems (discussed in Chapter 6, Box 6.2) are one approach to carbon sequestration and pasture improvement. In dryland pastures soils are prone to degradation and desertification, which have lead to dramatic reductions in the SOC pool (see Section 3.2.1 on livestock-related emissions from cultivated soils) (Dregne, 2002). However, some aspects of dryland soils may help in carbon sequestration. Dry soils are less likely to lose carbon than wet soils, as lack of water limits soil mineralization and therefore the flux of carbon to the atmosphere. Consequently, the residence time of carbon in dryland soils is sometimes 118 even longer than in forest soils. Although the rate at which carbon can be sequestered in these regions is low, it may be cost-effective, particularly taking into account all the side-benefits for soil improvement and restoration (FAO, 2004b). Soil-quality improvement as a consequence of increased soil carbon will have an important social and economic impact on the livelihood of people living in these areas. Moreover, there is a great potential for carbon sequestration in dry lands because of their large extent and because substantial historic carbon losses mean that dryland soils are now far from saturation. Some 18–28 billion tonnes of carbon have been lost as a result of desertification (see section on feed sourcing). Assuming that two-thirds of this can be re-sequestered through soil and vegetation restoration (IPCC, 1996), the potential of C sequestration through desertification control and restoration of soils is 12–18 billion tonnes C over a 50 year period (Lal, 2001, 2004b). Lal (2004b) estimates that the “eco-technological” (maximum achievable) scope for soil carbon sequestration in the dryland ecosystems may be about 1 billion tonnes C yr-1, though he suggests that realization of this potential would require a “vigorous and a coordinated effort at a global scale towards desertification control, restoration of degraded ecosystems, conversion to appropriate land uses, and adoption of recommended management practices on cropland and grazing land.” Taking just the grasslands in Africa, if the gains in soil carbon stocks, technologically achievable with improved management, were actually achieved on only 10 percent of the area concerned, this would result in a SOC gain rate of 1 3­28 million tonnes C per year for some 25 years (Batjes, 2004). For Australian rangelands, which occupy 70 percent of the country’s land mass, the potential sequestration rate through better management has been evaluated at 70 million tonnes C per year (Baker et al., 2000). Overgrazing is the greatest cause of degradation of grasslands and the overriding humaninfluenced factor in determining their soil carbon Rangeland Management Portion of RNR 384 Exam #1, Spring 2008, 35 total points 1. A rangeland ecosystem includes soils, plants, herbivores, carnivores and humans. How do rangeland soils and rangeland vegetation different from other types of land like forests or cropland? (4 points) ANSWER: Rangeland soils are less deep and less fertile Rangeland vegetation is wild and not cultivated, and it more herbaceous and shrubby than forests. 2. An argument can be made that the demand for rangeland managers is greater in Asia than in the United States because there is a greater increase in the amount of livestock production per capita. What critical piece of information about the source of livestock forage strengthens this argument? (3 points) ANSWER: A greater percent of the livestock diet comes from rangeland in Asia than in the United States. 3. There are three types of meristems in a grass plant: apical, axillary, and intercalary. Which type of meristem makes the greatest contribution to the rate of re-growth following defoliation? (2 points) ANSWER: intercalary, by cell division without cell differentiation Which type of meristem makes the greatest contribution to total biomass production of the plant? (2 points) ANSWER: axillary by developing new tillers After defoliation of the apical meristems, the axillary meristems become more active. What conditions will maximize the growth in those ancillary meristems? (2 points) ANSWER: abundant water, nutrients and light 4. According to this figure (below), the weight gain per animal and weight gain per area decrease after reaching some important level of grazing intensity. The authors of this figure suggest that the capture of solar energy contributes to the shape of these curves. Herbivore Production Why does the capture of solar energy capture decline as grazing intensity increases? (3 points) per area per animal Grazing Intensity ANSWER: greater intensity of defoliation reduces