BIOMASS AND LENGTH ESTIMATION OF FINE ROOTS IN Pinus taeda L. IN SOUTH BRAZIL
Hamilton Luiz Munari Vogel1, Mauro Valdir Schumacher2, Rudi Witschoreck3, Francine Neves Calil4, Lucas Zancan Pissinin5
1. INTRODUCTION
The Pinus was introduced in Brazil around 1954, eye sighting to replace the Araucaria angustifolia, however its settlements were accelerated since 1966/67 with the forest incentive politics. Nowadays, Brazil has a planted area of 1.840.000 hectares (SBS, 2001).
Due to the difficulties of sampling, many times the root system of the trees aren’t considered, which can cause considerable mistakes in the study of balance and nutrients cycling in forest stands (Reis and Barros, 1990).
To study the root system, it’s important to separate this component into two distinct fractions, the thick roots, responsible for the tree sustentation and the fine roots responsible for the water and nutrients absorption.
In forest biomass estimatives, the root system evaluation is generally restricted to the sustentation component, whereas studies with fine roots are few in Brazil, and practically non-existent for Pinus taeda.
The lack of information for the root system for forest species difficults the definition for soil tillage and fertilization, besides characterizing a subside for the echo physiological
1 Doutorando em Engenharia Florestal. Laboratório de Ecologia Florestal, UFSM, Brasil. hamiltonvogel@yahoo.com.br
2 Dr. nat. techn. Professor Adjunto do Departamento de Ciências Florestais. Laboratório de Ecologia Florestal, UFSM, RS, Brasil. schuma@ccr.ufsm.br
3 Engenheiro Florestal. Laboratório de Ecologia Florestal , UFSM, RS, Brazil. rwitschoreck@yahoo.com.br 4 MSc. em Engenharia Florestal. Laboratório de Ecologia Florestal, UFSM, Brasil. francine.calil@terra.com.br
understanding, mainly the ones related to mineral nutrition and hydrical balance of the trees (Gonçalves and Mello, 2004).
The way that the roots explore different soil layers is determined by the genetic component, associated to edaphic factors, such as: fertility, density, oxygen disponibility, texture, temperature etc, and also by the circumstances in which the specie develops, for example, competition, spacing between trees; in a way that its knowledge will help to adopt the cultural and silvicultural practices (Gonçalves and Mello, 2004).
Reis et al. (1985), studying the biomass in an sequency age of Eucalyptus grandis, in two areas with different productivity, found in the less productive area a higher percentage of root system, showing a tendency to increase the contact surface to compensate the low fertility of the soil.
Couto et al. (1977), Leite et al. (1997), Leles et al. (1998), Assis et al. (1999), Ladeira et al. (2001), Neto et al. (2003) found a different biomass distribution between species and for the same specie due to the factors like planting space, age of the stand and fertilization.
Krapfenbauer e Andrae (1983),when they studied the fine root distribution in two native species from the south of Brazil, (Podocarpos lambertii e Araucaria angustifolia), found concentration of fine roots near the soil surface, behavior that they believe, are linked to the higher disponibility of organic matter, such as, for a better aeration.
Mello et al. (1998), studying the fine root distribution in depth in the soil, found a great variability between the genetic material and the time of sampling. A 4,5 years old clone of Eucalyptus grandis vs. Eucalyptus urophylla showed to be more plastic due to environmental variations and the stand of Eucalyptus grandis (4,5 years old), propagated by seed, the less plastic. In winter, the clone showed a density of fine roots in the upper layers of the soil (until 30 cm depth) higher than in the summer. There weren’t difference between the genotypes due to the cumulative density of fine roots in the soil profile, in the winter sampling. About 70% of the roots were found above 30 cm soil depth. In a different way, in the summer, the cumulative distribution of fine roots of the clone was very well distinctive from the one observed in the winter, where only 30% of the fine roots were find in the upper 30 cm of soil.
This study had as objective to estimate the biomass and the lenght of the fine roots (≤ 2 mm of diamter), in 17 years old Pinus taeda, in different depths of the soil.
2. MATERIAL AND METHODS
The data collection was carried out in a 17 years old Pinus taeda stand in Cambará do Sul county, in Rio Grande do Sul state, Brazil. Due to Köppen classification, the weather is Cfb, with an average precipitation of 1.700 mm well distributed during the year. The yearly average temperature is about 15 ºC, the average of the higher temperature is 22°C and the average of the low temperature is 8,5° C (Moreno, 1961).
