Oecologia (1993) 94:457M71
Oecologia
9 Springer-Verlag 1993
Review article
Patterns in decomposition rates among photosynthetic organisms:
the importance of detritus C :N :P content
S. Enriquez ~, C.M. Duarte ~, K. Sand-Jensen 2
t Centro de Estudios Avanzados de Blanes, (CSIC), Cami de Santa BArbara, 17300 Blanes, Girona, Spain
2 Freshwater Biological Laboratory, University of Copenhagen, 51 Helsingorsgade, 3400 Hillerod, Denmark
Received: 30 January 1993 / Accepted: 4 April 1993
Abstract. The strength and generality of the relationship
between decomposition rates and detritus carbon, nitrogen, and phosphorus concentrations was assessed by
comparing published reports of decomposition rates of
detritus of photosynthetic organisms, from unicellular
algae to trees. The results obtained demonstrated the
existence of a general positive, linear relationship between plant decomposition rates and nitrogen and phosphorus concentrations. Differences in the carbon, nitrogen, and phosphorus concentrations of plant detritus
accounted for 89% of the variance in plant decomposition rates of detritus originating from photosynthetic
organisms ranging from unicellular microalgae to trees.
The results also demonstrate that moist plant material
decomposes substantially faster than dry material with
similar nutrient concentrations. Consideration of lignin,
instead of carbon, concentrations did not improve the
relationships obtained. These results reflect the coupling
of phosphorus and nitrogen in the basic biochemical
processes of both plants and their microbial decomposers, and stress the importance of this coupling for
carbon and nutrient flow in ecosystems.
Key words: Decomposition - Plant kingdom - Nutrients
Carbon fixed by photosynthetic organisms is made available to other ecosystem components via herbivores or
detritivores. The detrital path is a major determinant of
the flow of carbon fixed by plants in ecosystems were
herbivores consume a modest fraction of primary
production, as is often the case (Swift et al. 1979). Decomposition of plant detritus is largely conducted by
bacteria and fungi (e.g. Persson et al. 1980), and the rate
of this process depends, therefore, on all factors influencing their activity. These may be separated, following
Swift et al. (1979), into abiotic factors, the physicoThis work was funded through a grant of CICYT (MAR91~503)
to C.M.D.
Correspondence to: S. Enriquez
chemical conditions under which the decomposition occurs, and substrate quality (e.g. biochemical composition
of plant litter), which constrains its suitability for microbial growth. Photosynthetic organisms can directly influence decomposition rates through their biochemical
composition. For instance, plants may accumulate defence chemicals in their tissues which, besides decreasing
their palatability to grazers (e.g. Coley et al. 1985), also
reduce their quality as a substrate for decomposer microorganisms (Swift et al. 1979). Similarly, nutrient reabsorption before abscission of plant tissues may, in addition to improving the internal nutrient economy of the
plant (Chapin 1980), affect their suitability as substrate
for microbial decomposers.
Decomposer organisms tend to have very high nitrogen and phosphorus contents (Findlay 1934; Thayer
1974; Swift et al. 1979; Goldman et al. 1987; Vadstein
and Olsen 1989) indicative of high requirements for these
nutrients. For instance balanced bacterial growth requires substrates with carbon, nitrogen, and phosphorus
in an (atomic) ratio of 106:12:1 (Goldman et al. 1987),
although bacteria have some capacity to vary these requirements (e.g. Tezuka 1990). These high nutrient contents are only encountered in fast-growing phytoplankton cells (Goldman et al. 1979; Duarte 1992), and microbial decomposers are often supplied with plant detritus
depleted in nitrogen and phosphorus relative to their
requirements. Recent research has demonstrated that
bacterial growth efficiency (i.e. the fraction of the carbon
used allocated to growth) decreases about 100-fold with
increasing C/N and C/P ratios in their substrate (Goldman et al. 1987). Thus, detritus with high nitrogen and
phosphorus content should decompose fast because of
the associated fast growth of the microbial populations,
whereas excess carbon in the plant litter should lead to
nutrient-controlled carbon remineralization (cf. Goldman et al. 1987; Vadstein and Olsen 1989).
These arguments provide an explanation for the increase in decomposition rate with increasing nutrient
concentration, or decreasing carbon/nutrient ratios,
demonstrated six decades ago (Tenny and Waksman
1929), and confirmed since for different aquatic (e.g.
458
Valiela et al. 1984; Twilley et al. 1986; Harrison 1989;
Reddy and DeBusk 1991) and terrestrial (e.g. Gosz et al.
1973; Swift et al. 1979; Berg et al. 1982; Taylor et al.
1989; Upadhyay et al. 1989) systems. In addition to
reflecting direct nutrient effects, these relationships also
appear to have an indirect component, derived from a
tendency towards reduced carbon quality and increasing
amounts of secondary metabolites in plant litter as nutrient availability decreases (Coley et al. 1985, Chapin et
al. 1987). Hence, some ratios incorporating a descriptor
of carbon quality (e.g. lignin/N ratios) have also been
shown to be related to decay rates of plant litter (e.g.
Melillo et al. 1982; Aber et al. 1990). However, lignin/N
ratios appear to outperform C/nutrient ratios as a predictor of decay rates only when comparing plant litters of
similar lignin contents (Taylor et al. 1989).
Whether the widespread finding of strong relationships between litter nutrient content and decomposition
rates reflects the existence of a general relationship, applicable to detritus originating from different photosynthetic organism, is not known as yet. The existence of
such a general relationship is expected because all microbial decomposers have high nitrogen and phosphorus, in
addition to carbon, needs in both aquatic (Goldman et
al. 1987; Vadstein and Olsen 1989) and terrestrial (Findlay 1934; Thayer 1974; Swift et al. 1979) environments.
Conversely, these relationships might differ between different sorts of plant detritus if they were indirect, resulting from covariation between carbon quality (e.g. contents of lignin, polyphenols, etc.) and nutrient content
within plant types (e.g. Melillo et al. 1982; Abet et al.
1990; Upadhyay et al. 1989).
Here we examine the strength and generality of the
relationship between decomposition rates and plant nutrient concentrations by comparing published reports of
decomposition rates and litter nutrient contents across a
broad spectrum of plant detritus, from unicellular algae
to trees. We first examine the variability in decomposition rates of litter from different sources, and then
assess the power of differences in their nutrient concentration to statistically account for the observed variability. A subset of these data, for which lignin contents were
available in addition to nitrogen and phosphorus contents, was used to compare the strength of the relationship between lignin and nutrient contents and litter decomposition rates. Because plant nutrient concentrations
are often strongly intercorrelated (Garten 1976; Duarte
1992), we used path analysis (Williams et al. 1990) to
statistically resolve the direct contribution of carbon,
nitrogen, phosphorus, and, where available, lignin, to the
observed relationship between nutrient content and detritus decomposition rate.
