Litter Loss Research Articles

Leaf litter processing rates in a Kenyan highland stream, the Njoro River

Mass loss of leaf litter from five common riparian trees in Kenya was determined using mesh bags over a 70-day period. The study was carried out in a river which previous research has shown to be apparently devoid of invertebrate shredders. There was a five fold difference between the most rapid and slowest decay rates, but all were within the fast range identified from temperate zone trees, demonstrating high rates of microbial activity. We conclude, therefore, that the low biomass of invertebrate shredders in Kenyan highland streams cannot be explained by poor quality of the leaf litter that enters them.

Kin-preferential cooperation, dominance-dependent reproductive skew, and competition for mates in communally nesting female house mice

Little is known about the behavioural mechanisms facilitating kin-preferential communal breeding in wild house mice (Mus domesticus). We evaluated the effect of kinship and male availability on aggression, social structure and reproductive skew in groups of female mice freely interacting and reproducing in semi-natural indoor enclosures. Triplets of either sisters or non-sisters were established in enclosures provided with either one or three littermate males, which were unrelated and unfamiliar to the females. Sisters were more spatially associated and less aggressive than non-sisters, leading to higher incidences of communal breeding and reproduction. This is in agreement with theoretical considerations on kin selection in house mice. Reproductive success was highly skewed in favour of dominant females due to subordinate infertility or complete loss of first litters, which might have been caused by dominant females. In spite of this, subordinates only rarely dispersed from the enclosures, suggesting that perceived dispersal risk generally outweighed relatively reduced reproductive potentials. Aggression levels among females were significantly higher when one male was available, compared to when three males were available. We suggest that this might result from higher female-female competition for mates, due to the risk of missing fertilisation when synchronously oestrous females encounter limited numbers of males in a deme. Our results indicate that, first, communal nursing in house mice might have evolved to ‘make the best out of a bad job’ rather than to enhance offspring fitness; and, second, that female-female mate-competition might play an important role in shaping female social structure in this polygynous mammal.

Effects of roadway crossings on leaf litter processing and invertebrate assemblages in small streams.

The effects of the Maine Turnpike (Interstate 95) on leaf litter processing were examined in five first- and second-order coastal plain streams in southern Maine, U.S.A. Invertebrate assemblages and red maple leaf softening and loss rates were compared at 53 stations arrayed upstream and downstream of the turnpike. Litter softening rate was not affected by the roadway. Litter loss rate was significantly faster at downstream stations (-0.0024 degree-day(-1)) than at upstream stations or at stations nearest the roadway, which were not different from each other (-0.0022 degree-day(-1)). Litter softening and loss rates were more strongly related to physical and chemical habitat variables than to shredder assemblage characteristics. Significant among-stream differences were observed in most community structural metrics and in biomass of important shredder taxa, but effects of the roadway were rarely consistent among streams. This is attributed in part to habitat variation, which was greater among streams than within streams. This study suggests that while the presence of the Maine Turnpike may influence stream water quality and habitat structure, the relatively subtle effects of roadway runoff and associated habitat modifications on stream ecosystem processes are masked by within- and among-stream variability in litter processing and leaf pack invertebrate assemblage structure.

Comparative performance and restoration potential of two Albizia species planted on mine spoil in a dry tropical region, India

