Effects of Age, Stand Density, and Fertilizer Application on Bear Oak Reproduction Author(s): Leonard J. Wolgast and Benjamin B. Stout Source: The Journal of Wildlife Management, Vol. 41, No. 4 (Oct., 1977), pp. 685-691 Published by: Wiley on behalf of the Wildlife Society Stable URL: https://www.jstor.org/stable/3799990 Accessed: 01-11-2023 18:39 +00:00 REFERENCES Linked references are available on JSTOR for this article: https://www.jstor.org/stable/3799990?seq=1&cid=pdf-reference#references_tab_contents You may need to log in to JSTOR to access the linked references. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at https://about.jstor.org/terms Wiley, Wildlife Society are collaborating with JSTOR to digitize, preserve and extend access to The Journal of Wildlife Management This content downloaded from 73.84.198.143 on Wed, 01 Nov 2023 18:39:35 +00:00 All use subject to https://about.jstor.org/terms EFFECTS OF AGE, STAND DENSITY, AND FERTILIZER APPLICATION ON BEAR OAK REPRODUCTION LEONARD J. WOLGAST, Department of Horticulture and Forestry, Cook College, Rutgers University, New Brunswick, New Jersey 08903 BENJAMIN B. STOUT, Department of Biological Sciences, Rutgers University, New Brunswick, New Jersey 08903 Abstract: Bear oak (Quercus ilicifolia) is widely distributed in the northeastern and mid-Atlantic states. It grows on poor sites where its acorns are important in the diets of many wildlife species. Mature acorns were first produced by bear oak sprouts 3 growing seasons old. Stand density, at the levels measured in this study, had relatively little effect on the acorn production. Fertilizer application and age interacted significantly (P < 0.05) in their influence on acorn yields. Addition of 896 kg/ha of 5-10-5 applied in late March resulted in increased production of pistillate flowers, immature acorns, and mature acorns in 9-year-old and 13-year-old trees, but had relatively little influence on 5-year-old trees. J. WILDL. MANAGE. 41(4):685-691 Bear oak occurs from southern Maine, New York and Pennsylvania, south to West Virginia, western North Carolina, and Vir- ginia (Little 1953:332). This species oc- curs on acid, rocky or sandy, sterile soils, especially on dry sandy barrens and rocky hillsides, from sea level to about 900m (Society of American Foresters 1967:20). Wild turkeys (Meleagris gallopava), ruffed grouse (Bonasa umbellus), bobwhite quail ( Colinus virginianus), gray squirrels (Sciu- rus carolinensis), white-tailed deer (Odo- coileus virginianus) and black bears ( Ursus americanus) feed extensively on bear oak acorns. In addition, the acorns also are uti- lized by many nongame birds, particularly jays and woodpeckers (Edminster 1947: 128, Martin et al. 1951:309, Van Dersal 1938:211). The infertile soils of the outer coastal plain do not produce a variety of high quality foods for wildlife. Bear oak is im- portant throughout the whole coastal plain physiographic province (Widmer 1964: 91), in which over half of New Jersey's for- est is located, but is especially important on the two-thirds of that province known as the outer coastal plain. This paper deals with management of bear oak for acorn production on the outer coastal plain. The overstory vegetation on the study area is exclusively pitch pine (Pinus rigida). The understory is primarily bear oak with much lesser amounts of dwarf chinkapin oak (Quercus prinoides) and blackjack oak (Quercus marylandica). The shrub and herb layer contains highbush blueberry (Vaccinium corymbosum), low- bush blueberry (Vaccinium vacillans) and aromatic wintergreen (Gaultheria procum- bens). Occasional seedlings of sassafras (Sassafras albidum), black oak (Quercus velutina) and red maple (Acer rubrum) are also