BROWSE PRODUCTION AND UTILIZATION DURING 17 YEARS OF REGENERATION IN A WHITE SPRUCE FOREST 1

Transcription

1 BROWSE PRODUCTION AND UTILIZATION DURING 17 YEARS OF REGENERATION IN A WHITE SPRUCE FOREST 1 John 11. Stelfox Research Scientist, Canadian \Olildlife Service, Edmonton, Alberta ABSTRACT: A white spruce forest a1onp; the Athabasca Valley of western Alberta was logged in by c1earcutting strips 10 X 40 chains with intervening uncut strips measuring 5 X 40 chains. These un10gged strips were c1earcut 12 years later. Followlllg logging, all but one strip was scarified to flatten all vegetation and to disturb the ground surfact to produce a favorable seedbed for white spruce. Prior to logging the valley contained some 2.0 deer, 1.5 moose, 1.0 elk, 0.25 black and 0.10 grizzly bears per square mile. The number of browse plants decreased 44 percent during logging and scarification. Browse production decreased from 529 1bs/acre (green wt.) in the mature forest to 187 1bs/acre following logging and 101 1bs/acre after scarification. Six years after logging, the number of browse plants present was 30 oercent higher in the logged than the un10gged forest. Browse production in the scarified strips aged 1, 5, 9 and 17 years averaged 101, 860, 1438 and bs/acre The unscarified strip produced corresponding values of 187, 890, 1723, and bs/acre. The three main browse species comprised over 90 percent of the browse plants (rose 77 percent, willow 10 percent, poplar 7.5 percent) 17 years after logging. Poplar plants were 50 percent more abundant in the scarified area while willow 1 Paper for presentation at 10th North American Moose Workshop, Duluth Minnesota, March 25-29,

2 plants were 11 oercent more abundant in the unscarified area. Bi~!Same use was 18.6 and tmes llteater in the 17 "ear old scari~ied and unscarified areas resoectivelv than in the mature forest. Browse utilization in the scarified and unscarified strips of the 17 year old stands amounted to 1.4 and 12 percent of the available rose, 5.5 and 9.4 percent of the available willow and 5.7 and 4.4 of the available poplar. Browse in the 17 year old forest could theoretically support 0.13 moose, or 0.38 elk, or 1.36 deer per acre annually. Actually, the area supported 15 deer, 3 moose and 9 elk for a total 27 pieces of big game supported/sq. mile in the summer which is equivalent to moose, 0.01 elk and 0.02 deer per acre. Due to a lack of adequate winter cover the area only supported 0.5 big game/sq. mile in the winter. In 1956, a pulp-mill began logging a mature (125 to 150 year old) white spruce (Piceaglauca) forest in the foothills ot western Alberta near Hinton. Permanent range plots were established in a portion ot the mature forest Which would not be logged, and in two logged are&ll. Originally, two-thirds ot the forest was removed by clear-cut logging in strips 10 X 40 chains (20 X 804 meters). The logged strips were then scarified to flatten all remaining vegetation and to disturb the ground surfacs to produce a tavorable seedbed for whits spruce. One logged strip was maintained in an unscaritied condition. Twelve years later, the intervening residual etrips of mature timber (5 X 40 chains) were logged thus removing all mature timber except for narrow strips around each of four small lakes. Big game range data W&ll gathered from six sample areas, two in the 136

3 mature white spruce forest, two in a logged-over strip, and two in an adjacent scarified logged strip. The two logged strips were separated by a residual strip of mature timber 5 X 40 chains. Each sample area consisted of five replications, each containing six potential grid rows (from which three rows were selected at random) plus the grid line between replications. Each of the 15 selected grid rows per sample contained seven sample plots (9.6 square feet) spaced 30 feet apart in a straight line. Each sample encompassed an area approximately 60 X 350 meters. A total of 210 plots were established for each of the three areas studied (105 plots per sample), see Stelfox (1962). Big game species abundance and distribution were calculated from visual aerial and ground surveys, residual strip ''beat-out'' counts, pellet group and track counts. An estimate of the big game population immediately prior to logging activities in 1956 was 2.0 deer, 1.5 moose, 1.0 elk, 0.25 black bear, and 0.10 grizzly bear per square mile. The annual precipitation was 56.5 ems. Rainfall accounted for 40.2 cms and snowfall for 16.3 ems. Browse weight and utilization were gathered by clipping and weighing the green twigs (up to.66 ems diameter) from 22 plots for each species on a gram hand-scale. The data presented here refers only to stem production and does not include leaf production. Where part of the browse forage was utilized, an estimate of the percent and weight of the current year's growth utilized was recorded and added to the weight of vegetation clipped to estimate the total production. Eight photopoints were established to provide visual evidence of gross changes in deciduous and coniferous cover in the regenerating logged strips and the mature forest. Numbers of browse plants refer to actually numbers of plants rather than 137