Methods
We searched the literature for published reports of plant litter
decomposition rates and chemical composition (carbon, lignin,
nitrogen, and phosphorus concentrations) at initiation of decomposition. Decomposition rates (k, natural log units day-1) were
described from the changes in plant dry weight (W) with time (t,
days) since the initiation of the experiments using the equation,
wt = Woe-kt
which is the model most often used in the literature (Olson 1963)
and simpler than the double-exponential model (e.g. O'Connell
1987). Because these decomposition rates have logarithmic units, we
also described decomposition rates as the half-life of plant detritus
(Ta/2, days), which, although a function of exponential decomposition rates (T1/2 = k - 1 . In 2), provides a more intuitive description of detritus turnover times. Decomposition rates were often
reported in the studies, and were otherwise calculated from tabulated data or digitized graphs of weight remaining with time
elapsed. We included in the data set (Appendix) all studies encountered during our search that included estimates of decomposition
rates of plant litter (e.g. photosynthetic tissues, roots, rhizomes,
stems), and any of the descriptor of tissue chemical composition
needed to test our hypotheses (i.e. C, N, P, and lignin concentrations).
Additional detail in the general description of the data set was
obtained by grouping the data according to detritus origin (phytoplankton, macroalgae, seagrasses, freshwater angiosperms, amphibious plants, sedges, mangroves, grasses, shrubs, conifers, and
broad-leaved deciduous and evergreen trees). The relationships between decomposition rates and nutrient concentrations were described using least-squares regression analyses of log-transformed
data. Logarithmic transformation was found to be necessary to
avoid heteroscedasticity in these analyses (Draper and Smith 1965).
Differences in the relationship between plant litter decomposition
rate and nutrient content depending on detritus origin (as defined
above) were tested for using analysis of covariance (Draper and
Smith 1966). The simultaneous influence of carbon (or lingin),
nitrogen, and phosphorus on litter decomposition rates was tested
for using multiple least squares regression analyses, instead of
carbon/nutrient ratios, for the use of these ratios is conducive to
statistical artifacts (cf. Chayes 1971; Atchley and Anderson 1978).
The (statistical) influence of nitrogen, phosphorus, carbon (or lignin) contents on decomposition rates was partitioned into direct
and indirect effects using path analysis (e.g. Williams et al. 1990).
Separate path analyses were used to test the effects of C, N, and P,
on the one hand, and those oflignin, N, and P, on the other, because
lignin contents were only reported in a small subset of the studies,
which did not include any study on phytoplankton or macroalgae.
Results and discussion
The data set comprised 256 reports of decomposition
rates of plant litters originating from different photosynthetic organisms, from land an aquatic environments
(Appendix). These data were gathered under a broad
variety of conditions, from controlled laboratory experiments to field studies, and included decomposition of
plant litter originating from photosynthetic tissues,
roots, rhizomes, stems and branches, and mixtures of
these (Appendix). Unfortunately, detailed descriptions
of the experimental conditions (e.g. temperature, pH,
oxygen tension) were only reported in a few studies and
could not be included in the analysis.
Decomposition rates ranged between 0.00019 day -1
for non-photosynthetic tissues of an Australian shrub
(Leucospermun parile), and 0.098 day- i for the cells of
a cyanobacterium (Anabaena sp.) and the leaves of a
submerged freshwater angiosperm (Vallisneria spiralis),
and differed significantly according to their origin (ANOVA, F=41.3, P < 0.0001; Fig. 1). Decomposition rates
were faster for detritus derived from phytoplankton and
459
i
Microalgae
Freshwater plants
A m p h i b i o u s plants
Macroalgae
Seagrasses
Grasses
Sedges
Mangroves
Broad decid.tree leave:
Shrubs
Conifers
Broad perennial
tree leaves
**
I'---f]
I
t
I
I
,
I
I
7--3---1
i
m
I t'---
b
.
'
O
9
,
F ~
I
~
I
.
I
r-l----q
f-y-]
-
9
O
P
P
0.0001
0.1 0
0.01
0.001
Decomposition
[
I
rates
(day
Half-life
-1)
Fig. 1. Box plots showing the distribution of detritus decomposition
rates and half-lives for detritus of different sources. Boxes encom-
pass the 25 and 75% quartiles of all the data for each plant type,
the central line represents the median, bars extend to the 95%
500
1000
of
1500
detritus
2000
(days)
confidence limits, asterisks-represent observations extending beyond the 95% confidence limits, and circles represent observations
beyond the 99% confidence limits
Table 1. Regression equations between detritus decomposition rate (K, In units day x) and carbon (C), phosphorus (P), nitrogen (N), and
lignin concentrations (as % DW) in the plant litter
Variable
dependent
Intercept
Slope N
k
k
k
k
k
k
k
-2.45
- 1.42
1.17
- 1.38
- 1.89
-0.22
- 1.87
1.19+0.095
Slope P
Slope C
Slope
lignin
0.93 • 0.066
-2.1•
- 1.04• 0.20
0.80•
0.71 • 0.220
0.31 ~ 0.240
Submersed detritus:
k
-2.30
k
- 1.22
1.33•
Terrestrial detritus:
k
-2.77
k
- 2.20
0.48•
0.50•
0.66+0.154
0.39•
- 1.0•
1.01 •
0.46 • 0.09
-0.22•
n
rz
F
P
231
143
78
54
141
50
43
0.40
0.58
0.12
0.32
0.64
0.85
0.37
155
198
11.6
25.8
123
92
9.14
<0.001
< 0.001
<0.001
<0.001
<0.001
< 0.001
< 0.001
136
80
0.50
0.66
134
153
<0.001
<0.001
98
66
0.14
0.26
17
24
<0.001
< 0.001
All variables were tog-transformed prior to regression analyses.
Also shown are the SE of the regression coefficients, the number of
observations involved (n), the coefficient of determination (r2), the
F-statistic (F), and the associated probability level (P) for the regression analysis
a m p h i b i o u s and submerged freshwater plants (Fig. 1),
which had average half-lives between 17 a n d 58 days, a n d
were slowest for litter derived f r o m shrubs a n d perennialleaf trees, which h a d average half-lives ranging between
2 and 3 years (Fig. 1). Litter nutrient c o n c e n t r a t i o n s also
differed significantly a c c o r d i n g to the detritus source
( A N O V A , F = 17.9 a n d 16.8 for N and P, respectively,
P < 0.001), such that plants whose detritus d e c o m p o s e d
fast also tended to p r o d u c e detritus with high nitrogen
and p h o s p h o r u s concentrations.
D e c o m p o s i t i o n rates were strongly positively correlated with the initial nitrogen and p h o s p h o r u s concentration o f the detritus ( r = 0 . 6 4 a n d 0.76, respectively,
P < 0.0001 ; Table 1, Fig. 2), a n d were weakly, negatively
correlated to its c a r b o n c o n c e n t r a t i o n ( r = - 0 . 3 7 ;
P < 0 . 0 0 5 ; Table 1). Regression analysis indicated that
d e c o m p o s i t i o n rates ( k ) increased linearly (Ho:
slope= 1, t-test, P > 0.05) with increasing litter nitrogen
and p h o s p h o r u s concentrations (Table 1). This implies
that half-lives (half life = k -1 In 2), and, therefore, detritus t u r n o v e r times are inversely scaled to litter nutrient
concentration. Detritus lignin c o n t e n t was negatively
correlated with its nitrogen and p h o s p h o r u s contents
(r = - 0.36 and - 0.57, respectively, P < 0.05), and was
significantly, negatively related to litter d e c o m p o s i t i o n
rates (Table 1), supporting the i m p o r t a n c e o f c a r b o n
quality o n d e c o m p o s i t i o n rates (e.g. Melillo et al. 1982;
A b e r et al. 1990; U p a d h y a y et al. 1989).
