黃(huang)(huang)土(tu)高(gao)(gao)原地勢西北(bei)高(gao)(gao),東南(nan)低(di),自(zi)西北(bei)向東南(nan)呈波(bo)狀下降。以六盤山和呂(lv)梁山為界(jie)把(ba)黃(huang)(huang)土(tu)高(gao)(gao)原分(fen)為東、中(zhong)、西三(san)部分(fen):六盤山以西的(de)黃(huang)(huang)土(tu)高(gao)(gao)原西部,海拔(ba)2000-3000米,是黃(huang)(huang)土(tu)高(gao)(gao)原地勢高(gao)(gao)的(de)地區。
六盤山與呂梁山之司的黃(huang)土高原(yuan)中部,海拔1000-2000米,是黃(huang)土高原(yuan)的主(zhu)體。呂梁山以東的黃(huang)土高原(yuan)東部,地勢降(jiang)至500-1000米,河谷平(ping)原(yuan)占有較(jiao)大比例。
據此可將(jiang)黃土(tu)高原分(fen)為山地區(qu)、黃土(tu)丘陵區(qu)、黃土(tu)塬區(qu)、黃土(tu)臺塬區(qu)、河谷平原區(qu)。
黃(huang)(huang)土(tu)(tu)高原(yuan)基(ji)巖(yan)(yan)(yan)構造(zao)以(yi)六盤(pan)山為界分(fen)為東西(xi)(xi)兩部分(fen),西(xi)(xi)部屬西(xi)(xi)域陸塊,東部屬華(hua)北陸塊。六盤(pan)山以(yi)西(xi)(xi)黃(huang)(huang)土(tu)(tu)高原(yuan)以(yi)新生代斷陷(xian)盆地為構造(zao)特征,隴中(zhong)盆地黃(huang)(huang)土(tu)(tu)下(xia)伏(fu)基(ji)巖(yan)(yan)(yan)為直(zhi)接(jie)堆積在古老巖(yan)(yan)(yan)層之上的(de)中(zhong)新世到上新世早(zao)期的(de)甘肅群。甘肅群堆積后,上新世晚期地面抬(tai)升(sheng)(sheng),黃(huang)(huang)河(he)及其支流挑(tiao)河(he)、祖歷河(he)、葫蘆河(he)隨(sui)抬(tai)升(sheng)(sheng)而下(xia)切,基(ji)巖(yan)(yan)(yan)地面成(cheng)(cheng)(cheng)為起伏(fu)較(jiao)大(da)的(de)丘(qiu)陵狀。甘肅群為一套含有石膏(gao)的(de)紫(zi)紅色粘土(tu)(tu),砂(sha)質粘土(tu)(tu),砂(sha)巖(yan)(yan)(yan)和(he)砂(sha)礫巖(yan)(yan)(yan)。其成(cheng)(cheng)(cheng)巖(yan)(yan)(yan)性差,抗蝕(shi)力較(jiao)弱,在地下(xia)水浸泡(pao)和(he)潤滑作用下(xia)極易發生重力侵蝕(shi),常形成(cheng)(cheng)(cheng)大(da)型滑坡。六盤(pan)山以(yi)東的(de)華(hua)北陸臺由鄂爾多(duo)斯臺向斜和(he)山西(xi)(xi)臺背(bei)斜構成(cheng)(cheng)(cheng),中(zhong)間夾以(yi)黃(huang)(huang)河(he)凹陷(xian)。鄂爾多(duo)斯臺向斜和(he)山西(xi)(xi)臺背(bei)斜是未(wei)經褶皺變(bian)動的(de)前震旦紀陸臺。
陜北(bei)(bei)(bei)、隴東(dong)(dong)和晉西的(de)(de)(de)(de)(de)鄂(e)爾(er)(er)多(duo)(duo)(duo)斯臺(tai)向斜(xie)在中(zhong)生代(dai)發(fa)(fa)展成(cheng)(cheng)為(wei)一(yi)個大型的(de)(de)(de)(de)(de)內陸盆地(di),當(dang)時(shi)地(di)勢東(dong)(dong)南(nan)高(gao)西北(bei)(bei)(bei)低(di),與(yu)今況剛好相反。西北(bei)(bei)(bei)部堆積(ji)了(le)厚達(da)1500米完整(zheng)的(de)(de)(de)(de)(de)中(zhong)生代(dai)地(di)層(ceng)序列。其(qi)中(zhong)神木,準(zhun)格爾(er)(er)旗一(yi)帶廣泛出露的(de)(de)(de)(de)(de)中(zhong)生代(dai)灰(hui)綠色、黃(huang)綠色長(chang)石(shi)砂(sha)巖(yan)(yan),當(dang)地(di)叫(jiao)砒砂(sha)巖(yan)(yan),極易風化(hua)侵(qin)蝕(shi),是(shi)當(dang)地(di)及黃(huang)河(he)中(zhong)粗(cu)砂(sha)的(de)(de)(de)(de)(de)主要(yao)來(lai)源(yuan)。燕(yan)山運動使(shi)鄂(e)爾(er)(er)多(duo)(duo)(duo)斯臺(tai)向斜(xie)抬升,邊(bian)緣發(fa)(fa)生斷(duan)陷,形(xing)成(cheng)(cheng)汾渭(wei)谷(gu)(gu)地(di)等一(yi)系列地(di)塹谷(gu)(gu)地(di),到(dao)(dao)第(di)三(san)(san)紀的(de)(de)(de)(de)(de)中(zhong)新世末鄂(e)爾(er)(er)多(duo)(duo)(duo)斯臺(tai)向斜(xie)成(cheng)(cheng)為(wei)準(zhun)平(ping)原(yuan)。上(shang)(shang)新世鄂(e)爾(er)(er)多(duo)(duo)(duo)斯高(gao)原(yuan)長(chang)城以(yi)南(nan)的(de)(de)(de)(de)(de)準(zhun)平(ping)原(yuan)面上(shang)(shang)廣泛堆積(ji)了(le)三(san)(san)趾(zhi)馬(ma)紅(hong)土(tu),從三(san)(san)趾(zhi)馬(ma)紅(hong)土(tu)的(de)(de)(de)(de)(de)分布(bu)和厚度(du)看,上(shang)(shang)新世時(shi)長(chang)城以(yi)南(nan),渭(wei)北(bei)(bei)(bei)北(bei)(bei)(bei)山以(yi)北(bei)(bei)(bei),六盤(pan)山與(yu)呂梁山之(zhi)間是(shi)一(yi)個淺凹形(xing)的(de)(de)(de)(de)(de)巨大盆地(di)。地(di)勢西北(bei)(bei)(bei)高(gao),東(dong)(dong)南(nan)低(di),己與(yu)今相同。三(san)(san)趾(zhi)馬(ma)紅(hong)土(tu)透水性極差,是(shi)黃(huang)土(tu)下覆(fu)的(de)(de)(de)(de)(de)主要(yao)不透水層(ceng),而且三(san)(san)趾(zhi)馬(ma)紅(hong)土(tu)容(rong)易吸(xi)水膨脹,是(shi)黃(huang)土(tu)高(gao)原(yuan)大型滑坡的(de)(de)(de)(de)(de)主要(yao)滑移層(ceng)。