4 stems. In the case of willows, each plant may consist of several stems. Numbers of woody plants decreased as a result of logging to about 56 percent of their number in the un logged forest. However, six years after logging their numbers had more than doubled in the logged strips and they were about 30 percent more numerous than in the unlogged forest. Seventeen years after logging, woody plant numbers were three times greater in the logged areas than in the mature forest. At that time there were almost 25 percent more browse plants in the unscarified than in the scarified logged areas. The three main species: rose, willow and poplar canprised fran 92 to 96 percent of the browse plants in the logged and unlogged forest. Rose comprised 77 percent of the browse plants in both the scarified and unscarified areas 17 years after logging. Willow and balsam poplar comprised 10.0 and 7.5 percent of browse plants respectively. Poplar plants were 50 percent more numerous in the scarified than in the unscarified area. Conversely, willows were 11 percent more numerous in the unscarified area. White spruce plants numbered 9,094 and 3,068 per acre in the scarified and unscarified strips respectively, 17 years after logging. Six years after logging there were la7 and 422 spruce seedlings per acre respectively compared to only ll3 seedlings per acre in the mature forest. Poplar and willow heights averaged 60 and 30 inches respectively, 17 years after logging compared to 24 and 30 inches during the fifth year and 6 inches during the first year after logging. There were 9 and 17 percent of the poplar that were taller than 10 feet in year 17, whereas none of the willow exceeded 10 feet in the scarified or unscarified areas (Table 1). The browse species which contributed the most to big game forage in

5 year 17 were rose, willow and poplar in that order (Table 2). Rose received 10.4 and 12.1 percent utilization in the scarified and unscarified areas and comprised 76.h and 77.1 percent of the browse plants respectively. Willows received 5.5 and 9.4 percent utilization and comprised 10.3 and 9.4 percent of the browse plants. Poplar received 5.7 and 4.4 percent utilization and comprised 9.3 and 6.1 percent of the browse plants. Total browse production declined from 529 lbs/acre in the mature forest to 101 the year after logging and scarification, then increased to 860 in year 5, 1438 in year 9 and 1702 in year 17. Production in the unscarified area exceeded that in the scarified area each year since logging. By year 17 the unscarified area produced approx:ijnately one ton of available browse forage (green weight) per acre, about four times that of the mature forest (Table 1). Big game use was 18.6 and 64.8 times greater in the 17-year old scarified and unscarified strips respectively than in the mature forest. Deer and elk comprised all of the big game use in the 17-year old strips, whereas only moose use were observed in the mature forest. The logged areas supported more horse than big game use whereas no horse use was found in the mature forest (Table 1). The forage requirements and range carrying capacities for moose, elk and deer in the 17-year old regenerating white spruce forest are presented in Table 3. This table indicates that theoretically the 17-year old logged area could annually support 0.13 moose, 0.38 elk, or 1.36 deer per acre. The daily forage requirements for the three native ungulates are from Teller (1972). In actual fact, the area supported 27 big game per square mile in the summer (15 deer + 3 moose + 9 elk), compared to only 0.5 per 139

6 square mile in the winter. The lack of adequate winter cover and shelter appears responsible for the light winter use. The importance of adequate winter cover and shelter for western Alberta has been stressed previously (Stelfox, Telfer and Lynch 1973, The Canadian Institute of Forestry, 1973). The Canadian Forestry Institute (1973) summarized this problem in the Camp I area when they stated p 194: " The second cut, years later, ["after the original cut of two-thirds of the are~ which removed sheltering timber had and will have a considerable effect on the game population-causing a sharp decline. But even then, the populations are unlikely to decline to the level which existed prior to logging. There is reason to believe the big game potential will again increase when some patches of regeneration reach sufficient height, over 20 feet, and density to provide cover. Excellent range conditions should then exist for years until most of the area becomes closed forest and forage production is again reduced." ACKNOWLELGEMENTS The cooperative assistance of Gerry Lynch, Wildlife Biologist, Alberta Fish and Wildlife Division, Hinton, Alberta, and Joe McGillis, Wildlife Technician, Canadian Wildlife Service, Edmonton, Alberta is gratefully ackn0i0l1edged. The author wishes to thank Edmund S. Telfer, Research Scientist, Canadian Wildlife Service for his helpful I!Uggestions and for reading this paper in my absence. 140