present. Since acorns are a highly concentrated food, bear oak may play a vital role in wildlife nutrition on the area. Better than normal white-tail fawn produc- tion and antler development are associated with years of high acorn yields. In years of poor acorn crops, many 1.5 year old bucks do not grow antlers large enough to allow legal harvest (R. C. Lund, personal communication). The importance of bear oak acorns in the diet of south Jersey deer has been discussed by Little et al. (1958: 17-22) and McDowell (1975:19). The objective of this study was to deter- mine the influence of age, stand density, and fertilizer application on flowering, fruit set, and fruit development in bear oak. J. Wildl. Manage. 41 (4):1977 685 This content downloaded from 73.84.198.143 on Wed, 01 Nov 2023 18:39:35 +00:00 All use subject to https://about.jstor.org/terms 686 AGE, DENSITY, AND FERTILIZER EFFECTS ON BEAR OAK* Wolgast and Stout METHODS A major source of variation in acorn pro- duction in bear oak was on a tree-to-tree and stand-to-stand rather than a regional basis (Wolgast 1972:23-27). Therefore, our experiments were conducted at a single location within the outer coastal plain in southern New Jersey. Sprouts resulting from clear cuts were used to ascertain the earliest age at which acorns are produced. Two 0.005-ha plots in a 10-year-old mixed stand were clear cut during the winter of 1969. The stands on the plots were comprised mostly of bear oak and dwarf chinkapin oak. In a separate experiment to test the ef- fects of age, stand density, and fertilization on mast production, we used a full factorial design (3 x 4 x 2) with replication. In each of 3 age-classes of clumps at the start of the experiment, 16 0.01-ha plots were thinned to 1 of 4 levels of stand density and one-half of these plots were fertilized. At the start of the experiment (fall of 1969) clumps were 5, 9, and 13 years old. The stand densities after an initial thinning were 2,500-3,700 clumps/ha, 3,900-4,800 clumps/ha, 4,700-5,100 clumps/ha, and 5,500-6,600 clumps/ha. The fertilized plots received 896 kg/ha of 5-10-5 fertilizer dur- ing the last week of March 1970, 1971, and 1972. The fertilizer had a minimum guaran- teed analysis of 5 percent nitrogen, 10 per- cent available phosphoric acid as P205, and 5 percent soluble potash as K20. In those plots receiving fertilizer, the fertilizer was scattered evenly over the entire plot. The following responses were measured: (1) The number of pistillate flowers on each of 2 clumps selected at random within each of the 48 plots during May of 1970. Flowers were counted on these same clumps in 1971. (2) The total number of immature acorns in all 48 plots during the falls of 1970 and 1971. (3) The total num- Table 1. Analysis of variance of numbers of pistillate flowers-May, 1970. Source of variation df M.S. ( X 10) F P Total 47 Age 2 4.314 4.31 <0.05 Density 3 2.532 2.53 Fertilizer 1 2.014 2.01 A x D 6 1.073 1.07 A x F 2 4.663 4.66 <0.05 D X F 3 0.426 0.43 AX DX F 6 1.242 1.24 Replicates 24 1.001 ber of fully developed acorns in all 48 during the falls of 1970 and 1971. (4) total weight of mature acorns produc each plot during the fall of 1971. These data were treated by the appro ate analysis of variance. RESULTS In the first experiment flowers appeared on bear oak sprouts at the beginning of the second growing season, indicating that floral morphogenesis took place during the initial season. These plants produced 5,193 immature acorns on 166 clumps contain- ing 1,333 stems with a crown area of ap- proximately 0.004 ha. There ultimately de- veloped 808 mature acorns in 1972. The first mast crop therefore is produced after 3 growing seasons. Little et al. (1958:20) reported mature