上(shang)(shang)新世晚期到(dao)(dao)更新世,鄂(e)爾(er)(er)多(duo)(duo)(duo)斯高(gao)原(yuan)邊(bian)緣如汾渭(wei)地(di)塹谷(gu)(gu)地(di)進(jin)一(yi)步發(fa)(fa)展,同時(shi)高(gao)原(yuan)整(zheng)體發(fa)(fa)生掀(xian)斜(xie)運動,使(shi)地(di)面形(xing)成(cheng)(cheng)自西北(bei)(bei)(bei)向東(dong)(dong)南(nan)傾斜(xie)的(de)(de)(de)(de)(de)斜(xie)面,控(kong)制著河(he)流(liu)的(de)(de)(de)(de)(de)流(liu)向。在地(di)貌演變過程中(zhong)溝(gou)谷(gu)(gu)的(de)(de)(de)(de)(de)發(fa)(fa)展,谷(gu)(gu)間地(di)有(you)些形(xing)成(cheng)(cheng)面積(ji)不大的(de)(de)(de)(de)(de)平(ping)臺(tai),有(you)些成(cheng)(cheng)為(wei)長(chang)條(tiao)狀(zhuang)或橢(tuo)圓狀(zhuang)丘(qiu)陵,它(ta)們是(shi)鄂(e)爾(er)(er)多(duo)(duo)(duo)斯高(gao)原(yuan)塬、梁、峁地(di)形(xing)的(de)(de)(de)(de)(de)基(ji)礎。
山(shan)(shan)(shan)西(xi)臺背斜(xie)包(bao)括太行(xing)山(shan)(shan)(shan)以(yi)西(xi)、呂(lv)梁山(shan)(shan)(shan)以(yi)東。五臺山(shan)(shan)(shan)是(shi)山(shan)(shan)(shan)西(xi)臺背斜(xie)古(gu)老的(de)部(bu)分(fen),并(bing)以(yi)此為(wei)(wei)頂(ding)點向南沿伸,東部(bu)為(wei)(wei)太行(xing)山(shan)(shan)(shan),西(xi)部(bu)為(wei)(wei)呂(lv)梁山(shan)(shan)(shan),兩山(shan)(shan)(shan)之間為(wei)(wei)凹陷部(bu)分(fen)。古(gu)生代以(yi)來,凹陷部(bu)分(fen)堆(dui)(dui)積(ji)了(le)(le)巨厚的(de)陸相(xiang)碎屑(xie)物。燕山(shan)(shan)(shan)運動后山(shan)(shan)(shan)西(xi)臺背斜(xie)中(zhong)部(bu)受斷(duan)裂作用(yong)晉中(zhong)大(da)斷(duan)谷開始(shi)形成。中(zhong)新世(shi)末(mo)晉中(zhong)南的(de)漳沁地(di)區形成準(zhun)平原,其后接受了(le)(le)上(shang)(shang)新世(shi)的(de)三趾馬紅(hong)土堆(dui)(dui)積(ji)。喜馬拉雅運動使山(shan)(shan)(shan)西(xi)臺背斜(xie)進一步(bu)上(shang)(shang)升,晉中(zhong)斷(duan)谷不斷(duan)發(fa)育,河流下切,到更新世(shi)黃土堆(dui)(dui)積(ji)時(shi)地(di)面(mian)形成起伏較大(da)的(de)丘陵、成為(wei)(wei)山(shan)(shan)(shan)地(di)與(yu)斷(duan)谷、盆(pen)地(di)相(xiang)間分(fen)布(bu)的(de)地(di)形特征。
●黃土地層與黃土分布
黃土高原原生黃土是第四紀冰期干冷氣候條件下的風塵堆積物,次生黃土是原生黃土經洪積、沖積改造而成的。在第四紀黃土堆積時期,隨著冰期、間冰期的氣候旋迥,黃土地層呈現黃土與古土壤的更替變化。根據黃土中的古土壤,黃土地層自下而上可以分為午城黃土、離石黃上、馬蘭黃土和世黃土。按洛川黑木溝黃土剖面,第十五層黃土下界面之下為早更新世午城黃土。古土壤(rang)上界面之(zhi)下至(zhi)第十五層(ceng)(ceng)(ceng)黃(huang)(huang)(huang)土下界面之(zhi)間(jian)為(wei)(wei)中(zhong)更新離(li)石黃(huang)(huang)(huang)土。黃(huang)(huang)(huang)土層(ceng)(ceng)(ceng)是形(xing)成于(yu)晚更新世(shi)的(de)馬(ma)蘭(lan)(lan)黃(huang)(huang)(huang)土。馬(ma)蘭(lan)(lan)黃(huang)(huang)(huang)土之(zhi)上的(de)黑(hei)滬(hu)土為(wei)(wei)形(xing)成于(yu)古土壤(rang)層(ceng)(ceng)(ceng)。黃(huang)(huang)(huang)土高(gao)原黃(huang)(huang)(huang)土地(di)層(ceng)(ceng)(ceng)的(de)分(fen)布(bu)厚(hou)度(du)(du)(du)在六盤(pan)山(shan)與呂梁山(shan)之(zhi)間(jian)一(yi)般(ban)為(wei)(wei)150-250米(mi),六盤(pan)山(shan)以西(xi)一(yi)般(ban)在100米(mi)以內。不同(tong)地(di)層(ceng)(ceng)(ceng)黃(huang)(huang)(huang)土厚(hou)度(du)(du)(du)也不相(xiang)同(tong):午城(cheng)黃(huang)(huang)(huang)土厚(hou)度(du)(du)(du)不大,洛(luo)川(chuan)黑(hei)木溝為(wei)(wei)58米(mi),山(shan)西(xi)午城(cheng)為(wei)(wei)17.5米(mi)。離(li)石黃(huang)(huang)(huang)土是黃(huang)(huang)(huang)土高(gao)原黃(huang)(huang)(huang)土地(di)層(ceng)(ceng)(ceng)的(de)主(zhu)體(ti),一(yi)般(ban)厚(hou)度(du)(du)(du)100-150米(mi),厚(hou)度(du)(du)(du)分(fen)布(bu)在徑(jing)河與洛(luo)河的(de)中(zhong)游地(di)區。馬(ma)蘭(lan)(lan)黃(huang)(huang)(huang)土分(fen)布(bu)極為(wei)(wei)廣泛,一(yi)般(ban)厚(hou)度(du)(du)(du)10-30米(mi),天(tian)水附近(jin)小于(yu)10米(mi),董志源9.6米(mi),洛(luo)川(chuan)源10米(mi)左右。世(shi)黃(huang)(huang)(huang)土厚(hou)度(du)(du)(du)-般(ban)為(wei)(wei)2-3米(mi),其(qi)中(zhong)的(de)黑(hei)滬(hu)土層(ceng)(ceng)(ceng)厚(hou)度(du)(du)(du)1-2米(mi)。
