Land-use induced soil carbon stabilization at the expense of rock derived nutrients: insights from pristine Andean soils.

Soils contain significantly more carbon than the atmosphere, hence we should understand how best to stabilize it. Unfortunately, the role of human interventions on soil organic carbon (SOC) persistence in the Anthropocene remains vague, lacking adequate sites that allow unbiased direct comparisons of pristine and human influenced soils. Here we present data from a unique study system in the High Andes that guarantees pristineness of the reference sites by physical inaccessibility through vertical cliffs. By comparing the isotopic signatures of SOC, mineral related carbon stabilization, and soil nutrient status across grazed versus pristine soils, we provide counterintuitive evidence that thousands of years of pastoralism increased soil C persistence. Mineral associated organic carbon (MAOC) was significantly higher in pastures. Land use increased poorly crystalline minerals (PCM's), of which aluminum correlated best with MAOC. On the other hand, human's acceleration of weathering led to acidification and higher losses of cations. This highlights a dilemma of lower soil quality but higher persistence of SOC due to millennia of pastoralism. The dynamics of soil genesis in the Anthropocene needs better understanding, but if human-induced weathering proves generally to promote soil carbon persistence it will need to be included in climate-soil feedback projections.

New records and key to Poa (Pooideae, Poaceae) from the Flora of Southern Africa region and notes on taxa including a diclinous breeding system in Poa binata.

Four species of Poa L. are newly reported for sub-Saharan Africa and southern Africa, Poa compressa L., P. iconia Azn., P. infirma Kunth and P. nemoralis L. This is the first report of P. iconia from Africa. Vouchers at PRE of P. bulbosa L. all belong to var. vivipara Koeler, those of P. iconia belong to var. iconia and the one of P. trivialis L. belongs to var. trivialis. Two subspecies are recognised in P. pratensis L.: subsp. irrigata (Lindm.) H.Lindb. and subsp. pratensis. We also designate a lectotype for P. iconia and second-step lectotype for P. leptoclada Hochst. ex A.Rich. and report the first recording of a diclinous breeding system in P. binata Nees. Our account updates the treatment in Identification Guide to Southern African Grasses (Fish et al. 2015) including a key to the taxa and notes on infrageneric taxonomy, DNA subtypes, ecology, chromosome numbers and breeding systems.

Festuca drakensbergensis (Poaceae): A common new species in the F. caprina complex from the Drakensberg Mountain Centre of Floristic Endemism, southern Africa, with key and notes on taxa in the complex including the overlooked F. exaristata.

We present taxonomic notes on the Festuca caprina complex from southern Africa that includes description and illustration of the new species F. drakensbergensis from the Drakensberg Mountain Centre of Floristic Endemism of South Africa and Lesotho. Festuca drakensbergensis can be differentiated from F. caprina s.l. by forming lax short tufts with extravaginally-branching tillers and lateral-tending cataphyllous shoots or rhizomes present, basal foliage reaching < ½ the length of the culms, with generally shorter leaves and shorter anthers, 0.8-1.6(-1.8) mm long. The species also differs from the overlooked species F. exaristata - currently known from two collections from Lesotho - by its fibrous basal sheaths, usually sharp, keel-like leaf blade midrib, drooping panicle with lightly to densely scabrous pendent panicle branches, longer lemmas, 4.5-5.8 mm long, with awns usually present, 0.5-3 mm long, ovary apices sparsely to densely hairy and anthers 0.8-1.6(-1.8) mm long. Taxonomic notes on the different taxa of the F. caprina complex in southern Africa are also provided, including images, key, and lectotypification of F. caprina var. curvula. This research adds a further two endemic species (F. drakensbergensis and F. exaristata) and two endemic varieties (F. caprina var. irrasa and F. caprina var. macra) to the Drakensberg Mountain Centre of Floristic Endemism.

Relict high-Andean ecosystems challenge our concepts of naturalness and human impact.

