Tree species composition and diversity in relation to anthropogenic disturbances in broad-leaved forests of Bhutan

Figures & data

Figure 1. Map of the study area showing the three different management zones along with the inventory plots.

Table 1. Mean, minimum (Min), maximum (Max), and standard deviation (Sd) of (i) site characteristics elevation and slope as wells as (ii) the stand characteristics density, basal area, volume, mean dbh, and mean height.

	Natural forest (n = 36)				Semi-disturbed (n = 31)				Settlement&Agri (n = 29)
	Mean	Min	Max	Sd	Mean	Min	Max	Sd	Mean	Min	Max	Sd
Elevation (m)	1951	1392	2413	231	1429	675	1848	326	1229	906	1788	248
Slope (°)	27.5	3	61	13	26.8	5	44.5	7.8	22.5	5	39	7.7
Quadratic mean dbh (cm)	36.8	18.7	68.3	11.8	21.9	0	73.0	15.9	19.1	0	38.3	12.6
Mean tree height (m)	16.93	9.3	28.2	4.3	10,8	0	24	5.77	7.8	0	16.1	5.4
Trees (N ha^−1)	373	40	1080	236	175	0	820	200	114	0	540	145
Saplings (N ha^−1)	305	0	1220	277	241	0	1500	329	80	0	620	140
Estd.Seedl (N ha^−1)	1181	0	6250	1659	1427	0	8000	1950	655	0	3250	960
UnEstd.Seedl (N ha^−1)	2250	0	9750	2621	2161	0	40500	7196	1363	0	11750	2560
Recruits (N ha^−1)	2021	0	14000	3313	1395	0	2100	4072	500	0	6750	1341
Basal Area (m^2 ha^−1)	37.9	2.4	98.2	23.9	9.63	0	45.8	12.7	5.7	0	27.6	7.2
Volume (m^3 ha^−1)	418.9	13.2	1376.5	324.3	84.8	0	480	124.4	49.8	0	274.6	69.1

n = Number of Plots; Trees (dbh ≥10 cm), Saplings (dbh ≥5 to <10 cm), Estd.Seedl: Established Seedlings (dbh <5 cm and height >2 m), UnEstd.Seedl: Unestablished seedlings (dbh <5 cm and height <2 m), Recruits (current year seedlings).

Table 2. Density (N ha⁻¹) and standard deviation of the tree species in the three zones.