The relationships between d e c o m p o s i t i o n rates and
nitrogen and p h o s p h o r u s concentrations differed signifi-
460
0.1
,
,
-./t,
0.01
o ~/y'o_
w O ~ O e ~0
0.001
~
o
o
eo
0.0001
0.01
o
I
I
0.10
1
Nitrogen
'
Fig. 2. The relationships between decomposition rate and the initial nitrogen and phosphorus concentrations
in the detritus. S o l i d l i n e s represent
the fitted regression lines (Table 1),
and o p e n a n d s o l i d c i r c l e s represent
detritus decomposing on land and
submersed, respectively
10
0.001
(% DW)
I
I
I
0.01
0.1
1
Phosphorus
j
O.1
0.01
e~
0
i
10
(% DW)
0.1
2
1
3
5
8
t_
0.01
6
--
4
e~
0
9
9
6
0.0Ol
E
E
0.001
--
0
0
O.O00l
0.0001
0.01
0.1
Nitrogen
0
content
10
(%
DW)
0.001
I
I
I
0.01
0.1
0
content
(%
Phosphorus
10
DW)
Fig. 3. Regression lines describing the relationships between decomposition rates and nitrogen and phosphorus concentrations for
detritus of different sources. L i n e s extend the range of nutrient concentrations for detritus source in the data set. 1 - microalgae;
2 - freshwater plants; 3
amphibious plants; 4
macroalgae;
5 - seagrasses; 6 - grasses; 7 - sedges; 8 - mangroves; 9 - broad
deciduous tree leaves; 1 0 - shrubs; 11 - conifers; 1 2 - broad
perennial tree leaves
cantly depending on detritus origin (ANCOVA, F = 11.2
and 5.0, P < 0.001, for nitrogen and phosphorus concentrations, respectively), which accounted for 32 % and 24 %
of the unexplained variance in the relationship between
decomposition rate and litter nitrogen and phosphorus
concentrations, respectively. Decomposition rate of amphibious plant litter increased fastest with increasing
nitrogen and phosphorus concentration (Fig. 3, Table 2),
and no relationship between litter nitrogen or phosphorus content and decomposition rate was observed within
some litter sources (e.g. phytoplankton, freshwater
angiosperms; Fig. 3, Table 2). These differences were
partially attributable to the different habitats where the
detritus decomposed, for litter decomposed faster, for a
given nutrient concentration, in water than on land (ANCOVA, F=12.4 and 4.9, P<0.001, for nitrogen and
phosphorus, respectively), consistent with the stimulatory effect of moisture on decomposition rates (Swift et al.
1979). Moreover, decomposition rates of submerged
plant detritus were strongly, linearly scaled to nutrient
concentrations (Table 1), whereas those of plant material
decomposing on land were much weaker and scaled as
the 1/2 power of nutrient concentration (Table 1).
The large variance in detritus decomposition rates
unexplained by nitrogen or phosphorus concentration,
as well as the lack of relationship within some sources of
detritus, may be partially attributable to the need to
consider the effects of carbon, nitrogen and phosphorus
contents on plant decomposition in concert. This has
been achieved in the past using the carbon/nitrogen and
carbon/phosphorus ratios of the detritus, which reflect
the relative limitation of decomposers by carbon - and
energy - versus nutrients (e.g. Twilley et al. 1986; Taylor
et al. 1989; Reddy and DeBusk 1991; and others). We
also found strong negative correlations between decomposition rates and C/N and C/P ratios (Fig. 4), and
simultaneous consideration of detritus nitrogen, phosphorus, and carbon concentrations accounted for most
(89%, SE of regression estimates = 1.7-fold) of the variance in decomposition rates (Table 1), independently of
detritus origin (ANCOVA, F-test, P>0.05). A similar
relationship based on lignin, nitrogen, and phosphorus
461
Table 2. Regression equations between detritus decomposition rate (K, in units d 1) and nitrogen (N), and phosphorus (P) concentrations
(as % DW), for the different detritus sources in the data set
Plant type
Intercept
Slope N
Phytoplankton
- 1.51
0.314- 0.274
N
P
Macroalgae
N
P
Seagrasses
N
P
Freshwater
N
angiosperms
P
Amphibious plants
N
P
Sedges
N
P
Mangroves
N
P
Grasses
N
P
Shrubs
N
P
Conifers
N
P
Broad deciduous tree N
leaves
P
Broad perennial tree N
leaves
P
- 1.46
Intercept
Slope P
- 1.26
0.23 • 0.204
- 1.54
1.11 • 1.401
- 1.64
0.41 • 0.068
- 1.29
0.134-0.230
- 0.42
2.22 • 0.343
- 1.78
0.744- 0.188
-3.71
1.564-0.739
- 1.85
0.684-0.165
- 1.96
0.574- 0.208
-2.02
0.764-0.265
- 2.31
0.25 4- 0.291
- 1.57
0.76 • 0.329
- 1.30 • 0.662
-2.19
0.16•
- 1.55
0.40:t:0.516
- 2.35
1.98 4- 0.384
- 1.78
0.744- 0.188
-2.17
1.62:6 1.046
-2.48
0.6012.62
- 2.62
1.19 4- 0.464
- 2.91
0.71 4- 0.227
- 2.70
0.08 ~: 0.209
-2.14
1.53i363
All variables were log-transformed prior to regression analyses.
Also shown are the SE of the regression coefficients, the range of
nitrogen and phosphorus concentrations for the different sources of
0.1
z \0
66
I
od
~t.
00 o
n
r2
F
P
(8.94-2.30)
(1.70-0.26)
(3.92-1.00)
(0.36-O.19)
(4.36-0.53)
(2.50-0.04)
(3.66-1.15)
(0.85-0.10)
(3.25-0.59)
(0.47-0.08)
(2.77-0.18)
(0.29-0.01)
(1.24-0.36)
(0.13-0.06)
(3.52-0.18)
(0.58-0.02)
(2.15-0.44)
(0.56-0.005)
(4.96-0.35)
(0.55-0.02)
(3.07-0.07)
(0,28-0,02)
(0.70-0.13)
(0.06-0.004)
15
13
8
6
24
7
17
14
12
9
50
24
8
4
9
8
18
14
25
15
43
26
6
6
0.02
0.02
0.29
0.000
0.000
0.85
0.000
0.000
0.701
0.836
0.505
0.388
0.165
0.537
0.341
0.699
0.247
0.329
0.271
0.340
0.000
0.000
0.770
0.465
1.24
1.25
3.85
0.63
0.15
35.33
0.59
0.35
26.75
41.75
50.92
15.56
2.38
4.47
5.14
17.22
6.57
7.38
9.93
8.22
0.15
0.76
17.76
5.34
0.286
0.287
0.098
0.473
0.702
0.002
0.454
0.580
0.000
0.000
0.000
0.001
0.174
0.169
0.058
0.006
0.040
0.019
0.040
0.013
0.704
0.391
0.014
0.082
detritus, the number of observations involved (n), the coefficient of
determination (r2), the F-statistic (F), and the associated probability
level (P) for the regression analysis
9
o.~.