This study focussed on the comparative impact of young high density plantations of two Albizia species ( Albizia lebbeck and Albizia procera) on the soil redevelopment process during early phase of mine spoil restoration in a dry tropical environment. Plant-hostile features such as high levels of pyrites, etc. were not present. We compared vegetational (biomass, net primary production (NPP), production efficiency, litter fall and its decomposition rate) and soil characters (soil nutrients, microbial biomass and N-mineralization rate) for these plantations. The A. lebbeck plantation accumulated greater biomass and exhibited higher net primary production than the A. procera plantation. The tree layer NPP of A. lebbeck plantation at 6 years age (25.4 t ha −1 years −1) was even higher than that of native dry deciduous forest. The short-lived components (foliage, fine roots) accounted for a greater proportion of ecosystem function (productivity) than the long-lived component (stem). The efficiency of foliage for NPP was greater in A. lebbeck than in A. procera. Decomposition of leaf litter of A. lebbeck was faster than that of A. procera. Ninety five percent mass loss of leaf litter would require 922 days in A. lebbeck and 1328 days in A. procera. Amounts of N and P deposition through leaf fall and release of these nutrients increased with the age of plantation in both species but were higher for A. lebbeck plantation. There was a significant improvement in soil properties due to plantation of both species, but the organic C and kjeldahl N levels were higher in A. lebbeck plantation as were the N-mineralization rates and soil microbial biomass. The proportional increase in soil biomass was much higher than that in soil organic C. The study indicated that the restoration efficiency of A. lebbeck was greater than that of A. procera.

Using reproductive data to model American black bear cub orphaning in Manitoba due to spring harvest of females

Animal rights groups have lobbied for the cancellation of Manitoba's spring hunting season for American black bear (Ursus americanus), contending that hundreds of cubs are orphaned each year. We developed a mathematical model to estimate the number of black bear cubs that may be orphaned in Manitoba because of the spring hunting season. The model used information from annual questionnaires mailed to resident hunters, Outfitter Declaration Forms from operators who provide services to non-resident clients, and analysis of reproductive tracts (>200 for both spring and fall seasons) and tooth samples (>1,100). To accurately reflect the number of cubs orphaned each spring, the model accounted for cub losses (both litter reduction and total litter loss) prior to a female being harvested using values from the literature. Although the data was not used in the model, evidence from the examination of reproductive tracts suggests that total litter loss of hunter killed bears can be determined by examining the condition of the uterus and ovaries. The model estimated that on average, 41 cubs were orphaned for each of the spring seasons between 1996 and 2000. This number represents <2% of the estimated number of cubs that may die annually in Manitoba from natural causes.

Litter decomposition and faunal activity in Mediterranean forest soils: effects of N content and the moss layer

Accumulation of soil carbon is mainly controlled by the balance between litter production and litter decomposition. Usually In Mediterranean forests there are contrasting conditions in the distribution of faunal activity and the moss layer that may have different effects on litter decomposition. Decomposition and faunal activity were studied by exposing litter of contrasting quality ( Pinus halepensis Mill. and Quercus ilex L.) for 3.5 yr in three Mediterranean pine forests of the eastern Iberian Peninsula. The effects of mosses on decomposition and on faunal activity were studied by exposing P. halepensis litter either on moss patches or directly on the forest floor. Faecal pellet production was used as an indication of faunal activity. Water availability or soil characteristics seem to limit faunal activities in the drier sites. Faecal pellets were not found during the first stages of decomposition and in all sites they appeared when about a 30% of the initial litter had decomposed. Under wet conditions faecal pellet production was very high and a mass balance suggested that soil faunal activity may result in a net flow of organic matter from the lower organic horizons to the surface Oi horizon. Mosses slightly increased mass loss of pine litter probably as a consequence of high potentially mineralizable nitrogen in the Oa horizon of moss patches and also, perhaps, as a consequence of the higher moisture content measured in the Oi horizon needles sampled among the mosses. In contrast, moss patches reduced faunal activity. The effect of litter quality on mass loss was not always significant, suggesting an interaction between litter quality and site conditions. During the first stages of decomposition there was N immobilisation in P. halepensis litter (poorer in N) and N release from Q. ilex litter (richer in N). In conclusion, in these forests soil microclimate and/or N availability appear to be more important controlling litter decomposition than the distribution of faunal activity.