The soil is Aluminic Humic Cambisoil typical that has as origin material basalt rocks (Brazil, 1973; Streck ett al. 2002).
The sample collection consisted in the opening of 3 trenches distributed inside de stand. In each one of the trenches, 6 monoliths of 25 cm x 25 cm x 10 cm (6.250 cm3) were taken in the following depths: 0–10, 10–20, 20–30, 30–40, 40–50, 50–60 cm. The samples were packed in plastic bags and kept in freeze camera until the separation of the roots from the soil.
In the root separation, a complex of two sieves was used, one with 2 mm and the other with 1 mm. Until the length determination, these roots were kept in a 10 % alcohol preservative solution in a temperature of ± 5° C.
The method used for the length determination was the intersection, described by Tennant (1975). This method consists in the obtention of a photo by scanner. For this obtention, a glass tray with a 4 mm reticule in the inferior face. To the photo obtention, the roots are distributed over the tray with a water film.
With this photos, a counting of the intersections was done between the roots and the reticule. So, to the length determination, the following equation was used:
R = length (in cm); ¶ = 3,1416; N = number of intersections; G = reticule unit (0,4 cm).
After the length quantification, corresponding to each soil layer, the soil was dried in an oven at 70° C during 72 hours e after were weighed in an analytical scale with 0,01 g as precision.
3. RESULTS AND DISCUSSION
3.1 Fine roots biomass
In Table 1 are shown the values of fine roots biomass ( 2 mm) of Pinus taeda in different soil layers.
Table 1. Fine roots biomass of Pinus taeda (kg ha-1) in different soil layers.
1/ values in brackets refer to the percentage of fine roots in the respective layer related to the
total;
2/ values followed by the same letter in the vertical position don’t differem between each
other by the Tukey test 5%;
3/ coefficient of deviation.
In the previous Table it’s possible to see that 83,1% from the total biomass of the fine roots of Pinus taeda are concentrated in the first 30 cm of soil, indicating that ni this
Trench Soil layer (cm) 1 2 3 Average SD C.V. (%)3/ 0 – 10 515,2 502,4 489,6 502,4 (39,4)1/ a2/ 12,80 2,5 10 – 20 340,8 246,4 388,8 325,3 (25,5) b 72,45 22,3 20 – 30 208,0 272,0 214,4 231,5 (18,2) b 35,25 15,2 30 – 40 148,8 100,8 44,8 98,1 (7,7) c 52,05 53,0 40 – 50 80,0 97,6 28,8 68,8 (5,4) c 35,74 51,9 50 – 60 59,2 44,8 38,4 47,5 (3,7) c 10,65 22,4 Total 1.352,0 1.264,0 1.204,8 1.273,6 74,07 5,8
layer occurs the higher absorption of water and nutrient, which confirms the results of other studies of fine roots in forest species.
Witschoreck and Schumacher (2001) and Witschoreck et al. (2003), found with the same method, in 10 years old stand, a biomass of fine roots (≤ 2 mm) until 60 cm of depth 1.280,8 kg ha-1 in Eucalyptus grandis and 1.451, 6 kg ha-1 in Eucalyptus urophylla, , being 78,8 % and 72,8 % allocated in the first 30 cm of the soil respectively.
Neves (2000), studying the biomass production and nutritional aspects in 8 clonal stands of Eucalyptus grandis x Eucalyptus urophylla (urograndis), found a biomass of fine roots (< 2 mm), that variated from 760 kg ha-1 to 2.540, 0 kg ha-1, with the average of 1.950 kg ha -1.
Another gymnosperm, 27 years old Araucaria angustifolia, Schumacher et al. (2002) estimated a biomass of fine roots ( 2mm) in 1.115,6 and 1.548,4 kg ha-1, respectively until 60 cm and 100 cm of depth in the soil. The vertical distribution of the roots in this specie was well distributed, with a higher average density in the layers 20 – 30 cm and 30 – 40 cm (± 22%) and only 53,4% in the depth of 0 – 30 cm, if considered the biomass until 60 depth.
In Table 2 is shown the length of fine roots ( 2 mm), where it’s possible to verify that this parameter showed a similar behavior to the biomass, concentrating 78,2% of the length in the 30 cm of soil.