$" 4 i t . .
9
Range
9
9
0.01
"7
0.001
0.0001
1
I
r
10
100
1000
10
C/N
c o n c e n t r a t i o n s , was m u c h w e a k e r (37% o f the v a r i a n c e
e x p l a i n e d , SE o f r e g r e s s i o n e s t i m a t e s = 2.2-fold), p e r h a p s
b e c a u s e o f the n a r r o w e r r a n g e o f d e t r i t u s sources f o r
w h i c h e s t i m a t e s o f lignin c o n c e n t r a t i o n were available.
N i t r o g e n a n d p h o s p h o r u s c o n c e n t r a t i o n s in the p l a n t
d e t r i t u s were h i g h l y c o r r e l a t e d ( r = 0.83, P < 0.0001), as
d e m o n s t r a t e d for t e r r e s t r i a l ( G a r t e n 1976) a n d a q u a t i c
( D u a r t e 1990, 1992) p l a n t s . T h e s t r o n g c o l i n e a r i t y between p h o s p h o r u s a n d n i t r o g e n c o n c e n t r a t i o n s implies
t h a t the coefficients o f d e t e r m i n a t i o n o b t a i n e d in the
m u l t i p l e r e g r e s s i o n a n a l y s i s ( T a b l e 1) m a y be inflated,
a n d the r e g r e s s i o n coefficients b i a s e d ( D r a p e r a n d S m i t h
I
I
100
1000
Fig. 4. The relationship between
detritus decomposition rate and
initial C/N and C/P atomic ratios.
Solid lines represent the fitted regression lines
10000
C/P
1966). T h e statistical influence o f litter n i t r o g e n , p h o s p h o r u s , a n d c a r b o n (or lignin) c o n c e n t r a t i o n s o n dec o m p o s i t i o n rates is b e s t d e p i c t e d , therefore, as a m i x t u r e
o f direct (i.e. d e p e n d e n t o n the c o n c e n t r a t i o n o f a p a r t i c u l a r element) a n d i n d i r e c t effects, a c t i n g t h r o u g h the
r e l a t i o n s h i p to o t h e r n u t r i e n t s (Fig. 5). W e used p a t h
analysis ( W i l l i a m s et al. 1990) to e l u c i d a t e these different
effects. This s h o w e d t h a t i n d i r e c t effects were i n d e e d
i m p o r t a n t , a n d a c c o u n t e d for 52% a n d 44% o f the effect
o f n i t r o g e n a n d p h o s p h o r u s , respectively, o n litter dec o m p o s i t i o n rates (Fig. 5), w h e r e a s n o significant direct
effect c o u l d be a t t r i b u t e d to differences in c a r b o n c o n c e n -
462
~
-0 17
i'
986
Phosphorus
k
0
N, 0.41 P, 0.03 C)
0 . 8 7 ~
"
(0.48 P, 0.34 N, 0 . 0 4 y
99
Decomposition
rate
\
~
9 ~
13/
"0!36
"
\
Ca~rbon ~
Nitrogen
/
/0.61
Phosnl~orus
P--
-0.37 (-0"18 c, -0.07 N, -0.12 p)
~0.49(0.19
N, 0.26 P, 0.04 Lignin)
0.61N, 0.06 lignin~,,~"
~
.
(0.43 P, 0.12
Decomposition
\0.
~
Lignin
.
rate
....
/-0.43
(-0.11 Lignin, -0.07 N, -0.25 P)
tration. Similarly, path analysis on the smaller data set
for which lignin concentration was available also revealed no significant direct effect of lignin concentration
on detritus decomposition rates (Fig. 5).
These results provide evidence of the importance of
the nitrogen and phosphorus concentration in the plant
litter in regulating decomposition rates, consistent with
current knowledge of microbial nutrient requirements.
That detritus carbon concentrations were not particularly important in accounting for differences in decomposition rates is expected from the high C/N and C/P
ratios characteristic of plant detritus (Fig. 4), relative to
those of bacteria (Thayer 1974; Swift et al. 1979) and
saprophytic fungi (Findlay 1934; Swift et al. 1979). The
lack of strong relationships between detritus carbon or
lignin concentrations and decomposition rates does not
conflict with the important role of carbon quality in
regulating decomposition rates. Instead, it probably reflects the fact that carbon quality is a compound variable,
involving a broad array of compounds besides lignin in
the diverse set of detritus sources compared here. These
results are, therefore, consistent with previous reports
that differences in decomposition rates were best related
to nutrient content when comparing litters from a broad
range of plant sources, but to carbon quality when comparing litter derived from similar plants (Taylor et al.
1989). The relationship between plant decomposition
rates and detritus carbon, nitrogen and phosphorus concentration found here accounted for most (89%) of the
differences in the decomposition rates of detritus derived
from photosynthetic organisms ranging from unicellular
microalgae to trees. These results highlight, therefore, the
importance of the nutritional balance (C :N :P) of plant
detritus in regulating decomposition rates.
The nutritional balance of plant detritus plays,
therefore, an important role in the control of material
Fig. 5a, b. Path diagrams describing
the structure of the relationship between decompositionrates and a nitrogen, phosphorus and carbon, or
b lignin concentrations.Numbers in
bold type show the Pearson correlation coefficientsamong the variables,
and numbers in parentheses partition
the Pearson correlations betweendecomposition rates and nutrient concentration into direct and indirect
(i.e. attributable to indirect relationships to other variables) effects
(cf. Williams et al. 1990)
flow in ecosystems. Nutrient constraints on carbon flow
through detrital food webs may be, at least qualitatively,
similar to the demonstrated importance of plant nutrient
status for herbivory (e.g. Mattson 1980). Microbial decomposers also play a major role in the digestion of the
plant material ingested by herbivores, so that the digestion process in herbivore guts involves, in fact, decomposition. Thus, there are close relationships between
plant nutrient status and herbivory (Mattson 1980), and
between plant nutrient concentration and the efficiency
of conversion of ingested food (Mattson 1980). The parallel between detritivory and herbivory extends beyond
nutrient control of their rates. For instance, increasing
temperature accelerates decomposition rates (Godshalk
and Wetzel 1978; Swift et al. 1979; Best et al. 1990;
Aizaki and Takamura 1991). Likewise, the digestive
tracts of homeotherm herbivores provide, compared with
those of poikilotherms, a suitable "digestion reactor"
with high temperatures enabling efficient microbial activity (Swift et al. 1979). Thus, herbivory and detritivory
are, to some extent, constrained by similar factors,
through similar causes. The recent awareness of the importance of microbial heterotrophs as links between primary produceres and herbivores in planktonic ecosystems (i.e. the microbial loop, Azam et al. 1983), may well
reflect the general structure of ecosystems, where primary
producers and herbivores are linked by such microbial
loop (whether internally, i.e. intestinal flora, or externally, i.e. decomposers).
The important role of nutrients in controlling plant
decomposition rates has also the indirect effect of coupling growth and decomposition rates, for fast-growing
plants tend to have high nutrient concentrations (Chapin
et al. 1987), and also decompose fast because of the
adequacy of their litter as substrate for microbial growth.
