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Research Article

Forest Structure, Nutrients, and Pentaclethra macroloba Growth after Deforestation of Costa Rican Lowland Forests

Table 1

Comparison of the plants, nutrients, and microbial activity measured in primary and secondary forests with P. macroloba as the dominant N-fixing tree within the MNWLR of Costa Rica. The percent water in the soil (% Water), pH, ammonium (NH₄; mg/cc), nitrate (NO₃; mg/cc), total mineral N (TMN; mg/cc), the percent mineral N as nitrate (% as NO₃), phosphate (µg/cc), dissolved organic C (DOC; μg/cc), respiration (resp.; μg CO₂/cc/h), soil C biomass (C_mic; μg C/cc), qCO₂, and soil C biomass to dissolved organic C ratio (C_mic/DOC) are presented as mean values with the standard deviation (SD). The percent differences in mean values (% Diff), -test values, and Hedge’s effect size values are provided.


	Secondary forest		Primary forest		Statistical analyses
	Mean	SD	Mean	SD	%Diff	t-test	Hedge’s d value

Vegetative community
Veg. biomass	387.44	99.35	830.07	542.30	114.47	0.159	1.086
Spp. richness	18.75	4.86	25.75	4.57	37.33	0.081	1.417
Shrub cover (%)	67.75	11.33	65.40	21.83	3.47	0.855	0.129
Overstory (%)	96.00	8.00	100.00	0.00	4.17	0.356	0.675
Legume species richness	1.50	0.58	3.00	0.82	100.00	0.024	2.017
Legume density	5.50	7.14	5.00	4.00	9.09	0.907	0.083
Legume % cover	14.25	14.22	56.50	35.74	296.49	0.070	1.483
P. macroloba
Seedlings (<1 m)	34.00	30.77	45.00	42.14	32.35	0.688	0.285
Seedlings >1 m	33.50	19.14	2.75	2.22	91.79	0.019	2.156
Mean young tree height (m)	1.08	0.24	0.61	0.71	43.45	0.010	0.842
Mean adult tree height (m)	10.30	2.37	24.05	5.45	113.61	0.040	2.410
Adult tree density per 300 m²	39.50	8.35	5.25	2.87	86.71	0.000	5.240
DBH (cm)	7.38	1.80	28.00	4.57	279.40	0.000	5.671
Volume (m³)	0.07	0.02	1.44	0.36	2049.25	0.000	5.140
Soil nutrients
NH₄	4.44	0.32	4.80	0.46	8.11	0.246	0.725
NO₃	0.63	0.15	1.47	0.22	132.96	0.001	3.586
TMN	5.07	0.36	5.77	0.28	13.72	0.022	1.722
% as NO₃	20.10	9.49	48.50	2.77	141.29	0.001	3.242
Phosphate	9.08	6.57	47.15	20.70	419.27	0.013	1.978
% Water	67.75	1.71	30.25	1.71	123.97	0.000	20.97
pH	6.73	0.09	6.02	0.30	10.55	0.004	3.10
Microbial activity indicators
Resp	4.98	0.84	1.71	0.41	65.66	0.000	3.948
C_mic	217.30	21.70	403.80	63.70	85.83	0.002	3.127
qCO₂	4.42	1.18	2.74	0.70	38.01	0.049	1.382
C_mic/DOC	0.19	0.03	0.66	0.18	247.37	0.002	2.906