Genetic Analysis Reveals a Distinct Lineage of Hog Deer (Axis porcinus) in Kratie Province, Cambodia.

The hog deer (Axis porcinus) is an endangered cervid with drastic population declines. There are 2 recognized subspecies of hog deer: A. p. porcinus, ranging from Punjab Province in Pakistan, Nepal, and the Northern part of India to Myanmar, and A. p. annamiticus found in Indo-China, Thailand, Laos, Cambodia, and Vietnam. The current geographic range of A. p. annamiticus is still ambiguous. We analyzed variation in the mitochondrial DNA control region (mtDNA CR) to investigate the intra-species structure, differentiation, and demographic history of hog deer from Cambodia (Kratie Province), which we compared with the populations from India and Thailand. We also generated divergence time estimates using a concatenated dataset of complete Cyt b and partial CR. The CR data showed that Cambodian hog deer are genetically differentiated from the mainland Indian and Thai populations, forming a distinct basal clade. The time of divergence indicates that the Cambodian lineage split from the other 2 hog deer lineages around 0.51 Mya, during the Late Pleistocene. The results also suggest strong phylogeographic structure among hog deer: lineage A extends from Terai Arc (foothills of the Himalayas) to Assam, India (A. p. porcinus), lineage B from Manipur, India to Thailand (A. p. annamiticus), and lineage C is only known from Kratie Province, Cambodia. Lineage A exhibited a higher level of genetic diversity than lineages B and C, with recent demographic stability. Thus, the hog deer population in Kratie Province appears to be a distinct lineage that should be treated as an evolutionarily significant unit.

Quantification of water purification in South African palmiet wetlands.

Despite the importance of water purification to society, it is one of the more difficult wetland ecosystem services to quantify. It remains an issue in ecosystem service assessments where rapid estimates are needed, and poor-quality indicators are overused. We attempted to quantify the water purification service of South African palmiet wetlands (valley-bottom peatlands highly threatened by agriculture). First, we used an instantaneous catchment-scale mass balance sampling approach, which compared the fate of various water quality parameters over degraded and pristine sections of palmiet wetlands. We found that pristine palmiet wetlands acted as a sink for water, major cations, anions, dissolved silicon and nutrients, though there was relatively high variation in these trends. There are important limitations to this catchment-scale approach, including the fact that at this large scale there are multiple mechanisms (internal wetland processes as well as external inputs) at work that are impossible to untangle with limited data. Therefore, secondly, we performed a small field-scale field survey of a wetland fragment to corroborate the catchment-scale results. There was a reasonable level of agreement between the results of the two techniques. We conclude that it appears possible to estimate the water purification function of these valley-bottom wetlands using this catchment-scale approach.

Thieving rodents as substitute dispersers of megafaunal seeds.

The Neotropics have many plant species that seem to be adapted for seed dispersal by megafauna that went extinct in the late Pleistocene. Given the crucial importance of seed dispersal for plant persistence, it remains a mystery how these plants have survived more than 10,000 y without their mutualist dispersers. Here we present support for the hypothesis that secondary seed dispersal by scatter-hoarding rodents has facilitated the persistence of these large-seeded species. We used miniature radio transmitters to track the dispersal of reputedly megafaunal seeds by Central American agoutis, which scatter-hoard seeds in shallow caches in the soil throughout the forest. We found that seeds were initially cached at mostly short distances and then quickly dug up again. However, rather than eating the recovered seeds, agoutis continued to move and recache the seeds, up to 36 times. Agoutis dispersed an estimated 35% of seeds for >100 m. An estimated 14% of the cached seeds survived to the next year, when a new fruit crop became available to the rodents. Serial video-monitoring of cached seeds revealed that the stepwise dispersal was caused by agoutis repeatedly stealing and recaching each other's buried seeds. Although previous studies suggest that rodents are poor dispersers, we demonstrate that communities of rodents can in fact provide highly effective long-distance seed dispersal. Our findings suggest that thieving scatter-hoarding rodents could substitute for extinct megafaunal seed dispersers of tropical large-seeded trees.

Stable isotopes (δ13C, δ15N) and biomarkers as indicators of the hydrological regime of fens in a European east-west transect.