Exceptions to this rule are systems where climatic con-
463
ditions reduce d e c o m p o s i t i o n rates, such as water-logged
soils, lakes, and the sea floor, where plant d e c o m p o s i t i o n
is reduced by low p H a n d / o r anoxia ( G o d s h a l k a n d
Wetzel 1978; Swift et al. 1979; Best et al. 1990), leading
to an inordinate a c c u m u l a t i o n o f organic matter. H o w ever, the general association o f fast g r o w t h rates with fast
d e c o m p o s i t i o n rates, resulting f r o m the controlling role
o f nutrients in b o t h processes, acts to prevent the accum u l a t i o n o f c a r b o n and associated nutrients as plant
detritus. Conversely, the association between slow plant
g r o w t h rates and slow litter d e c o m p o s i t i o n rates ensures
the release o f nutrients f r o m plant detritus at rates slow
e n o u g h to allow for efficient recycling. These patterns are
conducive, therefore, to an overall balance between the
m a g n i t u d e o f living and detrital plant material, which is
p r o b a b l y a f u n d a m e n t a l aspect o f ecosystem functioning
and plant succession.
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Mixed natural community
Mixed natural community
Mixed natural community
Crysophyceae
Crysophyceae
Mixed natural community
Mixed natural community
Mixed natural community
Mixed natural community
Anabaena sp.
Microcystis sp.
Synechococcus sp.
Dunaliella sp.
Cylindrotheca sp.
Seston
Skeletonema costatum
Scenedesmus sp.
SkeIetonema costatum
Chaetoceros tricomutum
Thalassiosira anpstii
Mixed natural community
Chlorella sp.
Mixed natural community
Macrocystis integrifolia
Maerocystis inteyrifolia
Cladophora aft. albida
Cladophora aft. albida
Cladophora aft. albida
Cladophora aft. albida
Cladophora aft. albida
Ulva sp.
Zostera marina
Zostera marina
Zostera marina
Zostera marina
Thalassia testudinum
Zostera marina
Thalassia testudinum
Thalassia testudinum
Thalassia testudinum
Posidonia australis
Heterozostera tasmanica
Zostera marina
Cymodocea nodosa
Thalassia testudinum
Thalassia testudinum
Macroalgae
Seagrasses
Species
Phytoplankton
Aquatic plants ."
Plant type
Mixed litter
Mixed litter
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves (average)
Leaves (average)
Rhizomes
Roots
tissue
tissue
tissue
tissue
tissue
tissue
tissue
organism
organism
organism
organism
organism
organism
orgamsm
orgamsm
orgamsm
organism
orgamsm
organism
orgamsm
organism
organism
orgamsm
organasm
orgamsm
organism
organasm
orgamsm
orgamsm
orgamsm
Stipes
Photosyn.
Photosyn.
Photosyn.
Photosyn.
Photosyn.
Photosyn.
Photosyn.
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Whole
Fraction
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Conditions
0.340
1.090
1.097
6.63
5.95
1.90
4.00
2.80
3.50
2.00
1.80
1.80
1.90
3.00
2.64
2.76
1.12
1.00
1.00
2.10
2.50
3.92
3.44
3.21
2.73
2.89
0.388
0.602
0.850
0.983
0.800
0.260
0.690
8.94
4.34
6.08
4.52
4.19
2.40
3.30
8.00
5.92
2.30
3.59
0.550
0.500
0.190
0.335
0.291
0.313
0.278
0.360
1.700
0.800
0.800
%P
4.19
4.19
%N
55.00
37.00
34.40
32.00
29.50
30.00
40.00
43.50
40.70
43.40
40.30
31.2
49.6
45.00
29.27
45.40
25.50
15.10
27.40
48.00
31.30
18.08
22.60
25.50
25.50
%C
24.31
15.64
35.42
37.33
20.80
20.80
34.42
16.67
18.67
12.95
13.80
15.77
17.22
12.60
5.62
11.73
7.10
7.30
9.62
7.00
6.17
9.19
7.34
11.10
8.73
8.83
8.55
6.75
8.26
7.10
7.10
8.72
9.29
6.51
7.40
CN
258.33
191.17
543.86
330.51
362.56
361.67
372.74
223.89
117.55
106.00
171.90
52.17
88.96
119.29
82.34
146.00
102.00
82.34
82.34
CP
0.0010
0.0020
0.0035
0.0180
0.0007
0.0070
0.0170
0.0085
0.0080
0.0013
0.0040
0.0124
0.0230
0.0007
0.0183
0.0295
0.0321
0.0076
0.0082
0.0038
0.0076
0.0035
0.0230
0.0360
0.0560
0.0660
0.0360
0.0360
0.0470
0.0680
0.0270
0.0980
0.0980
0.0528
0.0956
0.0498
0.0417
0.0294
0.0449
0.0233
0.0676
0.0699
0.0388
0.0093
0.0540
0.0658
K(d-1)
(Godshalk & Wetzel 1978a)
(Godshalk & Wetzel 1978b)
(Harrison 1982)
(Harrison 1982)
(Harrison 1989)
(Harrison 1989)
(Harrison 1989)
(Harrison 1989)
(Harrison 1989)
(Harrison 1989)
(Harrison 1989)
(Hemminga & Nieuwenhuize 1991)
(Hemminga & Nieuwenhuize 1991)
(Kenworthy & Thayer 1984)
(Kenworthy & Thayer 1984)
(Albright et al. 1980)
(Albright et al. 1980)
(Birch et al. 1983)
(Gabrielson et al. 1983)
(Gabrielson et al. 1983)
(Gabrielson et al. 1983)
(Gabrielson et al. 1983)
(Twilley et al. 1986)
(Aizaki & Takamura 1991)
(Aizaki & Takamura 1991)
(Aizaki & Takamura 1991)
(Aizaki & Takamura 1991)
(Aizaki & Takamura 1991)
(Aizaki & Takamura 1991)
(Aizaki & Takamura 1991)
(Aizaki & Takamura 1991)
(Aizaki & Takamura 1991)
(Aizaki & Takamura 1991)
(Aizaki & Takamura 1991)
(Biddanda 1988)
(Biddanda 1988)
(Biddanda 1988)
(Garber 1984)
(Garber 1984)
(Golterman 1972)
(Newell et al. 1981)
(Newell et al. 1981)
(Newell et al. 1981)
(Otsuki & Hanya 1972)
(Twilley et al. 1986)
(Walsh et al. 1988)
Author
Appendix. Nutrient content, decomposition rate, and plant and experimental characteristics for the plant decomposition experiments compiled in the data set used here
Amphibious
Plants
Freshwater
angiosperms
Plant type
Roots
Rhizomes
Leaves (average)
Leaves (average)
Leaves
Leaves
Leaves
Mixed litter
Mixed litter (+wood)
Mixed litter (+wood)
Leaves
Leaves
Zostera marina
Zostera marina
Thalassia testudinum
Thalassia testudinum
Cymodocea nodosa
Zostera marina
Zostera marina
Zostera marina
Posidonia oceanica
Posidonia oeeanica
Thalassia testudinum
Halophila stipulacea
Potamogeton perfoliatus
Potamogeton lucens
Potamogeton lucens
Elodea canadensis
Elodea canadensis
Ceratophyllum
Vallisneria spiralis
Najasflexilis
Myriophyllum heterophyllum
Myriophyllum heterophyllum
Najasflexilis
Potamogeton nodosus
Potamogeton crispus
Potamogeton crispus
Justicia americana
Justicia americana
Potamogeton
Rappia
Myriophyllum
Sagittaria lanc~folia
Sagittaria lancifolia
Nymphoides peltata
Nymphoides peltata
Nymphoides peltata
Nymphoides peltata
Nymphoides peltata
Nymphoides peltata
Nymphoides peltata
Nymphoides peltata
Nymphoides peltata
Nymphoides peltata
Nuphar variegatum
Nuphar variegatum
Sparganium eurycarpum
Sparganium eurycarpum
Sparganium eurycarpum
Eichhornia crassipes
Leaves
Stems
Petioles
Long Shoots
Leaves
Leaves
Petioles
Roots
Roots
Short Shoots
Long Shoots
Short Shoots
Leaves
Leaves
Mixed litter
Mixed litter
Mixed litter
Mixed litter (average)
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves (average)
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves (average)
Leaves
Leaves
Leaves, petioles, stems
Roots and Rhizomes
Leaves
Leaves
Leaves
Fraction
Species
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water (20 m.)
