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Competition and individual size

This lab will observe the effects of competition on pine trees. All of the pine trees in each of the study areas were planted at the same time, and therefore are the same age. They are also known as "improved" trees. This means that they have been genetically selected from a few parent trees over two or more generations. Thus, these trees are similar in their genetic make-up.

There are three main factors that determine the rate of growth in trees: water, nutrients, and sunlight. All of the trees are on the same deep sandy soil. It is droughty and nutrient poor. Pines can grow under both of these conditions, so we will assume that competition for sunlight is the main factor responsible for the differences in the size of the trees. However, note that it is likely that competition for all three resources contributes to the size difference in the trees to some extent.

Experiment 1. Measure the circumference of 50 sand pine (Pinus clausa) trees along the road or other open area. Measure the circumference of 50 pine trees in the middle of the stand. Take the measurement at breast height (4½ feet or 1.4 m from the soil surface). Plot your results using histograms. Test the difference between your means with a t-test – see handout 5b. Discuss your results. What type of competition is this?

Experiment 2. Measure 100 longleaf pine (Pinus palustris) trees at random. Fifty will be from the area of high competition from hardwoods and 50 from the area where hardwood competition has been reduced by the use of fire. Determine the height (m) using a Merritt Hypsometer and the circumference at breast height (cm) with a tape. To use the Merritt Hypsometer, stand 66 feet from the tree that you wish to measure, plumb the hypsometer stick 25” from your eye. Line up the stick with the base of the tree (rather than stump height in this case), read the height on the scale, then multiply by 16 to get the height in feet. Report your data in SI (metric units - meters) see link below for metric converter. Note if the tree is in the open (O), or if hardwood trees shade it (S). Graph this information in the form of a scatter graph (see Fig. 1 below for example). Place height on the vertical axis and circumference on the horizontal axis, using different symbols or colors to represent the different populations (hardwood open, hardwood shaded, burnt area open, burnt area shaded). In addition, use histograms to graph the plants by height alone, and by circumference alone, again using different shading or colors to represent the different populations (hardwood open, hardwood shaded, burnt area open, burnt area shaded).  Discuss your results. Also use F and t-tests to see if the differences are statistically significant. Does competition effect growth height or circumference the most, or is it equal? What type of competition is this?

Figure 1. Example of a scatter graph.

Write up: Supplement your write up with information on sand pine and longleaf pine communities in the southeastern United States and on competition between pines and hardwoods. What type of management tool is used to reduce competition from hardwoods on pines?

Acknowledgments:

I would like to thank Dr. Alvin Diamond for his advice, suggestions and for providing me with his version of this lab.

References:

Smith, R. L. and T. M. Smith. 2001. Ecology and Field Biology (6th Ed.), Benjamin Cummings. Relevant sections of Chapter 12 and Chapter 14.

Links:

Metric converter: http://www.convert-me.com/en/

Sand pine: http://www.na.fs.fed.us/spfo/pubs/silvics_manual/Volume_1/pinus/clausa.htm

Longleaf pine: http://www.na.fs.fed.us/spfo/pubs/silvics_manual/Volume_1/pinus/palustris.htm