Peatland degradation is tightly connected to hydrological changes and microbial metabolism. To better understand these metabolism processes, more information is needed on how microbial communities and substrate cycling are affected by changing hydrological regimes. These activities should be imprinted in stable isotope bulk values (δ 15N, δ 13C) due to specific isotopic fractionation by different microbial communities, their metabolic pathways and nutrient sources. We hypothesize that stable isotope values and microbial abundance are correlated and act as indicators of different hydrological regimes. We sampled an East-West transect across European fens in 14 areas and conducted a stable isotope (δ 13C, δ 15N) and membrane fatty acid (mFA) analysis. Within each area an undrained, drained and rewetted site was selected. Rewetted sites were separated based on when rewetting occurred. We found differences in the upper layers of all sites in microbial-derived mFAs and stable isotope values corresponding to hydrological regimes. The highest and lowest quantities of microbial-derived mFAs were measured in undrained and drained sites, respectively. Fungal-derived mFAs were especially lower in drained sites. Simultaneously, δ15N stable isotope values were highest in drained sites. In addition, stable isotope values and microbial-derived mFAs showed distinct depth trends. In undrained sites stable isotopes values slightly increased with depth. In drained sites, δ15N values decreased downwards, whereas δ13C values increased. Overall microbial-derived mFAs decreased with depth. These patterns presumably result from anoxic conditions and high peat recalcitrance in the deeper layers. In sites with short time of rewetting, the microbial-derived mFAs and stable isotope values were similar to values of drained sites, while with increasing rewetting time values shifted to those of undrained sites. We conclude that biomarkers indicate that stable isotope values reflect specific microbial metabolic processes, which differ with hydrological regimes, and thus could indicate both drainage and rewetting in fens.

Recovery of fen peatland microbiomes and predicted functional profiles after rewetting.

Many of the world's peatlands have been affected by water table drawdown and subsequent loss of organic matter. Rewetting has been proposed as a measure to restore peatland functioning and to halt carbon loss, but its effectiveness is subject to debate. An important prerequisite for peatland recovery is a return of typical microbial communities, which drive key processes. To evaluate the effect of rewetting, we investigated 13 fen peatland areas across a wide (>1500 km) longitudinal gradient in Europe, in which we compared microbial communities between drained, undrained, and rewetted sites. There was a clear difference in microbial communities between drained and undrained fens, regardless of location. Community recovery upon rewetting was substantial in the majority of sites, and predictive functional profiling suggested a concomitant recovery of biogeochemical peatland functioning. However, communities in rewetted sites were only similar to those of undrained sites when soil organic matter quality (as expressed by cellulose fractions) and quantity were still sufficiently high. We estimate that a minimum organic matter content of ca. 70% is required to enable microbial recovery. We conclude that peatland recovery after rewetting is conditional on the level of drainage-induced degradation: severely altered physicochemical peat properties may preclude complete recovery for decades.

Soil Iron Content as a Predictor of Carbon and Nutrient Mobilization in Rewetted Fens.

Rewetted, previously drained fens often remain sources rather than sinks for carbon and nutrients. To date, it is poorly understood which soil characteristics stimulate carbon and nutrient mobilization upon rewetting. Here, we assess the hypothesis that a large pool of iron in the soil negatively affects fen restoration success, as flooding-induced iron reduction (Fe3+ to Fe2+) causes a disproportionate breakdown of organic matter that is coupled with a release of inorganic compounds. We collected intact soil cores in two iron-poor and two iron-rich drained fens, half of which were subjected to a rewetting treatment while the other half was kept drained. Prolonged drainage led to the mobilization of nitrate (NO3-, > 1 mmol L-1) in all cores, regardless of soil iron content. In the rewetted iron-rich cores, a sharp increase in pore water iron (Fe) concentrations correlated with concentrations of inorganic carbon (TIC, > 13 mmol L-1) and dissolved organic carbon (DOC, > 16 mmol L-1). Additionally, ammonium (NH4+) accumulated up to phytotoxic concentrations of 1 mmol L-1 in the pore water of the rewetted iron-rich cores. Disproportionate mobilization of Fe, TIC, DOC and NH4+ was absent in the rewetted iron-poor cores, indicating a strong interaction between waterlogging and iron-mediated breakdown of organic matter. Concentrations of dissolved phosphorus (P) rose slightly in all cores upon rewetting, but remained low throughout the experiment. Our results suggest that large pools of iron in the top soil of drained fens can hamper the restoration of the fen's sink-service for ammonium and carbon upon rewetting. We argue that negative effects of iron should be most apparent in fens with fluctuating water levels, as temporary oxygenation allows frequent regeneration of Fe3+. We conclude that rewetting of iron-poor fens may be more feasible for restoration.