acorns on bear oak sprouts 3 or 4 years old. The first response measured in the sec- ond experiment was the 1970 production of pistillate flowers. Significant effects of age and of age x fertilizer interaction are in- dicated (P < 0.05, Table 1). The nature of this interaction is depicted in Fig. 1. The 1971 pistillate flower data were col- lected 1 full year after the first fertilization. There were significant (P < 0.05) effects of fertilizer, age by fertilizer interaction, and age by density interaction (Table 2). The middle aged trees responded best in terms J. Wildl. Manage. 41(4):1977 This content downloaded from 73.84.198.143 on Wed, 01 Nov 2023 18:39:35 +00:00 All use subject to https://about.jstor.org/terms AGE, DENSITY, AND FERTILIZER EFFECTS ON BEAR OAK - Wolgast and Stout 687 Fertilized xN Unfertilized i-- w W e .lo 81 ijj i!1i zC 2 u- "fI IA y " 5 9 13 AGE in years Fig. 1. Number of pistillate flowers produced in 1970 in- cluding the 95 percent confidence intervals. of female flower production after 2 seasons of fertilizer application (Fig. 2). The higher 2 densities responded better to ferti- lizer than the lower 2 densities (Fig. 3). Fertilizer was applied before the 1971 flower buds were initiated during the late spring of 1970. The differences in flower numbers between 1970 and 1971 data were probably due to this fact. The 1970 flower Table 2. Analysis of variance of numbers of pistillate flowers-May, 1971. Source of variation df M.S. ( X10) F P Total 47 Age 2 1.020 1.04 Density 3 0.845 0.86 Fertilizer 1 7.579 7.75 <0.05 A X D 6 1.103 1.13 A x F 2 4.152 4.25 <0.05 D X F 3 3.456 3.54 <0.05 AX DX F 6 0.812 0.83 Replicates 24 0.977 14C Fertilized N Unfertilized ui sI- w 5 9 13 AGE in Fig. 2. Numbers of pistillate flowers produced in 1971 in- cluding the 95 percent confidence intervals. counts can have been influenced only by the effects of fertilizer on shoot elongation, although this response was not measured. The 1971 flower counts were also affected Fertilized .' Unfertilized m' Z 100 o 60 w 3100 4350 4900 6050 Density in Clumps p Fig. 3. Numbers of pistillate flowers produced in 1971 in- cluding the 95 percent confidence intervals. J. Wildl. Manage. 41(4):1977 This content downloaded from 73.84.198.143 on Wed, 01 Nov 2023 18:39:35 +00:00 All use subject to https://about.jstor.org/terms 688 AGE, DENSITY, AND FERTILIZER EFFECTS ON BEAR OAK *Wolgast and Stout Table 3. Analysis of variance of numbers of immature acorns-Fall, 1970. Source of variation df M.S. ( X106) F P Total 47 Age 2 12.504 2.40 Density 3 6.144 1.18 Fertilizer 1 6.580 1.26 A X D 6 2.571 0.49 A x F 2 27.607 5.31 <0.05 D x F 3 0.863 0.17 AX DX F 6 2.719 0.52 Replicates 24 5.201 by elongation in addition to the number of flower buds initiated. The numbers of immature acorns pro- duced in 1970 showed a significant age x fertilizer interaction (Table 3). This (Fig. 4) was similar to the 1971 pistillate flower data (Fig. 1). The numbers of immature acorns in 1971 showed that there is a highly significant age effect and a significant age Table 4. Analysis of variance of numbers of immature acorns-Fall, 1971. Source of variation df M.S. (X107) F P Total 47 Age 2 19.241 9.16 <0.05 Density 3 3.897 1.85 Fertilizer 1 27.251 12.94 <0.01 A X D 6 1.019 0.48 A x F 2 11.040 5.24 <0.05 D X F 3 1.582 0.75 AX DX F 6 2.069 0.98 Replicates 24 2.106 x fertilizer interaction (Table 4 again (Fig. 5) it was apparent tha oaks responded more positively younger age class. The density x fertilizer interacti was present when these immatur were flowers (Fig. 3) was no longer Fertilized -- Unfertilizedin- 6 Z" 5 9 13 AGE in years Fig. 4. Number of immature acorns produced in 1970 in- cluding the 95 percent confidence intervals. Fertilized ' - 26 Unfertilized M - 2 22 1aJ16 e 14 1 5 9 13 AGE Fig. 5. Numbers of immature acorns produced in 1971 in- cluding the 95 percent confidence intervals. J. Wildl. Manage. 