Effects of a split 48-h doe-litter separation on productivity of free-nursing rabbit does and their litters

To prevent the weight loss of litters, and the distress of both rabbit does and their litters due to doe-litter separation (DLS), without losing its beneficial effects on fertility, the DLS, lasting 48 h before artificial insemination (AI), was split into two periods of 24 h with a short controlled suckling. Initially, 105 does of different parity were divided into three groups. During the post partum, the free-nursing does were treated as follows: regular DLS (R-DLS), the nest-box was closed for 48 h, from days 9 to 11, before AI; split DLS (S-DLS), the nest-box was closed for 24 h and, after suckling, for other 24 h before AI; control, does had free access to the nest-box. Fertility improved ( P≤0.05) in both R-DLS (60.9%) and S-DLS (59.4%) does compared to control does (44.1%). R-DLS and S-DLS does showed lower rabbit losses from days 14 to 35 ( P≤0.001) and higher litter sizes at weaning ( P≤0.05) than control does. Whereas the S-DLS did not affect the growth-rate and the weight of nursed rabbits until the weaning, the R-DLS reduced growth from days 9 to 14 (9.3, 13.2 and 14.0 g/day for R-DLS, S-DLS and control, respectively; P≤0.001) and the weaning weight of rabbits (732, 777, 780 g for R-DLS, S-DLS and control, respectively; P≤0.01). Productivity improved by 35.4% and 44.2% with R-DLS and S-DLS, respectively.

The Decomposition of Leaf Litters of Some Tree Species in Temperate Deciduous Forest in Korea II. Changes in Nutrient Content During Litter Decomposition

Dry weight loss and nutrient release from leaf litter for six tree species were studied using litter bag methods. The litter bags were incubated for f6 months on the forest floor in temperate deciduous forest in Mt. Cheonma, located at the middle part of Korean Peninsula. The changes in nutrient content and the rate of dry weight loss in leaf litter varied with litter types. The litter of Pinus densiflora showed the lowest rate of mass loss (k=0.33), nitrogen concentration (0.89%) and ash concentration (2.50%), while showed the highest C/N ratio (63.40). On the other hand, the litter of Acer pseudo-sieboldianum showed the fastest rate of mass loss (k=0.82), the highest nitrogen concentration (1.11%), and the lowest C/N ratio (49.40). During the decomposition, nitrogen, phosphorus and calcium in the leaf litters showed relatively slow decreasing pattern compared to other elements (carbon, potassium, magnesium, manganese and sodium), but potassium and sodium decreased at early stage of the decomposition for all leaf litters. Differences in annual decomposition rates of litter among species were consistent with the particular chemical characteristics of their leaf litters. The initial concentration of nitrogen was positively correlated with litter decomposition rate for six species, while litter decomposition rate of six species was negatively correlated with C:N ratio of initial leaf litters.

Solar UV‐B decreases decomposition in herbaceous plant litter in Tierra del Fuego, Argentina: potential role of an altered decomposer community

AbstractTierra del Fuego, Argentina (55°S), receives increased solar ultraviolet‐B radiation (UV‐B) as a result of Antarctic stratospheric ozone depletion. We conducted a field study to examine direct and indirect effects of solar UV‐B radiation on decomposition ofGunnera magellanica, a native perennial herb, and on the native community of decomposer organisms. In general, indirect effects of UV‐B mostly occur due to changes in the chemical composition of litter, whereas direct effects during decomposition result from changes in decomposer organisms and/or differences in the photochemical breakdown of litter. We designed a full‐factorial experiment using senescent leaves that had received either near‐ambient or attenuated UV‐B during growth. The leaves were distributed in litterbags and allowed to decompose under near‐ambient or reduced solar UV‐B during the growing season. We evaluated initial litter quality, mass loss, and nutrient release of decomposing litter, and microbial colonization of both initial litter and decomposed litter. We found that litter that decomposed under near‐ambient UV‐B had significantly less mass loss than litter that decomposed under reduced UV‐B. The UV‐B conditions received by plants during growth, which did not affect mass loss and nutrient composition of litter, affected fungal species composition but in different ways throughout the decomposition period. Before the decomposition trial,Beauveria bassianaandPenicillium frequentanswere higher under reduced UV‐B, whereasCladosporium herbarumand pigmented bacteria were more common under the near‐ambient compared to the reduced UV‐B treatment. After the decomposition period, leaves that had grown under reduced UV‐B showed higher frequency ofPenicillium thomiiand lower frequency ofTrichoderma polysporumthan leaves that had grown under near‐ambient conditions. The UV‐B condition received during decomposition also affected fungal colonization, withPenicillium chrysogenumbeing more frequent in leaves that had decomposed under reduced UV‐B, while the other species were not affected. Our results demonstrate that, in this ecosystem, the effects of UV‐B radiation on decomposition apparently occurred mostly through changes in the fungal community, while changes in photochemical breakdown appeared to be less important.