●黃土粒度與黃土性質
黃土是在風力吹揚搬運下,在干旱半干旱環境堆積的風成堆積物,經過長距離的搬運和分選,其物質組成具有高度的均一性。黃土粒度以粒徑0.05-0.005毫米的粉砂為主,所占比例58-75%。其次為粒徑>0.05毫米的細砂,占15-32%。粒徑0<0.005毫米的粘土占10%左右。黃土粒徑存在著自西北向東南逐漸變細的特點,這一特點以砂粒和粘粒的變化明顯。北部榆林附近砂粒的重量比在30%以上,向南到清澗、延安附近降為20%左右,咸陽、寶雞一帶降至10%上下。相反,榆林粘粒僅占10%左右,延安、清澗一帶增至13-18%,咸陽、寶雞為23-26%。這樣自西北向東南根據黃土粒徑可以把黃土高原黃土分為砂黃土、典型黃土和粘黃土三個帶:靜樂北-綏德-子長-環縣-海原一線以北為砂黃上帶。陽泉-沁縣-浮山北-淳化-秦安-渭源以北,砂黃土帶以南為典型黃土帶。典型黃土帶以南為粘黃土帶。黃土在南北方向上的粒度分異對黃土地貌及土壤侵蝕具有深刻的影響。
黃土(tu)含(han)(han)有60多種礦物,其中石(shi)英占(zhan)重量(liang)的50%左右(you),長石(shi)占(zhan)20%左右(you),碳酸鈣占(zhan)10%左右(you)。就(jiu)化(hua)(hua)學組成而言,以(yi)二氧化(hua)(hua)硅占(zhan)優勢(50%),其次為三氧化(hua)(hua)二氯(lv)(8-15%),氧化(hua)(hua)鈣(10%左右(you)),以(yi)及三氧化(hua)(hua)二鐵,氧化(hua)(hua)鎂(mei),氧化(hua)(hua)鉀,氧化(hua)(hua)鈉等,黃土(tu)中易溶性化(hua)(hua)學成份含(han)(han)量(liang)較(jiao)高。
黃(huang)土結構為“點(dian)、棱接(jie)觸(chu)支架式多孔(kong)(kong)結構”,土體(ti)疏松(song),垂直節理發(fa)育(yu),極易(yi)滲水。黃(huang)土中細粒物(wu)質(zhi)如粘土、易(yi)溶性(xing)鹽(yan)類(lei)、石膏、碳酸(suan)鹽(yan)等在干燥(zao)時固結成(cheng)(cheng)聚(ju)積體(ti),使黃(huang)土具(ju)有較強(qiang)的強(qiang)度,而遇水后(hou)隨(sui)著礦(kuang)物(wu)溶解(jie)與分散,土體(ti)會迅速分散、崩(beng)解(jie)。黃(huang)土的抗侵蝕能力(li)很弱。黃(huang)土中孔(kong)(kong)隙度-般可(ke)達45-50%,尤其大孔(kong)(kong)隙特別突出,當受水浸潤后(hou)上(shang)(shang)體(ti)在自重和上(shang)(shang)部壓力(li)作用下,易(yi)發(fa)生濕(shi)陷。同時大孔(kong)(kong)隙也成(cheng)(cheng)為土體(ti)中水體(ti)和細粒物(wu)質(zhi)遷移的通(tong)道,使黃(huang)土易(yi)發(fa)生潛蝕。
黃(huang)(huang)土高原(yuan)是新(xin)構造運(yun)動比較(jiao)活躍的(de)區(qu)(qu)(qu)域(yu),新(xin)構造運(yun)動的(de)主(zhu)要表現(xian)是高原(yuan)內部間歇性的(de)大面(mian)積整體抬(tai)升(sheng),同(tong)時周圍的(de)拗陷區(qu)(qu)(qu)域(yu)不斷地(di)沉(chen)降。從黃(huang)(huang)土高原(yuan)廣(guang)大地(di)區(qu)(qu)(qu)河(he)谷多發育有3-4級階地(di)等判斷,第四紀以(yi)來黃(huang)(huang)上(shang)高原(yuan)以(yi)抬(tai)升(sheng)為(wei)主(zhu),抬(tai)升(sheng)幅度(du)在150-30米,地(di)殼抬(tai)升(sheng)有利河(he)流下切(qie)和侵蝕(shi)地(di)貌發育,也有利于土壤侵蝕(shi)過(guo)程的(de)加強。黃(huang)(huang)土高原(yuan)內部六(liu)盤(pan)山是新(xin)構造運(yun)動的(de)抬(tai)升(sheng)中心(xin),據(ju)現(xian)代水準(zhun)測量(liang),目前的(de)抬(tai)升(sheng)速(su)(su)度(du)為(wei)20毫(hao)(hao)米/年(nian)。六(liu)盤(pan)山以(yi)西地(di)區(qu)(qu)(qu)抬(tai)升(sheng)量(liang)大于以(yi)東地(di)區(qu)(qu)(qu),抬(tai)升(sheng)在華家嶺(ling)一帶,據(ju)1934-1955年(nian)隴(long)海鐵路水準(zhun)測量(liang),隴(long)西、渭源等地(di)現(xian)代抬(tai)升(sheng)速(su)(su)度(du)為(wei)31.4毫(hao)(hao)米/年(nian),隆德(de)、莊浪一帶溝床下切(qie)速(su)(su)率(lv)達45-240毫(hao)(hao)米/100年(nian)。
華(hua)家嶺(ling)以(yi)南(nan)地(di)(di)區(qu)(qu)河(he)(he)谷(gu)(gu)狹窄,一(yi)般有3-4級階(jie)地(di)(di),華(hua)家嶺(ling)以(yi)北河(he)(he)谷(gu)(gu)較(jiao)寬闊,只有2-3級階(jie)地(di)(di)發(fa)育,所以(yi)華(hua)家嶺(ling)以(yi)南(nan)抬(tai)(tai)(tai)升(sheng)幅度更大(da)。六盤(pan)山(shan)(shan)(shan)以(yi)東地(di)(di)區(qu)(qu)白于山(shan)(shan)(shan)至東勝一(yi)帶是新(xin)(xin)構(gou)造(zao)(zao)(zao)運(yun)(yun)動抬(tai)(tai)(tai)升(sheng)的(de)(de)中心。保德(de)附近(jin)現代抬(tai)(tai)(tai)升(sheng)速度在(zai)3毫(hao)米(mi)(mi)/年(nian)(nian)左右。山(shan)(shan)(shan)西臺(tai)背(bei)斜新(xin)(xin)構(gou)造(zao)(zao)(zao)運(yun)(yun)動抬(tai)(tai)(tai)升(sheng)幅度較(jiao)大(da)在(zai)五臺(tai)山(shan)(shan)(shan)-恒山(shan)(shan)(shan)一(yi)帶,這從五臺(tai)山(shan)(shan)(shan)、恒山(shan)(shan)(shan)山(shan)(shan)(shan)前發(fa)育的(de)(de)串珠狀(zhuang)洪積(ji)扇可以(yi)得(de)到證明。