41(4):1977 This content downloaded from 73.84.198.143 on Wed, 01 Nov 2023 18:39:35 +00:00 All use subject to https://about.jstor.org/terms AGE, DENSITY, AND FERTILIZER EFFECTS ON BEAR OAK* Wolgast and Stout 689 Table 5. Analysis of variance of number of mature acorns- Fall, 1970. Source of variation df M.S. (X10) F P Total 47 Age 2 88.829 9.13 <0.01 Density 3 3.159 0.53 Fertilizer 1 0.320 0.03 A x D 6 3.514 0.36 A x F 2 17.833 1.83 D X F 3 16.038 1.65 Ax DX F 6 15.618 1.60 Replicates 24 9.733 cant. The greater number of pistillate flow- ers at the higher 2 densities in fertilized plots may not have been pollinated as readi- ly as the fewer numbers of flowers present in the unfertilized plots at these 2 densities, or the flower result may have been due to Type I error (Sokal and Rohlf 1969:156). A comparison of Figs. 4 and 5 illustrates the relative sizes of the 1970 and 1971 imma- ture acorn crops. The mean number of im- mature acorns per 0.01-ha plot irrespective of treatment in 1970 was 3,932, whereas in 1971 it increased to 12,674. The number of mature acorns produced in 1970 indicated a significant age effect Table 6. Analysis of variance of numbers of mature acorns- Fall, 1971. Source of variation df M.S. (X106) F P Total 47 Age 2 6.288 1.61 Density 3 7.033 1.79 Fertilizer 1 6.956 1.77 A x D 6 1.585 0.40 A X F 2 20.080 5.11 <0.05 D x F 3 1.762 0.45 A X D X F 6 2.731 0.69' Replicates 24 3.933 (Table 5, Fig. 6), similar to that late flowers and immature acorns. These mature acorns were immature at the time of the first fertilizer application. No age x fertilizer interaction was expected since the number of flower buds initiated and the pollination success were complete before fertilizer was applied. The numbers of ma- ture acorns produced in 1971 show a sig- nificant age x fertilizer interaction (Table 6). It was the only significant effect (Fig. 7). Comparison of Figs. 7 and 4 indicates that, as expected, this interaction was very similar to that with regard to the produc- tion of immature acorns. Differences would 200 I,) z AGE in years 25 Fig. 6. Numbers of mature acorns produced in 1970 in- cluding the 95 percent confidence intervals. g 7 Fertilized VAl o Unfertilized 8 2 2L 5 9 13 AGE in y Fig. 7. Numbers of mature acorns produced in 1971 in- cluding the 95 percent confidence intervals. J. Wildl. Manage. 41(4):1977 This content downloaded from 73.84.198.143 on Wed, 01 Nov 2023 18:39:35 +00:00 All use subject to https://about.jstor.org/terms 690 AGE, DENSITY, AND FERTILIZER EFFECTS ON BEAR OAK" Wolgast and Stout Table 7. Analysis of variance of weights of mature acorns-- Fall, 1971. Source of variation df M.S. F P Total 47 Age 2 28.75 1.09, Density 3 44.40 1.69 Fertilizer 1 100.22 3.82 A x D 6 10.97 0.41 A X F 2 118.42 4.51 <0.05 D X F 3 14.13 0.53 AX DX F 6 20.41 0.77 Replicates 24 26.21 have occurred only if the varying treat- ments exerted their influence on the pro- portion of immature acorns which devel- oped into mature acorns. The 1971 weights of mature acorns showed a significant age x fertilizer inter- action (Table 7) very similar to that for 1971 mature acorn numbers (Fig. 7). Com- parison of Figs. 7 and 8 indicates that the fertilized acorns in all age classes tended to weigh more than an equal number of un- fertilized acorns. In the 1971 mature acorn crop 69,129 acorns produced by unfertilized trees weighed 74.31 kg (930 acorns/kg), whereas 87,402 acorns produced by ferti- lized trees weighed 105.52 kg (828 acorns/ kg). DISCUSSION Age and fertilizer interacted in their ef- fects on