Deposition and decomposition of cattle dung in forest grazing in southern Kyushu, Japan

Abstract

This study monitored deposition and decomposition of cattle dung in a grazed young Chamaecyparis obtusa (an evergreen conifer) plantation in southwestern Japan, as a part of exploring the impacts of livestock in the forest grazing system. Animals defecated 10-19 times hd À1 day À1 , producing feces of 2.2-3.5 kg DM and 33-73 g N per animal per day. The DM and N concentrations of feces ranged from 157-207 g DM kg À1 and 14.8À23.1 g (kg DM) À1 , respectively. Occurrence of defecation was spatially heterogeneous, with feces being concentrated mainly on areas for resting (forest roads, ridges and valleys) and moving (forest roads and along fence lines). Decomposition of dung pats was considerably slow, showing the rates of 1.37-3.05 mg DM (g DM) À1 day À1 as DM loss. Decomposition was further slower on the basis of N release, 0.51-1.63 mg N (g N) À1 day À1 , resulting in steadily increased N concentrations of dung pats with time after deposition. The results show that introduction of livestock into a forest (i.e., forest grazing) may limit nutrient availability to plants, by redistributing nutrients into areas with no vegetation (bare land and streams) and by establishing a large N pool as feces due to an imbalance between deposition and slow release, though further studies are necessary for investigating the occurrence of slow dung decomposition in other forest situations.

<b>Indicators of land use by cattle: associations among methods and role of environmental factors

“…Additionally, in both areas dung pats concentration was higher in regions with lower slopes, areas of resting and moving (e.g. along fence lines), confirming the results of previous studies using the distribution of dung pats as indicator of land occupation (Tate et al, 2003;Hirata et al, 2009). …”

“…For example, cattle tracks could reflect the occupation over a long period, even years, while the dung pats are likely to give information from few days to the whole grazing season (Hirata et al, 2009), in this case the summer 2008, because during winter the Nature Reserve and Private Area were not occupied by cattle. On the other hand, when using the direct observation of the animals we recorded information restricted to the sampling period and, it was subject to reduced sampling efficiency in forest areas, because of incomplete sightings of the animals.…”

“…Finally, the low predictive power of environmental characteristics may have occurred due to lack of one or more factors that affected land use patterns, not accounted in the present study. The major abiotic components associated with the spatial distribution of cattle in previous studies (Hirata et al, 2009;Kaufmann et al, 2013) were included in this study. Nevertheless, it is likely that other biotic environmental factors had played overwhelm influence on land use by animals, in special the forage characteristics (such as botanical composition, herbage biomass and protein concentration), described as major factors affecting land use by cattle in heterogeneous environments (Ganskopp & Bohnert, 2009;Kaufmann et al, 2013).…”

“…For example, it is usually expected that cattle presence in natural areas increases the risk of soil erosion, water pollution and loss of biodiversity (Carvalho & Batello, 2009;Hirata et al, 2009;Zamorano-Elgueta et al, 2014). However, livestock grazing may also have positive effects on natural and semi-natural grasslands, being beneficial for plant species richness (Putfarken, Dengler, Lehmann Härdtle, 2008) and reducing the risk of wildfires (Davies, Boyd, Bates, & Hulet, 2015).…”

“…These methods are usually representative of short-term land use, being limited to the periods of the day when the samplings are done (only during daylight in the case of visual sightings) or in terms of number of animals tracked (in the case of GPS collars). Another possibility to address the land occupation by cattle would be the use of indirect methods, for example, the location of cattle tracks on the terrain (Ganskopp, Cruz, & Johnson, 2000;Tate, Dudley, McDougald, & George, 2004) and the distribution of dung pats over the pastures (Tate, Atwill, McDougald, & George, 2003;Hirata et al, 2009). Such indirect indicators gather representative data of long-term land use throughout days and nights, as well as for an unlimited number of individuals; however, seasonal variations in the patterns of land occupation may not be evident.…”