Vegetation succession of arable old land after being abandoned in Loess Plateau hilly region & ascertaining dominant native herbages in the process, analyzing their chemical nutrient composition

Abstract

用系统聚类、撂荒年限两种方法对陕北黄土高原丘陵区撂荒演替序列进行分析,结果基本一致:1～6a,1年生杂草类群落→1年生杂草类+丛生禾草群落→1年生杂草类+根茎禾草群落或多年生草本群落→7～16a,多年生草本群落→多年生草本+小灌木群落→17～42a:根茎丛生型禾草+小灌木群落或小灌木+多年生草本群落→小灌木群落或多年生草本+丛生禾草群落,代表性群落依次为猪毛蒿(ArtemisiascopariaWaldstet.etkit)群落或猪毛蒿+长芒草(StipabungeanaTrin.)群落→猪毛蒿+铁杆蒿(ArtemisiasacrorumLeded.)群落或冰草(Agropyroncristatum(L.)Gaertn)群落→铁杆蒿群落→铁杆蒿+达乌里胡枝子(Lespedezavar.dahurica(Laxm.)Schindl)群落→白羊草(Bothriochloaischaemum(L.)Keng)+达乌里胡枝子群落或达乌里胡枝子+铁杆蒿群落或铁杆蒿+硬质早熟禾(PoasphondylodesTrin.etBge)群落。在此基础之上,提出将各物种在演替过程中重要值之和按大小排序,对前35位草种经适口性试验..