Soil carbon stocks and forest biomass fo

Forest Ecology and Management 324 (2014) 37–45

Contents lists available at ScienceDirect

Forest Ecology and Management
journal homepage: www.elsevier.com/locate/foreco

Soil carbon stocks and forest biomass following conversion of pasture to
broadleaf and conifer plantations in southeastern Brazil
Rachel L. Cook a,⇑, Dan Binkley b, João Carlos T. Mendes c, Jose Luiz Stape a,c
a

Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27695, United States
Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, CO 80523, United States
c
Department of Forest Sciences, University of Sao Paulo, Piracicaba, Sao Paulo 13419, Brazil
b

a r t i c l e

i n f o

Article history:
Received 7 January 2014
Received in revised form 10 March 2014
Accepted 11 March 2014

Keywords:
Soil carbon
Biomass
Tropical plantations
Brazil

a b s t r a c t
Increased soil carbon sequestration can potentially mitigate CO2 emission and can indicate sustainable
forest management. This study aims to determine the relative influence of commercial plantation tree
species on soil carbon following establishment on former tropical pastures. Soil carbon (organic horizon
plus mineral soil from 0 to 45 cm) and stemwood productivity were quantified from 6 to 34 year-old
conifer and broadleaf plantations in a sandy Oxisol (Typic Hapludox) in southeastern Brazil. Study plots
consisted of ten pastures paired with broadleaf plantations and ten additional broadleaf plantations
paired with conifer plantations. Pastures primarily consisted of Brachiaria decumbens Stapf., while broadleaf plantations were primarily Eucalyptus, but also included one plot each of three other broadleaf

species. Conifer stands were made up of Pinus species. Average stemwood productivity (± standard error)
was 9.7 (±1.0) Mg C ha 1 yr 1 for broadleaf and 5.7 (±0.5) Mg C ha 1 yr 1 for conifer plantations, but did
not correlate to soil C. The soil C in the paired Pasture–Broadleaf plots averaged 36.0 ± 1.7 Mg C ha 1 in
pastures and 36.8 ± 1.9 Mg C ha 1 in broadleaf plantations. The Broadleaf–Conifer plots averaged
38.3 ± 1.9 Mg C ha 1 for broadleaf plantations and 36.0 ± 1.6 Mg C ha 1 for conifers. Our results show
little difference in soil C across vegetation types, providing evidence that conifer and broadleaf plantations overall maintain similar levels of soil carbon to pasture land-use up to 34 years following land
conversion. Soil C differences between Pasture–Broadleaf pairs indicated a small decline in soil C
accretion early after plantation establishment, followed by recovery to slightly higher accretion rates.
Ó 2014 Elsevier B.V. All rights reserved.

1. Introduction
Soils store more carbon than the atmosphere and plant biomass
combined (Jobbágy and Jackson, 2000). Increasing soil organic
carbon can improve soil quality, thereby acting as an indicator
for sustainable land use practices, and can potentially contribute
to mitigating climate change (Schoenholtz et al., 2000; Pan et al.,
2011). When conditions allow for the accumulation of carbon in
soils from roots and plant litter, soil quality improves with
increased cation exchange capacity (CEC), aggregation, waterholding capacity, infiltration, microbial diversity, and pH-buffering
capacity (Lal, 2004). Enhancing soil carbon accumulation is particularly important in soils where inherent fertility has been depleted

⇑ Corresponding author. Present address: Department of Plant, Soil, and Agricultural Systems, Southern Illinois University, 1205 Lincoln Drive, Mailcode 4415,
Carbondale, IL 62901, United States. Tel.: +1 618 453 1795.
E-mail addresses: rachel.cook@siu.edu (R.L. Cook), dan.binkley@colostate.edu
(D. Binkley), jctmende@usp.br (J.C.T. Mendes), stape@ncsfnc.cfr.ncsu.edu
(J.L. Stape).
http://dx.doi.org/10.1016/j.foreco.2014.03.019
0378-1127/Ó 2014 Elsevier B.V. All rights reserved.

through natural weathering processes or erosion, as is often the
case in the tropics and subtropics (Batjes and Sombroek, 1997;
Maquere et al., 2008; Zinn et al., 2002).
Conversion of forests to agricultural land depletes soil carbon
concentrations by 20–50% on average (Post and Mann, 1990; Guo
and Gifford, 2002; Laganiére et al., 2010). Forest establishment
on agricultural land may increase soil carbon sequestration (Lal,
2005) but interactions of many factors lead to high variation
among case studies and limited ability to predict responses.
Trends from meta-analyses indicate that establishment of Eucalyptus and Pinus plantations increases soil carbon stocks by about
12% over former agricultural land, defined as land used for the
production of food or fiber, permanent pastures, and mixed crop

and pasture (Laganiére et al., 2010), but may range from 35% to
282% relative soil C change from grassland to secondary forest
(Don et al., 2011). In Brazil, forest plantation establishment has
shown variable results. Soil carbon was found to remain constant
after native savannah was replaced with Eucalyptus plantations
on loamy and clay soils in central Brazil (Neufeldt et al., 2002;

38

R.L. Cook et al. / Forest Ecology and Management 324 (2014) 37–45

Zinn et al., 2002; Zinn et al., 2007), while Lima et al. (2006) found
an increase in soil carbon following Eucalyptus establishment on
former pasture. One challenge in comparing soil carbon studies is
due to the fact that often studies provide incomplete accounting
of soil carbon by omitting the organic (O) horizon of soils under
trees (Guo and Gifford, 2002; Paul et al., 2002; Berthrong et al.,
2009). Maquere et al. (2008) found increased soil carbon stocks
by 35–53% in Eucalyptus plantations established on former pasture,
when including the O horizon.