Roles of Diverse Fungi in Larch Needle-Litter Decomposition

Functional biodiversity of fungi in larch (Larix leptolepis) forests needle-litter decomposition was examined by a pure-culture test. Weight loss of larch-needle litter, utilization pattern of lignocellulose and chemical composition of remaining litter were investigated and compared for 31 isolates in 27 species of basidiomycetes and ascomycetes. Weight loss (% original weight) of litter ranged from −2.0% to 14.2%. Mean weight loss of litter caused by the basidiomycetes was not significantly different from that caused by the ascomycetes. Basidiomycetes caused loss of lignin and carbohydrates in variable proportions, while ascomycetes exclusively attacked carbohydrates without delignification. The content of lignin and nitrogen in remaining litter was not significantly correlated when both basidiomycetes and ascomycetes were included. However, the correlation coefficient was significant when the relationship was examined separately for basidiomycetes, indicating that the degree of selective delignification determined the final nitrogen content in litter. Possible effects of fungal colonization on needle-litter decomposition in larch forests are discussed.

Roles of diverse fungi in larch needle-litter decomposition

Functional biodiversity of fungi in larch (Larix leptolepis) forests needle-litter decomposition was examined by a pure-culture test. Weight loss of larch-needle litter, utilization pattern of lignocellulose and chemical composition of remaining litter were investigated and compared for 31 isolates in 27 species of basidiomycetes and ascomycetes. Weight loss (% original weight) of litter ranged from −2.0% to 14.2%. Mean weight loss of litter caused by the basidiomycetes was not significantly different from that caused by the ascomycetes. Basidiomycetes caused loss of lignin and carbohydrates in variable proportions, while ascomycetes exclusively attacked carbohydrates without delignification. The content of lignin and nitrogen in remaining litter was not significantly correlated when both basidiomycetes and ascomycetes were included. However, the correlation coefficient was significant when the relationship was examined separately for basidiomycetes, indicating that the degree of selective delignification determined the final nitrogen content in litter. Possible effects of fungal colonization on needle-litter decomposition in larch forests are discussed.

Functional role of Collembola in successional coastal temperate forests on Vancouver Island, Canada

The interrelationships among collembolan feeding groups (FG), decomposition rates, microbial biomass, and forest successional stage were studied at three sites in Douglas-fir dominated stands on the dry leeward side of Vancouver Island, BC, Canada. Each site contained a basic suite (or chronosequence) of four stages of stand development: old-growth (>248 years), regeneration (7–9 years), immature (35–46 years), and mature (80–102 years). Principal component analysis (PCA) was used to identify four collembolan feeding groups on the basis of gut contents. Three of the feeding groups (FG 1–3) were fungal-feeders, but differed from one another in the types of fungal material consumed. The last group (FG 4) comprised species that ingested particulate organic matter (POM). Significant positive correlations between microbial biomass and collembolan abundance were obtained for the fungal-feeding Collembola (FG 1–3), but not for the detritivorous FG 4. The proportional representation of collembolan species feeding on darkly pigmented fungi (FG 1) was reduced in the regeneration stands, where species feeding on particulate organic matter predominated. Over the 4 years of this study, the mass loss of decomposing wood chips in litterbags was not significantly influenced by the age of the forest in which the bags were placed. In contrast, the mass loss of needle litter was significantly reduced in regeneration stands. Multiple regressions based on the abundance of the different feeding groups of Collembola provided better estimates of the mass loss of decomposing litter or wood chips than did regressions based on total collembolan numbers.