acorn productivity at all 3 stages of development-pistillate flowers, immature acorns, and mature acorns. Ferti- lizer exerted its greatest effect on bear oak stands that were at least 9 years old but failed to effect 5-year-old stands (Figs. 1, 2, 4, 5, 7, 8). Productivity in unfertilized stands declined between 5 and 13 years of age. Although fertilizer did not influence the mature acorn crop during the fall fol- lowing the first application, there was a positive response the following fall and, Fertilized %- Unfertilizedm-- ) 7 0 o ' w S4 J 3 0 z w 5 9 13 AGE in Fig. 8. Kilograms of mature acorns produced in 1971 in- cluding the 95 percent confidence intervals. based on immature acorn counts, this should be even greater after 2 growing sea- sons and 2 March applications of fertilizer. Differences in the total weight of mature acorns were even greater than differences in the total numbers produced. Several re- searchers have reported on the response to fertilizer of oaks (but not bear oak) (Det- wiler 1943:915, Farmer et al. 1970:132, Ward and Bowersox 1970:116, Auchmoody 1972:2-4) and other hardwoods and coni- fers (Hostetter 1943:88, Shoulders 1968: 194-95). Therefore, it is not surprising to find increased acorn yield in fertilizer treated bear oak. The cause of the age x fertilizer interaction cannot be determined from these studies. Stand density, measured as clumps-per- hectare, had relatively little influence on the amount of acorn production in bear oak. Interactions between stand density at the levels studied and both age and ferti- J. Wildl. Manage. 41(4):1977 This content downloaded from 73.84.198.143 on Wed, 01 Nov 2023 18:39:35 +00:00 All use subject to https://about.jstor.org/terms AGE, DENSITY, AND FERTILIZER EFFECTS ON BEAR OAK" Wolgast and Stout 691 lizer application were not significant in terms of acorn productivity. CONCLUSIONS To maximize the yield of acorns by bear oak, the land manager should develop a systematic plan of cutting back some old stands, while fertilizing other uncut older stands. The objective should be to maintain a high proportion of stands 5 to 7 years old or less. This would significantly increase food production for many species of wild- life. It would be especially valuable to white-tailed deer on New Jersey's outer coastal plain and in other areas where high quality winter food is in short supply. LITERATURE CITED AUCHMOODY, L. R. 1972. Effects of fertilizer- nutrient interactions on red oak seedling growth. U.S. Dept. Agric. For. Serv. Res. Paper NE-239. 5pp. DETWILER, S. B. 1943. Better acorns from a heavily fertilized white oak tree. J. For. 41( 12):915-916. EDMINSTER, F. C. 1947. The ruffed grouse. The Macmillan Co., New York. 385pp. FARMER, R. E., JR., C. W. BENGTSON, AND J. W. CURLIN. 1970. Response of pine and mixed hardwood stands in the Tennessee Valley to nitrogen and phosphorus fertilization. For. Sci. 16(2):130-136. HOSTETTER, L. K. 1943. The use of fertilizer in a walnut orchard. Northern Nut Growers Assoc. 34th Annu. Rep. 126pp. LITTLE, E. L. 1953. Check list of native and naturalized trees of the United States. U.S. Dept. Agric. Handb. 41. 472pp. LITTLE, S., G. R. MOORHEAD, AND H. A. SOMES. 1958. 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WIDMER, K. 1964. The geology and geography of New Jersey. D. Van Nostrand Co., Inc., Princeton, N.J. 193pp. WOLGAST, L. J. 1972. Mast production in scrub oak (Quercus ilicifolia) on the coastal plain in New Jersey. Ph.D. Thesis. Rutgers Univ., New Brunswick, N.J. 137pp. Received 17 February 1976. Accepted 13 July 1977. J. Wildl. Manage. 41 (4):1977 This content downloaded from 73.84.198.143 on Wed, 01 Nov 2023 18:39:35 +00:00 All use subject to https://about.jstor.org/terms