	Density (Mean ± SD)
Species	Natural forests	Semi-disturbed	Settlement and Agri
Acer campbellii	5.6 ± 18.9	0.6 ± 3.6	-
Acer hookeri	0.6 ± 3.3	-	-
Acer laevigatum	1.6 ± 5.6	-	-
Acer thompsonii	0.6 ± 3.3	-	-
Ailanthus integrifolia	-	0.6 ± 3.6	2.1 ± 8.2
Alangium chinense	-	-	1.4 ± 7.4
Albezia chinensis	-	-	0.7 ± 3.7
Albizia gambelii	-	5.2 ± 18.6	2.1 ± 6.2
Albizia jilibrissinn	-	0.6 ± 3.6	-
Albizia lebbeck	-	-	0.7 ± 3.7
Albizia procera	-	0.6 ± 3.6	-
Alnus nepalensis	-	17.4 ± 82.9	11 ± 52
Alseodaphne sp.	10.6 ± 33.6
Amoora wallichii	4.4 ± 12.7	-	3.44 ± 12
Aphanamixis polystachya	1.1 ± 6.7	-	-
Artocarpus chama	-	-	0.7 ± 3.7
Aurelia sp.	-	-	0.7 ± 3.7
Bauhinia purpurea	-	-	0.7 ± 3.7
Beilschmiedia sp.	22.8 ± 40.9	4.5 ± 19.1	-
Betula alnoides	1.7 ± 10	-	-
Bischofia javanica	-	-	1.4 ± 5.2
Bombax ceiba	-	2.6 ± 8.6	2.8 ± 11.6
Callicarpa arborea	-	1.3 ± 5	0.7 ± 3.7
Carpinus viminea	1.1 ± 4.6	-	-
Casearia glomerata	7.8 ± 18.1	7.1 ± 26.1	-
Casearia sp.	1.1 ± 4.6
Castanopsis hystrix	8.9 ± 23.1	0.6 ± 3.6	-
Castanopsis indica	1.7 ± 5.6	1.9 ± 7.9	-
Castanopsis tribuloides	5.6 ± 15.6	-	-
Celtis australis	-	1.2 ± 7.2	-
Celtis sp	-	1.3 ± 7.2	2.8 ± 10.3
Celtis tetranda	-	0.6 ± 3.6	1.4 ± 7.4
Choerospondias axill	-	0.6 ± 3.6	-
Chukrasia tabularis	-	-	1.3 ± 5.2
Cinnamomum bejolghota	8.9 ± 27.6	-	0.7 ± 3.7
Cinnamomum glaucescens	1.1 ± 4.6
Cinnamomum impressinervium	1.7 ± 10	-	-
Dalbergia sericea	-	4.5 ± 18.5	2.1 ± 6.2
Daphniphyllum sp.	1.7 ± 10	-	-
Debregeasia longifolia	-	1.3 ± 5	-
Echinocarpus decicarpus	1.1 ± 4.6
Elaeocarpus lanceifolius	1.7 ± 7.4	-	-
Elaeocarpus sp.	5.0 ± 21	1.3 ± 4.9	0.7 ± 3.7
Engelhardtia spicata	2.2 ± 8	12.9 ± 33.3	-
Eryobutrea sp.	3.3 ± 16.9	-	-
Erythrina arborescens	0.6 ± 3.3	-	0.7 ± 3.7
Exbucklandia populne	1.7 ± 7.4	-	-
Ficus auriculata	-	3.2 ± 18	6.2 ± 19.3
Ficus nerifolia	1.7 ± 7.4	0.6 ± 3.6	1.4 ± 7.4
Ficus semicordata	-	1.3 ± 7.2	2.8 ± 8.8
Ficus sp.	0.6 ± 3.3	1.3 ± 7.2	2.1 ± 6.2
Garcinia sp.	1.7 ± 7.4	-	-
Glochidion sp.	2.8 ± 7	2.6 ± 11.2	-
Gordonia excelsa	-	2.6 ± 14.4	-
Grewia sp.	-	0.6 ± 3.6	2.8 ± 14.9
Gynocardia odorata	-	-	0.7 ± 3.7
Helicea neligerica	0.6 ± 3.3	-	-
Lindera pulcherrima	15.6 ± 43.6	-	-
Lithocarpus elegans	13.3 ± 46.6	0.6 ± 3.6	-
Lithocarpus fenestratus	8.8 ± 29.3	-	-
Litsea luecaena	-	-	0.7 ± 3.7
Litsea sp.	9.4 ± 21.1	-	-
Macaranga denticulata	1.1 ± 6.7	1.3 ± 5	-
Macaranga indica	-	7.1 ± 27.6	2.8 ± 11.6
Macaranga pustulata	14.4 ± 54.8	9.7 ± 46.7	-
Macropanyx dispermus	8.3 ± 18.7	-	-
Magnolia campbellii	-	0.6 ± 3.6	-
Mallotus philippinensis	-	-	2.8 ± 8.8
Mangifera indica	-	2.6 ± 14.4	0.7 ± 3.7
Michelia cathcartii	7.8 ± 14.6	-	2.8 ± 14.9
Michelia doltsopa	2.2 ± 6.4	-	-
Michelia velutina	2.8 ± 7	1.3 ± 5	-
Morus laevigata	-	0.6 ± 3.4	-
Myrsine semiserrata	0.6 ± 3.3	-	-
Neolitsea sp.	0.6 ± 3.3	-	-
Nyssa javanica	2.8 ± 8.5	-	-
Olia sp (fodder tree)	7.8 ± 15.3	-	-
Oroxylum indicum	-	-	4.1 ± 22.3
Oroxylum sp.	-	1.9 ± 10.8
Ostodes paniculata	10.6 ± 31.2	18.7 ± 69.1	8.3 ± 22.4
Ostodes sp.	1.7 ± 5.6	0.6 ± 3.6	0.6 ± 3.7
Persea clarkeana	7.2 ± 23.5	-	-
Persea duthiei	0.6 ± 3.3	-	-
Persea fructifera	4.4 ± 9.7	-	-
Persea lanceolata	5.6 ± 24.2	-	-
Persea sp.	5.6 ± 13.2	0.6 ± 3.6	-
Phoebe attenuata	0.6 ± 3.3	-	-
Phoebe lanceolata	4.4 ± 23.5	-	-
Phyllanthus emblica	1.1 ± 6.7	-	-
Pieris formosa	1.7 ± 10	-	-
Pinus roxburghii	1.1 ± 6.7	-	-
Polygala auriculata	0.6 ± 3.3	-	-
Prunus sp.	1.1 ± 4.6	-	-
Pyrularia edulis	0.6 ± 3.3	1.3 ± 5	-
Quercus glauca	8.9 ± 53.3	-	-
Quercus griffithii	1.1 ± 6.7	-	-
Quercus lamellosa	5.6 ± 14	-	-
Quercus tribuloides	-	0.6 ± 3.6	-
Rapanea sp.	0.6 ± 3.3
Rhododendron arboreum	4.4 ± 26.7	-	-
Rhododendron grande	7.2 ± 31	-	-
Rhododendron griffithianum	1.7 ± 10	-	-
Rhododendron maddenii	1.1 ± 6.7	-	-
Rhus chinensis	1.1 ± 4.6	4.5 ± 10	0.7 ± 3.7
Rhus hookeri	-	2.6 ± 11.2
Rhus succedanea	0.6 ± 3.3	0.6 ± 3.6	2.8 ± 14.9
Sapindus mukorossi	-	-	2.1 ± 11.1
Sapium insigne	-	-	0.7 ± 3.7
Saurauja napaulensis	-	-	0.7 ± 3.7
Schefflera sp.	1.1 ± 4.6	-	-
Schima wallichii	1.1 ± 6.7	12.9 ± 38.8	25.5 ± 67.2
Sorbus cuspidata	1.1 ± 6.7	-	-
Sterculia sp.	4.4 ± 12.7	-	-
Symplocos ramosissima	20.6 ± 58.5	0.6 ± 3.6	-
Symplocus lucida	10.6 ± 24.1	1.3 ± 5	-
Symplocus sp.	0.6 ± 3.3	-	-
Syzigium cumini	-	0.6 ± 3.6
Syzigium sp.	8.3 ± 36.7	0.6 ± 3.6	-
Talauma hodgsoni	0.6 ± 3.3	-	-
Terminalia myriocarpa	-	0.6 ± 3.6	0.7 ± 3.7
Terpenia sp.	6.7 ± 19.7	-	-
Tetradium fraxinifolium	0.6 ± 3.3	-	-
Tetradium sp.	2.2 ± 10.5	0.6 ± 3.6	-
Toona ciliata	1.1 ± 4.7	-	-