第四紀黃(huang)(huang)(huang)(huang)土(tu)(tu)高(gao)原(yuan)(yuan)(yuan)在(zai)抬(tai)(tai)(tai)升(sheng)的(de)(de)同時(shi),邊緣拗陷區(qu)(qu)如(ru)銀川平(ping)(ping)原(yuan)(yuan)(yuan)、汾(fen)渭(wei)(wei)谷(gu)(gu)地(di)(di)在(zai)大(da)幅度下沉(chen),渭(wei)(wei)河(he)(he)平(ping)(ping)原(yuan)(yuan)(yuan)固始凹陷第四紀沉(chen)積(ji)物厚度接近(jin)1000米(mi)(mi)。據地(di)(di)形(xing)變形(xing)資料,汾(fen)渭(wei)(wei)地(di)(di)塹的(de)(de)下沈速度為3毫(hao)米(mi)(mi)/年(nian)(nian)。黃(huang)(huang)(huang)(huang)河(he)(he)自140萬年(nian)(nian)前后(hou)沖出三(san)門峽后(hou),汾(fen)渭(wei)(wei)谷(gu)(gu)地(di)(di)是黃(huang)(huang)(huang)(huang)河(he)(he)中游眾多支流的(de)(de)侵(qin)蝕基準面,一(yi)方(fang)面黃(huang)(huang)(huang)(huang)土(tu)(tu)高(gao)原(yuan)(yuan)(yuan)不斷(duan)抬(tai)(tai)(tai)升(sheng),另一(yi)方(fang)面汾(fen)渭(wei)(wei)谷(gu)(gu)地(di)(di)持續(xu)下沉(chen),必然對黃(huang)(huang)(huang)(huang)土(tu)(tu)高(gao)原(yuan)(yuan)(yuan)土(tu)(tu)壤侵(qin)蝕起促(cu)進作用(yong)。地(di)(di)震是黃(huang)(huang)(huang)(huang)土(tu)(tu)高(gao)原(yuan)(yuan)(yuan)新(xin)(xin)構(gou)造(zao)(zao)(zao)運(yun)(yun)動的(de)(de)強烈表現形(xing)式,對歷史時(shi)期(qi)黃(huang)(huang)(huang)(huang)土(tu)(tu)高(gao)原(yuan)(yuan)(yuan)地(di)(di)震記載(zai)進行統(tong)計,可以(yi)反(fan)映(ying)出黃(huang)(huang)(huang)(huang)土(tu)(tu)高(gao)原(yuan)(yuan)(yuan)歷史時(shi)期(qi)新(xin)(xin)構(gou)造(zao)(zao)(zao)運(yun)(yun)動的(de)(de)強弱(ruo)變化過程。
黃(huang)(huang)土(tu)(tu)高原(yuan)是中(zhong)(zhong)華民族的(de)發祥地(di)之(zhi)一(yi)(yi),新(xin)石器時(shi)(shi)期(qi)文(wen)化遺(yi)址(zhi)在(zai)(zai)黃(huang)(huang)土(tu)(tu)高原(yuan)南部(bu)分布廣泛,尤(you)其在(zai)(zai)汾渭河谷(gu)地(di)和(he)豫西地(di)區稠密(mi)(mi)。當(dang)時(shi)(shi)人(ren)們以(yi)漁獵、采(cai)集為(wei)生,說明(ming)當(dang)時(shi)(shi)黃(huang)(huang)土(tu)(tu)高原(yuan)南部(bu)維持著較好(hao)的(de)自(zi)然生態系統(tong)。商周(zhou)時(shi)(shi)期(qi)中(zhong)(zhong)國(guo)出(chu)現了文(wen)字記(ji)載,生產(chan)(chan)力水平(ping)的(de)提高,農(nong)業(ye)(ye)(ye)(ye)生產(chan)(chan)由原(yuan)始(shi)農(nong)業(ye)(ye)(ye)(ye)向(xiang)傳統(tong)農(nong)業(ye)(ye)(ye)(ye)轉(zhuan)變。商周(zhou)時(shi)(shi)周(zhou)人(ren)主要活(huo)動的(de)北(bei)豳(bin)(慶陽、西峰一(yi)(yi)帶)、古豳(bin)(彬縣、長(chang)武一(yi)(yi)帶)、周(zhou)原(yuan)(扶風(feng)、岐山一(yi)(yi)帶)鋤(chu)耕(geng)農(nong)業(ye)(ye)(ye)(ye)已(yi)發展到(dao)(dao)一(yi)(yi)定水平(ping)。夏代(dai)中(zhong)(zhong)國(guo)有(you)人(ren)口(kou)1355萬(wan),周(zhou)代(dai)1371萬(wan)人(ren),其中(zhong)(zhong)1/2左右分布在(zai)(zai)汾渭河谷(gu)和(he)豫西地(di)區,這兩(liang)地(di)區人(ren)口(kou)密(mi)(mi)度30-40人(ren)/平(ping)方千米(mi)。即便(bian)如此,從《詩經》中(zhong)(zhong)仍(reng)可看(kan)到(dao)(dao)黃(huang)(huang)土(tu)(tu)高原(yuan)南部(bu)野鹿成(cheng)群,虎豹(bao)出(chu)沒(mei),森林面(mian)積(ji)廣大,農(nong)耕(geng)面(mian)積(ji)有(you)限。春秋、戰國(guo)時(shi)(shi)期(qi)鐵器出(chu)現,犁耕(geng)農(nong)業(ye)(ye)(ye)(ye)逐漸代(dai)替鋤(chu)耕(geng)農(nong)業(ye)(ye)(ye)(ye),關中(zhong)(zhong)、汾河谷(gu)地(di)、洛陽盆地(di)、天水盆地(di)農(nong)業(ye)(ye)(ye)(ye)進一(yi)(yi)步發展。戰國(guo)時(shi)(shi)秦將(jiang)自(zi)己(ji)的(de)勢力向(xiang)渭河上游、陜北(bei)北(bei)部(bu)推進,趙(zhao)則向(xiang)晉北(bei)地(di)區擴張,在(zai)(zai)這些(xie)地(di)區建立城邑(yi),開墾土(tu)(tu)地(di),發展耕(geng)作(zuo),但(dan)直到(dao)(dao)戰國(guo)末農(nong)耕(geng)業(ye)(ye)(ye)(ye)主要集中(zhong)(zhong)在(zai)(zai)太原(yuan)一(yi)(yi)龍門一(yi)(yi)天水以(yi)南地(di)區,以(yi)北(bei)畜牧業(ye)(ye)(ye)(ye)仍(reng)占優勢,整個黃(huang)(huang)土(tu)(tu)高原(yuan)人(ren)口(kou)少(shao),開墾指數不(bu)高。