Water (5 m.)
Water
Water
Conditions
0.150
0.130
0.465
0.465
0.079
0.130
0.270
3.248
3.248
2.4
2.4
1.41
0.59
0.59
2.53
0.430
0.290
0.290
0.137
0.298
0.360
0.510
0.560
0.160
0.100
0.200
0.820
0.848
0.370
0.550
2.500
2.100
0.078
0.038
%P
2.40
1.40
1.77
1.37
2.79
1.15
2.40
1.20
1.26
3.66
3.44
2.61
1.80
2
2
1.80
2.40
2.15
1.90
0.73
0.53
2.10
1.80
4.36
1.61
2.41
1.27
1.40
0.58
1.86
%N
39.3
39.3
38.67
38.43
38.43
88.91
50.04
50.04
77
178
22
16
48
179
137
143
151
152
19.14
19.10
32
76
76
41
21.03
27.76
12.71
20.22
14.41
14.41
20.22
20.22
31.2
24.7
24.7
31.2
41.60
31.9
32.6
30.4
18.78
51.14
74.84
20.17
21.97
13.54
21.00
16.36
22.14
26.00
47.67
17.68
CN
55.38
32.00
34.40
36.30
33.90
50.60
28.98
33.80
24.10
31.20
23.70
28.18
%C
0.0048
0.0035
0.0048
0.0279
0.0039
0.0136
0.0357
0.0357
0.0087
0.0066
0.0149
0.0032
K (d 1)
570.00
570.00
710.00
0.0058
0.0076
0.0420
0.0440
0.0560
0.0910
0.0450
0.0790
0.0490
0.0350
0.0370
0.0550
0.0600
0.0200
0.0076
0.0021
0.0017
0.0095
0.0446
0.0517
0.0458
0.0475
0.0859
168.69 0.0247
0.0987
0.0070
0.0090
0.0340
0.0280
249.2
0.0483
0.0648
0.0640
0.0138
0.0398
228.912 0.0310
165.130 0.0280
140.238 0.0450
140.91
34.93
29.65
1040
1633
CP
(Bayley et al. 1985)
(Bayley et al. 1985)
(Brock /984)
(Brock 1984)
(Brock 1984)
(Brock 1984)
(Brock 1984)
(Brock 1984)
(Brock 1984)
(Brock 1984)
(Brock 1984)
(Brock 1984)
(Godshalk & Wetzel 1978a)
(Godshalk & Wetzel 1978a)
(Neeley & Davis 1985)
(Neeley & Davis 1985)
(Neeley & Davis 1985)
(Reddy & DeBusk 1991)
(Bastardo 1979)
(Bastardo 1979)
(Bastardo 1979)
(Bastardo 1979)
(Bastardo 1979)
(Best et al. 1990)
(Briggs et al. 1985)
(Godshalk & Wetzel 1978a)
(Godshalk & Wetzel 1978a)
(Godshalk & Wetzel 1978a)
(Godshalk & Wetzel 1978a)
(Hill 1979)
(Rogers & Breen 1982)
(Rogers & Breen 1982)
(Twilley et al. 1985)
(Twilley et al. 1985)
(Twilley et al. 1986)
(Twilley et al. 1986)
(Twilley et al. 1986)
(Kenworthy & Thayer 1984)
(Kenworthy & Thayer 1984)
(Newell et al. 1986)
(Newell et al. 1986)
(Peduzzi & Herndl 1991)
(Pellikaan 1982)
(Pellikaan 1984)
(Pellikaan 1984)
(Romero et al. 1992)
(Romero et al. 1992)
(Rublee & Roman 1982)
(Wahbeh & Mahasneh 1985)
Author
Sedges
Phragmites
communis
Phragmites communis
Panicum sp.
Spartina alterniflora
Spartina alternifolia (short form)
Spartina alternifolia (tall form)
Spartina alternifolia (short form)
Spartina alternifolia (tall form)
Typha domingensis
Typha domingensis
Cladiumjamaicense
Cladium jamaicense
Cladium jamaicense
Typha domingensis
Typha marsh
Scirpus subterminalis
Scirpus acutus
Scirpus acutus
Scirpus subterminalis
Spartina alterniflora
Juncus roemerianus
Spartina anglica
Spartina anglica
Trigloehin maritima
Spartina angliea
Spartina angIica
Triglochin maritima
Spartina anglica
Typha 9lauca
Typha glauca
Typha glauca
Typha glauca
Typha glauca
Juncus roemerianus
Phragmites eommunis
Spartina
Spartina alternifolia
Spartina alternifolia
Typha glauca
Scolochloafestucacea
Scirpus laeustris
Phragmites australis
Scolochloafestucacea
Typha x g!auca
Phragmites australis
Mixed litter
Mixed litter
Mixed litter
Roots
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Leaves
Mixed litter
Mixed litter
Mixed litter
Leaves
Mixed litter
Mixed litter
Mixed litter
Leaves (senesced)
Leaves (green)
Mixed litter
Leaves
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Water
Water
Water
Belowground
Soil/Fertilized
Soil/Fertilized
Soil/Control
Soil/Control
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
Leaves, petioles, stems Water
Roots and rhizomes
Water
Nuphar luteum
Nuphar luteum
Conditions
Fraction
Species
Terrestrial plants :
Plant type
1.04
0.60
1.60
0.39
2.54
1.20
0.77
0.53
0.50
0.35
0.40
0.50
0.30
0.50
0.48
1.2
1.5
1.5
1.2
1.33
0.79
1.12
0.71
2.54
0.90
1.29
2.09
1.67
0.48
0.55
0.48
0.63
2.77
0.70
0.71
1.07
0.71
1.64
0.82
0.77
0.40
0.30
0.87
0.75
0.18
2.92
1.67
%N
47.10
43.10
45.40
47.50
43.35
46.00
48.60
0.150
0.108
0.053
0.034
0.029
0.060
0.092
0.016
67.01
65.30
132.42
187.85
58.13
71.56
315
76.03
65.73
46.12
0.025
0.050
0.290
45.62
40.00
42.3
29.56
33.91
33.91
29.56
114.39
19.25
40.54
65.30
92.23
CN
94
82
94
30.4
43.6
43.6
30.4
38.24
41.90
41.70
43.10
41.90
%C
38.67
38.66
38.67
0.050
0.014
0.012
0.020
0.022
0.006
0.028
0.070
0.383
0.245
%P
1131.86
2100.79
3449.51
4305.56
1866.46
1291.67
7846.88
728.5
1800.00
1800.00
CP
0.001.8
0.0014
0.0071
0.0067
0.0052
0.0081
0.0033
0.0063
0.0010
0.00099
0.0013
0.0007
0.0007
0.0021
0.001
0.0090
0.0020
0.0050
0.0020
0.0111
0.0091
0.0079
0.0022
0.0256
0.0033
0.0093
0.0025
0.0061
0.0011
0.0016
0.0011
0.0104
0.0235
0.0017
0.0045
0.0098
0.0043
0.0071
0.0012
0.0016
0.001
0.0007
0.0022
0.0012
0.0003
0.0988
0.0142
K (d-l)
(Andersen 1978)