Table 3. Density (N ha⁻¹) and standard deviation of the shrub species in the three zones.

	Density (Mean ± SD)
Species	Natural Forests	Semi-disturbed	Settlement and Agri
Aeglia sp.	0.6 ± 3.3	-
Brassaiopsis dispermum	2.2 ± 8	-
Brassaiopsis mitis	0.6 ± 3.3	1.3 ± 5	0.7 ± 3.7
Clerodendron sp.	1.7 ± 7.4	0.6 ± 3.6	-
Eurya acuminata	5.6 ± 14	15.5 ± 43.4	2.8 ± 14.9
Homalia sp.	0.6 ± 3.3	-	-
Hydrangea sp.	1.1 ± 6.7	-	-
Ilex sp.	0.6 ± 3.3	-	-
Lyonia ovalifolia	12.2 ± 49.5	0.6 ± 3.6
Maesa chesea	1.1 ± 4.6	3.2 ± 11.7	-
Mussaenda sp.	-	0.6 ± 3.6	-
Premna sp.	-	-	0.7 ± 3.7
Sauraria sp.	0.6 ± 3.3	-	-
Vernonia sp.	1.1 ± 6.7	-	-
Wendlandia sp.	-	1.9 ± 7.9	-
Zanthoxylum sp.	-	0.6 ± 3.6	-

Table 4. Mean values ± standard deviations of density, basal area, and diversity indices for the different zones.