秦(qin)漢、隋唐黃土(tu)(tu)高(gao)(gao)原(yuan)是(shi)中(zhong)國的(de)(de)(de)(de)政(zheng)治(zhi)、經濟中(zhong)心,人(ren)日與土(tu)(tu)地(di)(di)(di)(di)利用變化較大(da)(da)。秦(qin)統一(yi)(yi)(yi)全(quan)(quan)國后統治(zhi)范圍向(xiang)(xiang)(xiang)北推(tui)進到黃土(tu)(tu)高(gao)(gao)原(yuan)北部(bu)秦(qin)長城一(yi)(yi)(yi)線(xian)(xian)(xian)。西(xi)(xi)(xi)漢時(shi)期(qi)統治(zhi)范圍進一(yi)(yi)(yi)步向(xiang)(xiang)(xiang)北、向(xiang)(xiang)(xiang)西(xi)(xi)(xi)推(tui)進,漢武帝時(shi)向(xiang)(xiang)(xiang)北到達陰山,向(xiang)(xiang)(xiang)西(xi)(xi)(xi)到達河西(xi)(xi)(xi)走廊,黃土(tu)(tu)高(gao)(gao)原(yuan)幾乎全(quan)(quan)部(bu)都在(zai)西(xi)(xi)(xi)漢的(de)(de)(de)(de)統治(zhi)之下。秦(qin)漢時(shi)期(qi)是(shi)中(zhong)國農業發展的(de)(de)(de)(de)高(gao)(gao)峰,農耕(geng)(geng)文化大(da)(da)舉(ju)進入黃土(tu)(tu)高(gao)(gao)原(yuan),從(cong)綏德、米脂(zhi)一(yi)(yi)(yi)帶(dai)出(chu)土(tu)(tu)的(de)(de)(de)(de)漢畫(hua)像石可以(yi)清(qing)楚(chu)地(di)(di)(di)(di)反映出(chu)這一(yi)(yi)(yi)點。西(xi)(xi)(xi)漢時(shi)曾向(xiang)(xiang)(xiang)黃土(tu)(tu)高(gao)(gao)原(yuan)大(da)(da)量移民,再加上大(da)(da)批吏卒(zu)屯守邊防(fang),黃土(tu)(tu)高(gao)(gao)原(yuan)人(ren)口迅速(su)增(zeng)加。據(ju)《漢書·地(di)(di)(di)(di)理志》記(ji)載,西(xi)(xi)(xi)漢元始二年(2年)黃土(tu)(tu)高(gao)(gao)原(yuan)地(di)(di)(di)(di)區(qu)有人(ren)口880萬人(ren),其中(zhong)洛(luo)陽盆地(di)(di)(di)(di)人(ren)口密度高(gao)(gao)為(wei)132人(ren)/平(ping)方(fang)千(qian)米,關(guan)中(zhong)為(wei)30一(yi)(yi)(yi)90人(ren)/平(ping)方(fang)千(qian)米,陜北及晉西(xi)(xi)(xi)北為(wei)10一(yi)(yi)(yi)13人(ren)/跑平(ping)方(fang)千(qian)米,天(tian)水盆地(di)(di)(di)(di)為(wei)10.74人(ren)/平(ping)方(fang)千(qian)米。人(ren)口的(de)(de)(de)(de)增(zeng)加和(he)農耕(geng)(geng)的(de)(de)(de)(de)發展使部(bu)分(fen)林草地(di)(di)(di)(di)被開墾(ken),但開墾(ken)程度較高(gao)(gao)主要在(zai)南部(bu)的(de)(de)(de)(de)關(guan)中(zhong)、洛(luo)陽盆地(di)(di)(di)(di)和(he)天(tian)水盆地(di)(di)(di)(di),當時(shi)農牧業界線(xian)(xian)(xian)在(zai)太原(yuan)一(yi)(yi)(yi)龍門一(yi)(yi)(yi)寶雞一(yi)(yi)(yi)線(xian)(xian)(xian)。此線(xian)(xian)(xian)以(yi)北的(de)(de)(de)(de)廣大(da)(da)黃土(tu)(tu)丘陵地(di)(di)(di)(di)區(qu)耕(geng)(geng)地(di)(di)(di)(di)主要分(fen)布在(zai)河谷平(ping)原(yuan),其余(yu)地(di)(di)(di)(di)區(qu)仍保持(chi)自然狀態。東(dong)漢、三國、兩晉、十(shi)六國、南北朝時(shi)期(qi)黃土(tu)(tu)高(gao)(gao)原(yuan)戰(zhan)爭(zheng)頻(pin)繁,社會動(dong)亂(luan),人(ren)口大(da)(da)量減(jian)少,原(yuan)來的(de)(de)(de)(de)農耕(geng)(geng)區(qu)向(xiang)(xiang)(xiang)南退縮,黃土(tu)(tu)高(gao)(gao)原(yuan)的(de)(de)(de)(de)廣大(da)(da)地(di)(di)(di)(di)區(qu)重新成(cheng)為(wei)游牧區(qu),生態環境得以(yi)恢復。
據《續漢(han)(han)書(shu)·郡國志》記載(zai),東(dong)漢(han)(han)永(yong)和五年(140年)黃土(tu)高原總(zong)人(ren)口為(wei)(wei)(wei)507.6萬(wan)人(ren),比(bi)西(xi)漢(han)(han)減(jian)(jian)(jian)少(shao)了43%。當時(shi)陜北及晉西(xi)北人(ren)口4.94萬(wan)人(ren),比(bi)西(xi)漢(han)(han)的(de)(de)130.55萬(wan)人(ren)減(jian)(jian)(jian)少(shao)96%,人(ren)口密度減(jian)(jian)(jian)為(wei)(wei)(wei)0.5人(ren)/平(ping)方(fang)(fang)千(qian)米(mi)以(yi)下(xia)。西(xi)晉時(shi)黃土(tu)高原人(ren)口比(bi)東(dong)漢(han)(han)又(you)有減(jian)(jian)(jian)少(shao),據《晉書(shu)·地(di)理(li)志》記載(zai),西(xi)晉太(tai)康(kang)元年(280年)黃土(tu)高原總(zong)人(ren)口204萬(wan)人(ren),比(bi)東(dong)漢(han)(han)減(jian)(jian)(jian)少(shao)4%5。《晉書(shu)》中山西(xi)河(he)曲、偏關、保(bao)德(de)、陜北、隴(long)東(dong)馬連河(he)流域為(wei)(wei)(wei)游牧民族居住區,無人(ren)日記載(zai),人(ren)口當比(bi)東(dong)漢(han)(han)時(shi)更為(wei)(wei)(wei)稀疏(shu)。當時(shi)西(xi)安附近的(de)(de)京兆人(ren)口密度為(wei)(wei)(wei)34.88人(ren)/平(ping)方(fang)(fang)千(qian)米(mi),關中東(dong)部(bu)的(de)(de)左馮詡(xu)為(wei)(wei)(wei)3.29人(ren)/平(ping)方(fang)(fang)千(qian)米(mi),關中西(xi)部(bu)的(de)(de)右扶(fu)風為(wei)(wei)(wei)9.46人(ren)/平(ping)方(fang)(fang)千(qian)米(mi),洛陽(yang)附近為(wei)(wei)(wei)55.85人(ren)/平(ping)方(fang)(fang)千(qian)米(mi),天水附近為(wei)(wei)(wei)5.55人(ren)/平(ping)方(fang)(fang)千(qian)k/耐,比(bi)西(xi)漢(han)(han)時(shi)減(jian)(jian)(jian)少(shao)l2/以(yi)上。