In the works from Witschoreck and Schumacher (2001) with Eucalyptus grandis and Witschoreck et al. (2003) with Eucalyptus urophylla, the average length of the roots ( 2 mm), until 60 cm of depth, was of 31.966,9 km ha-1and 27.968,9 km ha-1, being respectively, 74% and 76,1% in the first 30 cm of soil.
Schumacher et al. (2002), in 27 years old Araucaria angustifolia, estimated an average length of fine roots ( 2 mm) of 13.113, 1 km ha-1until 100 cm of depth and 9.214,8 km ha-1 until 60 cm of depth.
Since the showed data, it’s acceptable to say that the angiosperms (Eucalyptus grandis and Eucalyptus urophylla), showed about two times the length of the fine roots when comparated to species as Pinus taeda and Araucaria angustifolia (gymnosperms), despite having very similar biomass values.
In Figure 1 is shown the density of fine roots in Pinus taeda, in different layers of soil, due to biomass parameters (g dm-3) and length (cm cm-3).
Table 2. Length of fine roots of Pinus taeda (km ha-1) in different soil depths .
Trench Soil layer (cm) 1 2 3 Average SD C.V. (%)3/ 0 – 10 3.917,3 4.601,8 4.456,4 4.325,2 (39,1)1/ a2/ 360,61 8,3 10 – 20 2.587,4 1.789,6 2.561,6 2.312,9 (20,8) b 453,37 19,6 20 – 30 2.260,7 1.660,7 2.208,5 2.043,3 (18,3) bc 332,38 16,3 30 – 40 1.445,9 1.341,9 585,2 1.124,3 (10,0) cd 469,79 41,8 40 – 50 865,2 735,3 392,6 664,4 (5,9) d 244,14 36,7 50 – 60 905,6 601,3 474,9 660,6 (5,9) d 221,37 33,5 Total 11.982,2 10.730,4 10.679,2 11.130,6 737,96 6,6
1/ values in brackets refer to the percentage of fine roots in the respective layer related to the
total;
2/ values followed by the same letter in the vertical position don’t differem between each
other by the Tukey test 5%;
0 10 20 30 40 50 60 0,0 0,1 0,2 0,3 0,4 0,5 0,6 Fine root density (< 2,0 mm)
D e p th ( c m ) (c m ) g/dm³ cm/cm³
Figure 1. Fine roots density in g dm-3 and cm cm-3, in different soil depths.
In Figure 1 it’s possible to verify that the density lines are in function to the biomass and the fine roots of Pinus taeda are not coincident along the soil profile, which suggests, a variation in the medium diameter of the fine roots (within the considered classes 2 mm), in function of soil depth. Apparently happens an elevation of the medium diameter of the roots ( 2 mm) in the 0 – 30 cm layer.
This can be related to an expanding and increase of mass, due to the mycorrhizal frequency of the fine roots in the superficial layers of the soil, where the aerative conditions and nutrition are better.
4. CONCLUSIONS
The fine roots biomass ( 2 mm), until the depth of 60 cm, was of 1.273,6 kg ha-1, being 83,1 % are in the first 30 cm of the soil;
The length of the fine roots ( 2 mm) was estimated in 11.130,6 km ha-1, being 78,2% in the first 30 cm of the soil.
5. REFERENCES
ASSIS, R.L.; FERREIRA, M.M.; MORAIS, E.J.; FERNANDES, L.A. Produção de biomassa de Eucalyptus urophylla S.T. Blake sob diferentes espaçamentos da região de cerrado de Minas Gerais. Revista Árvore, v.23, n.2, p.151–156, 1999.
COUTO, L.; BRANDI, R.M.; CONDÉ, A.R.; NETO, F.P. Influência do espaçamento no crescimento do Eucalyptus “urophylla” de origem híbrida, cultivado na região de Corronel Fabriciano, Minas Gerais. Revista Árvore, v.1, n.2, p.57-71, 1977.
GONÇALVES, J.L.M. Características do sistema radicular de absorção do Eucalyptus grandis sob diferentes condições edáficas: I Distribuição de raízes nas camadas de solo. In: CONGRESSO BRASILEIRO DE CIÊNCIAS DO SOLO, 21.,1995, Viçosa. Anais... Viçosa, MG: Sociedade Brasileira de Ciência do Solo, 1995. p.876-878.
GONÇALVES, J.L. M.; MELLO, S.L.M. The root system of trees. In: GONÇALVES, J.L.M.; BENEDETTI, V. (eds.) Forest nutrition and fertilization. Piracicaba: IPEF, 2004. p.223-267.