the leaf area of plants, and the reduced leaf area reduces the ability to capture solar energy and convert it to chemical energy stored in plants 5. The animal unit concept is commonly applied to estimate forage demand by herbivores and to set sustainable herbivore stocking rates. We discussed 3 general reasons why the animal unit concept of fixed quantity of intake per body weight may not fully represent forage intake on rangelands. One of those reasons is the nonlinear relationship between animal metabolism and body weight. Another reason is that diet selection will vary among animals. What is the third reason? (2 points) ANSWER: forage quality 6. Given that diet selection varies among animals, why will forage consumption by cattle and elk not meet a consumption rate of 2% of body weight per day that is needed to maintain body weight if the vegetation is dominated by shrubs and trees. (3 points) ANSWER: these animals prefer a diet of grass and herbaceous plants and will avoid shrubs and trees 7. Estimate the grazing capacity for an area that is grazed by cattle for 100 days each year. The area covers 5000 hectares (ha) that produces 350 kg/ha of forage per year. The allowable use of the forage is 30%. Fifty percent of the area has a slope of 0%, and fifty percent of the area has a slope of 20% (requiring a 30% reduction). What is the grazing capacity for cattle in this situation if they consume 9.1 kg/animal/day (5 points)? ANSWER: 490 cattle Available: 350 kg/ha x 5000 ha x 0.3 allowable use = 525,000 kg Demand: 9.1 kg/animal/day x 100 days = 910 kg/animal Slope reduction: (0.5 x 1.0)+(0.5 x 0.7) = 0.85 Capacity: (525,000 kg / 910 kg/animal) x 0.85 adjustment = 490.38 animals for 100 days 8. After making the grazing capacity estimate in Question #7 (above) you will need to monitor the situation to make sure that your estimate is accurate. This monitoring effort should be simple, efficient, repeatable among observers, and repeated over time. Why is it important to repeat monitoring protocols over time? (2 points) ANSWER: by definition monitoring is a measurement effort repeated over time, and it is important because the conditions of plant growth change between years, and therefore available forage and type of forage changes over time. Why is it important to have monitoring protocols that are repeatable among observers? (2 points) ANSWER: Because monitoring efforts happen over time, there may be change in personnel, and the results of performing the monitoring should not differ simply because the personnel change. 9. In the assigned reading “Future Social Changes and the Rangeland Manager”, the authors suggest that there are 2 parts to being a professional. One part is being paid for providing services. What is the second part? (2 points) ANSWER: Providing specialized skills and knowledge. 10. Rangeland managers and all natural resource managers strive to understand how to maintain use impacts to levels that are sustainable for long periods of time. We know that the impacts can vary among types of use. What are the other 3 aspects of use that managers address when establishing sustainable use levels? (3 points) ANSWER: intensity, season, and frequency of use References Asner, G.P, A.J. Elmore, L.P. Olander, R.E. Martin, and A.T. Harris. 2004. Grazing systems, ecosystem response, and global change. Annual Review of Environment and Resources 29: 261-299. Dyksterhuis, E.J. 1949. Condition and management of range land based on quantitative ecology. Journal of Range Management 2:104-115. FAO (Food and Agriculture Organization). 2006. Livestock’s Long Shadow: Environmental Issues and Options. United Nations. http://www.fao.org/docrep/010/a0701e/a0701e00.HTM. Heitschmidt, R.K. and J.W. Stuth (eds.). 1991. Grazing Management: An Ecological Perspective. Timber Press. Holechek, J.L., R.D. Pieper and C.H. Herbel. 1998. Rangeland Management: Principles and Practices. Prentice Hall. 3rd Edition. McClaran, M.P., Brunson, M. W., and Huntsinger, L. 2001. Future social changes and the rangeland manager. Rangelands 23(6): 33-35. McClaran, M.P. 1995. Desert Grasses and Grasslands. In, M.P. McClaran and T.R. Van Devender (eds.). 1995. The Desert Grassland. University of Arizona Press. pgs. 1-30. Task Group on Unity in Concepts and Terminology. 1995. New concepts for assessment of range condition. Journal of Range Management 48:271-282. Westman, W.E. 1978. Measuring the inertia and resilience of ecosystems. Bioscience 28:705710. Westoby, M., B. Walker and I. Noy-Meir. 1989. Opportunistic management for rangelands not at equilibrium. Journal of Range Management 42:266-74. ...
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