隋(sui)唐(tang)時(shi)中(zhong)(zhong)國重(zhong)新歸于(yu)統一(yi),而且(qie)社會安(an)定,經(jing)(jing)濟繁榮,成為(wei)中(zhong)(zhong)國農(nong)(nong)業(ye)(ye)發展(zhan)的(de)第二個鼎盛時(shi)期。隨著(zhu)經(jing)(jing)濟的(de)發展(zhan),黃(huang)(huang)土(tu)(tu)(tu)高(gao)(gao)(gao)原(yuan)人(ren)口增(zeng)加(jia),農(nong)(nong)耕業(ye)(ye)逐步代替游牧業(ye)(ye)。《隋(sui)書·地理志》記載,隋(sui)大業(ye)(ye)五(wu)年(nian)(609年(nian))黃(huang)(huang)土(tu)(tu)(tu)高(gao)(gao)(gao)原(yuan)總人(ren)口為(wei)1104萬(wan)人(ren),是(shi)(shi)西(xi)(xi)(xi)漢的(de)125%、西(xi)(xi)(xi)晉的(de)5.14倍。陜北、晉西(xi)(xi)(xi)北人(ren)口密度己經(jing)(jing)趕上了(le)(le)西(xi)(xi)(xi)漢,徑河(he)上游、馬連河(he)上游己是(shi)(shi)西(xi)(xi)(xi)漢的(de)數(shu)倍,唐(tang)初實行(xing)均田制,關中(zhong)(zhong)大興(xing)水(shui)(shui)利,不(bu)僅使關中(zhong)(zhong)、汾河(he)下(xia)游,洛陽盆地全部(bu)成為(wei)農(nong)(nong)業(ye)(ye)區(qu)(qu),而且(qie)農(nong)(nong)耕業(ye)(ye)擴大到地勢較高(gao)(gao)(gao)的(de)黃(huang)(huang)上臺源、北山(shan)南麓黃(huang)(huang)土(tu)(tu)(tu)覆蓋的(de)山(shan)前平源。農(nong)(nong)耕區(qu)(qu)還(huan)沿渭(wei)河(he)向西(xi)(xi)(xi)到達天水(shui)(shui)、隴西(xi)(xi)(xi),直至(zhi)涅水(shui)(shui)湟水(shui)(shui)河(he)谷(gu)地。天寶時(shi)(742一(yi)755年(nian))唐(tang)代經(jing)(jing)濟達到了(le)(le)頂峰,當時(shi)黃(huang)(huang)土(tu)(tu)(tu)高(gao)(gao)(gao)原(yuan)人(ren)口1015萬(wan)人(ren),關中(zhong)(zhong)、汾河(he)下(xia)游、洛陽盆地人(ren)口密度50-100人(ren)/平方(fang)千米。隋(sui)唐(tang)時(shi)期基本(ben)奠定了(le)(le)黃(huang)(huang)上高(gao)(gao)(gao)原(yuan)南部(bu)農(nong)(nong)業(ye)(ye)生(sheng)產(chan)的(de)格(ge)局,人(ren)口增(zeng)加(jia),植被破壞(huai),城鎮(zhen)興(xing)起,對這一(yi)地區(qu)(qu)土(tu)(tu)(tu)壤(rang)侵蝕產(chan)生(sheng)了(le)(le)明顯的(de)影響。但(dan)黃(huang)(huang)土(tu)(tu)(tu)高(gao)(gao)(gao)原(yuan)中(zhong)(zhong)部(bu)、北部(bu)自然環境的(de)總體破壞(huai)程(cheng)度并不(bu)甚嚴重(zhong),黃(huang)(huang)土(tu)(tu)(tu)丘陵地區(qu)(qu)畜牧業(ye)(ye)仍(reng)占較大比(bi)重(zhong)。
唐以(yi)(yi)后的(de)五代十國(907一(yi)(yi)979年)黃土(tu)高原(yuan)人(ren)口(kou)(kou)(kou)有較(jiao)大(da)幅度減少,但到宋(song)(song)代人(ren)口(kou)(kou)(kou)得到恢(hui)復(fu)。據研究(jiu)南(nan)(nan)(nan)宋(song)(song)嘉定三年(1210年)山西(xi)人(ren)口(kou)(kou)(kou)密度為(wei)(wei)(wei)45.72人(ren)/平方千(qian)(qian)(qian)米,陜(shan)西(xi)為(wei)(wei)(wei)21.44人(ren)/平方千(qian)(qian)(qian)米。北宋(song)(song)在黃上高原(yuan)上形成(cheng)一(yi)(yi)條(tiao)(tiao)(tiao)(tiao)與遼、西(xi)夏(xia)對(dui)(dui)峙(zhi)的(de)軍事(shi)分界(jie)線(xian)(xian),這條(tiao)(tiao)(tiao)(tiao)界(jie)線(xian)(xian)東起大(da)同以(yi)(yi)南(nan)(nan)(nan),經陜(shan)北、寧夏(xia)南(nan)(nan)(nan)部(bu)、蘭州以(yi)(yi)北直至西(xi)寧以(yi)(yi)西(xi),綿延1000千(qian)(qian)(qian)米。沿這條(tiao)(tiao)(tiao)(tiao)分界(jie)線(xian)(xian),北宋(song)(song)修(xiu)筑了大(da)量城鎮、堡寨、派駐大(da)批軍隊戍邊防衛。為(wei)(wei)(wei)解(jie)決軍隊給養,招募(mu)人(ren)口(kou)(kou)(kou)沿邊屯耕,沿分界(jie)線(xian)(xian)形成(cheng)了一(yi)(yi)條(tiao)(tiao)(tiao)(tiao)人(ren)口(kou)(kou)(kou)稠密,墾殖程(cheng)度較(jiao)高的(de)地(di)帶,也使此(ci)分界(jie)線(xian)(xian)所經地(di)區生態嚴(yan)重惡化。此(ci)線(xian)(xian)以(yi)(yi)南(nan)(nan)(nan)的(de)黃土(tu)丘陵溝壑(he)區仍然以(yi)(yi)牧為(wei)(wei)(wei)主,與唐代后期比較(jiao),土(tu)地(di)利用沒有太大(da)變化。元(yuan)代統(tong)一(yi)(yi)后,黃上高原(yuan)雖(sui)結(jie)束了軍事(shi)對(dui)(dui)壘(lei),但元(yuan)代連年殘(can)酷的(de)戰爭(zheng)和元(yuan)對(dui)(dui)漢人(ren)實行(xing)的(de)屠殺政策,黃土(tu)高原(yuan)人(ren)口(kou)(kou)(kou)大(da)幅減少,元(yuan)至元(yuan)二十七年(1290年)山西(xi)人(ren)口(kou)(kou)(kou)密度僅為(wei)(wei)(wei)8.20人(ren)/平方千(qian)(qian)(qian)米,陜(shan)西(xi)2.57人(ren)/平方千(qian)(qian)(qian)米,寧夏(xia)2.82人(ren)/平方千(qian)(qian)(qian)米,甘肅(su)2.15人(ren)/平方千(qian)(qian)(qian)米。