(Andersen 1978)
(Bayley et al. 1985)
(Benner et al. 1991)
(Breteler & Teal 1981)
(Breteler & Teal 1981)
(Breteler & Teal 1981)
(Breteler & Teal 1981)
(Davis 1991)
(Davis 1991)
(Davis 1991)
(Davis 1991)
(Davis 1991)
(Davis 1991)
(Findley et al. 1990)
(Godshalk & Wetzel 1978a)
(Godshalk & Wetzel 1978a)
(Godshalk & Wetzel 1978a)
(Godshalk & Wetzel 1978a)
(Haines & Hanson 1979)
(Haines & Hanson 1979)
(Hemminga & Buth 1991)
(Hemminga & Buth 1991)
(Hemminga & Buth 1991)
(Hemminga & Buth 1991)
(Hemminga & Buth 1991)
(Hemminga & Buth 1991)
(Hemminga & Buth 1991)
(Neeley & Davis 1985)
(Neeley & Davis 1985)
(Neeley & Davis 1985)
(Nelson et al. 1990)
(Nelson et al. 1990)
(Newell et al. 1984)
(Tanaka 1991)
(Twilley et al. 1986)
(Valiela et al. 1984)
(Valiela et al. 1984)
(Van der Valk et al. 1991)
(Van der Valk et al. 1991)
(Van der Valk et al. 1991)
(Van der Valk et al. 1991)
(Van der Valk et al. 1991)
(Van der Valk et al. 1991)
(Van der Valk et al. 1991)
(Twilley et al. 1985)
(Twilley et al. 1985)
Author
4~
Broad
deciduous
tree leaves
Grasses
Mangroves
Plant type
Sugar maple
Alnus ineana
Betulapubescens
Betula pubescens
Populus tremuloides
Quercus ellipsoidalis
Betula papyrifera
Frangula alnus
Quercus pyrenaica
Betula pubeseens
Salix fragilis
Alnus glutinosa
Fagus sylvatica
Red maple
Red oak
Aspen
Red oak
Sugar maple
Paper birch
Red maple
Red oak
White oak
Sugar maple
Pinus roxburghii
Tallgrass prairie
White pine
Hemlock
White spruce
Douglas fir
Avicennia marina
Avicennia marina
Molinia caerulea
Elymus pycnanthus
Erythrina sp.
Cajanus cajan
Inga edulis
Mixed
Mixed
Mixed
Mixed
Mixed
Scirpus lacustris
Typhaxglauca
Seoloehloafestucaeea
Phragmites australis
Scirpus lacustris
Kandelia candel,
Avicennia marina
Rhizophora mangle
Rhizophora spp.
Rhizophora spp.
Avicennia marina
Avicennia marina
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter
Mixed litter (average)
Needles
Needles
Needles
Needles
Needles
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Roots
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Roots
Leaves
Soil
Water
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Water
Water
Soil
Soil
Water
Soil
Soil
Water/Bagged
Water/
Unbagged
Water
Water
(+wood)
(+wood)
(+wood)
(+wood)
(+wood)
Mixed
Mixed
Mixed
Mixed
Mixed
litter
litter
litter
litter
litter
Water
Water
Water
Water
Water
Water
Conditions
Mixed litter ( + w o o d )
litter
litter
litter
litter
litter
Fraction
Species
1.95
0.90
3.52
3.48
3.18
0.18
0.35
0.66
0.52
0.61
0.67
1.59
1.90
2.14
1.94
2.05
2.22
1.80
2.26
1.67
2.62
3.07
0.77
1.74
0.84
1.40
0.92
0.88
0.6
0.61
1.20
2.60
0.71
0.57
1.18
1.24
0.40
0.37
0.36
0.74
0.76
0.75
0.63
0.89
0.97
0.41
0.86
%N
0.137
0.105
0.180
0,120
0.120
0.110
0.030
0,042
0,029
0.100
0,118
0.030
0.020
0.060
0.110
0.050
0.210
0.180
0.220
0.015
0,580
0.106
0.127
0.065
0.061
0.051
0.123
0.067
0.041
0.067
%P
43.35
37.19
34.48
31.50
45.35
48.20
43.60
46.40
45.30
%C
126.44
117.27
111.74
49
83.98
63.18
52.44
132.03
61.45
CN
2319.88
1012.33
1681.09
2923.58
1746.64
CP
0.0153
0.0079
0.0095
0.0047
0.0025
0.0009
0.0012
0.00096
0.0014
0.0017
0.0021
0.0020
0.0011
0.0014
0,0011
0.0023
0.0017
0.0019
0.0009
0.0012
0.0006
0.0009
0,0009
0.0009
0.0012
0.0009
0.0012
0.0054
0.0030
0.0033
0.0246
0.0252
0.0007
0.0014
0.0038
0.0071
0.0095
0.0008
0.0002
0.0114
0.0189
0.0018
0.0015
0.0010
0.0023
0.0008
0.0011
K (d-1)
der
der
der
der
der
Valk
Valk
Valk
Valk
Valk
et
et
et
et
et
al.
al.
al.
al.
al.
1991)
1991)
1991)
1991)
1991)
(Aerts 1989)
(Hemminga & Buth 1991)
(Palm & Sanchez 1990)
(Palm & Sanchez 1990)
(Palm & Sanchez 1990)
(Seastedt 1988)
(McClaugherty et al. 1985)
(McClaugherty et al. 1985)
(Taylor et al. 1989)
(Taylor et al. 1989)
(Upadhyay et al. 1989)
(Aber et al. 1990)
(Abet et al. 1990)
(Aber et al. 1990)
(Aber et al. 1990)
(Aber et al. 1990)
(Abet et al. 1990)
(Aber et al. 1990)
(Abet et al. 1990)
(Aber et al. 1990)
(Aber et al. 1990)
(Berg & Ekbohm 1991)
(Berg & Ekbohm 1991)
(Berg & Ekbohm 1991)
(Bockheim et al. 1991)
(Bockheim et al. 1991)
(Bockheim et al. 1991)
(Escudero et al. 1991)
(Escudero et al. 1991)
(Escudero et al. 1991)
(Gessner et al. 1991)
(Gessner et al. 1991)
(Gosz et al. 1973)
(Gosz et al. 1973)
(Van der Valk & Attiwill 1984)
(Van der Valk & Attiwill 1984)
(Newell et al. 1984)
(Robertson & Daniel 1989)
(Robertson & Daniel 1989)
(Van der Valk & Attiwill 1984)
(Van der Valk & Attiwill 1984)
(Lee 1989)
(Van
(Van
(Van
(Van
(Van
Author
Conifers
Shrubs
Plant type
Lodgepole pine
Lodgepole pine
Brown spruce
Pinus sylvestris
Pinus sylvestris
White pine
Hemlock
White pine
Red pine
Scots pine
Scots pine
Scots pine
Mallotusphilippensis
Pinus contorta
Rose sp.