Climatic effects on litter decomposition from arctic tundra to tropical rainforest

AbstractClimatic effects on the decomposition rates of various litter types in different environments must be known to predict how climatic changes would affect key functions of terrestrial ecosystems, such as nutrient and carbon cycling and plant growth. We developed regression models of the climatic effects on the first‐year mass loss of Scots pine needle litter in boreal and temperate forests across Europe (34 sites), and tested the applicability of these models for other litter types in different ecosystems from arctic tundra to tropical rainforest in Canada (average three year mass loss of 11 litter types at 18 sites), the USA and Central America (four litter types at 26 sites).A temperature variable (annual mean temperature, effective temperature sum or its logarithm) combined with a summer drought indicator (precipitation minus potential evapotranspiration between May and September) explained the first‐year mass loss of the Scots pine needle litter across Europe with a higher R2 value than actual evapotranspiration (0.68–0.74 vs. 0.51) and with less systematic error for any sub‐region. The model with temperature sum and the summer drought indicator appeared best suited to the other litter types and environments. It predicted the climatic effects on the decomposition rates in North and Central America with least systematic error and highest R2 values (0.72–0.80). Compared with Europe, the decomposition rate was significantly less sensitive to annual mean temperature in Canada, and to changes in actual evapotranspiration in the USA and Central America.A simple model distinguishing temperature and drought effects was able to explain the majority of climatic effects on the decomposition rates of the various litter types tested in the varying environments over the large geographical areas. Actual evapotranspiration summarizing the temperature and drought effects was not as general climatic predictor of the decomposition rate.

Controls on mass loss and nitrogen dynamics of oak leaf litter along an urban-rural land-use gradient.

Using reciprocal leaf litter transplants, we investigated the effects of contrasting environments (urban vs. rural) and intraspecific variations in oak leaf litter quality on mass loss rates and nitrogen (N) dynamics along an urban-rural gradient in the New York City metropolitan area. Differences in earthworm abundances and temperature had previously been documented in the stands along this gradient. Red oak leaf litter was collected and returned to its original source stand as native litter to measure decay rates along the gradient. To separate site effects from litter quality effects on decay, reciprocal transplants of litter were also made between stands at the extremes of the environmental gradient (urban and rural stands). Land-use had no effect on mass loss and N dynamics of native litter by the end of the 22-month incubation period. The lack of differences in native litter suggests the factors affecting decay were similar across the stands in this study. However, in the transplant study both environment and litter type strongly affected decay of oak leaf litter. On average urban and rural litter decomposed faster over the incubation period in urban than in rural stands (P=0.016 and P=0.001, respectively, repeated measures ANOVA). Differences in mass loss between urban and rural stands resulted in rural environments having less mass remaining than urban environments at the end of the incubation period (25.6 and 46.2% for urban and rural sites, respectively). Likewise, less N remained in leaf residue in urban sites (71.3%) compared to that in rural sites (115.1%). Litter type also affected mass loss rates during the 22-month incubation period. On average rural litter mass loss rates were faster than urban litter rates in both urban and rural stands (P=0.030 and P=0.026, respectively, repeated measures ANOVA). By the end of the incubation period, rural litter exhibited 43 and 20% greater mass loss and retained 44 and 5% less N than urban litter decomposing in the same urban and rural sites, respectively. These results suggest that different factors were controlling mass loss and N release rates along this urban-rural gradient. In urban stands, exotic earthworms and warmer temperatures may be compensating for what would otherwise be slowly decaying leaf litter because of its lower quality. Likewise, the lower quality litter produced in the urban stands may be decreasing the net release of N from litter despite higher temperatures and earthworm activity. Even though native litter decay rates were similar, the differential importance of the factors affecting decay along this gradient could alter the response of these forests to disturbance and variations in climate.