明代黃(huang)(huang)土(tu)高原人(ren)(ren)(ren)口得到(dao)恢復,明弘治四年(1491年)山(shan)西人(ren)(ren)(ren)口密(mi)度達到(dao)31.6人(ren)(ren)(ren)/平(ping)方(fang)千(qian)(qian)(qian)(qian)(qian)米(mi)(mi),陜(shan)西15.68人(ren)(ren)(ren)/平(ping)方(fang)千(qian)(qian)(qian)(qian)(qian)米(mi)(mi),寧夏5.02人(ren)(ren)(ren)/平(ping)方(fang)千(qian)(qian)(qian)(qian)(qian)米(mi)(mi),,甘肅(su)4.41人(ren)(ren)(ren)/平(ping)方(fang)千(qian)(qian)(qian)(qian)(qian)米(mi)(mi),青海(hai)1.45人(ren)(ren)(ren)/平(ping)方(fang)千(qian)(qian)(qian)(qian)(qian)米(mi)(mi)。明自建(jian)國之初就在黃(huang)(huang)土(tu)高原北部(bu)修筑長(chang)城(cheng)(cheng),在修建(jian)長(chang)城(cheng)(cheng)的同時(shi),沿(yan)長(chang)城(cheng)(cheng)大興(xing)城(cheng)(cheng)鎮聚落,移(yi)民實(shi)邊,長(chang)城(cheng)(cheng)沿(yan)線形成人(ren)(ren)(ren)口密(mi)集的地帶,其人(ren)(ren)(ren)口遠較長(chang)城(cheng)(cheng)以(yi)南的黃(huang)(huang)土(tu)丘(qiu)陵溝壑(he)區稠密(mi)。如嘉慶《重修一統志》記(ji)載,嘉慶二十(shi)五年(1820年)山(shan)西寧武人(ren)(ren)(ren)口密(mi)度為40.26人(ren)(ren)(ren)/平(ping)方(fang)千(qian)(qian)(qian)(qian)(qian)米(mi)(mi),保(bao)德(de)為50.64人(ren)(ren)(ren)/平(ping)方(fang)千(qian)(qian)(qian)(qian)(qian)米(mi)(mi),而其南部(bu)的爆州僅(jin)(jin)(jin)22.88人(ren)(ren)(ren)/平(ping)方(fang)千(qian)(qian)(qian)(qian)(qian)米(mi)(mi);榆林人(ren)(ren)(ren)口密(mi)度41.99人(ren)(ren)(ren)/平(ping)方(fang)千(qian)(qian)(qian)(qian)(qian)米(mi)(mi),而其南部(bu)的綏德(de)僅(jin)(jin)(jin)33.17人(ren)(ren)(ren)/平(ping)方(fang)千(qian)(qian)(qian)(qian)(qian)米(mi)(mi),延安(an)僅(jin)(jin)(jin)19.58人(ren)(ren)(ren)/平(ping)方(fang)千(qian)(qian)(qian)(qian)(qian)米(mi)(mi),。當時(shi)的長(chang)城(cheng)(cheng)是農牧業的分界線,長(chang)城(cheng)(cheng)沿(yan)線不僅(jin)(jin)(jin)分布著數百萬邊民,而且駐(zhu)軍(jun)也三(san)分戍守,七分屯田(tian)(tian),每個屯田(tian)(tian)士(shi)卒(zu)須種地50畝(mu),使(shi)長(chang)城(cheng)(cheng)沿(yan)線被(bei)徹底開墾,長(chang)城(cheng)(cheng)以(yi)南則農牧業兼有。
清(qing)(qing)代國(guo)家(jia)統一(yi),社會安定,人(ren)(ren)(ren)(ren)(ren)口增長(chang)快(kuai)。明弘治四年(nian)(nian)(1491年(nian)(nian))黃(huang)土(tu)高原(yuan)(yuan)總人(ren)(ren)(ren)(ren)(ren)口達(da)(da)到(dao)1500萬人(ren)(ren)(ren)(ren)(ren)。經200多(duo)年(nian)(nian)到(dao)嘉慶(qing)(qing)二(er)(er)十五年(nian)(nian)(1820年(nian)(nian))人(ren)(ren)(ren)(ren)(ren)口達(da)(da)到(dao)1995萬。到(dao)道光二(er)(er)十年(nian)(nian)(1840年(nian)(nian))人(ren)(ren)(ren)(ren)(ren)口增至4100萬人(ren)(ren)(ren)(ren)(ren),達(da)(da)到(dao)封建時(shi)代黃(huang)土(tu)高原(yuan)(yuan)人(ren)(ren)(ren)(ren)(ren)口的峰值。1820年(nian)(nian)黃(huang)土(tu)高原(yuan)(yuan)人(ren)(ren)(ren)(ren)(ren)口密(mi)度是:山(shan)(shan)西(xi)(xi)91.36人(ren)(ren)(ren)(ren)(ren)/平(ping)方(fang)(fang)千(qian)(qian)(qian)米(mi)(mi)(mi)(mi),陜西(xi)(xi)61.16人(ren)(ren)(ren)(ren)(ren)/平(ping)方(fang)(fang)千(qian)(qian)(qian)米(mi)(mi)(mi)(mi),甘肅(su)34.24人(ren)(ren)(ren)(ren)(ren)/平(ping)方(fang)(fang)千(qian)(qian)(qian)米(mi)(mi)(mi)(mi),寧(ning)夏31.37人(ren)(ren)(ren)(ren)(ren)/平(ping)方(fang)(fang)千(qian)(qian)(qian)米(mi)(mi)(mi)(mi),青海(hai)6.95人(ren)(ren)(ren)(ren)(ren)/平(ping)方(fang)(fang)千(qian)(qian)(qian)米(mi)(mi)(mi)(mi)。