Parameters		Natural forest (n = 36)	Semi-disturbed (n = 31)	Settlement and Agri (n = 29)
Density (N/ha)	Trees	373 ± 235.62^a	175 ± 199.74^a	114 ± 145.41^b
Basal Area (m^2ha^−1)	Trees	37.89 ± 23.9^a	9.63 ± 12.73^b	5.71 ± 7.19^b
Volume (m^3ha^−1)	Trees	418.9 ± 324.29^a	84.77 ± 124.4^b	49.8 ± 69.1^b
Shannon index	Trees	1.73 ± 0.62^a	0.92 ± 0.74^b	0.74 ± 0.74^b
	Saplings	1.23 ± 0.72^a	0.99 ± 0.73^a	0.45 ± 0.72^b
	Estd.Seedl	0.53 ± 0.62^a	0.59 ± 0.52^a	0.33 ± 0.59^a
	UnEstd.Seedl	0.80 ± 0.72	0.46 ± 0.58	0.52 ± 0.59
	Recruits	0.40 ± 0.51	0.24 ± 0.47	0.15 ± 0.40
Simpsons index	Trees	5.49 ± 2.97^a	2.70 ± 2.05^b	2.24 ± 2.13^b
	Saplings	3.52 ± 2.36^a	2.79 ± 2.04^a,b	1.50 ± 2.23^c,b
	Estd.Seedl	1.60 ± 1.56 ^a	1.74 ± 1.21^a	1.13 ± 1.61^a
	UnEstd.Seedl	2.34 ± 2.06	1.47 ± 1.41	1.43 ± 1.52
	Recruits	1.21 ± 1.27	0.71 ± 1.12	0.50 ± 1.08
Evenness	Trees	0.85 ± 0.18^a	0.59 ± 0.43^b	0.56 ± 0.46^b
	Saplings	0.72 ± 0.35^a	0.62 ± 0.41^a	0.30 ± 0.43^b
	Estd.Seedl	0.45 ± 0.46^a	0.56 ± 0.44^a,b	0.25 ± 0.42^a,c
	UnEstd.Seedl	0.56 ± 0.40	0.41 ± 0.45	0.44 ± 0.47
	Recruits	0.37 ± 0.45	0.21 ± 0.40	0.12 ± 0.33

Values in columns followed by the same letter(s) are not significantly different (p < 0.05) according to GLM and Tukey’s multiple comparison of means test.

n = Number of plots in each zone; Trees (dbh ≥10 cm), Saplings (dbh ≥5 to <10 cm), Estd.Seedl: Established Seedlings (dbh <5 cm and height >2 m), UnEstd.Seedl: Unestablished seedlings (dbh <5 cm and height <2 m), Recruits (current year seedlings).

Figure 2. Species richness and diversity: (a) mean number of species per plot, (b) Shannon–Weaver index, and (c) Simpson’s index. Minima, median, maxima, and outliers are indicated. a = Trees (dbh ≥10 cm), b = Saplings (dbh ≥5 to <10 cm), c = Established Seedlings (dbh <5 cm and height >2 m), d = Unestablished seedlings (dbh <5 cm and height <2 m), e = Recruits (current year seedlings).

Figure 3. Mean Shannon–Weaver biodiversity values of trees, saplings, and seedlings grouped by quadratic mean dbh class of trees. (a) Trees (dbh ≥10 cm), (b) saplings (dbh ≥5 to <10 cm), and (c) established seedlings (dbh <5 cm and height >2 m).

Figure 4. Diameter distribution of timber and non-timber species across the three zones. (a) Timber species distribution, (b) timber species above dbh class of 40 cm, (c) non-timber species distribution, and (d) non-timber species of dbh above 40 cm. * dbh of 40 cm and above are usually cut for timber.

Figure 5. Basal area for the timber species across the three zones: (a) basal area/ha and (b) basal area/ha (plots below 2000 m.a.s.l). a = Acer spp., b = Alnus nepalensis, c = Castanopsis spp., d = Cinnamomum spp., e = Michelia spp., f = Persea spp., g = Phoebe spp., h = Quercus spp., i = Schima wallichi, j = Syzigium spp, k = Terminalia myriocarpa, l = Toona ciliata.

Table 5. Density (N ha⁻¹) ± standard deviation of saplings and seedlings for the different zones.