Tree species vary in their inputs into soil, both in terms of biomass production and nutrient content, and resultant C storage
(Zinn et al., 2002; Russell et al., 2004; Laganiére et al., 2010;
Pérez-Cruzado et al., 2012). Commercial plantation tree species
are of particular importance due to their increasing area of
production. Broadleaf plantations of Eucalyptus currently cover
over 20 million hectares (ha) worldwide (Iglesias-Trabado and
Wilstermann, 2009). Brazil is the largest producer of Eucalyptus,
with these plantations extending across 4.75 million ha, and also
has extensive commercial pine plantations covering 1.8 million ha
(ABRAF, 2011).
Many plantation forests in Brazil have been established on pastures (primarily Brachiaria species) that were formerly used for cattle production for decades. Most pastures were established
following brief row cropping after initial deforestation. A greater
capability to predict how land-use change affects soil carbon could
improve management decisions and climate change mitigation
policy. A recent meta-analysis has shown that afforestation tends
to have the same effect in both subtropical and tropical environments (Laganiére et al., 2010), which makes up most of Brazil
(Alvares et al., 2013). However, major challenges remain for assessing the effects of land-use change due to the inherent variability in
soils, interactions among soil properties, climate, and vegetation as
well as the long time scale required to detect small changes.
In this study we ask these four questions: (1) Does soil carbon

differ beneath pasture and broadleaf trees? (2) Does soil carbon
differ beneath broadleaf trees and coniferous trees? (3) Does the
effect of tree type increase over time? (4) Does soil carbon relate
to aboveground biomass and/or forest productivity? To answer
these questions, we examined soils in pastures and plantations of
broadleaf and conifer trees in southeastern Brazil. This study
expands on previously published work evaluating the isotopic signatures of pasture- and forest-derived carbon in only the mineral
soil (Cook et al., 2014).
2. Materials and methods
2.1. Site description
Soil samples for this project were collected at the Anhembi
Experimental Research Station, which lies in the center of the state
of Sao Paulo, Brazil, and has been owned by the University of Sao
Paulo (USP) since 1972 (Fig. 1). Native seasonal semi-deciduous
Atlantic Forest was cleared between 1950 and 1955, most likely
burned and planted for several years in cotton agriculture before
being replaced with Brachiaria decumbens Stapf. and managed for
cattle pasture. The 660 ha field site has been mostly converted
from pasture to broadleaf and conifer forest plantations consisting
primarily of Eucalyptus and Pinus stands, but with some remaining

areas of pasture and one remaining hectare of native, broadleaf,
‘‘reference’’ forest. Many of the remaining pastures, or ‘‘Areas of
Permanent Preservation,’’ were preserved as a result of the riparian
buffer required by Brazilian law and cannot be disturbed for forest
plantations or crops (Sparovek et al., 2010). Pastures ranged in age
from 25 to 53 years prior to plantation forest establishment, and
pasture sites sampled in this study were 54–59 years old. Forest
stands sampled in this study were on average 2.3 hectares and

range from 0.2 to 5.5 ha in size. The native tree species in this ecosystem and the remaining ‘‘reference’’ forest on the experimental
site included: Aspidosperma spp. (Apocynaceae), Hymenaeacourbaril (Fabaceae), Astronium graveolens (Anacardiaceae), Ocotea spp.
(Lauraceae), and Cariniana spp. (Lecythidaceae) (Assumpção et al.,
1982). A private forest reserve, Barreiro Rico, located 6 km away
on similar soils and landform provides an example of undisturbed
mature Atlantic Forest and a comparison with the reference native
forest on site (Ferez, 2010; Assumpção et al., 1982; Oliveira et al.,
1999).
The Research Station is located at latitude 22°400 S and longitude 48°100 W about 230 km northwest of Sao Paulo city at an elevation of 455 m. The topography is flat, and the climate is humid
subtropical (Cwa) in the Köppen system, with hot, rainy summers
and slightly cooler, dry winters (Alvares et al., 2013). The mean

annual temperature is 21.0 °C, with the coldest month having an
average of 17.1 °C and the hottest month averaging 23.7 °C. Annual
mean rainfall averages 1350 mm, with a dry season between the
months of April and September (Hijmans et al., 2005; Campoe
et al., 2010).
Soils are deep sandy Oxisols (Typic Hapludox) in the U.S. taxonomic system, or Typic Dystrophic Red–yellow Latosols according
to the Brazilian taxonomic system (Andrade et al., 2010; Campoe
et al., 2010). The texture is mostly sandy loam in the A horizon
(0–10 cm) followed by sandy clay loam texture in the AB
(10–35 cm), BA (35–80 cm), Bw (80–175 cm), and C (>175 cm)
horizons with sand content between 61% and 76%. These soils have
low water-holding capacity, good drainage, and are resistant to
compaction. Cation exchange capacity is typically