7 LITERATURE CITED Canadian Institute of Forestry, Rocky Mtn. Section Rocky Mountain Section assesses a controversial cut. The Forestry Chronicle 49(4): Stelfox, J.G Effects on big game of harvesting coniferous forests in western Alberta. Forestry Chronicle 38(1): Stelfox, J.G., E.S. Telfer and G.M. Lynch Effects of logging on wildlife. FiAh & Game Sportsman Fall 1973 Edition. Telfer, E.S Report on the establishment of range trend transects at Elk Island National Park. Typescript Progress Report, Canadian Wildlife Service, Edmonton, Alberta, 57 pp. 141

8 Table/. Browse production, height and utilization, and big game abundance in a mature white spruce forest (Camp Hirlton) ~efcre and after logging. I. N. II. P. S. Power Mature Year Forest 5 ca r. Unsee Years Years 5 ca r. Unsee Scar. Unsc. 17 Vea rs 5 ca r. Unsee Br'Jw:;e ~roduction (Pounds/aore) Green \,.Its. Up to 8.0 feoat s rq~'15i! % ijti I izatio:'1 Poplar wi II ow Ros(; Others Totals Spruce/acre ** Pop I a r IIi Ilow Rose Poplar & liillow Totals 20.7 I I ,3.3 I"". " " " "0." I ~ "5" "" f.5.0 3" I " I "9. I " "7 " " ".8 6. I " "15 21 I " "." 9." 10. " 12. I '-OW5 e & Spruce HeiSh'5 (inches) Poplar \Ji J low Rose Spruce "." " ".9 5. I 2.5 I a BIG GAME PER SQUARE MILE Mature Year Years 9 Years 15 Years ::J.!e r Moose Elk Totals Summer 'wi in te r Surr:mer \oj i n te r Summer Wir:ter Summer \.Ii n te r I " a a !)~e r Moose [J,; I-' Totals. r'shorse Year Ha t u re Sea r. Un'i c a PELLET GROUPS PER ACRE 3 Years 6 Yea rs Sea r. Uns c. Scar. Unsee a a a a a a " Years Sea r. Unsee 86.4 a a *65.0 is a ca!culated estimate ce.ived from trend in data from years 3 and 4. ~~ Nu~b~rs of spruce saplings per acre present dur:ng 17 years rege~eration that remained from prior to logging were 0 In ~carifjed. and 7 In unscarified areas..

9 Table~. * Forage production, utilization and diet composition of browse plants in a 17-year old logged white spruce forest, Camp I, N.W.P. & Power lease, Hinton, Species Pba *** Ssp *** Rac *** Sca *** Post-Logging Treatment Unscarified Unscarified Unscari fied Unscarified Production lbs/ kgs/ acre hectare % of Forage Produced I % I Uti lizatton lbs/ kgs/ acre hectare '<I <1 2 % Diet Composition P. I,~* I. I Others Unscarified Totals Unscarified ~ w * Forage production Is based on green weights. ** P.I... Preference Index % Diet Composition rforage-p roduced (fo-t~li) preference. The greater the value, the higher the *** Pba Populusbalsamtfera; Ssp -Salix species; Rac ROsa acicularis; Sca Shepherdia canadensis. N '"

10 Table 3. Forage requirements and range carrying capacities (50% utilization basis), for moose, elk and deer in a 17-y ear:.old reg:e'n eratin.g.'white spruce (orest, Camp I, Hinton, Alberta Species Ave. Live Wt. (all ages) Ibs. Daily Food Req u ire. ( I b s) (2.2 Ibs*1 100 I bs live wt.) Days-Use Possible Per Acre. Scar. Unscar.',Animals Acres Required Possible Per Animal Yr. 'long**/acre'" Sea r. Unscar; Year-long Sea r. Unscar. Moose Elk I Deer I , Dry weight basis ** Year-long is based on the assumption that most browsing by elk and deer occurs during the 210 day period from October I through April 30, with foraging primarily conffned to her~aceous vegetation during the remaining five months. For moose, year-long refers to 365 days assuming their yearlong diet is primari Iy browse. ~ -I=""