		Density (Mean ± SD)
Species groups		Natural forests	Semi-disturbed	Settlment and Agri
Timber	Saplings	56 ± 83^a	21 ± 48^a	25 ± 53^a
	Estd.Seedl	215 ± 397^a	242 ± 518^a	52 ± 140^a
	UnEstd.Seedl	847 ± 1064^a	685 ± 2657^b	328 ± 1024^b
	Recruits	1403 ± 2619^a	484 ± 2213^b	86 ± 278^b
Non-timber	Saplings	158 ± 149^a	88 ± 79^a	49 ± 101^b,^c
	Estd.Seedl	674 ± 1253^a	782 ± 1269^a	439 ± 719^a
	UnEstd.Seedl	1181 ± 1894^a	1024 ± 2994^a	759 ± 1410^a
	Recruits	535 ± 1156^a	532 ± 1308^a	371 ± 1085^a
Shrubs	Saplings	91 ± 181^a	132 ± 274^a	6 ± 14^b,c
	Estd.Seedl	292 ± 553^a	403 ± 746^a	164 ± 355^a
	UnEstd.Seedl	222 ± 450^a	452 ± 1645^a	276 ± 588^a
	Recruits	83 ± 260^a	379 ± 1510^a	43 ± 165^a

Values in columns followed by the same letter(s) are not significantly different (p < 0.05) according to Pairwise comparisons using posthoc Kruskal Nemenye test.

Saplings (dbh ≥5 to <10 cm), Estd.Seedl: Established Seedlings (dbh <5 cm and height >2 m), UnEstd.Seedl: Unestablished seedlings (dbh <5 cm and height <2 m), Recruits (current year seedlings).

Figure 6. Seedling and Sapling density (N ha⁻¹) of the timber, non-timber and shrub species across the three zones. (a) Recruits (current year seedlings), (b) Unestablished Seedlings (dbh <5 cm and height <2 m), (c) Established Seedlings (dbh <5 cm and height >2 m), and (d) Saplings (dbh ≥5 to <10 cm).

Table

Forest type	Altitude (m.a.s.l)	Dominant tree species
Cool-temperate Broad-leaved forests	>2000	Acer campbellii* Symplocos ramosissima Beilschmiedia sp. Castanopsis tribuloides* Castanopsis hystrix* Lithocarpus elegans Casearia glomerata	Lindera pulcherrima Lyonia ovalifolia Persea clarkeana* Rhododendron grande Symplocos lucia Terpena sp.
Warm-temperate Broad-leaved forests	1000–2000	Schima wallichii** Alnus nepalensis** Beilschimiedia sp. Alseodaphne sp. Casearia glomerata Cinnamomum bejolghota* Dalbergia sericea Engelhardia spicata Terminalia myriocarpa** Eurya acuminata Castanopsis tribuloides* Castanopsis indica*	Ficus auriculata Macaranga indica Macaranga pustulata Michelia cathcartii** Michelia doltsopa** Michelia velutina** Ostodes paniculata Quercus glauca Toona ciliata** Phoebe spp.** Persea fructifera**
Sub-tropical forests	<1000	Schima wallichii** Rhus succedanea Ostodes paniculata Grewia sp.	Albizia gambelii Ficus semicordata Bombax ceiba** Alangium chinense

* Timber from other records.