http://www.archives.state.al.us/emblems/st_tree.html

Data sheet for pine lab

Species of pine: Longleaf pine (Pinus palustris) Date: 09/17/13

Experimental group (circle one): Burnt area Hardwood area

#	Height (ft logs)	Height (ft)	Height (m)	Circumference (cm)	O or S	#	Height (ft logs)	Height (ft)	Height (m)	Circumference (cm)	O or S
1	1.8	28.8		45	S	26	1.8			49	O
2	2.0			52	O	27	3.1			82	O
3	1.75			51	O	28	1.6			49	O
4	2.3			66	O	29	2.3			67	O
5	2.0			80	O	30	2.2			72	O
6	2.5			71	O	31	2.3			64	O
7	2.8			58	O	32	2.7			86	O
8	2.5			65	O	33	3.0			80	O
9	2.4			65	O	34	3.1			88	O
10	3.0			66	O	35	2.5			67	S
11	2.6			62	O	36	2.8			90	O
12	2.3			81	O	37	3.2			78	O
13	2.5			78	O	38	3.0			80	O
14	2.6			71	O	39	2.0			71	O
15	2.8			66	O	40	3.0			92	O
16	2.5			69	O	41	2.3			75	O
17	2.8			80	O	42	2.3			89	O
18	2.9			79	S	43	2.5			79	O
19	3.1			70	O	44	2.0			78	O
20	2.8			79	O	45	2.3			64	O
21	2.0			70	O	46	2.7			80	O
22	1.75			65	O	47	2.0			74	O
23	3.1			65	S	48	2.1			98	O
24	2.0			55	O	49	2.4			79	O
25	1.8			52	O	50	2.5			73	O

Height in the Height (ft) column is height in foot-logs column x 16

Data sheet for pine lab for RM&ED FA2016

Species of pine: Longleaf pine (Pinus palustris) Date: 09/17/13

Experimental group (circle one): Burnt area Hardwood area

#	Height (ft logs)	Height (ft)	Height (m)	Circumference (cm)	O or S	#	Height (ft logs)	Height (ft)	Height (m)	Circumference (cm)	O or S
1	1.7	27.2		42	S	26	-	-	1.0	11	S
2	1.6			50	S	27	2.7			68	S
3	1.5			48	O	28	2.3			74	S
4	2.3			50	O	29	1.75			48	S
5	1.7			61	O	30	2.6			65	O
6	2.0			49	S	31	2.6			58	S
7	2.5			40	O	32	2.0			58	O
8	1.8			62	O	33	2.0			59	O
9	1.9			58	O	34	1.75			70	O
10	2.7			42	S	35	2.75			68	O
11	2.5			42	S	36	1.7			80	O
12	1.9			46	O	37	1.8			52	O
13	1.9			57	S	38	2.3			69	O
14	2.2			60	O	39	2.5			77	O
15	2.8			46	S	40	2.5			76	O
16	2.5			43	S	41	2.2			56	O
17	2.8			58	O	42	1.9			76	O
18	2.3			65	O	43	1.8			61	S
19	2.5			64	O	44	2.4			58	S
20	2.5			63	S	45	1.9			40	S
21	2.2			57	O	46	2.0			68	O
22	2.0			33	S	47	2.2			75	O
23	2.0			54	O	48	2.0			41	S
24	2.6			48	S	49	2.0			64	O
25	1.8			52	O	50	1.5			43	S

Height in the Height (ft) column is height in foot-logs column x 16

Data sheet for pine lab for BIO/EBS 6691

Species of pine: Sand pine (Pinus clausa) Date: 09/17/13

Road side/Open area Inside stand

#	Circumference at BH (cm)	#	Circumference at BH (cm)	#	Circumference at BH (cm)	#	Circumference at BH (cm)
1	127	26	98	1	89	26	46
2	115	27	120	2	76	27	116
3	111	28	111	3	90	28	113
4	125	29	112	4	77	29	120
5	72	30	97	5	99	30	111
6	136	31	90	6	86	31	79
7	116	32	102	7	116	32	107
8	114	33	123	8	95	33	100
9	109	34	130	9	97	34	117
10	84	35	97	10	77	35	100
11	79	36	85	11	116	36	118
12	106	37	117	12	75	37	89
13	126	38	106	13	112	38	103
14	102	39	104	14	83	39	70
15	124	40	78	15	106	40	87
16	71	41	90	16	54	41	76
17	79	42	128	17	92	42	78
18	102	43	114	18	99	43	87
19	126	44	121	19	113	44	84
20	114	45	88	20	61	45	102
21	113	46	97	21	90	46	66
22	121	47	130	22	69	47	79
23	81	48	90	23	70	48	110
24	102	49	85	24	63	49	93
25	111	50	108	25	69	50	54

Pine Competition – statistical tables

From: Zar, J. H. (1974) Biostatistical Analysis. Prentice Hall, Englewod Cliffs, N. J.