Decomposition of and nutrient dynamics in leaf litter and roots of Poa ligularis and Stipa gyneriodes

A field experiment was conducted in a temperate semi-arid grassland of central Argentina to determine mass loss and P and N concentrations of decaying leaf litter and roots of Poa ligularis (high-quality litter) and Stipa gynerioides (poor-quality litter). Leaf litter and roots of each species were incubated on sites dominated by P. ligularis and on sites dominated by S. gynerioides, to separate species from site effects. The experiment lasted up to 21 months. Mass loss of leaf litter and roots was higher ( p<0.01) in P. ligularis than in S. gynerioides. Mass loss of leaf litters were higher ( p<0.01) on P. ligularis sites, whereas mass loss of roots were similar ( p>0.05) on both type of sites. Both species showed similar pattern of P and N dynamics in the leaf litter and roots, but net mineralization was higher ( p<0.01) in P. ligularis than in S. gynerioides.

Effects of prior decomposition of beech leaf litter by phyllosphere fungi on substrate utilization by fungal decomposers

Changes in litter quality resulting from pretreatment of leaf litter by phyllosphere fungi may affect its subsequent decomposition by succeeding fungi. The purpose of this study is to clarify the effect of prior decomposition of leaf litter by two phyllosphere fungi of beech, Xylaria sp. and Ascochyta sp., on substrate utilization of 12 fungal species in the Basidiomycota, the Ascomycota, and the Zygomycota, in a laboratory experiment. Mycena sp. caused significantly higher weight loss in litter previously partly decomposed by Xylaria sp. than in control litter without fungal inoculation and litter previously partly decomposed by Ascochyta sp., whereas prior decomposition retarded litter decomposition or had no significant effect on 11 other species. Prior decomposition by phyllosphere fungi affected the substrate utilization patterns of two Mycena species in the Basidiomycota, shifting from simultaneous removal of lignin and carbohydrates to selective delignification.

Demography of barren-ground grizzly bears

Between May 1995 and June 1999, we equipped 81 barren-ground grizzly bears (Ursus arctos) with satellite radio collars within a study area of 235 000 km2, centred 400 km northeast of Yellowknife, Northwest Territories, Canada. We used data from radiotelemetry to estimate survival rates, reproductive parameters, and the finite rate of increase of the population (λ). The annual survival rate of adult females was estimated at 0.979 (95% confidence intervals (CI) = 0.955–0.998), while the survival rate of adult males was 0.986 (95% CI = 0.942–1.0). The cub survival rate was 0.737 (95% CI = 0.600–0.844) and the yearling survival rate was 0.683 (95% CI = 0.514–0.821). Cub litter size averaged 2.23 (SE = 0.13, n = 35), while yearling litter size decreased to a mean of 1.86 (SE = 0.12, n = 35). The mean litter size of females with 2-year-olds was 1.85 (SE = 0.15, n = 20). The mean birth interval was 2.8 years (SE = 0.3 years, n = 17). The mean reproductive interval, which is calculated by excluding the loss of whole litters from the sample, was 3.9 years (SE = 0.4 years, n = 9). Mean litter size divided by mean birth interval yielded an annual natality rate of 0.81 cubs per adult female per year. The mean age at first parturition was 8.1 years (SE = 0.5 years, n = 10). We believe the population to be currently stable or slightly increasing (λ = 1.033, 95% CI = 1.008–1.064).