What would current ecosystems be like without the impact of mankind? This question, which is critical for ecosystem management, has long remained unanswered due to a lack of present-day data from truly undisturbed ecosystems. Using mountaineering techniques, we accessed pristine relict ecosystems in the Peruvian Andes to provide this baseline data and compared it with the surrounding accessible and disturbed landscape. We show that natural ecosystems and human impact in the high Andes are radically different from preconceived ideas. Vegetation of these 'lost worlds' was dominated by plant species previously unknown to science that have become extinct in nearby human-affected ecosystems. Furthermore, natural vegetation had greater plant biomass with potentially as much as ten times more forest, but lower plant diversity. Contrary to our expectations, soils showed relatively little degradation when compared within a vegetation type, but differed mainly between forest and grassland ecosystems. At the landscape level, a presumed large-scale forest reduction resulted in a nowadays more acidic soilscape with higher carbon storage, partly ameliorating carbon loss through deforestation. Human impact in the high Andes, thus, had mixed effects on biodiversity, while soils and carbon stocks would have been mainly indirectly affected through a suggested large-scale vegetation change.

An updated checklist and key to the open-panicled species of Poa L. (Poaceae) in Peru including three new species, Poa ramoniana, Poa tayacajaensis, and Poa urubambensis.

We provide an updated checklist and key to the 30 Poa species with open panicles from Peru which includes previously circumscribed Dissanthelium and Aphanelytrum species, new taxon records, and three undescribed species. Poa compressa, Poa grisebachii, and Poa leioclada are recorded from Peru for the first time. A number of species are placed in synonymy: Poa carazensis, Poa ferreyrae and Poa tovarii are synonymized under the name Poa fibrifera; Poa adusta (tentatively) and Poa pilgeri are synonymized under Poa candamoana; Poa superata is synonymized under Poa grisebachii; and Poa paramoensis is synonymized under Poa huancavelicae. Included within this treatment are three new species, Poa ramoniana, Poa tayacajaensis and Poa urubambensis, which are described and illustrated. Poa ramoniana, found growing near lakes in high elevation Puna grasslands of Junín, is similar to a small form of Poa glaberrima, but differs in having rhizomes and growing to only 5 cm tall. Poa tayacajaensis, found from shrublands on Andean slopes of Huancavelica and Huánuco, bears similarities to Poa aequatoriensis but differs in having shorter lemmas which are pubescent between the veins, densely scabrous sheaths with smooth, glabrous throats, and shorter ligules. Poa urubambensis, a common element of the undisturbed Polylepis forest understory of the Cordillera Urubamba, Cusco, is distinct from all other members of open-panicled Poa's by having glabrous lemmas with a smooth and glabrous callus, and notably small anthers. The type material for the name Poa adusta is discussed and a lectotype is selected.

ResúmenAportamos una lista actualizada y una clave para las 30 especies de Poa con panículas abiertas de Perú que incluye las especies de Dissanthelium y Aphanelytrum anteriormente circunscritas, nuevos registros de taxones y tres especies no descritas. Poa compressa, Poa grisebachii, y Poa leioclada se registran para Perú por primera vez. Un número de especies son sinonimizadas: Poa carazensis, Poa ferreyrae y Poa tovarii son sinonimizadas bajo el nombre de Poa fibrifera; Poa adusta (tentativamente) y Poa pilgeri son sinonimizadas bajo el nombre de Poa candamoana; Poa superata es sinonimizada bajo Poa grisebachii; y Poa paramoensis es sinonimizada bajo Poa huancavelicae. Dentro de este tratamiento se incluyen dos especies nuevas, Poa ramoniana, Poa tayacajaensis y Poa urubambensis que a continuación se describen e ilustran. Poa ramoniana, que se encuentra creciendo en pastizales de alta elevación cercanos a lagos en la Puna de Junín, es similar a la forma pequeña de Poa glaberrima, pero se diferencia por tener rizomas y crecer hasta sólo 5 cm de altura. Poa tayacajaensis, que se encuentra en matorrales de las laderas andinas de Huancavelica y Huánuco, tiene un parecido a Poa aequatoriensis, pero se diferencia por tener lemas cortas que son pubescentes entre las venas, vainas densamente escabrosas con suaves gargantas glabras, y lígulas cortas. Poa urubambensis, un elemento común de sotobosque no perturbado de los bosques de Polylepis de la Cordillera Urubamba, Cusco, se distingue de todos los otros miembros de Poa con panícula-abierta por tener lemas glabras con un callo suave y glabro, y sus notables anteras pequeñas. El material tipo del nombre Poa adusta es discutido y un lectotipo es seleccionado.