** Timber species as per local preference.

Table

^(Reference)Name of the species		Volume equations	n	R^2	Eq.no.
^(1)Acer spp.	G	V = 0.03873 + 0.36273	250	-	E.1
^(1)Ailanthus integrifolia	G	ln(V) = −1.94825 + 1.7273*ln(D) + 1.1669*ln(H)	103	-	E.2
^(2)Albezia chinensis	G	V = −1.5567 + 0.0006182 + 0.0000054684 + 0.090192 H	36	0.865	E.3
^(2)Albizia spp.	G	V = 0.009134 + 0.171315	255	0.75	E.4
^(1)Alnus nepalensis	G	ln(V) = −0.565323 + 1.984601*ln(D) + 0.822937*ln(H)	150		E.5
^(2)Amoora wallichii	G	V = 0.0778 + 0.0000286 (Dia in cm)	-	-	E.6
^(1)Aphanamixis polystachya	G	V = −0.09768 + 0.01051 H	48	-	E.7
^(1)Beilschmiedia spp.	G	ln(V) = −0.565323 + 1.984601*ln(D) + 0.822937*ln(H)	150	-	E.8
^(1)Betula alnoides	G	ln(V) = −0.46151 + 2.039844*ln(D) + 0.837461*ln(H)	77	-	E.9
^(2)Bischofia javanica	L	V = 0.25571–2.33118D + 11.12071	19	0.999	E.10
^(1)Bombax ceiba	G	ln(V) = −0.70448 + 2.13777*ln(D) + 0.91127*ln(H)	81	-	E.11
^(2)Callicarpa arborea	L	−0.04506 + 2.33446D	61	0.926	E.12
^(2)Casearia spp.	L	V = 0.14031–2.06478D + 11.25750	23	0.997	E.13
^(1)Castanopsis spp.	G	V = −0.00794 + 0.34759	82	-	E.14
^(3)Cinnamomum spp.	L	V = 0.00003*D^2,813 (Dia in cm)			E.15
^(2)Dalbergia sericea	L	0.76896 + 7.31777*D −4.01953*D	16	0.915	E.16
^(2)Elaeocarpus spp.	L	0.43843 + 5.72522D −2.59907D	15	0.991	E.17
^(1)Engelhardtia spicata	G	ln(V) = −0.14969 + 2.1532*ln(D) + 0.76463*ln(H)	40	-	E.18
^(2)Exbucklandia populnea	G	V = 0.0258 + 0.000172 + 0.0000332H			E.19
^(2)Grewia spp.	L	V = −0.44075 + 7.49221D-36.09962 + 71.91238	78	0.977	E.20
^(3)Litsea spp.	L	V = 0.0001D^2.438 (Dia in cm)	-	-	E.21
^(2)Mallotus philippinensis	L	V = 0.14749–2.87503*D + 19.61977-19.116303*	-	-	E.22
^(1)Michelia spp.	G	V = 0,00667 + 0,32947H	94	-	E.23
^(3)Morus laevigata	L	V = 0.00009D^2,5249 (Dia in cm)	-	-	E.24
^(3)Myrsine semiserrata	L	V = 0,00009 D^2,5249 (Dia in cm)	-	-	E.25
^(1)Persea spp.	G	ln(V) = −0.56664 + 2.03335ln(D) + 0,87279*ln(H)	122	-	E.26
^(1)Phoebe spp.	G	V = −0.0432 + 0.3622H	34	-	E.28
^(1)Pinus roxburghii	G	V = −0.00156 + 0.32159H	154	-	E.29
^(1)Quercus spp.	G	V = −0,002111 + 0.392382H	148	-	E.30
^(3)Rhododendron spp.	L	V = 0,00009*D^2,4641	-	-	E.31
^(1)Schima wallichii	G	ln(V) = −0.565323 + 1.984601*Ln(D) + 0.822937*Ln(H)	150	-	E.32
^(1)Sterculia spp.	G	V = 0.00231 + 0.34018H	75	-	E.33
^(1)Symplocos spp.	G	V = 0.00155 + 0.34028H	69	-	E.34
^(2)Syzigium cumini	L	V = −0.00094 + 6.15921	30	0.982	E.35
^(2)Syzigium spp.	L	V = −0.13284 + 1.88944D −4.96385 + 21.41051	78	0.935	E.36
^(1)Terminalia myriocarpa	G	V = 0.00635 + 0,35936H	59	-	E.37
^(2)Toona ciliata	L	V = 0.21869 – 2.04074D + 10.41713 + 1.85232	74	0.996	E.38
^(3)Rest of the Species(South)	L	V = 0.00009D^2,5249 (Dia in cm)			E.39

- = Not available; n = total number of sample trees used for deriving regression equation; R² = co-efficient of determination. (G) = General equation; (L) = Local Equation. References: 1 = (Laumans 1994), 2 = (FSI 1996), 3 = (FRDD 2005c).

Laumans P. 1994. Height-diameter functions from PIS for country level site classification and local volume table selection. Working Document No.11(FO: DP/BHU/911002). Thimphu (Bhutan): UNDP/FAO Forest Resources Management and Institutional Development Project, Deparment of Forestry, Ministry of Agriculture, Royal Government of Bhutan.

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FSI. 1996. Volume equations for forests of India, Nepal and Bhutan. Dehradun (India): Ministry of Environment and Forests, Govt. of India.

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FRDD. 2005c. Volume table of Bhutan. Thimphu (Bhutan): Department of Forests, Ministry of Agriculture, Royal Government of Bhutan.

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