Acute seasonal drought does not permanently alter mass loss and nitrogen dynamics during decomposition of red maple (Acer rubrum L.) litter

AbstractLitter decomposition is a major component of nutrient cycling in forest ecosystems and is known to be sensitive to both temperature and moisture. A drought during periods of the year when moisture is normally abundant may impact decomposition more than moisture limitation during seasons that are routinely dry. We excluded precipitation for a 3‐month period during each of four seasons and measured mass loss and nitrogen (N) dynamics in Acer rubrum leaf litter by using a litterbag approach. We hypothesized that rainfall exclusion would retard mass loss during the exclusion period, with the maximum effect occurring during the spring and summer months when moisture was normally adequate and temperatures optimum for decomposition, and that exclusion during these two periods would have the greatest impact on subsequent timing of decomposition events, particularly N mineralization. Mass loss in litterbags was initially reduced by precipitation exclusion in the spring treatment only. For each season, a set of bags exposed to drying in the same way and allowed to remain in the field under ambient conditions for an additional 9 months no longer showed a difference in mass loss relative to control bags. Nitrogen accumulation was immediately and significantly reduced in the exclusion treatments in all seasons; however, like mass loss, there was no difference 9 months later. We conclude that short‐term effects of drought do occur, especially with regard to N accumulation, and that these effects do not persist and are unlikely to have any substantial effect on nutrient cycling.

Decomposition of litter in a dry sclerophyll eucalypt forest and a Pinus radiata plantation in southeastern Australia

AbstractThis study of litter decomposition was part of an extensive project examining the partitioning of rainfall, the associated chemistry, and litterfall in a dry sclerophyll eucalypt forest and a Pinus radiata plantation in southeastern Australia. The eucalypt species studied were Eucalyptus rossii, E. mannifera and E. dives. The components tested were Pinus radiata needles, leaves of the three eucalypt species, and the bark of E. rossii and E. mannifera.During the first 16 weeks of the decomposition experiment there was a rapid decrease in the concentrations of potassium, magnesium, sodium and phosphorus; this was attributed to leaching. During this period, concentrations of nitrogen and calcium increased for most components. After this period, decomposition became the dominant process, during which the concentrations of most elements increased. By the end of the experiment there was, compared with the initial values, a marked reduction in concentrations of sodium, magnesium and potassium for all eucalypt and pine litter. Calcium concentrations increased through time, with eucalypt bark showing a mid‐period decline. Phosphorus concentrations decreased for the eucalypt leaves but increased substantially for the pine needles and the eucalypt bark. For all components of both the eucalypts and pines, total nitrogen concentrations rose consistently throughout the decomposition period. This was attributed to the formation of nitrogen‐substituted lignin, which was more resistant to decomposition than the other nitrogen‐containing compounds, as well as some nitrogen being stored in the micro‐organisms responsible for decomposition. Because of loss of fragmented litter from the litter bags after 16 weeks, the weight changes could not be confidently measured after this period. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Einfluss des nach der TOBEC-Methode bestimmten Fettgehaltes bei Kaninchen auf die Wurfleistungen und die Körperzusammensetzung der Nachkommen

Abstract. Title of the paper: Effect of selection on body fat content by means of the TOBEC method on some reproductive traits of rabbit does and on the body composition of growing rabbits In this experiment body fat content of Pannon White growing rabbits was determined at 10 weeks of age using an EM-SCAN SA-3152 type Small Animal Body Composition Analyser (TOBEC method). Based on the fat content determined the best and worst 16% of the does and the best and worst 8% of the bucks were chosen and mated with each other (fatty doe with fatty buck and lean doe with lean buck). It was found that the conception rate was significantly higher and the number of inseminations needed for the second kindling significantly lower in the case of fatty rabbits. An important, but not significant difference was observed in the case of total litter size at birth, which decreased in the case of live born litter size. This reason was the significantly higher ratio of the dead born pups in the case of non-fatty rabbits. Due to the higher ratio of total litter loss and suckling mortality in the case of fatty rabbits the litter size at 21 days differed notably, but again not significantly. In the offsprings of the F1 generation it was found that the fat content estimated and also the ratio of scapular and abdominal fat to the live weight calculated differed significantly (P &lt; 0.05) from each other in the two experimental groups. The estimated fat content was 42% higher in the offsprings of fatty than in the offsprings of non-fatty rabbits. The differences in the ratio of the scapular and abdominal fat content to the live weight were 26% and 51%, respectively.