KRAPFENBAUER, A.; ANDRAE, F. Inventário de um reflorestamento de Araucaria angustifólia de 17 anos em Passo Fundo-RS (Parte 1: inventário da biomassa). In: ANDRAE, F.; KRAPFENBAUER, A. Pesquisa Austríaco-brasileira (1973-1982). Santa Maria, 1983, p.16-29.
LADEIRA, B.C.; REIS, G.G.; REIS, M.G.F.; BARROS, N.F. Produção de biomassa de eucalipto sob três espaçamentos em uma seqüência de idade. Revista Árvore, v.25, n.1, p.69 – 78, 2001.
LEITE, F.P.; BARROS, N.F.; NOVAIS, R.F. et al. Crescimento de Eucalyptus grandis em diferentes densidades populacionais. Revista Árvore, v.21, n.3, p.313-321, 1997.
LELES, P.S.S.; REIS, G.G.; REIS, M.G.F. et al. Relações hídricas e crescimento de árvores de Eucalyptus camaldulensis e Eucalyptus pellita sob diferentes espaçamentos na região de cerrado. Revista Árvore, v.22, n.1, p.41-50, 1998.
MELLO, S.L.M.; GONÇALVES, J.L.M.; OLIVEIRA, L.E.G. Características do sistema radicular em povoamentos de eucaliptos propagados por sementes e estacas. Scientia Forestalis, n.54, p.17-28, dez. 1998.
MORENO, J.A. Clima do Rio Grande do Sul. Porto Alegre: Secretaria da Agricultura, 1961. 73p.
NETO, S.N.O.; REIS, G.G.; REIS, M.G.F.; NEVES, J.C.L. Produção e distribuição de biomassa em Eucalyptus camaldulensis Dehn. em resposta a adubação e ao espaçamento. Revista Árvore, v.27, n.1, p.15 – 23, 2003.
NEVES, J.C.L. Produção e partição de biomassa, aspectos nutricionais e hídricos em plantios clonais de eucalipto na região litorânea do Espírito Santo. 2000. 191f. Tese (Doutorado em Produção Vegetal) – Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ, 2000.
REIS, M.G.F.; BARROS, N.F. Ciclagem de nutrientes em plantios de eucalipto. In: BARROS, N.F.; NOVAIS, R.F. (eds). Relação solo eucalipto. Viçosa: Ed. Folha de Viçosa, 1990. cap.7, p.265-302.
REIS, M.G.F.; KIMMINS, J.P.; REZENDE, G.C.; BARROS, N.F. Acúmulo de biomassa em uma seqüência de idade de Eucalyptus grandis plantado no cerrado em duas áreas com diferentes produtividades. Revista Árvore, v.9, n.2, p.149-162, 1985.
SCHUMACHER, M.V.; HOPPE, J.M.; BARBIERI, S.J. et al. Quantificação da biomassa e do conteúdo de nutrientes no corte raso de uma floresta de Araucaria angustifolia
(Bert.) O. Ktze. na região de Quedas do Iguçu – PR. Santa Maria: UFSM/FATEC, 2002. 78p. (Relatório Técnico).
SOCIEDADE BRASILEIRA DE SILVICULTURA – SBS. Disponível em: http://www.sbs.org.br, 2001. Acesso em: 25 maio de 2004.
STRECK, E.V.; KÄMPF, N.; DALMOLIN, R.S.D. et al. Solos do Rio Grande do Sul. Porto Alegre: UFRGS, EMATER/RS, 2002. 107p.
TENNANT, D.A. A test of a modified line intersect method of estimating root length. Journal of Ecology, v.63, p.995 – 1001, 1975.
WITSCHORECK, R.; SCHUMACHER, M.V. Estimativa da biomassa e do comprimento de raízes finas em Eucalyptus grandis W. Hill ex Maid. no município de Santa Maria-RS. In: SIMPÓSIO LATINO-AMERICANO SOBRE MANEJO FLORESTAL, 2., 2001, Santa Maria. Anais... Santa Maria: UFSM. CCR. Programa de Pós-Graduação em Engenharia Florestal, 2001. p.589-602.
WITSCHORECK, R.; SCHUMACHER, M.V.; CALDEIRA, M.V.W. Estimativa da biomassa e do comprimento de raízes finas em Eucalyptus urophylla S.T. Blake no município de Santa Maria-RS. Revista Árvore, v.27, n.2, p.177–183, 2003.