其中關中、諫汾河谷地,洛陽盆地達(da)(da)100-200人(ren)(ren)(ren)(ren)(ren)/平(ping)方(fang)(fang)千(qian)(qian)(qian)米(mi)(mi)(mi)(mi),晉西(xi)(xi)北(bei)、陜北(bei)、隴東達(da)(da)40-80人(ren)(ren)(ren)(ren)(ren)/平(ping)方(fang)(fang)千(qian)(qian)(qian)米(mi)(mi)(mi)(mi),如(ru)平(ping)涼(liang)82.62人(ren)(ren)(ren)(ren)(ren)/平(ping)方(fang)(fang)千(qian)(qian)(qian)米(mi)(mi)(mi)(mi),慶(qing)(qing)陽57.33人(ren)(ren)(ren)(ren)(ren)/平(ping)方(fang)(fang)千(qian)(qian)(qian)米(mi)(mi)(mi)(mi),徑陽101.61人(ren)(ren)(ren)(ren)(ren)/平(ping)方(fang)(fang)千(qian)(qian)(qian)米(mi)(mi)(mi)(mi)。明清(qing)(qing)時(shi)期(qi)(qi)長(chang)城以(yi)南的疏(shu)林灌(guan)叢(cong)已被(bei)連片開墾。另一(yi)方(fang)(fang)面由于人(ren)(ren)(ren)(ren)(ren)地矛盾(dun)加(jia)劇,清(qing)(qing)末移(yi)入黃(huang)土(tu)高原(yuan)(yuan)的移(yi)民向(xiang)人(ren)(ren)(ren)(ren)(ren)煙少的山(shan)(shan)區(qu)遷移(yi),如(ru)寧(ning)夏南部地區(qu)、呂梁山(shan)(shan)西(xi)(xi)側、黃(huang)龍山(shan)(shan)區(qu)等(deng),使這些原(yuan)(yuan)來的林區(qu)也逐步轉變為(wei)農耕區(qu)。可以(yi)說明清(qing)(qing)時(shi)期(qi)(qi)黃(huang)土(tu)高原(yuan)(yuan)丘陵溝壑區(qu)徹底演變成了農耕區(qu)。
20世紀(ji)前半葉由于戰亂和(he)自然(ran)災害,黃土(tu)(tu)高(gao)原(yuan)(yuan)(yuan)人(ren)(ren)口有所減(jian)少,1935年(nian)(nian)(nian)總人(ren)(ren)口為2960萬(wan)人(ren)(ren),1949年(nian)(nian)(nian)為3936萬(wan)人(ren)(ren),人(ren)(ren)口分布和(he)清末(mo)沒(mei)有大的不(bu)同。建國(guo)后(hou),黃土(tu)(tu)高(gao)原(yuan)(yuan)(yuan)人(ren)(ren)口增(zeng)長極(ji)快,70年(nian)(nian)(nian)代(dai)以前平(ping)(ping)(ping)均(jun)人(ren)(ren)口增(zeng)長速度35.3‰。遠高(gao)于中(zhong)(zhong)國(guo)的21.2‰的水平(ping)(ping)(ping);70年(nian)(nian)(nian)代(dai)以后(hou)人(ren)(ren)口增(zeng)長速度14.6-21.0‰,仍高(gao)于中(zhong)(zhong)國(guo)平(ping)(ping)(ping)均(jun)水平(ping)(ping)(ping),是中(zhong)(zhong)國(guo)人(ren)(ren)口增(zeng)長快的地(di)區之一。1960年(nian)(nian)(nian)總人(ren)(ren)口達(da)到4913.4萬(wan)人(ren)(ren),1980年(nian)(nian)(nian)達(da)到7521.萬(wan)人(ren)(ren),1990年(nian)(nian)(nian)達(da)到9031萬(wan)人(ren)(ren),人(ren)(ren)口的增(zeng)加(jia)(jia)使耕(geng)(geng)地(di)面(mian)積(ji)不(bu)斷(duan)增(zeng)加(jia)(jia),林(lin)地(di)、草地(di)面(mian)積(ji)減(jian)少。1949-1985年(nian)(nian)(nian)黃土(tu)(tu)高(gao)原(yuan)(yuan)(yuan)耕(geng)(geng)地(di)增(zeng)加(jia)(jia)393.3x10000平(ping)(ping)(ping)方(fang)百(bai)米,增(zeng)長率為30.6%。耕(geng)(geng)地(di)增(zeng)加(jia)(jia)主(zhu)要集中(zhong)(zhong)在(zai)水土(tu)(tu)流失(shi)嚴(yan)重的黃土(tu)(tu)丘(qiu)陵地(di)區,凈增(zeng)耕(geng)(geng)地(di)272x10000平(ping)(ping)(ping)方(fang)百(bai)米,占黃土(tu)(tu)高(gao)原(yuan)(yuan)(yuan)凈增(zeng)耕(geng)(geng)地(di)的69%,使這些(xie)地(di)區陷入(ru)“越窮(qiong)越墾,越墾越窮(qiong)”的經濟、生態雙重貧(pin)困。
中國(guo)(guo)實行改革(ge)開放以后,黃土高(gao)原(yuan)地(di)區的(de)(de)國(guo)(guo)內(nei)(nei)生(sheng)產(chan)總(zong)值(zhi)(zhi)總(zong)量呈現持續的(de)(de)增(zeng)長態勢。西部大開發戰(zhan)略(lve)的(de)(de)實施成為該(gai)地(di)區2000年以后國(guo)(guo)內(nei)(nei)生(sheng)產(chan)總(zong)值(zhi)(zhi)占中國(guo)(guo)比重迅速提高(gao)的(de)(de)主要誘因(yin),而晉陜蒙地(di)區能礦(kuang)產(chan)資(zi)源的(de)(de)開發則是其直接動因(yin)。黃土高(gao)原(yuan)地(di)區人均國(guo)(guo)內(nei)(nei)生(sheng)產(chan)總(zong)值(zhi)(zhi)的(de)(de)空(kong)間(jian)(jian)(jian)分(fen)布(bu)(bu)整體上呈現出“兩高(gao)一(yi)低”的(de)(de)帶狀分(fen)布(bu)(bu)格(ge)局(ju),且這種空(kong)間(jian)(jian)(jian)分(fen)布(bu)(bu)格(ge)局(ju)明顯地(di)隨著(zhu)時間(jian)(jian)(jian)受到極化增(zeng)長的(de)(de)擾(rao)動和重塑。能礦(kuang)資(zi)源開發、農業密集程度、人口分(fen)布(bu)(bu)狀況和自然本底條件等(deng)是影響(xiang)該(gai)地(di)區人均國(guo)(guo)內(nei)(nei)生(sheng)產(chan)總(zong)值(zhi)(zhi)空(kong)間(jian)(jian)(jian)分(fen)布(bu)(bu)格(ge)局(ju)及(ji)其變動關(guan)鍵的(de)(de)因(yin)素。