Salicornia virginiea
Halimione portulacoides
Lirnonium vulgare
Limonium vulgare
Halimione portulaeoides
Leucosperrnumparile
Acacia urophylla
Trymalium spathulatum
Bossiaea laidlawaiana
Casuarina decussata
Acacia urophylla
B. laidlawaiana pods
Ceanothus megacarpus
Salvia melifera
Salvia melifera
Ceanothus megacarpus
Aspen
Balsam poplar
Cow-parsnip
Grass
Dogwood leaf litter
Alnus nepalensis
Aspen
White oak
Red maple
Sugar maple
sylvatica
sylvatica
sylvatica
sylvatica
Needles
Roots
Needles
Needles
Needles
Needles
Needles
Needles
Needles
Needles
Needles
Needles
Needles
Mixed litter
Mixed litter
Mixed litter
Leaves
Mixed litter
Mixed litter
Mixed litter
Leaves
Leaves
Leaves
Leaves
Pods
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
(+wood)
(+wood)
(+wood)
(+wood)
(+wood)
(+wood)
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves (average)
Leaves
Leaves
Leaves
Wood chips
Leaves
Wood part
Leaves
Leaves
Mixed litter
Mixed litter
Leaves
Sugar maple
Yellow birch
Yellow birch
Fagus
Fagus
Fagus
Fagus
Fraction
Species
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil/
Fertilizeed
Water
Water o
Water
Water
Water
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Water
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Conditions
0.45
1.83
1.50
0.97
1.26
1.89
0.37
1.22
0.48
1.51
0.48
1.05
0.42
1.56
2.09
2.06
2.15
1.70
0.53
0.71
0.6
1.78
0.44
1.27
0.61
0.63
0.58
0.65
0.67
1.15
0.50
0.62
1.09
0.85
0.82
0.67
1.12
1.12
0.66
0.67
0.07
0.66
2.56
0.64
0.58
1.31
0.81
0.78
%N
0.033
0.131
0.033
0.082
0.041
0.023
0.010
0.019
0.019
0.005
0.015
0.006
0.028
0.105
0.133
0.046
0.190
0.130
0.560
0.072
0.120
0.130
0.290
0.060
0.080
0.020
0.080
0.060
0.090
%P
51.0666
%C
112.41
CN
5653.81
CP
0.0004
0.0008
0.001
0.001
0.0009
0.0008
0.0007
0.0009
0.0008
0.0010
0.0008
0.0008
0.0006
0.0413
0.0090
0.0025
0.0048
0.0090
0.0002
0.0010
0.0031
0.0016
0.0012
0.0015
0.0008
0.0010
0.0011
0.0009
0.001
0.0032
0.0110
0.0009
0.0017
0.0023
0.0010
0.0035
0.0021
0.0013
0.0016
0.0015
0.0008
0.0022
0.0029
0.0018
0.0016
0.0036
0.0022
0.0021
K (d 1)
1985)
1985)
1985)
1985)
1987)
1990)
(Yavitt & Fahey 1986)
(Aber et al. 1990)
(Aber et al. 1990)
(Aber et al. 1990)
(Aber et al. 1990)
(Berg et al. 1982)
(Berg et al. 1982)
(Berg et al. 1982)
(Berg & Ekbohm 1991)
(Berg & Ekbohm 1991)
(Berg & Ekbohm 1991)
(Berg & Ekbohm 1991)
(Berg & Tamm 1991)
(Haines & Hanson 1979)
(Hemminga & Buth 1991a)
(Hemminga & Buth 1991a)
(Hemminga & Buth 1991a)
(Hemminga & Buth 1991a)
(Mitchell et al. 1986)
(O'Connell 1987)
(O'Connell 1987)
(O'Connell 1987)
(O'Connell 1987)
(O'Connell 1987)
(O'Connell 1987)
(Schlesinger 1985)
(Schlesinger 1985)
(Schlesinger 1985)
(Schlesinger 1985)
(Taylor et al. 1988)
(Upadhyay et al. 1989)
(Gosz et al. 1973)
(Gosz et al. 1973)
(Gosz et al. 1973)
(Gosz et al. 1973)
(Iversen 1973)
(Joergensen & Meyer
(Joergensen 1991)
(McClaugherty et al.
(McClaugherty et al.
(McClaugherty et al.
(McClaugherty et al.
(Sharma & Ambasht
(Taylor et al. 1989)
(Taylor et al. 1989)
(Taylor et al. 1989)
(Taylor et al. 1989)
(Taylor et al. 1989)
Author
4~
Quercus lanuginosa
Lyonia ovalifolia
Quereus glauca
Shorea robusta
Quercusfloribunda
Quercus leucotrichophora
Sitka spruce
Pinus banksiana
Pinus pinaster
Pinus sylvestris
Eucalyptus diversicolor
Eucalyptus diversicolor
Myrica esculenta
Rhododendron arboreum
Fruit
Leaves
Twigs
Bark
Leaves
Leaves
Needles
Needles
Needles
Needles
Branches
Leaves
Leaves
Leaves
Leaves
Leaves
Leaves
Needles
Needles
Brown spruce
Green spruce
Green spruce
Fraction
Species
Broad perennial Eucalyptus diversicolor
tree leaves
Eucalyptus diversicolor
Plant type
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil/
Fertilizeed
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Soil
Conditions
0.21
0.41
0.21
0.13
0.58
0.70
0.85
0.88
0.4
0.69
4.96
1.32
0.80
0.94
0.99
0.97
1.15
0.43
0.85
%N
0.027
0.010
0.008
0.004
0.057
0.060
0.132
0.080
0.017
0.037
0.550
0.120
0.080
0.070
0.280
0.120
0.220
0.041
0.132
%P
%C
CN
CP
0.0005
0.0015
0.0003
0.0006
0.0043
0.0048
0.001
0.0005
0.0010
0.0020
0.0355
0.0049
0.0073
0.0073
0.0076
0.0051
0.0052
0.0005
0.0008
K (d- 1)
(O'Connell
(O'Connell
(O'Connell
(O'Connell
(Upadhyay
(Upadhyay
1988)
1988)
1988)
1988)
et al. 1989)
et al. 1989)
(Berg & Tamm 1991)
(Bockheim et al. 1991)
(Escudero et al. 1991)
(Escudero et al. 1991)
(Fahey et al. 1991)
(Upadhyay et al. 1989)
(Upadhyay et al. 1989)
(Upadhyay et al. 1989)
(Upadhyay et al. 1989)
(Upadhyay et al. 1989)
(Upadhyay et al. 1989)
(Berg & Tamm 1991)
(Berg & Tamm 1991)
Author